KECK OBSERVATIONS OF THE YOUNG METAL-POOR HOST GALAXY OF THE SUPER-CHANDRASEKHAR-MASS TYPE Ia SUPERNOVA SN 2007if
/ Authors
Michael Childress, Michael Childress, G. Aldering, C. Aragon, P. Antilogus, S. Bailey, C. Baltay, S. Bongard, C. Buton, A. Canto
and 25 more authors
N. Chotard, Y. Copin, H. Fakhouri, H. Fakhouri, E. Gangler, M. Kerschhaggl, M. Kowalski, E. Hsiao, S. Loken, P. Nugent, K. Paech, R. Pain, E. Pecontal, R. Pereira, S. Perlmutter, S. Perlmutter, D. Rabinowitz, K. Runge, R. Scalzo, R. Scalzo, R. Thomas, G. Smadja, C. Tao, B. Weaver, C. Wu
/ Abstract
We present Keck LRIS spectroscopy and g-band photometry of the metal-poor, low-luminosity host galaxy of the super-Chandrasekhar-mass Type Ia supernova SN 2007if. Deep imaging of the host reveals its apparent magnitude to be mg = 23.15 ± 0.06, which at the spectroscopically measured redshift of zhelio = 0.07450 ± 0.00015 corresponds to an absolute magnitude of Mg = −14.45 ± 0.06. Galaxy g − r color constrains the mass-to-light ratio, giving a host stellar mass estimate of log(M*/M☉) = 7.32 ± 0.17. Balmer absorption in the stellar continuum, along with the strength of the 4000 Å break, constrains the age of the dominant starburst in the galaxy to be tburst = 123+165−77 Myr, corresponding to a main-sequence turnoff mass of M/M☉ = 4.6+2.6−1.4. Using the R23 method of calculating metallicity from the fluxes of strong emission lines, we determine the host oxygen abundance to be 12 + log(O/H)KK04 = 8.01 ± 0.09, significantly lower than any previously reported spectroscopically measured Type Ia supernova host galaxy metallicity. Our data show that SN 2007if is very likely to have originated from a young, metal-poor progenitor.
Journal: The Astrophysical Journal