to about a factor of two in raw metallicity and resolves much of the difference between the LGRB host metallicity cutoffs determined by [@diff_rate_letter] and [@Perley_shoals_masses]. As LGRB hosts do not follow the general mass metallicity relations, there is no substitute for actually measuring their metallicities.'
author:
- 'J. F. Graham$^{\hyperref[jfg]{1}}$'
- 'P. Schady$^{\hyperref[ps]{2},\hyperref[ops]{3}}$'
- 'A. S. Fruchter$^{\hyperref[af]{4}}$'
bibliography:
- 'XS\_paper.bib'
title: A Surprising Lack of LGRB Metallicity Evolution with Redshift
---

Introduction
============

Upon collecting the first samples of the galaxies hosting Long-soft Gamma-Ray Bursts (LGRBs) it was apparent that LGRBs occur in blue, highly starforming, and often irregular galaxies with a preponderance that clearly separated them from the general galaxy population [@Fruchter1999; @Fruchter; @LeFlochblue; @LeFlochblue2002; @Christensen; @LeFloch2006; @Savaglio]. The seminal work of [@Fruchter] compared the hosts of LGRBs with those of Core-Collapse Supernovae (CCSNe) found in the Great Observatories Origins Deep Survey (GOODS) and found that while half of the GOODs CCSNe occurred in grand design spirals (with the other half in irregulars), only one out of the 18 LGRB host galaxies of a comparable redshift distribution was in a grand design spiral. This comparison with SNe allowed [@Fruchter] to establish that this difference was beyond that expected 