Gamow’s GRB Photo-z Estimate Performance for Studying the Young Universe

Gamma-ray bursts (GRBs) are effective probes for studying the high-redshift Universe. They provide crucial information about the first stars and galaxies, and the epoch of reionization. The proposed Gamow mission aims to use high-redshift GRBs to enable the study of the young Universe. A key component of Gamow is its ability to quickly identify high-redshift GRBs by determining their photometric redshift using its Photo-z Infrared telescope (PIRT). This instrument will simultaneously collect data in 5 broad photometric bands with wavelengths ranging from 0.5 to 2.4 microns. We performed simulations to assess PIRT’s ability to estimate GRB redshifts. We model GRBs using a power-law spectrum with intergalactic attenuation and host galaxy extinction, and include the expected PIRT characteristics. In our Markov-Chain Monte Carlo simulations we use priors for spectral index, near-infrared brightness, host galaxy extinction and redshift, based on observed distributions and theoretical expectations. We present our methodology and the results of our simulations. PIRT achieves a high completeness of GRBs above redshift 5 detected by Gamow, and a low rate of false positives due to dusty interlopers at low redshifts.