Supernovae and their host galaxies — VI. Normal Type Ia and 91bg-like supernovae in ellipticals. (arXiv:1906.10501v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Barkhudaryan_L/0/1/0/all/0/1">L. V. Barkhudaryan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hakobyan_A/0/1/0/all/0/1">A. A. Hakobyan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Karapetyan_A/0/1/0/all/0/1">A. G. Karapetyan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mamon_G/0/1/0/all/0/1">G. A. Mamon</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kunth_D/0/1/0/all/0/1">D. Kunth</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Adibekyan_V/0/1/0/all/0/1">V. Adibekyan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Turatto_M/0/1/0/all/0/1">M. Turatto</a>
With the aim to find links between the properties of supernova (SN) Ia
progenitors and elliptical host stellar populations, we present an analysis of
the galactocentric distributions of the “normal” and peculiar “91bg-like”
subclasses of SNe Ia, and study the global parameters (absolute magnitude,
colour, size, stellar mass, metallicity and age) of their host galaxies. We use
a well-defined sample of morphologically non-disturbed 109 SNe Ia host
ellipticals from the Sloan Digital Sky Survey. The galactocentric distributions
of normal and 91bg-like SNe are consistent with each other, and with the radial
light distribution of host stellar populations, when excluding bias against
central SNe. Among the global parameters, only the distributions of u-r colours
and ages are inconsistent significantly between the ellipticals of different SN
Ia subclasses: the hosts of normal SNe are on average bluer and younger than
those of 91bg-like SNe. In the colour-mass diagram, the tail of colour
distribution of normal SN hosts stretches into the Green Valley – transitional
state of galaxy evolution, while the same tail of 91bg-like SN hosts barely
reaches that region. Therefore, the bluer and younger ellipticals might have
more residual star formation that gives rise to younger “prompt” progenitors,
resulting in normal SNe Ia with shorter delay times. These ellipticals can also
produce “delayed” 91bg-like events with lower rate, because of long delay times
of these SNe. The redder and older ellipticals that already exhausted their gas
for star formation may produce significantly less normal SNe Ia with shorter
delay times, outnumbered by 91bg-like SNe with long delay times. Our results
favor SN Ia progenitor models such as He-ignited violent mergers as a unified
model for normal and 91bg-like SNe that have the potential to explain their
observed properties.
With the aim to find links between the properties of supernova (SN) Ia
progenitors and elliptical host stellar populations, we present an analysis of
the galactocentric distributions of the “normal” and peculiar “91bg-like”
subclasses of SNe Ia, and study the global parameters (absolute magnitude,
colour, size, stellar mass, metallicity and age) of their host galaxies. We use
a well-defined sample of morphologically non-disturbed 109 SNe Ia host
ellipticals from the Sloan Digital Sky Survey. The galactocentric distributions
of normal and 91bg-like SNe are consistent with each other, and with the radial
light distribution of host stellar populations, when excluding bias against
central SNe. Among the global parameters, only the distributions of u-r colours
and ages are inconsistent significantly between the ellipticals of different SN
Ia subclasses: the hosts of normal SNe are on average bluer and younger than
those of 91bg-like SNe. In the colour-mass diagram, the tail of colour
distribution of normal SN hosts stretches into the Green Valley – transitional
state of galaxy evolution, while the same tail of 91bg-like SN hosts barely
reaches that region. Therefore, the bluer and younger ellipticals might have
more residual star formation that gives rise to younger “prompt” progenitors,
resulting in normal SNe Ia with shorter delay times. These ellipticals can also
produce “delayed” 91bg-like events with lower rate, because of long delay times
of these SNe. The redder and older ellipticals that already exhausted their gas
for star formation may produce significantly less normal SNe Ia with shorter
delay times, outnumbered by 91bg-like SNe with long delay times. Our results
favor SN Ia progenitor models such as He-ignited violent mergers as a unified
model for normal and 91bg-like SNe that have the potential to explain their
observed properties.
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