Lunch talk on Mar. 6, 2023

Investigating the stellar density of long gamma-ray burst host galaxies at z < 3

Speaker: Benjamin Schneider (MIT)

Venue: Video Conference

Time: 12:30 PM, Monday, Mar. 6, 2023

Abstract: 

Gamma-Ray Bursts (GRBs) are brief flashes of gamma-ray photons produced by ultra-relativistic jets of a newly born stellar black hole and are the most energetic phenomena known in the Universe. Long GRBs, believed to be associated with the death of massive stars, offer a promising way to trace the cosmic star formation rate history (CSFRH) up to very high redshift where traditional method suffer from intrinsic biases. However, previous works suggested that some conditions might affect the LGRB formation, related for instance to the metallicity of the progenitor or its surrounding environment. The characterization of the conditions necessary to produce a burst is crucial to assess their ability to probe the CSFRH. In this talk, I will present our effort to better understand the possible bias affecting long GRB formation using the properties of their host galaxy. Considering a sample of long GRB hosts at 1 < z < 3 observed in the infrared band with Hubble, we investigated how the galaxy size and the stellar density affect the GRB production. We showed that long GRBs at z < 2 tend to prefer compact and dense galaxies compared to the typical star-forming galaxies at a similar epoch. To finish this talk, I will briefly review our recent works on the brightest GRB of all time (GRB 221009A) using James Webb and Hubble follow-up observations, with a particular focus on the host galaxy visible in the last HST epoch.