Suchergebnisse

The Type Ia supernova (SN Ia) LSQ14fmg exhibits exaggerated properties that may help to reveal the origin of the "super-Chandrasekhar" (or 03fg-like) group. The optical spectrum is typical of a 03fg-like SN Ia, but the light curves are unlike those of any SNe Ia observed. The light curves of LSQ14fmg rise extremely slowly. At -23 rest-frame days relative toB-band maximum, LSQ14fmg is already brighter thanJandHbands, far more luminous than any 03fg-like SNe Ia with near-infrared observations. At 1 month past maximum, the optical light curves decline rapidly. The early, slow rise and flat color evolution are interpreted to result from an additional excess flux from a power source other than the radioactive decay of the synthesized Ni-56. The excess flux matches the interaction with a typical superwind of an asymptotic giant branch (AGB) star in density structure, mass-loss rate, and duration. The rapid decline starting at around 1 month pastB-band maximum may be an indication of rapid cooling by active carbon monoxide (CO) formation, which requires a low-temperature and high-density environment. These peculiarities point to an AGB progenitor near the end of its evolution and the core degenerate scenario as the likely explosion mechanism for LSQ14fmg. ; National Science Foundation (NSF) AST-1008343 AST-1613426 AST-1613455 AST-1613472 AST-1008962 AST-1907570 AST1920392 AST-1911074 AST-1515927 AST1908570 AST-0908816 Danish Agency for Science and Technology and Innovation through a Sapere Aude Level 2 grant European Union's Horizon 2020 research and innovation program under Marie Sklodowska-Curie grant 839090 European Union (EU) PGC2018-095317-B-C21 DiRAC Institute in the Department of Astronomy at the University of Washington George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy Mitchell Foundation Academy of Finland 324504 328898 National Aeronautics & Space Administration (NASA) 80NSSC19K1717 Gordon and Betty Moore Foundation GBMF5490 Mt. Cuba Astronomical Foundation Ohio State University Chinese Academy of Sciences South America Center for Astronomy (CASSACA) Villum Foundation Independent Research Fund Denmark (IRFD) 8021-00170B VILLUM FONDEN 13261 28021 ESO Telescopes at the Paranal Observatory 099. D-0022(A)

Galaxies with stellar masses near M* contain the majority of stellar mass in the universe, and are therefore of special interest in the study of galaxy evolution. The Milky Way (MW) and Andromeda (M31) have present-day stellar masses near M*, at 5 x 10(10) M-circle dot (defined here to be MW-mass) and 10(11) M-circle dot (defined to be M31-mass). We study the typical progenitors of these galaxies using the FOURSTAR Galaxy Evolution Survey (ZFOURGE). ZFOURGE is a deep medium-band near-IR imaging survey, which is sensitive to the progenitors of these galaxies out to z similar to 3. We use abundance-matching techniques to identify the main progenitors of these galaxies at higher redshifts. We measure the evolution in the stellar mass, rest-frame colors, morphologies, far-IR luminosities, and star formation rates, combining our deep multiwavelength imaging with near-IR Hubble Space Telescope imaging from Cosmic Near-IR Deep Extragalactic Legacy Survey (CANDELS), and Spitzer and Herschel far-IR imaging from Great Observatories Origins Deep Survey-Herschel and CANDELS-Herschel. The typical MW-mass and M31-mass progenitors passed through the same evolution stages, evolving from blue, star-forming disk galaxies at the earliest stages to redder dust-obscured IR-luminous galaxies in intermediate stages and to red, more quiescent galaxies at their latest stages. The progenitors of the MW-mass galaxies reached each evolutionary stage at later times (lower redshifts) and with stellar masses that are a factor of two to three lower than the progenitors of the M31-mass galaxies. The process driving this evolution, including the suppression of star formation in present-day M* galaxies, requires an evolving stellar-mass/halo-mass ratio and/or evolving halo-mass threshold for quiescent galaxies. The effective size and SFRs imply that the baryonic cold-gas fractions drop as galaxies evolve from high redshift to z similar to 0 and are strongly anticorrelated with an increase in the Sersic index. Therefore, the growth of galaxy bulges in M* galaxies corresponds to a rapid decline in the galaxy gas fractions and/or a decrease in the star formation efficiency. ; National Science Foundation AST-1009707, AST-0808133 ; ERC HIGHZ 227749 ; NL-NWO Spinoza ; NASA NAS5-26555 ; HST program GO-12060 ; National Collaborative Research Infrastructure Strategy of the Australian Federal Government ; Texas A&M University ; George P. and Cynthia Woods Institute for Fundamental Physics and Astronomy ; Astronomy