Thomas Matheson

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We present constraints on the dark energy equation-of-state parameter, w = P/(ρc), 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 (ΩM, w) from baryon acoustic oscillations, we obtain a value for a static(More)
The High-z Supernova Search Team has discovered and observed 8 new supernovae in the redshift interval z = 0.3–1.2. These independent observations, analyzed by similar but distinct methods, confirm the result of Riess et al. (1998a) and Perlmutter et al. (1999) that supernova luminosity distances imply an accelerating universe. More importantly, they extend(More)
The Arizona-NOAO Temporal Analysis and Response to Events System (ANTARES) is a joint project of the National Optical Astronomy Observatory and the Department of Computer Science at the University of Arizona. The goal is to build the software infrastructure necessary to process and filter alerts produced by time-domain surveys, with the ultimate source of(More)
We present extensive optical and infrared photometry of the afterglow of gamma-ray burst (GRB) 030329 and its associated supernova (SN) 2003dh over the first two months after detection (2003 March 30-May 29 UT). Optical spectroscopy from a variety of telescopes is shown and, when combined with the photometry, allows an unambiguous separation between the(More)
Based on data from the MMTO 6.5m telescope, the Magellan 6.5m Clay telescope, and the FLWO 1.5m telescope Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138; kstanek, tmatheson, ncaldwell, pchallis, wbrown, rschild, dbersier@cfa.harvard.edu Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre(More)
Type Ic supernovae, the explosions after the core collapse of massive stars that have previously lost their hydrogen and helium envelopes, are particularly interesting because of their link with long-duration gamma ray bursts. Although indications exist that these explosions are aspherical, direct evidence has been missing. Late-time observations of(More)
Core-collapse supernovae (CC-SNe) are the explosions that announce the death of massive stars. Some CC-SNe are linked to long-duration gamma-ray bursts (GRBs) and are highly aspherical. One important question is to what extent asphericity is common to all CC-SNe. Here we present late-time spectra for a number of CC-SNe from stripped-envelope stars and use(More)
We report the successful identification of the type of the supernova responsible for the supernova remnant SNR 0509-675 in the Large Magellanic Cloud (LMC) using Gemini spectra of surrounding light echoes. The ability to classify outbursts associated with centuries-old remnants provides a new window into several aspects of supernova research and is likely(More)
The spectra of SN 2003dh, identified in the afterglow of GRB030329, are modelled using radiation transport codes. It is shown that SN 2003dh had a high explosion kinetic energy (∼ 4× 10 erg), making it one of the most powerful hypernovae observed so far, and supporting the case for association between hypernovae and Gamma Ray Bursts. However, the light(More)
The two peculiar Type Ic supernovae (SNe) 1997ef and 1997dq are shown to have very similar photometric and spectral evolution in the epochs when both SNe are observed (i.e., beyond ∼ 80 days after the explosion). The early light curves and spectra of SN 1997ef suggested that this was a “hypernova,” or “SN 1998bw-like Type Ic supernova.” The fact that the(More)