Photometric redshift estimation for gamma-ray bursts from the early Universe

H. M. Fausey, A. J. Van Der Horst, N. E. White, M. Seiffert, P. Willems, E. T. Young, D. A. Kann, G. Ghirlanda, R. Salvaterra, N. R. Tanvir, A. Levan, M. Moss, T. C. Chang, A. Fruchter, S. Guiriec, D. H. Hartmann, C. Kouveliotou, J. Granot, A. Lidz

Research output: Contribution to journalArticlepeer-review


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.

Original languageEnglish
Pages (from-to)4599-4612
Number of pages14
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
StatePublished - 1 Dec 2023

Bibliographical note

Publisher Copyright:
© 2023 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society.


  • gamma-ray bursts
  • methods: statistical
  • software: simulations
  • techniques: photometric


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