Showing papers by "Robert Quimby published in 2005"
University of Michigan1, Goddard Space Flight Center2, Universities Space Research Association3, Max Planck Society4, University of New South Wales5, Sabancı University6, Istanbul University7, Middle East Technical University8, Çanakkale Onsekiz Mart University9, University of Texas at Austin10, Louisiana State University11, Los Alamos National Laboratory12
TL;DR: In this paper, the ROTSE-IIIa telescope at Siding Spring Observatory, Australia, detected prompt optical emission from Swift GRB 050401, which was neither exceptionally long nor bright.
Abstract: The ROTSE-IIIa telescope at Siding Spring Observatory, Australia, detected prompt optical emission from Swift GRB 050401. We present observations of the early optical afterglow, first detected by the ROTSE-IIIa telescope 33 s after the start of γ-ray emission, contemporaneous with the brightest peak of this emission. This GRB was neither exceptionally long nor bright. This is the first prompt optical detection of a GRB of typical duration and luminosity. We find that the early afterglow decay does not deviate significantly from the power-law decay observable at later times and is uncorrelated with the prompt γ-ray emission. We compare this detection with the other two GRBs with prompt observations, GRB 990123 and GRB 041219a. All three bursts exhibit quite different behavior at early times.
66 citations
TL;DR: In this article, the spectral evolution, light curve, and corresponding interpretation for the "normal-bright" Type Ia Supernova 2005cg discovered by ROTSE-IIIc were presented.
Abstract: We present the spectral evolution, light curve, and corresponding interpretation for the "normal-bright" Type Ia Supernova 2005cg discovered by ROTSE-IIIc. The host is a low-luminosity (M_r = -16.75), blue galaxy with strong indications of active star formation and an environment similar to that expected for SNe Ia at high redshifts. Early-time (t ~ -10 days) optical spectra obtained with the HET reveal an asymmetric, triangular-shaped Si II absorption feature at about 6100 \AA with a sharp transition to the continuum at a blue shift of about 24,000 km s^-1. By 4 days before maximum, the Si II absorption feature becomes symmetric with smoothly curved sides. Similar Si II profile evolution has previously been observed in other supernovae, and is predicted by some explosion models, but its significance has not been fully recognized. Although the spectra predicted by pure deflagration and delayed detonation models are similar near maximum light, they predict qualitatively different chemical abundances in the outer layers and thus give qualitatively different spectra at the earliest phases. The Si line observed in SN 2005cg at early times requires the presence of burning products at high velocities and the triangular shape is likely to be formed in an extended region of slowly declining Si abundance that characterizes delayed detonation models. The spectra show a high-velocity Ca II IR feature that coincides in velocity space with the Si II cutoff. This supports the interpretation that the Ca II is formed when the outer layers of the SN ejecta sweep up about 5 x 10^-3 M_sun of material within the progenitor system. (Abridged)
59 citations
TL;DR: In this paper, the results of a search for untriggered gamma-ray burst (GRB) afterglows with the Robotic Optical Transient Search Experiment-III (ROTSE-III) telescope array were presented.
Abstract: We present the results of a search for untriggered gamma-ray burst (GRB) afterglows with the Robotic Optical Transient Search Experiment-III (ROTSE-III) telescope array. This search covers observations from 2003 September to 2005 March. We have an effective coverage of 1.74 deg2 yr for rapidly fading transients that remain brighter than ~17.5 mag for more than 30 minutes. This search is the first large-area survey to be able to detect typical untriggered GRB afterglows. Our background rate is very low and purely astrophysical. We have found four previously unknown cataclysmic variables (CVs) and one new flare star. We have not detected any candidate afterglow events or other unidentified transients. We can place an upper limit on the rate of fading optical transients with quiescent counterparts dimmer than ~20th magnitude at a rate of less than 1.9 deg-2 yr-1 with 95% confidence. This places limits on the optical characteristics of off-axis (orphan) GRB afterglows. As a by-product of this search, we have an effective ~52 deg2 yr of coverage for very slowly decaying transients, such as CVs. This implies an overall rate of outbursts from high Galactic latitude CVs of 0.1 deg-2 yr-1.
50 citations
Pierre-and-Marie-Curie University1, Stockholm University2, European Southern Observatory3, Lawrence Berkeley National Laboratory4, Colorado College5, University of California, Berkeley6, American Astronomical Society7, California Institute of Technology8, Centra9, University of Oxford10, Vanderbilt University11, University of Barcelona12
TL;DR: In this article, the authors presented a technique for fitting restframe I-band light curves on a data set of 42 type la supernovae (SNe Ia) and constructed a Hubble diagram with 26 SNe from the subset at 0.01 < z < 0.1.
Abstract: We present a novel technique for fitting restframe I-band light curves on a data set of 42 type la Supernovae (SNe Ia). Using the result of the fit, we construct a Hubble diagram with 26 SNe from the subset at 0.01 < z < 0.1. Adding two SNe at z ∼ 0.5 yields results consistent with a flat Λ-dominated "concordance universe" (ΩM, ΩΛ) = (0.25, 0.75). For one of these, SN 2000fr, new near infrared data are presented. The high redshift supernova NIR data are also used to test for systematic effects in the use of SNe la as distance estimators. A flat, Λ = 0, universe where the faintness of supernovae at z ∼ 0.5 is due to grey dust homogeneously distributed in the intergalactic medium is disfavoured based on the high-z Hubble diagram using this small data-set. However, the uncertainties are large and no firm conclusion may be drawn. We explore the possibility of setting limits on intergalactic dust based on B - I and B - V colour measurements, and conclude that about 20 well measured SNe are needed to give statistically significant results. We also show that the high redshift restframe I-band data points are better fit by light curve templates that show a prominent second peak, suggesting that they are not intrinsically underluminous. © ESO 2005.
48 citations
Stockholm University1, University of Paris2, Association of Universities for Research in Astronomy3, Lawrence Berkeley National Laboratory4, University of Paris-Sud5, INAF6, University of California, Berkeley7, American Astronomical Society8, California Institute of Technology9, Technical University of Lisbon10, University of Arizona11, Vanderbilt University12, New Mexico State University13, University of Oxford14, University of Toronto15, Fermilab16, European Southern Observatory17, University of Barcelona18, San Diego State University19, University of Illinois at Urbana–Champaign20, Centre national de la recherche scientifique21, Rensselaer Polytechnic Institute22, Princeton University23, Louisiana State University24, University of Cambridge25
TL;DR: In this paper, the authors present optical spectra of the peculiar Type Ia supernova (SN Ia) 1999ac, which extends from -15 to +42 days with respect to B-band maximum and reveal an event that is unusual in several respects.
Abstract: The authors present optical spectra of the peculiar Type Ia supernova (SN Ia) 1999ac. The data extend from -15 to +42 days with respect to B-band maximum and reveal an event that is unusual in several respects. prior to B-band maximum, the spectra resemble those of SN 1999aa, a slowly declining event, but possess stronger Si II and Ca II signatures (more characteristic of a spectroscopically normal SN). Spectra after B-band maximum appear more normal. The expansion velocities inferred from the Iron lines appear to be lower than average; whereas, the expansion velocity inferred from Calcium H and K are higher than average. The expansion velocities inferred from the Iron lines appear to be lower than average; whereas, the expansion velocity inferred from Calcium H and K are higher than average. The expansion velocities inferred from Si II are among the slowest ever observed, though SN 1999ac is not particularly dim. The analysis of the parameters v{sub 10}(Si II), R(Si II), v, and {Delta}m{sub 15} further underlines the unique characteristics of SN 1999ac. They find convincing evidence of C II {lambda}6580 in the day -15 spectrum with ejection velocity v > 16,000 km s{sup -1}, but this signature disappears bymore » day -9. This rapid evolution at early times highlights the importance of extremely early-time spectroscopy.« less
47 citations
European Southern Observatory1, Lawrence Berkeley National Laboratory2, University of Toronto3, Stockholm University4, Pierre-and-Marie-Curie University5, Colorado College6, University of California, Berkeley7, American Astronomical Society8, University of Tokyo9, California Institute of Technology10, Centra11, University of Oxford12, Vanderbilt University13, University of Barcelona14, Louisiana State University15, University of Cambridge16
TL;DR: In this article, the authors presented VLT FORS1 and FORS2 spectra of 39 candidate high-redshift supernovae that were discovered as part of a cosmological study using type Ia supernova (SNe Ia) over a wide range of redshifts.
Abstract: We present VLT FORS1 and FORS2 spectra of 39 candidate high-redshift supernovae that were discovered as part of a cosmological study using type Ia supernovae (SNe Ia) over a wide range of redshifts. From the spectra alone, 20 candidates are spectrally classified as SNe Ia with redshifts ranging from z = 0.212 to z = 1.181. Of the remaining 19 candidates, 1 might be a type II supernova and 11 exhibit broad supernova-like spectral features and/or have supernova-like light curves. The candidates were discovered in 8 separate ground-based searches. In those searches in which SNe Ia at z {approx} 0.5 were targeted, over 80 percent of the observed candidates were spectrally classified as SNe Ia. In those searches in which SNe Ia with z > 1 were targeted, 4 candidates with z > 1 were spectrally classified as SNe Ia and later followed with ground and space based observatories. We present the spectra of all candidates, including those that could not be spectrally classified as supernova.
45 citations
Journal Article•
University of Paris1, Stockholm University2, Association of Universities for Research in Astronomy3, Lawrence Berkeley National Laboratory4, University of Paris-Sud5, INAF6, University of California, Berkeley7, American Astronomical Society8, California Institute of Technology9, Technical University of Lisbon10, University of Arizona11, Vanderbilt University12, New Mexico State University13, University of Oxford14, University of Toronto15, Fermilab16, European Southern Observatory17, University of Barcelona18, San Diego State University19, University of Illinois at Urbana–Champaign20, Centre national de la recherche scientifique21, Rensselaer Polytechnic Institute22, Princeton University23, Louisiana State University24, University of Cambridge25
TL;DR: In this paper, the authors present optical spectra of the peculiar Type Ia supernova (SN Ia) 1999ac, which extends from -15 to +42 days with respect to B-band maximum and reveal an event that is unusual in several respects.
Abstract: The authors present optical spectra of the peculiar Type Ia supernova (SN Ia) 1999ac. The data extend from -15 to +42 days with respect to B-band maximum and reveal an event that is unusual in several respects. prior to B-band maximum, the spectra resemble those of SN 1999aa, a slowly declining event, but possess stronger Si II and Ca II signatures (more characteristic of a spectroscopically normal SN). Spectra after B-band maximum appear more normal. The expansion velocities inferred from the Iron lines appear to be lower than average; whereas, the expansion velocity inferred from Calcium H and K are higher than average. The expansion velocities inferred from the Iron lines appear to be lower than average; whereas, the expansion velocity inferred from Calcium H and K are higher than average. The expansion velocities inferred from Si II are among the slowest ever observed, though SN 1999ac is not particularly dim. The analysis of the parameters v{sub 10}(Si II), R(Si II), v, and {Delta}m{sub 15} further underlines the unique characteristics of SN 1999ac. They find convincing evidence of C II {lambda}6580 in the day -15 spectrum with ejection velocity v > 16,000 km s{sup -1}, but this signature disappears bymore » day -9. This rapid evolution at early times highlights the importance of extremely early-time spectroscopy.« less
7 citations
01 Apr 2005
TL;DR: In this paper, the authors presented a technique for fitting restframe I-band light curves on a data set of 42 type Ia supernovae (SNe Ia), and constructed a Hubble diagram with 26 SNe from the subset at 0.01 < z < 0.1.
Abstract: We present a novel technique for fitting restframe I-band light curves on a data set of 42 type Ia supernovae (SNe Ia). Using the result of the fit, we construct a Hubble diagram with 26 SNe from the subset at 0.01 < z < 0.1. Adding two SNe at z ~; 0.5 yields results consistent with a flat Lambda-dominated concordance universe (OmegaM, Omega Lambda) = (0.25, 0.75). For one of these, SN 2000fr, new near infrared data are presented. The high redshift supernova NIR data are also used to test for systematic effects in the use of SNe Ia as distance estimators. A flat, Lambda = 0, universe where the faintness of supernovae at z ~; 0.5 is due to grey dust homogeneously distributed in the intergalactic medium is disfavoured based on the high-z Hubble diagram using this small data-set. However, the uncertainties are large and no firm conclusion may be drawn. We explore the possibility of setting limits on intergalactic dust based on B - I and B - V colour measurements, and conclude that about 20 well measured SNe are needed to give statistically significant results. We also show that the high redshift restframe I-band data points are better fit by light curve templates that show a prominent second peak, suggesting that they are not intrinsically underluminous.
1 citations