# Probing the Nature of High-z Short GRB 090426 with Its Early Optical and X-ray Afterglows - Astrophysics > High Energy Astrophysical Phenomena

Probing the Nature of High-z Short GRB 090426 with Its Early Optical and X-ray Afterglows - Astrophysics > High Energy Astrophysical Phenomena - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Abstract: GRB 090426 is a short duration burst detected by Swift $T {90}\sim 1.28$ sin the observer frame, and $T {90}\sim 0.33$ s in the burst frame at$z=2.609$. Its host galaxy properties and some $\gamma$-ray relatedcorrelations are analogous to those seen in long duration GRBs, which arebelieved to be of a massive-star origin so-called Type II GRBs. We presentthe results of its early optical observations with the 0.8-m TNT telescope atXinglong observatory, and the 1-m LOAO telescope at Mt. Lemmon OpticalAstronomy Observatory in Arizona. Our well-sampled optical afterglow lightcurvecovers from $\sim 90$ seconds to $\sim 10^4$ seconds post the GRB trigger. Itshows two shallow decay episodes that are likely due to energy injection, whichend at $\sim 230$ seconds and $\sim 7100$ seconds, respectively. The decayslopes post the injection phases are consistent with each other $\alpha\simeq1.22$. The X-ray afterglow lightcurve appears to trace the optical, althoughthe second energy injection phase was missed due to visibility constraintsintroduced by the {\em Swift} orbit. The X-ray spectral index is $\beta X\sim1.0$ without temporal evolution. Its decay slope is consistent with theprediction of the forward shock model. Both X-ray and optical emission isconsistent with being in the same spectral regime above the cooling frequency$u c$. The fact that $u c$ is below the optical band from the very earlyepoch of the observation provides a constraint on the burst environment, whichis similar to that seen in classical long duration GRBs. We therefore suggestthat death of a massive star is the possible progenitor of this short burst.

Autor: Liping Xin, Enwei Liang, Jianyan Wei, Bing Zhang, Houjun Lv, Weikang Zheng, Yuji Urata, Myungshin Im, Jing Wang, Yulei Qiu, Jinso

Fuente: https://arxiv.org/