Highly extinguished host galaxy of the dark GRB 020819

Abstract

We analysed the properties of the host galaxy of the optically dark gamma‐ray burst (GRB) 020819 (z = 0.41) and discussed the possible implications in the context of dark GRBs. Here we present g′ r′ i′ z′ JHK photometry of the host galaxy and fit of the broad spectral energy distribution including the public Spitzer IRAC data, using stellar population models. The broad spectral energy distribution shows a high extinction of AV∼1.8–2.6 mag. This is the highest global extinction for a GRB host galaxy with a robust spectroscopic redshift. It implies that the dust extinction is one of the main reasons for the darkness of low‐redshift bursts and that the long GRB host population is far more diverse than previously anticipated.