NOAO > Observing Info > Approved Programs > 2013B-0344
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NOAO > Observing Info > Approved Programs > 2013B-0344 |
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PI: Melissa L. Graham, UCSB/LCOGT, mgraham@lcogt.net
Address: 6740 Cortona Drive, Goleta, CA 93117, USA
CoI: David Sand, Texas Tech
CoI: Jerod Parrent, Dartmouth/LCOGT
CoI: D. Andrew Howell, UCSB/LCOGT
CoI: Stefano Valenti, UCSB/LCOGT
Title: Understanding the Power Source in Type Ia Supernovae with Nebular Phase Spectroscopy
Abstract:
Type Ia supernovae (SNeIa) will not be above suspicion as standard candles
until their progenitor scenario and explosion mechanism are well understood.
Nebular phase spectra, taken once the ejecta is optically thin, provide
several unique diagnostics and are the only way to directly observe the power
source in SNeIa: radioactive nickel-56. We propose to obtain 1-2 epochs of
nebular phase spectroscopy for 4 bright SNeIa with GMOS. Our science goals
are threefold: 1) identify the binary companion star type in the progenitor
system by constraining the amount of hydrogen in the circumstellar medium, 2)
explore the physical cause of the width-luminosity relation (through which
SNeIa are standardized) by investigating the discrepancy between nickel mass
estimates from peak luminosity and nebular spectra, and 3) evaluate the
asymmetric explosion model by comparing the silicon line velocity at early
times with shifts of the iron lines in nebular spectra. This proposal
leverages both the wide-field low-z discovery power of recent surveys, and
the new robotic capabilities of the Las Cumbres Observatory Global Telescope
Network with which requisite early-time spectroscopic and photometric
monitoring is done or underway. Every rare nebular spectrum provides unique
constraints on SNIa explosion models; these data will advance our
understanding of SNeIa and help improve their use as cosmological probes.
National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360
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NOAO > Observing Info > Approved Programs > 2013B-0344 |
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