The influence of host galaxy morphology on the properties of Type Ia supernovae from the JLA compilation

Abstract

The observational cosmology with distant Type Ia supernovae (SNe) as standard candles claims that the Universe is in accelerated expansion, caused by a large fraction of dark energy. In this paper we investigate the SN Ia environment, studying the impact of the nature of their host galaxies on the Hubble diagram fitting. The supernovae (192 SNe) used in the analysis were extracted from Joint-Light-curves-Analysis (JLA) compilation of high-redshift and nearby supernovae which is the best one to date. The analysis is based on the empirical fact that SN Ia luminosities depend on their light curve shapes and colors. We confirm that the stretch parameter of Type Ia supernovae is correlated with the host galaxy type. The supernovae with lower stretch are hosted mainly in elliptical and lenticular galaxies. No significant correlation between SN Ia colour and host morphology was found.We also examine how the luminosities of SNe Ia change depending on host * Corresponding author Email addresses: henne-vincent@wanadoo.fr (V. Henne), pruzhinskaya@gmail.com (M. V. Pruzhinskaya), philippe.rosnet@clermont.in2p3.fr (P. Rosnet), pierre-francois.leget@clermont.in2p3.fr (P.-F. Léget), emille.ishida@clermont.in2p3.fr (E. E. O. Ishida), ciulli@clermont.in2p3.fr (A. Ciulli), philippe.gris@clermont.in2p3.fr (P. Gris), louis-pierre.says@clermont.in2p3.fr (L.-P. Says), emmanuel.gangler@clermont.in2p3.fr (and E. Gangler) Preprint submitted to New AstronomyAugust 15, 2016 galaxy morphology after stretch and colour corrections. Our results show that in old stellar populations and low dust environments, the supernovae are slightly fainter. SNe Ia in elliptical and lenticular galaxies have a higher α (slope in luminosity-stretch) and β (slope in luminosity-colour) parameter than in spirals. However, the observed shift is at the 1-σ uncertainty level and, therefore, can not be considered as significant. We confirm that the supernova properties depend on their environment and that the incorporation of a host galaxy term into the Hubble diagram fit is expected to be crucial for future cosmological analyses.

Type Ia supernovae with and without blueshifted narrow Na i D lines – how different is their structure?

“…We note that the low value of Fe-group elements in the analysed layers of no-Na SNe may simply reflect a lower-than-average 56 Ni production in these SNe (rather than only a difference in the distribution, as expected between equally-luminous double-degenerate and singledegenerate explosions). The lower value for the no-Na subsample would then be in line with the typically lower luminosities in the explosion sites of these objects, which are mainly early-type galaxies (Hamuy et al 2000;Gallagher et al 2008;Maguire et al 2013;Ashall et al 2016a;Henne et al 2017). For redshifted-Na SNe, a more likely explanation would be 'real' differences in the explosion properties (as luminosities are relatively similar among our redshifted-Na and blueshifted-Na objects).…”

Projected distances to host galaxy reduce SNIa dispersion

“…They found a strong difference in the stretch parameter, x1, for the two groups, but no significant difference in the colour, concluding that SNIae must have the same intrinsic colour variations in all galaxy types. This conclusion was confirmed by Henne et al (2017), who examined the influence of galaxy morphology by classifying hosts in three groups -ellipticals/lenticulars (E,S0), early-type spirals (Sa-Sc), late-type spirals (Sd-Ir)for 192 SNIae from JLA. While they reported 1σ shifts in the reconstructed values of α, β depending on galactic morphology group, they did not find any significant correlation between colour and host morphology.…”

Influence of Type Ia Supernova Environment and Their Peculiar Velocities on Distance measurements

“…To understand the reason of the remaining luminosity variability in standardization models, we investigate how the model parameters correlate with supernovae environment: the galocentric distance and the galaxy morphology (see [1,18]).…”

“…In [1] the host galaxy morphology for 192 SNe Ia from the nearby and SDSS JLA (Joint Lightcurve Analysis, [14]) sample was derived. The supernovae were divided into three subsamples depending on host morphology: elliptical/lenticular (E/L), early-type spiral (ES), and late-type spiral galaxies (LS).…”