Magnetar Giant Flare Origin for GRB 210410A?

Abstract

In general, giant flares (GFs) produced by magnetars have a very short-hard initial spike that is followed by a weak oscillatory phase. GFs from a nearby galaxy would appear as cosmic short-hard gamma-ray bursts (GRBs), such as GRB 200415A. In this paper, we search for GF-originated bursts in the Fermi GRB category and report GRB 210410A, which is presented with a very short-hard spike followed by an extended tail emission. In the E p,z − E iso plane, GRB 210410A with a duration of T 90 ∼ 48 s differs from long GRBs, might be classified as a short GRB with a redshift of z ∼ 0.28, and could be regarded as a GF with a distance of ∼2.7 Mpc. Here, E p,z , E iso, and L iso denote the rest-frame peak photon energy, the isotropic energy, and the isotropic luminosity of the burst, respectively. The radiation spectrum of GRB 210410A, similar to that of GRB 200415A, can be well fitted with a non-dissipative photospheric emission. However, GRB 210410A in the E p,z − L iso plane is beyond the death line of cosmic GRBs for non-dissipated photospheric emission with a general initial size of the fireball. Since the E p,z − L iso relation of GFs is far beyond the death line of cosmic GRBs, GRB 210410A may have originated from the same channel that produces GFs. We also perform the analysis and discuss both the highest photon energy event (4.2 GeV) and the extended tail emission in this burst.