The Dwarf Starburst Host Galaxy of a Type Ia SN at z = 1.55 from CANDELS

TL;DR

This study characterizes a high-redshift Type Ia supernova host galaxy, revealing its properties as a young, low-mass, metal-poor starburst galaxy with high star formation activity, which may influence cosmological measurements.

Contribution

First detailed spectroscopic and photometric analysis of a z=1.55 SN Ia host galaxy, providing insights into its physical properties and their evolution with redshift.

Findings

Host galaxy is young, low mass, and metal-poor.

High specific star formation rate compared to lower redshift counterparts.

Potential implications for using SN Ia as standard candles in cosmology.

Abstract

We present VLT/X-shooter observations of a high redshift, type Ia supernova host galaxy, discovered with HST/WFC3 as part of the CANDELS Supernova project. The galaxy exhibits strong emission lines of Ly{\alpha}, [O II], H{\beta}, [O III], and H{\alpha} at z = 1.54992(+0.00008-0.00004). From the emission-line fluxes and SED fitting of broad-band photometry we rule out AGN activity and characterize the host galaxy as a young, low mass, metal poor, starburst galaxy with low intrinsic extinction and high Ly{\alpha} escape fraction. The host galaxy stands out in terms of the star formation, stellar mass, and metallicity compared to its lower redshift counterparts, mainly because of its high specific star-formation rate. If valid for a larger sample of high-redshift SN Ia host galaxies, such changes in the host galaxy properties with redshift are of interest because of the potential impact on the use of SN Ia as standard candles in cosmology.