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Photometric redshift estimation for gamma-ray bursts from the early Universe
journal contributionposted on 2024-01-22, 17:04 authored by HM Fausey, AJ Van Der Horst, NE White, M Seiffert, P Willems, ET Young, DA Kann, G Ghirlanda, R Salvaterra, NR Tanvir, A Levan, M Moss, TC Chang, A Fruchter, S Guiriec, DH Hartmann, C Kouveliotou, J Granot, A Lidz
Future detection of high-redshift gamma-ray bursts (GRBs) will be an important tool for studying the early Universe. Fast and accurate redshift estimation for detected GRBs is key for encouraging rapid follow-up observations by ground- and space-based telescopes. Low-redshift dusty interlopers pose the biggest challenge for GRB redshift estimation using broad photometric bands, as their high extinction can mimic a high-redshift GRB. To assess false alarms of high-redshift GRB photometric measurements, we simulate and fit a variety of GRBs using phozzy, a simulation code developed to estimate GRB photometric redshifts, and test the ability to distinguish between high- and low-redshift GRBs when using simultaneously observed photometric bands. We run the code with the wavelength bands and instrument parameters for the Photo-z Infrared Telescope (PIRT), an instrument designed for the Gamow mission concept. We explore various distributions of host galaxy extinction as a function of redshift, and their effect on the completeness and purity of a high-redshift GRB search with the PIRT. We find that for assumptions based on current observations, the completeness and purity range from ∼82 to 88 per cent and from ∼84 to, respectively. For the priors optimized to reduce false positives, only of low-redshift GRBs will be mistaken as a high-redshift one, corresponding to ∼1 false alarm per 500 detected GRBs.
Author affiliationSchool of Physics & Astronomy, University of Leicester
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