Short GRB Host Galaxies. II. A Legacy Sample of Redshifts, Stellar Population Properties, and Implications for their Neutron Star Merger Origins

Understand

We present the stellar population properties of 69 short gamma-ray burst (GRB) host galaxies, representing the largest uniformly-modeled sample to-date.

• Using the Prospector stellar population inference code, we jointly fit photometry and/or spectroscopy of each host galaxy.
• We find a population median redshift of $z=0.64^{+0.83}_{-0.32}$ ($68\%$ confidence), including 10 new or revised photometric redshifts at $z\gtrsim1$.
• We further find a median mass-weighted age of $t_m=0.8^{+2.71}_{-0.53}$Gyr, stellar mass of $\log(M_*/M_\odot)=9.69^{+0.75}_{-0.65}$, star formation rate of SFR=$1.44^{+9.37}_{-1.35}M_\odot$yr$^{-1}$, stellar metallicity of $\log(Z_*/Z_\odot)=-0.38^{+0.44}_{-0.42}$, and dust attenuation of $A_V=0.43^{+0.85}_{-0.36}$~mag (68\% confidence).