2024-03-28T08:43:09Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/2126212021-05-05T04:30:36Zcom_10261_97com_10261_4col_10261_350
Kangas, Tuomas
Fruchter, Andrew S.
Cenko, S. Bradley
Corsi, Alessandra
Ugarte Postigo, Antonio de
Pe'er, Asaf
Vogel, Stuart N.
Cucchiara, Antonino
Gompertz, Benjamin
Graham, John
Levan, Andrew
Misra, Kuntal
Perley, Daniel A.
Racusin, Judith
Tanvir, Nial
2020-05-29T07:04:03Z
2020-05-29T07:04:03Z
2020
Astrophysical Journal 894(1): 43 (2020)
0004-637X
http://hdl.handle.net/10261/212621
10.3847/1538-4357/ab8799
http://dx.doi.org/10.13039/100000001
http://dx.doi.org/10.13039/501100000780
http://dx.doi.org/10.13039/501100000781
http://dx.doi.org/10.13039/100000104
http://dx.doi.org/10.13039/100007698
We present post-jet-break Hubble Space Telescope, Very Large Array, and Chandra observations of the afterglow of the long gamma-ray bursts GRB 160625B (between 69 and 209 days) and GRB 160509A (between 35 and 80 days). We calculate the post-jet-break decline rates of the light curves and find the afterglow of GRB 160625B is inconsistent with a simple t(-3/4) steepening over the break, expected from the geometric effect of the jet edge entering our line of sight. However, the favored optical post-break decline is also inconsistent with the f(nu) proportional to t(-p) decline (where p 2.3 from the pre-break light curve), which is expected from exponential lateral expansion of the jet; perhaps suggesting lateral expansion that only affects a fraction of the jet. The post-break decline of GRB 160509A is consistent with both the t(-3/4) steepening and with f(nu) proportional to t(-p). We also use boxfit to fit afterglow models to both light curves and find both to be energetically consistent with a millisecond magnetar central engine, but the magnetar parameters need to be extreme (i.e., E similar to 3 x 10(52) erg). Finally, the late-time radio light curves of both afterglows are not reproduced well by boxfit and are inconsistent with predictions from the standard jet model; instead, both are well represented by a single power-law decline (roughly f(nu) proportional to t(-1)) with no breaks. This requires a highly chromatic jet break and possibly a two-component jet for both bursts.© 2020. The American Astronomical Society. All rights reserved.
eng
openAccess
Gamma-ray bursts
Relativistic jets
The Late-time Afterglow Evolution of Long Gamma-Ray Bursts GRB 160625B and GRB 160509A
artículo