X-ray flares raising upon magnetar plateau as an implication of a surrounding disk of newborn magnetized neutron star
Abstract
The X-ray flares have usually been ascribed to long-lasting activities of the central engine of gamma-ray bursts (GRBs), e.g., fallback accretion. The GRB X-ray plateaus, however, favor a millisecond magnetar central engine. The fallback accretion can be significantly suppressed due to the propeller effect of a magnetar. Therefore, if the propeller regime cannot resist the mass flow onto the surface of the magnetar efficiently, the X-ray flares raising upon the magnetar plateau would be expected. In this work, such peculiar cases are connected to the accretion process of the magnetars, and an implication for magnetar-disc structure is given. We investigate the repeated accretion process with multi-flare GRB 050730, and give a discussion for the accretion-induced variation of the magnetic field in GRB 111209A. Two or more flares exhibit in the GRB 050730, 060607A and 140304A; by adopting magnetar mass M = 1.4 M ⊙ and radius R = 12 km, the average mass flow rates of the corresponding surrounding disk are 3.53 × 10-4 M ⊙ s-1, 4.23 × 10-4 M ⊙ s-1, and 4.33 × 10-4 M ⊙ s-1, and the corresponding average sizes of the magnetosphere are 5.01 × 106 cm, 6.45 × 106 cm, and 1.09 × 107 cm, respectively. A statistic analysis that contains eight GRBs within 12 flares shows that the total mass loading in single flare is ~ 2 × 10-5 M ⊙. In the lost mass of a disk, there are about 0.1% used to feed a collimated jet.
- Publication:
-
Research in Astronomy and Astrophysics
- Pub Date:
- December 2021
- DOI:
- 10.1088/1674-4527/21/12/300
- arXiv:
- arXiv:2109.11114
- Bibcode:
- 2021RAA....21..300Z
- Keywords:
-
- accretion;
- accretion disk;
- stars: magnetars;
- gamma-ray burst: individual (GRB 050730;
- GRB 111209A);
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 15 pages, 4 figures, 2 tables, to be published in RAA