GRB 211211A: prolonged central engine under strong magnetic field environment. (arXiv:2205.05031v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Gao_H/0/1/0/all/0/1">He Gao</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lei_W/0/1/0/all/0/1">Wei-Hua Lei</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhu_Z/0/1/0/all/0/1">Zi-Pei Zhu</a>
Recently, a Kilonova-associated gamma-ray burst (GRB 211211A) has attracted
great attentions, whose lightcurve consists a precursor ($sim 0.2$ s), a hard
spiky emission ($sim 10$ s), and a soft long extended emission ($sim 40$ s).
Kilonova association could prove its merger origin, while the detection of the
precursor infers at least one highly magnetized NS being involved in the
merger. In this case, a strong magnetic flux $Phi$ is expected to surround the
central engine of GRB 211211A. Here we suggest that when $Phi$ is large
enough, the accretion flow could be halted far from the innermost stable
radius, which will significantly prolong the lifetime of the accretion process,
so as the GRB duration. For example, we show that as long as the central BH is
surrounded by a strong magnetic flux $Phisim 10^{29}rm cm^2 G$, an accretion
flow with $dot{M}_{rm ini} simeq 0.1 M_odot s^{-1}$ could be halted at 40
times gravitational radius and slowly transfer into the black hole in order of
$sim$10 s, which naturally explains the duration of hard spiky emission. After
most of the disk mass has been accreted onto the BH, the inflow rate will be
reduced, so a long and soft extended emission is expected when a new balance
between the magnetic field and the accretion current is reconstructed at a
further radius. Our results further support that the special behavior of GRB
211211A is mainly due to the strong magnetic field of its progenitor stars.
Multi-messenger detections of GRB 211211A-like events (sometimes may disguise
as a typical LGRBs without extended emission) could help to diagnose their
progenitor system and to better study the events of compact binary mergers
involving high magnetic field NSs.
Recently, a Kilonova-associated gamma-ray burst (GRB 211211A) has attracted
great attentions, whose lightcurve consists a precursor ($sim 0.2$ s), a hard
spiky emission ($sim 10$ s), and a soft long extended emission ($sim 40$ s).
Kilonova association could prove its merger origin, while the detection of the
precursor infers at least one highly magnetized NS being involved in the
merger. In this case, a strong magnetic flux $Phi$ is expected to surround the
central engine of GRB 211211A. Here we suggest that when $Phi$ is large
enough, the accretion flow could be halted far from the innermost stable
radius, which will significantly prolong the lifetime of the accretion process,
so as the GRB duration. For example, we show that as long as the central BH is
surrounded by a strong magnetic flux $Phisim 10^{29}rm cm^2 G$, an accretion
flow with $dot{M}_{rm ini} simeq 0.1 M_odot s^{-1}$ could be halted at 40
times gravitational radius and slowly transfer into the black hole in order of
$sim$10 s, which naturally explains the duration of hard spiky emission. After
most of the disk mass has been accreted onto the BH, the inflow rate will be
reduced, so a long and soft extended emission is expected when a new balance
between the magnetic field and the accretion current is reconstructed at a
further radius. Our results further support that the special behavior of GRB
211211A is mainly due to the strong magnetic field of its progenitor stars.
Multi-messenger detections of GRB 211211A-like events (sometimes may disguise
as a typical LGRBs without extended emission) could help to diagnose their
progenitor system and to better study the events of compact binary mergers
involving high magnetic field NSs.
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