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A Review on Scientific Knowledge Extraction using Large Language Models in Biomedical Sciences
Authors:
Gabriel Lino Garcia,
João Renato Ribeiro Manesco,
Pedro Henrique Paiola,
Lucas Miranda,
Maria Paola de Salvo,
João Paulo Papa
Abstract:
The rapid advancement of large language models (LLMs) has opened new boundaries in the extraction and synthesis of medical knowledge, particularly within evidence synthesis. This paper reviews the state-of-the-art applications of LLMs in the biomedical domain, exploring their effectiveness in automating complex tasks such as evidence synthesis and data extraction from a biomedical corpus of docume…
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The rapid advancement of large language models (LLMs) has opened new boundaries in the extraction and synthesis of medical knowledge, particularly within evidence synthesis. This paper reviews the state-of-the-art applications of LLMs in the biomedical domain, exploring their effectiveness in automating complex tasks such as evidence synthesis and data extraction from a biomedical corpus of documents. While LLMs demonstrate remarkable potential, significant challenges remain, including issues related to hallucinations, contextual understanding, and the ability to generalize across diverse medical tasks. We highlight critical gaps in the current research literature, particularly the need for unified benchmarks to standardize evaluations and ensure reliability in real-world applications. In addition, we propose directions for future research, emphasizing the integration of state-of-the-art techniques such as retrieval-augmented generation (RAG) to enhance LLM performance in evidence synthesis. By addressing these challenges and utilizing the strengths of LLMs, we aim to improve access to medical literature and facilitate meaningful discoveries in healthcare.
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Submitted 4 December, 2024;
originally announced December 2024.
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Generalizable Temperature Nowcasting with Physics-Constrained RNNs for Predictive Maintenance of Wind Turbine Components
Authors:
Johannes Exenberger,
Matteo Di Salvo,
Thomas Hirsch,
Franz Wotawa,
Gerald Schweiger
Abstract:
Machine learning plays an important role in the operation of current wind energy production systems. One central application is predictive maintenance to increase efficiency and lower electricity costs by reducing downtimes. Integrating physics-based knowledge in neural networks to enforce their physical plausibilty is a promising method to improve current approaches, but incomplete system informa…
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Machine learning plays an important role in the operation of current wind energy production systems. One central application is predictive maintenance to increase efficiency and lower electricity costs by reducing downtimes. Integrating physics-based knowledge in neural networks to enforce their physical plausibilty is a promising method to improve current approaches, but incomplete system information often impedes their application in real world scenarios. We describe a simple and efficient way for physics-constrained deep learning-based predictive maintenance for wind turbine gearbox bearings with partial system knowledge. The approach is based on temperature nowcasting constrained by physics, where unknown system coefficients are treated as learnable neural network parameters. Results show improved generalization performance to unseen environments compared to a baseline neural network, which is especially important in low data scenarios often encountered in real-world applications.
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Submitted 5 April, 2024;
originally announced April 2024.
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SN 2005at - A neglected type Ic supernova at 10 Mpc
Authors:
E. Kankare,
M. Fraser,
S. Ryder,
C. Romero-Canizales,
S. Mattila,
R. Kotak,
P. Laursen,
L. A. G. Monard,
M. Salvo,
P. Vaisanen
Abstract:
We present a photometric and spectroscopic study of a reddened type Ic supernova (SN) 2005at. We report our results based on the available data of SN 2005at, including late-time observations from the Spitzer Space Telescope and the Hubble Space Telescope. In particular, late-time mid-infrared observations are something rare for type Ib/c SNe. In our study we find SN 2005at to be very similar photo…
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We present a photometric and spectroscopic study of a reddened type Ic supernova (SN) 2005at. We report our results based on the available data of SN 2005at, including late-time observations from the Spitzer Space Telescope and the Hubble Space Telescope. In particular, late-time mid-infrared observations are something rare for type Ib/c SNe. In our study we find SN 2005at to be very similar photometrically and spectroscopically to another nearby type Ic SN 2007gr, underlining the prototypical nature of this well-followed type Ic event. The spectroscopy of both events shows similar narrow spectral line features. The radio observations of SN 2005at are consistent with fast evolution and low luminosity at radio wavelengths. The late-time Spitzer data suggest the presence of an unresolved light echo from interstellar dust and dust formation in the ejecta, both of which are unique observations for a type Ic SN. The late-time Hubble observations reveal a faint point source coincident with SN 2005at, which is very likely either a declining light echo of the SN or a compact cluster. For completeness we study ground-based pre-explosion archival images of the explosion site of SN 2005at, however this only yielded very shallow upper limits for the SN progenitor star. We derive a host galaxy extinction of $A_{V} \approx 1.9$ mag for SN 2005at, which is relatively high for a SN in a normal spiral galaxy not viewed edge-on.
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Submitted 3 December, 2014; v1 submitted 5 September, 2014;
originally announced September 2014.
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Underluminous Type II Plateau Supernovae: II. Pointing towards moderate mass precursors
Authors:
S. Spiro,
A. Pastorello,
M. L. Pumo,
L. Zampieri,
M. Turatto,
S. J. Smartt,
S. Benetti,
E. Cappellaro,
S. Valenti,
I. Agnoletto,
G. Altavilla,
T. Aoki,
E. Brocato,
E. M. Corsini,
A. Di Cianno,
N. Elias-Rosa,
M. Hamuy,
K. Enya,
M. Fiaschi,
G. Folatelli,
S. Desidera,
A. Harutyunyan,
D. A. Howell,
A. Kawka,
Y. Kobayashi
, et al. (16 additional authors not shown)
Abstract:
We present new data for five under-luminous type II-plateau supernovae (SNe IIP), namely SN 1999gn, SN 2002gd, SN 2003Z, SN 2004eg and SN 2006ov. This new sample of low-luminosity SNe IIP (LL SNe IIP) is analyzed together with similar objects studied in the past. All of them show a flat light curve plateau lasting about 100 days, an under luminous late-time exponential tail, intrinsic colours that…
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We present new data for five under-luminous type II-plateau supernovae (SNe IIP), namely SN 1999gn, SN 2002gd, SN 2003Z, SN 2004eg and SN 2006ov. This new sample of low-luminosity SNe IIP (LL SNe IIP) is analyzed together with similar objects studied in the past. All of them show a flat light curve plateau lasting about 100 days, an under luminous late-time exponential tail, intrinsic colours that are unusually red, and spectra showing prominent and narrow P-Cygni lines. A velocity of the ejected material below 10^3 km/s is inferred from measurements at the end of the plateau. The 56Ni masses ejected in the explosion are very small (less than 10^-2 solar masses). We investigate the correlations among 56Ni mass, expansion velocity of the ejecta and absolute magnitude in the middle of the plateau, confirming the main findings of Hamuy (2003), according to which events showing brighter plateau and larger expansion velocities are expected to produce more 56Ni. We propose that these faint objects represent the low luminosity tail of a continuous distribution in parameters space of SNe IIP. The physical properties of the progenitors at the explosion are estimated through the hydrodynamical modeling of the observables for two representative events of this class, namely SN 2005cs and SN 2008in. We find that the majority of LL SNe IIP, and quite possibly all, originate in the core-collapse of intermediate mass stars, in the mass range 10-15 solar masses.
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Submitted 21 January, 2014;
originally announced January 2014.
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Enhancement of microbial motility due to speed-dependent nutrient absorption
Authors:
Mario E. Di Salvo,
C. A. Condat
Abstract:
Marine microorganisms often reach high swimming speeds, either to take advantage of evanescent nutrient patches or to beat Brownian forces. Since this implies that a sizable part of their energetic budget must be allocated to motion, it is reasonable to assume that some fast-swimming microorganisms may increase their nutrient intake by increasing their speed v. We formulate a model to investigate…
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Marine microorganisms often reach high swimming speeds, either to take advantage of evanescent nutrient patches or to beat Brownian forces. Since this implies that a sizable part of their energetic budget must be allocated to motion, it is reasonable to assume that some fast-swimming microorganisms may increase their nutrient intake by increasing their speed v. We formulate a model to investigate this hypothesis and its consequences, finding the steady state solutions and analyzing their stability. Surprisingly, we find that even modest increases in nutrient absorption may lead to a significant increase of the microbial speed. In fact, evaluations obtained using realistic parameter values for bacteria indicate that the speed increase due to the enhanced nutrient absorption may be quite large.
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Submitted 16 July, 2013;
originally announced July 2013.
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The normal Type Ia SN 2003hv out to very late phases
Authors:
G. Leloudas,
M. D. Stritzinger,
J. Sollerman,
C. R. Burns,
C. Kozma,
K. Krisciunas,
J. R. Maund,
P. Milne,
A. V. Filippenko,
C. Fransson,
M. Ganeshalingam,
M. Hamuy,
W. Li,
M. M. Phillips,
B. P. Schmidt,
J. Skottfelt,
S. Taubenberger,
L. Boldt,
J. P. U. Fynbo,
L. Gonzalez,
M. Salvo,
J. Thomas-Osip
Abstract:
An extensive dataset for SN 2003hv that covers the flux evolution from maximum light to day +786 is presented. The data are combined with published nebular-phase infrared spectra, and the observations are compared to model light curves and synthetic nebular spectra. SN 2003hv is a normal Type Ia supernova (SN Ia) with photometric and spectroscopic properties consistent with its rarely observed B…
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An extensive dataset for SN 2003hv that covers the flux evolution from maximum light to day +786 is presented. The data are combined with published nebular-phase infrared spectra, and the observations are compared to model light curves and synthetic nebular spectra. SN 2003hv is a normal Type Ia supernova (SN Ia) with photometric and spectroscopic properties consistent with its rarely observed B-band decline-rate parameter, Delta m_15 = 1.61 +- 0.02. The blueshift of the most isolated [Fe II] lines in the nebular-phase optical spectrum appears consistent with those observed in the infrared at similar epochs. At late times there is a prevalent color evolution from the optical toward the near-infrared bands. We present the latest-ever detection of a SN Ia in the near-infrared in Hubble Space Telescope images. The study of the ultraviolet/optical/infrared (UVOIR) light curve reveals that a substantial fraction of the flux is "missing" at late times. Between 300-700 days past maximum brightness, the UVOIR light curve declines linearly following the decay of radioactive Co56, assuming full and instantaneous positron trapping. At 700 days we detect a possible slowdown of the decline in optical bands, mainly in the V band. The data are incompatible with a dramatic infrared catastrophe. However, the idea that an infrared catastrophe occurred in the densest regions before 350 days can explain the missing flux from the UVOIR wavelengths and the flat-topped profiles in the near-infrared. We argue that such a scenario is possible if the ejecta are clumpy. The observations suggest that positrons are most likely trapped in the ejecta.
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Submitted 17 February, 2010; v1 submitted 4 August, 2009;
originally announced August 2009.
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SN 1999ga: a low-luminosity linear type II supernova?
Authors:
A. Pastorello,
R. M. Crockett,
R. Martin,
S. J. Smartt,
G. Altavilla,
S. Benetti,
M. T. Botticella,
E. Cappellaro,
S. Mattila,
J. R. Maund,
S. D. Ryder,
M. Salvo,
S. Taubenberger,
M. Turatto
Abstract:
Type II-linear supernovae are thought to arise from progenitors that have lost most of their H envelope by the time of the explosion, and they are poorly understood because they are only occasionally discovered. It is possible that they are intrinsically rare, but selection effects due to their rapid luminosity evolution may also play an important role in limiting the number of detections. In th…
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Type II-linear supernovae are thought to arise from progenitors that have lost most of their H envelope by the time of the explosion, and they are poorly understood because they are only occasionally discovered. It is possible that they are intrinsically rare, but selection effects due to their rapid luminosity evolution may also play an important role in limiting the number of detections. In this context, the discovery of a subluminous type II-linear event is even more interesting. We investigate the physical properties and characterise the explosion site of the type II SN 1999ga, which exploded in the nearby spiral galaxy NGC 2442. Spectroscopic and photometric observations of SN 1999ga allow us to constrain the energetics of the explosion and to estimate the mass of the ejected material, shedding light on the nature of the progenitor star in the final stages of its life. The study of the environment in the vicinity of the explosion site provides information on a possible relation between these unusual supernovae and the properties of the galaxies hosting them. Despite the lack of early-time observations, we provide reasonable evidence that SN 1999ga was probably a type II-linear supernova that ejected a few solar masses of material, with a very small amount of radioactive elements of the order of 0.01 solar masses.
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Submitted 3 April, 2009;
originally announced April 2009.
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Exploring the Outer Solar System with the ESSENCE Supernova Survey
Authors:
A. C. Becker,
K. Arraki,
N. A. Kaib,
W. M. Wood-Vasey,
C. Aguilera,
J. W. Blackman,
S. Blondin,
P. Challis,
A. Clocchiatti,
R. Covarrubias,
G. Damke,
T. M. Davis,
A. V. Filippenko,
R. J. Foley,
A. Garg,
P. M. Garnavich,
M. Hicken,
S. Jha,
R. P. Kirshner,
K. Krisciunas,
B. Leibundgut,
W. Li,
T. Matheson,
A. Miceli,
G. Miknaitis
, et al. (14 additional authors not shown)
Abstract:
We report the discovery and orbit determination of 14 trans-Neptunian objects (TNOs) from the ESSENCE Supernova Survey difference imaging dataset. Two additional objects discovered in a similar search of the SDSS-II Supernova Survey database were recovered in this effort. ESSENCE repeatedly observed fields far from the Solar System ecliptic (-21 deg < beta < -5 deg), reaching limiting magnitudes…
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We report the discovery and orbit determination of 14 trans-Neptunian objects (TNOs) from the ESSENCE Supernova Survey difference imaging dataset. Two additional objects discovered in a similar search of the SDSS-II Supernova Survey database were recovered in this effort. ESSENCE repeatedly observed fields far from the Solar System ecliptic (-21 deg < beta < -5 deg), reaching limiting magnitudes per observation of I~23.1 and R~23.7. We examine several of the newly detected objects in detail, including 2003 UC_414 which orbits entirely between Uranus and Neptune and lies very close to a dynamical region that would make it stable for the lifetime of the Solar System. 2003 SS_422 and 2007 TA_418 have high eccentricities and large perihelia, making them candidate members of an outer class of trans-Neptunian objects. We also report a new member of the ''extended'' or ''detached'' scattered disk, 2004 VN_112, and verify the stability of its orbit using numerical simulations. This object would have been visible to ESSENCE for only ~2% of its orbit, suggesting a vast number of similar objects across the sky. We emphasize that off-ecliptic surveys are optimal for uncovering the diversity of such objects, which in turn will constrain the history of gravitational influences that shaped our early Solar System.
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Submitted 29 May, 2008;
originally announced May 2008.
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Optical and IR observations of SN 2002dj: some possible common properties of fast expanding SNe Ia
Authors:
G. Pignata,
S. Benetti,
P. A. Mazzali,
R. Kotak,
F. Patat,
P. Meikle,
M. Stehle,
B. Leibundgut,
N. B. Suntzeff,
L. M. Buson,
E. Cappellaro,
A. Clocchiatti,
M. Hamuy,
J. Maza,
J. Mendez,
P. Ruiz-Lapuente,
M. Salvo,
B. P. Schmidt,
M. Turatto,
W. Hillebrandt
Abstract:
As part of the European Supernova Collaboration we obtained extensive photometry and spectroscopy of the type Ia SN 2002dj covering epochs from 11 days before to nearly two years after maximum. Detailed optical and near-infrared observations show that this object belongs to the class of the high-velocity gradient events as indicated by Si, S and Ca lines. The light curve shape and velocity evolu…
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As part of the European Supernova Collaboration we obtained extensive photometry and spectroscopy of the type Ia SN 2002dj covering epochs from 11 days before to nearly two years after maximum. Detailed optical and near-infrared observations show that this object belongs to the class of the high-velocity gradient events as indicated by Si, S and Ca lines. The light curve shape and velocity evolution of SN 2002dj appear to be nearly identical to SN 2002bo. The only significant difference is observed in the optical to near-IR colours and a reduced spectral emission beyond 6500 A. For high-velocity gradient Type Ia supernovae, we tentatively identify a faster rise to maximum, a more pronounced inflection in the V and R light curves after maximum and a brighter, slower declining late-time B light curve as common photometric properties of this class of objects. They also seem to be characterized by a different colour and colour evolution with respect to ``normal'' SNe Ia. The usual light curve shape parameters do not distinguish these events. Stronger, more blueshifted absorption features of intermediate-mass elements and lower temperatures are the most prominent spectroscopic features of Type Ia supernovae displaying high velocity gradients. It appears that these events burn more intermediate-mass elements in the outer layers. Possible connections to the metallicity of the progenitor star are explored.
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Submitted 11 June, 2008; v1 submitted 7 May, 2008;
originally announced May 2008.
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The Broad-lined Type Ic SN 2003jd
Authors:
S. Valenti,
S. Benetti,
E. Cappellaro,
F. Patat,
P. Mazzali,
M. Turatto,
K. Hurley,
K. Maeda,
A. Gal-Yam,
R. J. Foley,
A. V. Filippenko,
A. Pastorello,
P. Challis,
F. Frontera,
A. Harutyunyan,
M. Iye,
K. Kawabata,
R. P. Kirshner,
W. Li,
Y. M. Lipkin,
T. Matheson,
K. Nomoto,
E. O. Ofek,
Y. Ohyama,
E. Pian
, et al. (5 additional authors not shown)
Abstract:
The results of a world-wide coordinated observational campaign on the broad-lined Type Ic SN 2003jd are presented. In total, 74 photometric data points and 26 spectra were collected using 11 different telescopes. SN 2003jd is one of the most luminous SN Ic ever observed. A comparison with other Type Ic supernovae (SNe Ic) confirms that SN 2003jd represents an intermediate case between broad-line…
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The results of a world-wide coordinated observational campaign on the broad-lined Type Ic SN 2003jd are presented. In total, 74 photometric data points and 26 spectra were collected using 11 different telescopes. SN 2003jd is one of the most luminous SN Ic ever observed. A comparison with other Type Ic supernovae (SNe Ic) confirms that SN 2003jd represents an intermediate case between broad-line events (2002ap, 2006aj), and highly energetic SNe (1997ef, 1998bw, 2003dh, 2003lw), with an ejected mass of M_{ej} = 3.0 +/- 1 Mo and a kinetic energy of E_{k}(tot) = 7_{-2}^{+3} 10^{51} erg. SN 2003jd is similar to SN 1998bw in terms of overall luminosity, but it is closer to SNe 2006aj and 2002ap in terms of light-curve shape and spectral evolution. The comparison with other SNe Ic, suggests that the V-band light curves of SNe Ic can be partially homogenized by introducing a time stretch factor. Finally, due to the similarity of SN 2003jd to the SN 2006aj/XRF 060218 event, we discuss the possible connection of SN 2003jd with a GRB.
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Submitted 26 October, 2007;
originally announced October 2007.
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The early spectral evolution of SN 2004dt
Authors:
G. Altavilla,
M. Stehle,
P. Ruiz-Lapuente,
P. Mazzali,
G. Pignata,
A. Balastegui,
S. Benetti,
G. Blanc,
R. Canal,
N. Elias-Rosa,
A. Goobar,
A. Harutyunyan,
A. Pastorello,
F. Patat,
J. Rich,
M. Salvo,
B. P. Schmidt,
V. Stanishev,
S. Taubenberger,
M. Turatto,
W. Hillebrandt
Abstract:
Aims. We study the optical spectroscopic properties of Type Ia Supernova (SN Ia) 2004dt, focusing our attention on the early epochs.
Methods. Observation triggered soon after the SN 2004dt discovery allowed us to obtain a spectrophotometric coverage from day -10 to almost one year (~353 days) after the B band maximum. Observations carried out on an almost daily basis allowed us a good sampling…
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Aims. We study the optical spectroscopic properties of Type Ia Supernova (SN Ia) 2004dt, focusing our attention on the early epochs.
Methods. Observation triggered soon after the SN 2004dt discovery allowed us to obtain a spectrophotometric coverage from day -10 to almost one year (~353 days) after the B band maximum. Observations carried out on an almost daily basis allowed us a good sampling of the fast spectroscopic evolution of SN 2004dt in the early stages. To obtain this result, low-resolution, long-slit spectroscopy was obtained using a number of facilities.
Results. This supernova, which in some absorption lines of its early spectra showed the highest degree of polarization ever measured in any SN Ia, has a complex velocity structure in the outer layers of its ejecta. Unburnt oxygen is present, moving at velocities as high as ~16,700 km/s, with some intermediate-mass elements (Mg, Si, Ca) moving equally fast. Modeling of the spectra based on standard density profiles of the ejecta fails to reproduce the observed features, whereas enhancing the density of outer layers significantly improves the fit. Our analysis indicates the presence of clumps of high-velocity, intermediate-mass elements in the outermost layers, which is also suggested by the spectropolarimetric data.
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Submitted 30 August, 2007;
originally announced August 2007.
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ESC observations of SN 2005cf: II. Optical Spectroscopy and the high velocity features
Authors:
G. Garavini,
S. Nobili,
S. Taubenberger,
A. Pastorello,
N. Elias--Rosa,
V. Stanishev,
G. Blanc,
S. Benetti,
A. Goobar,
P. A. Mazzali,
S. F. Sanchez,
M. Salvo,
B. P. Schmidt,
W. Hillebrandt
Abstract:
The ESC-RTN optical spectroscopy data-set for SN 2005cf is presented and analyzed. The observations range from -11.6 and +77.3 days with respect to B-band maximum light. The evolution of the spectral energy distribution of SN 2005cf is characterized by the presence of high velocity SiII and CaII features. SYNOW synthetic spectra are used to investigate the ejecta geometry of silicon. Based on th…
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The ESC-RTN optical spectroscopy data-set for SN 2005cf is presented and analyzed. The observations range from -11.6 and +77.3 days with respect to B-band maximum light. The evolution of the spectral energy distribution of SN 2005cf is characterized by the presence of high velocity SiII and CaII features. SYNOW synthetic spectra are used to investigate the ejecta geometry of silicon. Based on the synthetic spectra the SiII high velocity feature appears detached at 19500 km/s. We also securely establish the presence of such feature in SN 1990N, SN 1994D, SN 2002er and SN 2003du. On a morphological study both the CaII IR Triplet and H&K absorption lines of SN 2005cf show high velocity features centered around 24000 km/s. When compared with other Type Ia SNe based on the scheme presented in Benetti et al. 2005 SN 2005cf definitely belongs to the LVG group.
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Submitted 21 February, 2007;
originally announced February 2007.
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ESC observations of SN 2005cf. I. Photometric Evolution of a Normal Type Ia Supernova
Authors:
A. Pastorello,
S. Taubenberger,
N. Elias-Rosa,
P. A. Mazzali,
G. Pignata,
E. Cappellaro,
G. Garavini,
S. Nobili,
G. C. Anupama,
D. D. R. Bayliss,
S. Benetti,
F. Bufano,
N. K. Chakradhari,
R. Kotak,
A. Goobar,
H. Navasardyan,
F. Patat,
D. K. Sahu,
M. Salvo,
B. P. Schmidt,
V. Stanishev,
M. Turatto,
W. Hillebrandt
Abstract:
We present early-time optical and near-infrared photometry of supernova (SN) 2005cf. The observations, spanning a period from about 12 days before to 3 months after maximum, have been obtained through the coordination of observational efforts of various nodes of the European Supernova Collaboration and including data obtained at the 2m Himalayan Chandra Telescope. From the observed light curve w…
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We present early-time optical and near-infrared photometry of supernova (SN) 2005cf. The observations, spanning a period from about 12 days before to 3 months after maximum, have been obtained through the coordination of observational efforts of various nodes of the European Supernova Collaboration and including data obtained at the 2m Himalayan Chandra Telescope. From the observed light curve we deduce that SN 2005cf is a fairly typical SN Ia with a post-maximum decline (Delta m_15(B) = 1.12) close to the average value and a normal luminosity of M_B,max = -19.39+/-0.33. Models of the bolometric light curve suggest a synthesised 56Ni mass of about 0.7 solar masses. The negligible host galaxy interstellar extinction and its proximity make SN 2005cf a good Type Ia supernova template.
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Submitted 21 February, 2007;
originally announced February 2007.
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ESC and KAIT Observations of the Transitional Type Ia SN 2004eo
Authors:
A. Pastorello,
P. A. Mazzali,
G. Pignata,
S. Benetti,
E. Cappellaro,
A. V. Filippenko,
W. Li,
W. P. S. Meikle,
A. A. Arkharov,
G. Blanc,
F. Bufano,
A. Derekas,
M. Dolci,
N. Elias-Rosa,
R. J. Foley,
M. Ganeshalingam,
A. Harutyunyan,
L. L. Kiss,
R. Kotak,
V. M. Larionov,
J. R. Lucey,
N. Napoleone,
H. Navasardyan,
F. Patat,
J. Rich
, et al. (9 additional authors not shown)
Abstract:
We present optical and infrared observations of the unusual Type Ia supernova (SN) 2004eo. The light curves and spectra closely resemble those of the prototypical SN 1992A, and the luminosity at maximum (M_B = -19.08) is close to the average for a SN Ia. However, the ejected 56Ni mass derived by modelling the bolometric light curve (about 0.45 solar masses) lies near the lower limit of the 56Ni…
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We present optical and infrared observations of the unusual Type Ia supernova (SN) 2004eo. The light curves and spectra closely resemble those of the prototypical SN 1992A, and the luminosity at maximum (M_B = -19.08) is close to the average for a SN Ia. However, the ejected 56Ni mass derived by modelling the bolometric light curve (about 0.45 solar masses) lies near the lower limit of the 56Ni mass distribution observed in normal SNe Ia. Accordingly, SN 2004eo shows a relatively rapid post-maximum decline in the light curve (Delta m_(B) = 1.46), small expansion velocities in the ejecta, and a depth ratio Si II 5972 / Si II 6355 similar to that of SN 1992A. The physical properties of SN 2004eo cause it to fall very close to the boundary between the faint, low velocity gradient, and high velocity gradient subgroups proposed by Benetti et al. (2005). Similar behaviour is seen in a few other SNe Ia. Thus, there may in fact exist a few SNe Ia with intermediate physical properties.
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Submitted 21 February, 2007;
originally announced February 2007.
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The ESSENCE Supernova Survey: Survey Optimization, Observations, and Supernova Photometry
Authors:
G. Miknaitis,
G. Pignata,
A. Rest,
W. M. Wood-Vasey,
S. Blondin,
P. Challis,
R. C. Smith,
C. W. Stubbs,
N. B. Suntzeff,
R. J. Foley,
T. Matheson,
J. L. Tonry,
C. Aguilera,
J. W. Blackman,
A. C. Becker,
A. Clocchiatti,
R. Covarrubias,
T. M. Davis,
A. V. Filippenko,
A. Garg,
P. M. Garnavich,
M. Hicken,
S. Jha,
K. Krisciunas,
R. P. Kirshner
, et al. (11 additional authors not shown)
Abstract:
We describe the implementation and optimization of the ESSENCE supernova survey, which we have undertaken to measure the equation of state parameter of the dark energy. We present a method for optimizing the survey exposure times and cadence to maximize our sensitivity to the dark energy equation of state parameter w=P/rho c^2 for a given fixed amount of telescope time. For our survey on the CTI…
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We describe the implementation and optimization of the ESSENCE supernova survey, which we have undertaken to measure the equation of state parameter of the dark energy. We present a method for optimizing the survey exposure times and cadence to maximize our sensitivity to the dark energy equation of state parameter w=P/rho c^2 for a given fixed amount of telescope time. For our survey on the CTIO 4m telescope, measuring the luminosity distances and redshifts for supernovae at modest redshifts (z~0.5 +- 0.2) is optimal for determining w. We describe the data analysis pipeline based on using reliable and robust image subtraction to find supernovae automatically and in near real-time. Since making cosmological inferences with supernovae relies crucially on accurate measurement of their brightnesses, we describe our efforts to establish a thorough calibration of the CTIO 4m natural photometric system. In its first four years, ESSENCE has discovered and spectroscopically confirmed 102 type Ia SNe, at redshifts from 0.10 to 0.78, identified through an impartial, effective methodology for spectroscopic classification and redshift determination. We present the resulting light curves for the all type Ia supernovae found by ESSENCE and used in our measurement of w, presented in Wood-Vasey et al, 2007.
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Submitted 2 January, 2007;
originally announced January 2007.
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Observational Constraints on the Nature of the Dark Energy: First Cosmological Results from the ESSENCE Supernova Survey
Authors:
W. M. Wood-Vasey,
G. Miknaitis,
C. W. Stubbs,
S. Jha,
A. G. Riess,
P. M. Garnavich,
R. P. Kirshner,
C. Aguilera,
A. C. Becker,
J. W. Blackman,
S. Blondin,
P. Challis,
A. Clocchiatti,
A. Conley,
R. Covarrubias,
T. M. Davis,
A. V. Filippenko,
R. J. Foley,
A. Garg,
M. Hicken,
K. Krisciunas,
B. Leibundgut,
W. Li,
T. Matheson,
A. Miceli
, et al. (12 additional authors not shown)
Abstract:
We present constraints on the dark energy equation-of-state parameter, w=P/(rho c^2), using 60 Type Ia supernovae (SNe Ia) from the ESSENCE supernova survey. We derive a set of constraints on the nature of the dark energy assuming a flat Universe. By including constraints on (Omega_M, w) from baryon acoustic oscillations, we obtain a value for a static equation-of-state parameter w=-1.05^{+0.13}…
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We present constraints on the dark energy equation-of-state parameter, w=P/(rho c^2), using 60 Type Ia supernovae (SNe Ia) from the ESSENCE supernova survey. We derive a set of constraints on the nature of the dark energy assuming a flat Universe. By including constraints on (Omega_M, w) from baryon acoustic oscillations, we obtain a value for a static equation-of-state parameter w=-1.05^{+0.13}_{-0.12} (stat; 1 sigma) +- 0.11 (sys) and Omega_M=0.274^{+0.033}_{-0.020} (stat; 1 sigma) with a best-fit chi^2/DoF of 0.96. These results are consistent with those reported by the SuperNova Legacy Survey in a similar program measuring supernova distances and redshifts. We evaluate sources of systematic error that afflict supernova observations and present Monte Carlo simulations that explore these effects. Currently, the largest systematic currently with the potential to affect our measurements is the treatment of extinction due to dust in the supernova host galaxies. Combining our set of ESSENCE SNe Ia with the SuperNova Legacy Survey SNe Ia, we obtain a joint constraint of w=-1.07^{+0.09}_{-0.09} (stat; 1 sigma) +- 0.12 (sys), Omega_M=0.267^{+0.028}_{-0.018} (stat; 1 sigma) with a best-fit chi^2/DoF of 0.91. The current SN Ia data are fully consistent with a cosmological constant.
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Submitted 2 January, 2007;
originally announced January 2007.
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The Peculiar Type Ia Supernova 2005hk
Authors:
V. Stanishev,
S. Taubenberger,
G. Blanc,
G. C. Anupama,
S. Benetti,
E. Cappellaro,
N. Elias-Rosa,
C. Feron,
A. Goobar,
K. Krisciunas,
A. Pastorello,
D. K. Sahu,
M. E. Salvo,
B. P. Schmidt,
J. Sollerman,
C. C. Thone,
M. Turatto,
W. Hillebrandt
Abstract:
We present a preliminary analysis of an extensive set of optical observations of the Type Ia SN 2005hk. We show that the evolution of SN 2005hk closely follows that of the peculiar SN 2002cx. SN 2005hk is more luminous than SN 2002cx, while still under-luminous compared to normal Type Ia supernovae. The spectrum at 9 days before maximum is dominated by conspicuous Fe III and Ni III lines, and th…
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We present a preliminary analysis of an extensive set of optical observations of the Type Ia SN 2005hk. We show that the evolution of SN 2005hk closely follows that of the peculiar SN 2002cx. SN 2005hk is more luminous than SN 2002cx, while still under-luminous compared to normal Type Ia supernovae. The spectrum at 9 days before maximum is dominated by conspicuous Fe III and Ni III lines, and the Si II 6355 line is also clearly visible. All these features have low velocity (~6000 km/s). The near maximum spectra show lines of Si II, S II, Fe II, Fe III, as well as other intermediate mass and iron group elements. Analysis with the code for synthetic spectra SYNOW indicates that all these spectral lines have similar velocities.
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Submitted 10 November, 2006;
originally announced November 2006.
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The Type Ia supernova 2004S, a clone of SN 2001el, and the optimal photometric bands for extinction estimation
Authors:
Kevin Krisciunas,
Peter M. Garnavich,
Vallery Stanishev,
Nicholas B. Suntzeff,
Jose Luis Prieto,
Juan Espinoza,
David Gonzalez,
Maria Elena Salvo,
Nancy Elias de la Rosa,
Stephen J. Smartt,
Justyn R. Maund,
Rolf-Peter Kudritzki
Abstract:
We present optical (UBVRI) and near-infrared (YJHK) photometry of the normal Type Ia supernova 2004S. We also present eight optical spectra and one near-IR spectrum of SN 2004S. The light curves and spectra are nearly identical to those of SN 2001el. This is the first time we have seen optical and IR light curves of two Type Ia supernovae match so closely. Within the one parameter family of ligh…
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We present optical (UBVRI) and near-infrared (YJHK) photometry of the normal Type Ia supernova 2004S. We also present eight optical spectra and one near-IR spectrum of SN 2004S. The light curves and spectra are nearly identical to those of SN 2001el. This is the first time we have seen optical and IR light curves of two Type Ia supernovae match so closely. Within the one parameter family of light curves for normal Type Ia supernovae, that two objects should have such similar light curves implies that they had identical intrinsic colors and produced similar amounts of Ni-56. From the similarities of the light curve shapes we obtain a set of extinctions as a function of wavelength which allows a simultaneous solution for the distance modulus difference of the two objects, the difference of the host galaxy extinctions, and R_V. Since SN 2001el had roughly an order of magnitude more host galaxy extinction than SN 2004S, the value of R_V = 2.15 (+0.24 -0.22) pertains primarily to dust in the host galaxy of SN 2001el. We have also shown via Monte Carlo simulations that adding rest frame J-band photometry to the complement of BVRI photometry of Type Ia SNe decreases the uncertainty in the distance modulus by a factor of 2.7. A combination of rest frame optical and near-IR photometry clearly gives more accurate distances than using rest frame optical photometry alone.
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Submitted 10 September, 2006;
originally announced September 2006.
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A Spectacular Radio Flare from XRF 050416a at 40 days and Implications for the Nature of X-ray Flashes
Authors:
A. M. Soderberg,
E. Nakar,
S. B. Cenko,
P. B. Cameron,
D. A. Frail,
S. R. Kulkarni,
D. B. Fox,
E. Berger,
A. Gal-Yam,
D-S. Moon,
P. A. Price,
G. Anderson,
B. P. Schmidt,
M. Salvo,
J. Rich,
A. Rau,
E. O. Ofek,
R. A. Chevalier,
M. Hamuy,
F. A. Harrison,
P. Kumar,
A. MacFadyen,
P. J. McCarthy,
H. S. Park,
B. A. Peterson
, et al. (4 additional authors not shown)
Abstract:
We present detailed optical, near-infrared, and radio observations of the X-ray flash 050416a obtained with Palomar and Siding Springs Observatories as well as HST and the VLA, placing this event among the best-studied X-ray flashes to date. In addition, we present an optical spectrum from Keck LRIS from which we measure the redshift of the burst, z=0.6528. At this redshift the isotropic-equival…
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We present detailed optical, near-infrared, and radio observations of the X-ray flash 050416a obtained with Palomar and Siding Springs Observatories as well as HST and the VLA, placing this event among the best-studied X-ray flashes to date. In addition, we present an optical spectrum from Keck LRIS from which we measure the redshift of the burst, z=0.6528. At this redshift the isotropic-equivalent prompt energy release was about 10^51 erg, and using a standard afterglow synchrotron model we find that the blastwave kinetic energy is a factor of 10 larger, E_K,iso ~ 10^52 erg. The lack of an observed jet break to t ~ 20 days indicates that the opening angle is larger than 7 deg and the total beaming-corrected relativistic energy is larger than 10^50 erg. We further show that the burst produced a strong radio flare at t ~ 40 days accompanied by an observed flattening in the X-ray band which we attribute to an abrupt circumburst density jump or an episode of energy injection (either from a refreshed shock or off-axis ejecta). Late-time observations with HST show evidence for an associated supernova with peak optical luminosity roughly comparable to that of SN 1998bw. Next, we show that the host galaxy of XRF 050416a is actively forming stars at a rate of at least 2 M_solar per year with a luminosity of L_B ~ 0.5L* and metallicity of Z ~ 0.2-0.8 Z_solar. Finally, we discuss the nature of XRF 050416a in the context of short-hard gamma-ray bursts and under the framework of off-axis and dirty fireball models for X-ray flashes.
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Submitted 20 April, 2007; v1 submitted 23 July, 2006;
originally announced July 2006.
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SN 2004aw: Confirming Diversity of Type Ic Supernovae
Authors:
S. Taubenberger,
A. Pastorello,
P. A. Mazzali,
S. Valenti,
G. Pignata,
D. N. Sauer,
A. Arbey,
O. Bärnbantner,
S. Benetti,
A. Della Valle,
J. Deng,
N. Elias-Rosa,
A. V. Filippenko,
R. J. Foley,
A. Goobar,
R. Kotak,
W. Li,
P. Meikle,
J. Mendez,
F. Patat,
E. Pian,
C. Ries,
P. Ruiz-Lapuente,
M. Salvo,
V. Stanishev
, et al. (2 additional authors not shown)
Abstract:
Optical and near-infrared observations of the Type Ic supernova (SN) 2004aw are presented, obtained from day -3 to day +413 with respect to the B-band maximum. The photometric evolution is characterised by a comparatively slow post-maximum decline of the light curves. The peaks in redder bands are significantly delayed relative to the bluer bands, the I-band maximum occurring 8.4 days later than…
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Optical and near-infrared observations of the Type Ic supernova (SN) 2004aw are presented, obtained from day -3 to day +413 with respect to the B-band maximum. The photometric evolution is characterised by a comparatively slow post-maximum decline of the light curves. The peaks in redder bands are significantly delayed relative to the bluer bands, the I-band maximum occurring 8.4 days later than that in B. With an absolute peak magnitude of -18.02 in the V band the SN can be considered fairly bright, but not exceptional. This also holds for the U through I bolometric light curve, where SN 2004aw has a position intermediate between SNe 2002ap and 1998bw. Spectroscopically SN 2004aw provides a link between a normal Type Ic supernova like SN 1994I and the group of broad-lined SNe Ic. The spectral evolution is rather slow, with a spectrum at day +64 being still predominantly photospheric. The shape of the nebular [O I] 6300,6364 line indicates a highly aspherical explosion. Helium cannot be unambiguously identified in the spectra, even in the near-infrared. Using an analytical description of the light curve peak we find that the total mass of the ejecta in SN 2004aw is 3.5-8.0 M_Sun, significantly larger than in SN 1994I, although not as large as in SN 1998bw. The same model suggests that about 0.3 M_Sun of {56}Ni has been synthesised in the explosion. No connection to a GRB can be firmly established.
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Submitted 17 August, 2006; v1 submitted 5 July, 2006;
originally announced July 2006.
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Anomalous extinction behaviour towards the Type Ia SN 2003cg
Authors:
N. Elias-Rosa,
S. Benetti,
E. Cappellaro,
M. Turatto,
P. A. Mazzali,
F. Patat,
W. P. S. Meikle,
M. Stehle,
A. Pastorello,
G. Pignata,
R. Kotak,
A. Harutyunyan,
G. Altavilla,
H. Navasardyan,
Y. Qiu,
M. E. Salvo,
W. Hillebrandt
Abstract:
We present optical and near-infrared photometry and spectroscopy of the Type Ia SN 2003cg, which exploded in the nearby galaxy NGC 3169. The observations cover a period between -8.5 and +414 days post-maximum. SN 2003cg is a normal but highly-reddened Type Ia event. Its B magnitude at maximum B_max = 15.94+/-0.04 and Delta m_15(B)_obs = 1.12+/-0.04 (Delta m_15(B)_intrinsic = 1.25+/-0.05). Allowi…
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We present optical and near-infrared photometry and spectroscopy of the Type Ia SN 2003cg, which exploded in the nearby galaxy NGC 3169. The observations cover a period between -8.5 and +414 days post-maximum. SN 2003cg is a normal but highly-reddened Type Ia event. Its B magnitude at maximum B_max = 15.94+/-0.04 and Delta m_15(B)_obs = 1.12+/-0.04 (Delta m_15(B)_intrinsic = 1.25+/-0.05). Allowing R_v to become a free parameter within the Cardelli et al. (1989) extinction law, simultaneous matches to a range of colour curves of normal SNe Ia yielded E(B-V) = 1.33+/-0.11, and R_v = 1.80+/-0.19. While the value obtained for R_v is small, such values have been invoked in the past, and may imply a grain size which is small compared with the average value for the local ISM.
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Submitted 31 March, 2006; v1 submitted 13 March, 2006;
originally announced March 2006.
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Using Line Profiles to Test the Fraternity of Type Ia Supernovae at High and Low Redshifts
Authors:
S. Blondin,
L. Dessart,
B. Leibundgut,
D. Branch,
P. Hoeflich,
J. L. Tonry,
T. Matheson,
R. J. Foley,
R. Chornock,
A. V. Filippenko,
J. Sollerman,
J. Spyromilio,
R. P. Kirshner,
W. M. Wood-Vasey,
A. Clocchiatti,
C. Aguilera,
B. Barris,
A. C. Becker,
P. Challis,
R. Covarrubias,
T. Davis,
P. Garnavich,
M. Hicken,
S. Jha,
K. Krisciunas
, et al. (12 additional authors not shown)
Abstract:
Using archival data of low-redshift (z < 0.01) Type Ia supernovae (SN Ia) and recent observations of high-redshift (0.16 < z <0.64; Matheson et al. 2005) SN Ia, we study the "uniformity'' of the spectroscopic properties of nearby and distant SN Ia. We find no difference in the measures we describe here. In this paper, we base our analysis solely on line-profile morphology, focusing on measuremen…
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Using archival data of low-redshift (z < 0.01) Type Ia supernovae (SN Ia) and recent observations of high-redshift (0.16 < z <0.64; Matheson et al. 2005) SN Ia, we study the "uniformity'' of the spectroscopic properties of nearby and distant SN Ia. We find no difference in the measures we describe here. In this paper, we base our analysis solely on line-profile morphology, focusing on measurements of the velocity location of maximum absorption (vabs) and peak emission (vpeak). We find that the evolution of vabs and vpeak for our sample lines (Ca II 3945, Si II 6355, and S II 5454, 5640) is similar for both the low- and high-redshift samples. We find that vabs for the weak S II 5454, 5640 lines, and vpeak for S II 5454, can be used to identify fast-declining [dm15 > 1.7] SN Ia, which are also subluminous. In addition, we give the first direct evidence in two high-z SN Ia spectra of a double-absorption feature in Ca II 3945, an event also observed, though infrequently, in low-redshift SN Ia spectra (6/22 SN Ia in our local sample). We report for the first time the unambiguous and systematic intrinsic blueshift of peak emission of optical P-Cygni line profiles in Type Ia spectra, by as much as 8000 km/s. All the high-z SN Ia analyzed in this paper were discovered and followed up by the ESSENCE collaboration, and are now publicly available.
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Submitted 6 October, 2005; v1 submitted 4 October, 2005;
originally announced October 2005.
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Supernova Cosmology and the ESSENCE project
Authors:
Jesper Sollerman,
Claudio Aguilera,
Andy Becker,
Stephane Blondin,
Pete Challis,
Alejandro Clocchiatti,
Alex Filippenko,
Ryan Foley,
Peter M. Garnavich,
Malcolm Hicken,
Saurabh Jha,
Robert Kirshner,
Kevin Krisciunas,
Bruno Leibundgut,
Weidong Li,
Thomas Matheson,
Gajus Miknaitis,
Armin Rest,
Adam G. Riess,
Maria Elena Salvo,
Brian P. Schmidt,
Chris Smith,
Jason Spyromilio,
Chris Stubbs,
Nicholas B. Suntzeff
, et al. (5 additional authors not shown)
Abstract:
The proper usage of Type Ia supernovae (SNe Ia) as distance indicators has revolutionized cosmology, and added a new dominant component to the energy density of the Universe, dark energy. Following the discovery and confirmation era, the currently ongoing SNe Ia surveys aim to determine the properties of the dark energy. ESSENCE is a five year ground-based supernova survey aimed at finding and c…
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The proper usage of Type Ia supernovae (SNe Ia) as distance indicators has revolutionized cosmology, and added a new dominant component to the energy density of the Universe, dark energy. Following the discovery and confirmation era, the currently ongoing SNe Ia surveys aim to determine the properties of the dark energy. ESSENCE is a five year ground-based supernova survey aimed at finding and characterizing 200 SNe Ia in the redshift domain z=[0.2-0.8]. The goal of the project is to put constraints on the equation of state parameter, w, of the dark energy with an accuracy of <10%. This paper presents these ongoing efforts in the context of the current developments in observational cosmology.
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Submitted 2 October, 2005;
originally announced October 2005.
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Hubble Space Telescope Observations of Nine High-Redshift ESSENCE Supernovae
Authors:
Kevin Krisciunas,
Peter M. Garnavich,
Peter Challis,
Jose Luis Prieto,
A. G. Riess,
B. Barris,
C. Aguilera,
A. C. Becker,
S. Blondin,
R. Chornock,
A. Clocchiatti,
R. Covarrubias,
A. V. Filippenko,
R. J. Foley,
M. Hicken,
S. Jha,
R. P. Kirshner,
B. Leibundgut,
W. D. Li,
T. Matheson,
A. Miceli,
G. Miknaitis,
A. Rest,
M. E. Salvo,
B. P. Schmidt
, et al. (7 additional authors not shown)
Abstract:
We present broad-band light curves of nine supernovae ranging in redshift from 0.5 to 0.8. The supernovae were discovered as part of the ESSENCE project, and the light curves are a combination of Cerro Tololo 4-m and Hubble Space Telescope (HST) photometry. On the basis of spectra and/or light-curve fitting, eight of these objects are definitely Type Ia supernovae, while the classification of on…
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We present broad-band light curves of nine supernovae ranging in redshift from 0.5 to 0.8. The supernovae were discovered as part of the ESSENCE project, and the light curves are a combination of Cerro Tololo 4-m and Hubble Space Telescope (HST) photometry. On the basis of spectra and/or light-curve fitting, eight of these objects are definitely Type Ia supernovae, while the classification of one is problematic. The ESSENCE project is a five-year endeavor to discover about 200 high-redshift Type Ia supernovae, with the goal of tightly constraining the time average of the equation-of-state parameter [w = p/(rho c^2)] of the "dark energy." To help minimize our systematic errors, all of our ground-based photometry is obtained with the same telescope and instrument. In 2003 the highest-redshift subset of ESSENCE supernovae was selected for detailed study with HST. Here we present the first photometric results of the survey. We find that all but one of the ESSENCE SNe have slowly declining light curves, and the sample is not representative of the low-redshift set of ESSENCE Type Ia supernovae. This is unlikely to be a sign of evolution in the population. We attribute the decline-rate distribution of HST events to a selection bias at the high-redshift edge of our sample and find that such a bias will infect other magnitude-limited SN Ia searches unless appropriate precautions are taken.
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Submitted 31 August, 2005;
originally announced August 2005.
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SN 1998A: Explosion of a Blue Supergiant
Authors:
A. Pastorello,
E. Baron,
D. Branch,
L. Zampieri,
M. Turatto,
M. Ramina,
S. Benetti,
E. Cappellaro,
M. Salvo,
F. Patat,
A. Piemonte,
J. Sollerman,
B. Leibundgut,
G. Altavilla
Abstract:
We present spectroscopic and photometric observations of the peculiar Type II supernova (SN) 1998A. The light curves and spectra closely resemble those of SN 1987A, suggesting that the SN 1998A progenitor exploded when it was a compact blue supergiant. However, the comparison with SN 1987A also highlights some important differences: SN 1998A is more luminous and the spectra show bluer continua a…
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We present spectroscopic and photometric observations of the peculiar Type II supernova (SN) 1998A. The light curves and spectra closely resemble those of SN 1987A, suggesting that the SN 1998A progenitor exploded when it was a compact blue supergiant. However, the comparison with SN 1987A also highlights some important differences: SN 1998A is more luminous and the spectra show bluer continua and larger expansion velocities at all epochs. These observational properties indicate that the explosion of SN 1998A is more energetic than SN 1987A and more typical of SNe II. Comparing the observational data to simulations, we deduce that the progenitor of SN 1998A was a massive star (~ 25 Mo) with a small pre-supernova radius (< 6 x 10^{12} cm). The Ba II lines, unusually strong in SN 1987A and some faint II--P events, are almost normal in the case of SN 1998A, indicating that the temperature plays a key role in determining their strength.
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Submitted 5 April, 2005;
originally announced April 2005.
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High-Velocity Features: a ubiquitous property of Type Ia SNe
Authors:
P. A. Mazzali,
S. Benetti,
G. Altavilla,
G. Blanc,
E. Cappellaro,
N. Elias-Rosa,
G. Garavini,
A. Goobar,
A. Harutyunyan,
R. Kotak,
B. Leibundgut,
P. Lundqvist,
S. Mattila,
J. Mendez,
S. Nobili,
R. Pain,
A. Pastorello,
F. Patat,
G. Pignata,
Ph. Podsiadlowski,
P. Ruiz-Lapuente,
M. Salvo,
B. P. Schmidt,
J. Sollerman,
V. Stanishev
, et al. (4 additional authors not shown)
Abstract:
Evidence of high-velocity features such as those seen in the near-maximum spectra of some Type Ia Supernovae (eg SN 2000cx) has been searched for in the available SNIa spectra observed earlier than one week before B maximum. Recent observational efforts have doubled the number of SNeIa with very early spectra. Remarkably, all SNeIa with early data (7 in our RTN sample and 10 from other programme…
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Evidence of high-velocity features such as those seen in the near-maximum spectra of some Type Ia Supernovae (eg SN 2000cx) has been searched for in the available SNIa spectra observed earlier than one week before B maximum. Recent observational efforts have doubled the number of SNeIa with very early spectra. Remarkably, all SNeIa with early data (7 in our RTN sample and 10 from other programmes) show signs of such features, to a greater or lesser degree, in CaII IR, and some also in SiII 6255A line. High-velocity features may be interpreted as abundance or density enhancements. Abundance enhancements would imply an outer region dominated by Si and Ca. Density enhancements may result from the sweeping up of circumstellar material by the highest velocity SN ejecta. In this scenario, the high incidence of HVFs suggests that a thick disc and/or a high-density companion wind surrounds the exploding white dwarf, as may be the case in Single Degenerate systems. Large-scale angular fluctuations in the radial density and abundance distribution may also be responsible: this could originate in the explosion, and would suggest a deflagration as the more likely explosion mechanism. CSM-interaction and surface fluctuations may coexist, possibly leaving different signatures on the spectrum. In some SNe the HVFs are narrowly confined in velocity, suggesting the ejection of blobs of burned material.
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Submitted 25 February, 2005;
originally announced February 2005.
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Spectroscopy of High-Redshift Supernovae from the ESSENCE Project: The First Two Years
Authors:
T. Matheson,
S. Blondin,
R. J. Foley,
R. Chornock,
A. V. Filippenko,
B. Leibundgut,
R. C. Smith,
J. Sollerman,
J. Spyromilio,
R. P. Kirshner,
A. Clocchiatti,
C. Aguilera,
B. Barris,
A. C. Becker,
P. Challis,
R. Covarrubias,
P. Garnavich,
M. Hicken,
S. Jha,
K. Krisciunas,
W. Li,
A. Miceli,
G. Miknaitis,
J. L. Prieto,
A. Rest
, et al. (6 additional authors not shown)
Abstract:
We present the results of spectroscopic observations of targets discovered during the first two years of the ESSENCE project. The goal of ESSENCE is to use a sample of ~200 Type Ia supernovae (SNe Ia) at moderate redshifts (0.2 < z < 0.8) to place constraints on the equation of state of the Universe. Spectroscopy not only provides the redshifts of the objects, but also confirms that some of the…
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We present the results of spectroscopic observations of targets discovered during the first two years of the ESSENCE project. The goal of ESSENCE is to use a sample of ~200 Type Ia supernovae (SNe Ia) at moderate redshifts (0.2 < z < 0.8) to place constraints on the equation of state of the Universe. Spectroscopy not only provides the redshifts of the objects, but also confirms that some of the discoveries are indeed SNe Ia. This confirmation is critical to the project, as techniques developed to determine luminosity distances to SNe Ia depend upon the knowledge that the objects at high redshift are the same as the ones at low redshift. We describe the methods of target selection and prioritization, the telescopes and detectors, and the software used to identify objects. The redshifts deduced from spectral matching of high-redshift SNe Ia with low-redshift SNe Ia are consistent with those determined from host-galaxy spectra. We show that the high-redshift SNe Ia match well with low-redshift templates. We include all spectra obtained by the ESSENCE project, including 52 SNe Ia, 5 core-collapse SNe, 12 active galactic nuclei, 19 galaxies, 4 possibly variable stars, and 16 objects with uncertain identifications.
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Submitted 12 November, 2004;
originally announced November 2004.
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The diversity of Type Ia Supernovae: evidence for systematics?
Authors:
S. Benetti,
E. Cappellaro,
P. A. Mazzali,
M. Turatto,
G. Altavilla,
F. Bufano,
N. Elias-Rosa,
R. Kotak,
G. Pignata,
M. Salvo,
V. Stanishev
Abstract:
The photometric and spectroscopic properties of 26 well observed Type Ia Supernovae (SNeIa) were analyzed with the aim to explore SNIa diversity. The sample includes (Branch-)normal SNe as well as extreme events like SNe 1991T and 1991bg, while the truly peculiar SNIa, SN2000cx and SN2002cx are not included in our sample . A statistical treatment reveals the existence of three different groups.…
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The photometric and spectroscopic properties of 26 well observed Type Ia Supernovae (SNeIa) were analyzed with the aim to explore SNIa diversity. The sample includes (Branch-)normal SNe as well as extreme events like SNe 1991T and 1991bg, while the truly peculiar SNIa, SN2000cx and SN2002cx are not included in our sample . A statistical treatment reveals the existence of three different groups. The first group (FAINT) consists of faint SNeIa similar to SN1991bg, with low expansion velocities and rapid evolution of SiII velocity. A second group consists of ``normal'' SNeIa, also with high temporal velocity gradient (HVG), but with brighter mean absolute magnitude <M_B>=-19.3 and higher expansion velocities than the FAINT SNe. The third group includes both ``normal'' and SN1991T-like SNeIa: these SNe populate a narrow strip in the SiII velocity evolution plot, with a small velocity gradient (SVG), but have absolute magnitudes similar to HVGs. While the FAINT and HVG SNeIa together seem to define a relation between RSi(II) and Dm15(B), the SVG ones either do not conform with that relation or define a new, looser one. The RSi(II) pre-maximum evolution of HVGs is strikingly different from that of SVGs. The impact of this evidence on the understanding of SNIa diversity, in terms of explosion mechanisms, degree of ejecta mixing, and ejecta-CSM interaction, is discussed.
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Submitted 3 January, 2005; v1 submitted 2 November, 2004;
originally announced November 2004.
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Death rate of massive stars at redshift ~0.3
Authors:
E. Cappellaro,
M. Riello,
G. Altavilla,
M. T. Botticella,
S. Benetti,
A. Clocchiatti,
J. I. Danziger,
P. Mazzali,
A. Pastorello,
F. Patat,
M. Salvo,
M. Turatto,
S. Valenti
Abstract:
We report the first result of a supernova search program designed to measure the evolution of the supernova rate with redshift. To make the comparison with local rates more significant we copied, as much as possible, the same computation recepies as for the measurements of local rates. Moreover, we exploited the multicolor images and the photometric redshift technique to characterize the galaxy…
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We report the first result of a supernova search program designed to measure the evolution of the supernova rate with redshift. To make the comparison with local rates more significant we copied, as much as possible, the same computation recepies as for the measurements of local rates. Moreover, we exploited the multicolor images and the photometric redshift technique to characterize the galaxy sample and accurately estimate the detection efficiency.
Combining our data with the recently published meaurements of the SN Ia rate at different redshifts, we derived the first, direct measurement of the core collapse supernova rate at z = 0.26 as r_cc = 1.45^{+0.55}{-0.45} h^2 SNu [h=H_0/75]. This is a factor three {+/- 50%)} larger than the local estimate. The increase for a look back time of "only" 2.8 Gyr is more rapid than predicted by most of the published models of the SN rate evolution. Core-collapse SN rates measure the death rate of massive star and, because of the short time scale of evolution, can be translated in a measurement of the ongoing SFR. Assuming a Salpeter IMF and the standard scenario for core-collapse progenitors we derived to an estimate of the star formation rate at redshift 3.1^{+1.1}{-1.0} 10^-2 h^3 M_sun yr^-1 Mpc^{-3} which compare very well with a recent estimate based on the measurement of the Halpha luminosity density at the same redshift.
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Submitted 16 September, 2004; v1 submitted 12 July, 2004;
originally announced July 2004.
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Observational Properties of Type II Plateau Supernovae
Authors:
A. Pastorello,
M. Ramina,
L. Zampieri,
H. Navasardyan,
M. Salvo,
M. Fiaschi
Abstract:
We present spectroscopic and photometric data of a sample of Type II plateau Supernovae, covering a wide range of properties, from the $^{56}$Ni rich, high luminosity events (e.g. SN 1992am) to the low-luminosity, $^{56}$Ni poor SNe (e.g. SN 1997D). We provide an observational framework to analyze correlations among observational data, physical parameters and progenitors characteristics of Type…
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We present spectroscopic and photometric data of a sample of Type II plateau Supernovae, covering a wide range of properties, from the $^{56}$Ni rich, high luminosity events (e.g. SN 1992am) to the low-luminosity, $^{56}$Ni poor SNe (e.g. SN 1997D). We provide an observational framework to analyze correlations among observational data, physical parameters and progenitors characteristics of Type II Supernovae.
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Submitted 2 October, 2003;
originally announced October 2003.
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Low Luminosity Type II Supernovae: Spectroscopic and Photometric Evolution
Authors:
A. Pastorello,
L. Zampieri,
M. Turatto,
E. Cappellaro,
W. P. S. Meikle,
S. Benetti,
D. Branch,
E. Baron,
F. Patat,
M. Armstrong,
G. Altavilla,
M. Salvo,
M. Riello
Abstract:
In this paper we present spectroscopic and photometric observations for four core collapse supernovae (SNe), namely SNe 1994N, 1999br, 1999eu and 2001dc. Together with SN 1997D, we show that they form a group of exceptionally low-luminosity events. These SNe have narrow spectral lines (indicating low expansion velocities) and low luminosities at every phase (significantly lower than those of typ…
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In this paper we present spectroscopic and photometric observations for four core collapse supernovae (SNe), namely SNe 1994N, 1999br, 1999eu and 2001dc. Together with SN 1997D, we show that they form a group of exceptionally low-luminosity events. These SNe have narrow spectral lines (indicating low expansion velocities) and low luminosities at every phase (significantly lower than those of typical core-collapse supernovae). The very low luminosity during the ^{56}Co radioactive decay tail indicates that the mass of ^{56}Ni ejected during the explosion is much smaller (M(Ni) ~ 2-8 x 10^{-3} Mo) than the average (M(Ni) ~ 6-10 x 10^{-2} Mo). Two supernovae of this group (SN 1999br and SN 2001dc) were discovered very close to the explosion epoch, allowing us to determine the lengths of their plateaux (~ 100 days) as well as establishiing the explosion epochs of the other, less-completely observed SNe. It is likely that this group of SNe represent the extreme low-luminosity tail of a single continuous distribution of SN II-P events. Their kinetic energy is also exceptionally low. Although an origin from low mass progenitors has also been proposed for low-luminosity core-collapse SNe, recent work provides evidence in favour of the high mass progenitor scenario. The incidence of these low--luminosity SNe could be as high as 4-5$ $ of all type II SNe.
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Submitted 9 September, 2003;
originally announced September 2003.
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SN1999E: Another piece in the SN-GRB connection puzzle
Authors:
L. Rigon,
M. Turatto,
S. Benetti,
A. Pastorello,
E. Cappellaro,
I. Aretxaga,
O. Vega,
V. Chavushyan,
F. Patat,
I. J. Danziger,
M. Salvo
Abstract:
Detailed optical and near-IR observations of SN 1999E have confirmed early suggestions that this supernova was indeed a twin of the peculiar type II SN 1997cy: it was exceptionally luminous and had evolved slowly, and the line profiles had narrow peaks and broad wings, indicating interaction with the circumstellar material. Nevertheless, the most intriguing characteristic was that, in analogy to…
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Detailed optical and near-IR observations of SN 1999E have confirmed early suggestions that this supernova was indeed a twin of the peculiar type II SN 1997cy: it was exceptionally luminous and had evolved slowly, and the line profiles had narrow peaks and broad wings, indicating interaction with the circumstellar material. Nevertheless, the most intriguing characteristic was that, in analogy to SN 1997cy, it exploded at a position consistent in time and location with a BATSE event (GRB980910). The "a posteriori" probability that the only two SNe with such an optical appearance are associated with two different BATSE GRB is only 0.2%. This raises the possibility that some GRB are associated with H--rich SNe.
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Submitted 19 November, 2002;
originally announced November 2002.
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Photometry and Spectroscopy of the Type IIP SN 1999em from Outburst to Dust Formation
Authors:
A. Elmhamdi,
I. J. Danziger,
N. Chugai,
A. Pastorello,
M. Turatto,
E. Cappellaro,
G. Altavilla,
S. Benetti,
F. Patat,
M. Salvo
Abstract:
We present photometry and spectra of the type IIP SN1999em in NGC 1637 from several days after the outburst till day 642. An amount of $\approx 0.02 M_{\odot}$ of ejected $^{56}$Ni is inferred using the recovered bolometric light curve . The H$α$ and He I 10830 Ålines at the nebular epoch show that the distribution of the bulk of $^{56}$Ni can be represented approximately by a sphere of $^{56}$N…
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We present photometry and spectra of the type IIP SN1999em in NGC 1637 from several days after the outburst till day 642. An amount of $\approx 0.02 M_{\odot}$ of ejected $^{56}$Ni is inferred using the recovered bolometric light curve . The H$α$ and He I 10830 Ålines at the nebular epoch show that the distribution of the bulk of $^{56}$Ni can be represented approximately by a sphere of $^{56}$Ni with a velocity of 1500 km s$^{-1}$, which is shifted towards the far hemisphere by about 400 km s$^{-1}$. The fine structure of the H$α$ at the photospheric epoch reminiscent of the "Bochum event" in SN 1987A is analysed . The late time spectra show a dramatic transformation of the [O I] 6300 Åline profile between days 465 and 510, which we interpret as an effect of dust condensation during this period. Late time photometry supports the dust formation scenario after day 465. The [O I] line profile suggests that the dust occupies a sphere with velocity $\approx 800$ km s$^{-1}$ and optical depth $\gg10$. The plateau brightness and duration combined with the expansion velocity suggest a presupernova radius of $120-150 R_{\odot}$, ejecta mass of $10-11 M_{\odot}$ and explosion energy of $(0.5-1)\times10^{51}$ erg. The ejecta mass combined with the neutron star and a conservative assumption about mass loss implies the main sequence progenitor of $M_{\rm ms}\approx 12-14 M_{\odot}$. From the [O I] 6300,6364 Ådoublet luminosity we infer the oxygen mass to be a factor four lower than in SN 1987A which is consistent with the estimated SN 1999em progenitor mass . We note a "second-plateau" behaviour of the light curve after the main plateau at the beginning of the radioactive tail. This feature seems to be common to SNe IIP with low $^{56}$Ni mass.
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Submitted 30 September, 2002;
originally announced September 2002.
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The Fundamental Plane of Radio Galaxies
Authors:
D. Bettoni,
R. Falomo,
G. Fasano,
F. Govoni,
M. Salvo,
R. Scarpa
Abstract:
We collected photometrical and dynamical data for 73 low red-shift (z<0.2) Radio Galaxies (LzRG) in order to study their Fundamental Plane (FP). For 22 sources we also present new velocity dispersion data, that complement the photometric data given in our previous study of LzRG (Govoni et al. 2000a). It is found that the FP of LzRG is similar to the one defined by non-active elliptical galaxies,…
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We collected photometrical and dynamical data for 73 low red-shift (z<0.2) Radio Galaxies (LzRG) in order to study their Fundamental Plane (FP). For 22 sources we also present new velocity dispersion data, that complement the photometric data given in our previous study of LzRG (Govoni et al. 2000a). It is found that the FP of LzRG is similar to the one defined by non-active elliptical galaxies, with LzRG representing the brightest end of the population of early type galaxies. Since the FP mainly reflects the virial equilibrium condition, our result implies that the global properties of early--type galaxies (defining the FP) are not influenced by the presence of gas accretion in the central black hole. This is fully in agreement with the recent results in black hole demography, showing that virtually all luminous spheroidal galaxies host a massive black hole and therefore may potentially become active. We confirm and extend to giant ellipticals the systematic increase of the mass-to-light ratio with galaxy luminosity.
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Submitted 26 February, 2002; v1 submitted 18 October, 2001;
originally announced October 2001.
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Detection of a light echo from SN1998bu
Authors:
E. Cappellaro,
F. Patat,
P. A. Mazzali,
S. Benetti,
J. I. Danziger,
A. Pastorello,
L. Rizzi,
M. Salvo,
M. Turatto
Abstract:
About 500d after explosion the light curve of the Type Ia SN1998bu suddenly flattened and at the same time the spectrum changed from the typical nebular emission to a blue continuum with broad absorption and emission features reminiscent of the SN spectrum at early phases. We show that in analogy to SN1991Tbu (Schmidt et al. 1994), this can be explained by the emergence of a light echo from a fo…
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About 500d after explosion the light curve of the Type Ia SN1998bu suddenly flattened and at the same time the spectrum changed from the typical nebular emission to a blue continuum with broad absorption and emission features reminiscent of the SN spectrum at early phases. We show that in analogy to SN1991Tbu (Schmidt et al. 1994), this can be explained by the emergence of a light echo from a foreground dust cloud. Based on a simple model we argue that the amount of dust required can consistently explain the extinction which has been estimated by completely independent methods. Because of the similar echo luminosity but much higher optical depth of the dust in SN1998bu compared with SN1991T, we expect that the echo ring size of SN1998bu grows faster than in SN1991T. HST observations have indeed confirmed this prediction.
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Submitted 19 January, 2001;
originally announced January 2001.
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The template type Ia supernova 1996X
Authors:
M. E. Salvo,
E. Cappellaro,
P. A. Mazzali,
S. Benetti,
I. J. Danziger,
F. Patat,
M. Turatto
Abstract:
UBVRIJ photometry and optical spectra of the Type Ia SN 1996X obtained at ESO during a one-year-long observational campaign are presented, and supplemented by late time HST photometry. Spectroscopically, SN 1996X appears to be a `normal' SN Ia. The apparent magnitude at maximum was B=13.24 +/- 0.02, and the colour B-V=0.00 +/- 0.03. The luminosity decline rate, Delta m_B(15) = 1.31 +/- 0.08, is…
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UBVRIJ photometry and optical spectra of the Type Ia SN 1996X obtained at ESO during a one-year-long observational campaign are presented, and supplemented by late time HST photometry. Spectroscopically, SN 1996X appears to be a `normal' SN Ia. The apparent magnitude at maximum was B=13.24 +/- 0.02, and the colour B-V=0.00 +/- 0.03. The luminosity decline rate, Delta m_B(15) = 1.31 +/- 0.08, is close to average for a SN Ia. The best estimate of the galactic extinction is A_B=0.30 +/- 0.05, and there is evidence that reddening within the parent galaxy is negligible. Detailed comparison of the light and colour curves of various `normal' SNe Ia shows that the assumption that multicolour light curves can be described simply as a one-parameter family is not perfect. Together with problems in the calibration of the templates, this may explain the discrepancies in the distance modulus derived adopting different calibrations of the absolute magnitude vs. light curve shape relations. Indeed we found that M_B ranges from -19.08 to -19.48 and M-m range from 32.02 to 32.48 depending on the method used (Hamuy et al. 1996a,Phillips et al. 1999, Riess et al. 1998a). Computations of model light curve and synthetic spectra for both early- and late-times, confirm that 1996X is a normal Type Ia SN and that a satisfactory fit can be obtained using a W7 progenitor structure only if we adopt the short distance. A larger distance would imply a too large Ni mass for this fainter than average SNIa.
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Submitted 5 September, 2000;
originally announced September 2000.