NOAO >   Observing Info >   Approved Programs >   2016A-0046

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Program Information for 2016A-0046


PI: Melissa L. Graham, UC Berkeley, mlg3k@uw.edu
Address: Astronomy Department, 501 Campbell Hall # 3411, University of California at Berkeley, Berkeley, CA, 94720-3411 USA

CoI: David Sand, Texas Technical University
CoI: Jerod Parrent, Harvard-Smithsonian Center for Astrophysics
CoI: D. Andrew Howell, Las Cumbres Observatory
CoI: Stefano Valenti, Las Cumbres Observatory
CoI: Paolo Mazzali, Liverpool John Moores University
CoI: Iair Arcavi, Las Cumbres Observatory
CoI: Sahana Kumar, UC Berkeley
CoI: Curtis McCully, Las Cumbres Observatory

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 nearby SNeIa with GMOS-South. 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 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 advance our understanding of SNeIa and help improve their use as cosmological probes.

Program Type: Standard/Extragalactic

Scheduled Nights:
Run 1 (2016A):  GEM-SQ/GMOSS -- 23.9hrs band 2 (GS-2016A-Q-61)


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NOAO >   Observing Info >   Approved Programs >   2016A-0046

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