ZTF22aabjpxh/AT2022cva: NICER X-ray detection is consistent with a GRB afterglow
Abstract
NICER observed the rapidly fading transient AT2022cva (Ho et al. GCN 31619) for 2.4 ks starting at 2022-02-21T22:56:03. X-rays are clearly detected above the background in the 0.3-5.0 keV band with a mean background-subtracted count rate of 0.92+-0.02 counts/seconds. We fit the 0.3-5 keV X-ray spectrum with a redshifted powerlaw modified by neutral absorption in Milkway and host galaxy (tbabs*ztbabs*zpow in XSPEC). Using a Galactic nH value for tbabs (0.023e22 cm^2; HI4PI Collaboration, Bekhti et al. 2016) and a redshift of 0.293 (Fremling et al., GCN 31619) gives a good fit with a c-stat/degrees of freedom of 57/57. The best-fit power law index and host column density values are 1.36(+0.14,-0.12) and <5e20 cm^-2, respectively. The 0.3-5 keV observed flux is (2.24+-0.07)e-12 erg/s/cm^2. This corresponds to an observed luminosity of 5.04(+0.03,-0.33)e44 erg/s at a redshift of 0.293, which is typical for a GRB afterglow at a similar phase. NICER can carry out prompt follow-up observations of transients and is planning to systematically follow up alerts from LIGO/Virgo and other X-ray bright extra-galactic transients in the future. NICER is a 0.2-12 keV X-ray telescope operating on the International Space Station. The NICER mission and portions of the NICER science team activities are funded by NASA.
- Publication:
-
GRB Coordinates Network
- Pub Date:
- February 2022
- Bibcode:
- 2022GCN.31635....1P