Supernovae and their host galaxies

Abstract

Context. In this first paper of a series, we report the creation of large and well-defined database that combines extensive new measurements and a literature search of 3876 supernovae (SNe) and their 3679 host galaxies located in the sky area covered by the Sloan Digital Sky Survey (SDSS) Data Release 8 (DR8). Aims. This database should be much larger than previous ones, and should contain a homogenous set of global parameters of SN hosts, including morphological classifications and measures of nuclear activity. Methods. The measurements of apparent magnitudes, diameters (D 25 ), axial ratios (b/a), and position angles (PA) of SN host galaxies were made using the images extracted from the SDSS g-band. For each host galaxy, we analyzed RGB images of the SDSS to accurately measure the position of its nucleus to provide the SDSS name. With these images, we also provide the host galaxy's morphological type, and note if it has a bar, a disturbed disk, and whether it is part of an interacting or merging system. In addition, the SDSS nuclear spectra were analyzed to diagnose the central power source of the galaxies. Special attention was paid to collect accurate data on the spectroscopic classes, coordinates, offsets of SNe, and heliocentric redshifts of the host galaxies. Results. Identification of the host galaxy sample is 91% complete (with 3536 SNe in 3340 hosts), of which the SDSS names of ∼1100 anonymous hosts are listed for the first time. The morphological classification is available for 2104 host galaxies, including 73 (56) hosts in interacting (merging) systems. The total sample of host galaxies collects heliocentric redshifts for 3317 (∼90%) galaxies. The g-band magnitudes, D 25 , b/a, and PA are available for 2030 hosts of the morphologically classified sample of galaxies. Nuclear activity measures are provided for 1189 host galaxies. We analyze and discuss many selection effects and biases that can significantly affect any future analysis of our sample. Conclusions. The creation of this large database will help to better understand how the different types of SNe are correlated with the properties of the nuclei and global physical parameters of the host galaxies, and minimize possible selection effects and errors that often arise when data are selected from different sources and catalogs.

Supernovae and their host galaxies – II. The relative frequencies of supernovae types in spirals

“…In this second paper of a series, using a well-defined and homogeneous sample of host galaxies from the SDSS, presented in the first paper (Hakobyan et al 2012), we analyse the number ratios of different SN types (NIa/NCC, N Ibc /NII, and NIc/N Ib ) in spirals with various morphologies and in barred or unbarred galaxies. We also explore the variations in the number ratios with different levels of morphological disturbance of the hosts.…”

“…It is important to take into account the fact that SNe Ia explode in all morphological types of galaxies, while CC SNe explode mostly in spiral and irregular hosts (e.g. van den Bergh, Li & Filippenko 2005;Hakobyan et al 2008Hakobyan et al , 2012. Therefore, to exclude SNe type biasing due to host-galaxy morphology, we further restrict the sample to SNe detected in spiral galaxies (including S0/a types).…”

LOSS Revisited. I. Unraveling Correlations between Supernova Rates and Galaxy Properties, as Measured in a Reanalysis of the Lick Observatory Supernova Search

“…We do not show these measurements in Figure 10, but note that as they vary in the range ≈ 0.2-0.4, they would be broadly consistent with the other measurements in the plot. Hakobyan et al (2012Hakobyan et al ( , 2014 used a subsample of SNe from the Asiago Supernova Catalog (Barbon et al 1999) and the Sternberg Astronomical Institute (SAI) Supernova Catalog (Tsvetkov et al 2004) to measure N Ibc /N II in galaxies with different morphologies and disturbance levels (e.g., interacting vs. merging galaxies). They found that N Ibc /N II is lower in late-type (Sc-Sm) galaxies than in early-type (S0/a-Sbc) at a 5% significance level, which is consistent with the trend we observe.…”

Moderately luminous Type II supernovae

“…SN 2007pk (Fig. 2), discovered in the Scd galaxy NGC 579 (Hakobyan et al 2012) on 2007 November 10.31 UT, has been classified as a young "peculiar" type IIn SN resembling SN 1998S at early phases (Parisky et al 2007). Immler et al (2007) reported a bright X-ray source within 23 .5 from the SN position although, due to the large point-spread-function of the XRT instrument (18 half-power diameter at 1.5 keV) the error box include the galaxy nucleus.…”

“…3. SN 2010aj was discovered in the Sc galaxy (Hakobyan et al 2012) MGC-01-32-035 by Newton et al (2010) on 2010 March 12.39 UT and was classified as a young type II SN resembling the type IIP SN 2006bp near maximum brightness (Cenko et al 2010). The recession velocity of MGC-01-32-035 corrected for the Virgo infall is v Virgo = 6386 ± 20km s −1 (Mould et al 2000, from NED), corresponding to a distance modulus µ = 34.71 ± 0.15 mag.…”