Characterizing Supernova Host Galaxies with FrankenBlast: A Scalable Tool for Transient Host Galaxy Association, Photometry, and Stellar Population Modeling

TL;DR

This paper introduces FrankenBlast, a scalable framework that couples fast transient-host association, multi-survey aperture photometry, and SBI++-based SED fitting to derive host stellar-population properties, designed for the data volumes expected from Rubin/Roman. Applied to 14,432 SNe (≈ half spectroscopically classified), it achieves 13,111 confident host associations and 11,153 hosts with usable photometry, enabling robust comparisons of host properties such as $M_*$, sSFR, and $A_V$. The study finds that differences between spectroscopic and photometric SN classes largely reflect misclassification and redshift effects, with SNe II/IIn showing stronger SFR dependence and SNe Ia showing stronger $M_*$ dependence, while SNe Ib/c vs II hosts present intriguing environmental trends. All data products and FrankenBlast code are public, with extensions planned for Rubin/ Roman science outputs.

Abstract

We present FrankenBlast, a customized and improved version of the Blast web application. FrankenBlast associates transients to their host galaxies, performs host photometry, and runs a innovative SED fitting code to constrain host stellar population properties--all within minutes per object. We test FrankenBlast on 14,432 supernovae (SNe), ~half of which are spectroscopically-classified, and are able to constrain host properties for 9262 events. When contrasting the host stellar masses ($M_*$), specific star formation rates (sSFR), and host dust extinction ($A_V$) between spectroscopically and photometrically-classified SNe Ia, Ib/c, II, and IIn, we determine that deviations in these distributions are primarily due to misclassified events contaminating the photometrically-classified sample. We further show that the higher redshifts of the photometrically-classified sample also force their $M_*$ and sSFR distributions to deviate from those of the spectroscopically-classified sample, as these properties are redshift-dependent. We compare host properties between spectroscopically-classified SN populations and determine if they primarily trace $M_*$ or SFR. We find that all SN populations seem to both depend on $M_*$ and SFR, with SNe II and IIn somewhat more SFR-dependent than SNe Ia and Ib/c, and SNe Ia more $M_*$-dependent than all other classes. We find the difference in the SNe Ib/c and II hosts the most intriguing and speculate that SNe Ib/c must be more dependent on higher $M_*$ and more evolved environments for the right conditions for progenitor formation. All data products and FrankenBlast are publicly available, along with a developing FrankenBlast version intended for Rubin Observatory science products.

Figures (1)

• Figure 1: The breakdown of our spectroscopically and photometrically classified SN samples. Left: The number of SNe Ia, SNe II, SNe IIn, SNe Ib/c, and SLSNe-I in our spectroscopically-classified sample (outer circle), and the number of events, separated by class, with and without Pröst host associations (inner circle). We claim that the events without host associations are "hostless". Middle: The same, but for the photometrically-classified SN sample. Right: The number of spectroscopically (top) versus photometrically (bottom) classified events with host SED fits through SBI++.