3,247 research outputs found
Magnetic Fields and Afterglows of BdHNe: Inferences from GRB 130427A, GRB 160509A, GRB 160625B, GRB 180728A and GRB 190114C
GRB 190114C is the first binary-driven hypernova (BdHN) fully observed from
the initial supernova appearance to the final emergence of the optical SN
signal. It offers an unprecedented testing ground for the BdHN theory and it is
here determined and further extended to additional gamma-ray bursts (GRBs).
BdHNe comprise two subclasses of long GRBs with progenitors a binary system
composed of a carbon-oxygen star (CO) and a neutron star (NS)
companion. The CO explodes as a SN leaving at its center a
newborn NS (NS). The SN ejecta hypercritically accretes both on the
NS and the NS companion. BdHNe I are the tightest binaries where the
accretion leads the companion NS to gravitational collapse into a black hole
(BH). In BdHN II the accretion onto the NS is lower, so there is no BH
formation. We observe the same structure of the afterglow for GRB 190114C and
other selected examples of BdHNe I (GRB 130427A, GRB 160509A, GRB 160625B) and
for BdHN II (GRB 180728A). In all the cases the explanation of the afterglow is
reached via the synchrotron emission powered by the NS: their magnetic
fields structures and their spin are determined. For BdHNe I, we discuss the
properties of the magnetic field embedding the newborn BH, inherited from the
collapsed NS and amplified during the gravitational collapse process, and
surrounded by the SN ejecta.Comment: 7 figures, 3 tables, submitted to Ap
GRB 081024B and GRB 140402A: two additional short GRBs from binary neutron star mergers
Theoretical and observational evidences have been recently gained for a
two-fold classification of short bursts: 1) short gamma-ray flashes (S-GRFs),
with isotropic energy ~erg and no BH formation, and 2) the
authentic short gamma-ray bursts (S-GRBs), with isotropic energy
~erg evidencing a BH formation in the binary neutron star
merging process. The signature for the BH formation consists in the on-set of
the high energy (--~GeV) emission, coeval to the prompt emission, in
all S-GRBs. No GeV emission is expected nor observed in the S-GRFs. In this
paper we present two additional S-GRBs, GRB 081024B and GRB 140402A, following
the already identified S-GRBs, i.e., GRB 090227B, GRB 090510 and GRB 140619B.
We also return on the absence of the GeV emission of the S-GRB 090227B, at an
angle of from the \textit{Fermi}-LAT boresight. All the correctly
identified S-GRBs correlate to the high energy emission, implying no
significant presence of beaming in the GeV emission. The existence of a common
power-law behavior in the GeV luminosities, following the BH formation, when
measured in the source rest-frame, points to a commonality in the mass and spin
of the newly-formed BH in all S-GRBs.Comment: 16 pages, submitted to ApJ, second version addressing the comments by
the refere
A common behavior in the late X-ray afterglow of energetic GRB-SN systems
The possibility to divide GRBs in different subclasses allow to understand
better the physics underlying their emission mechanisms and progenitors. The
induced gravitational collapse scenario proposes a binary progenitor to explain
the time-sequence in GRBs-SNe. We show the existence of a common behavior of
the late decay of the X-ray afterglow emission of this subclass of GRBs,
pointing to a common physical mechanism of their late emission, consistent with
the IGC picture.Comment: 3 pages, to appear in the proceedings of the Gamma-Ray Burst
Symposium 2012 - IAA-CSIC - Marbella, editors: Castro-Tirado, A. J.,
Gorosabel, J. and Park, I.
GRB 170817A-GW170817-AT 2017gfo and the observations of NS-NS, NS-WD and WD-WD mergers
The LIGO-Virgo Collaboration has announced the detection of GW170817 and has
associated it with GRB 170817A. These signals have been followed after 11 hours
by the optical and infrared emission of AT 2017gfo. The origin of this complex
phenomenon has been attributed to a neutron star-neutron star (NS-NS) merger.
In order to probe this association we confront our current understanding of the
gravitational waves and associated electromagnetic radiation with four observed
GRBs originating in binaries composed of different combinations NSs and white
dwarfs (WDs). We consider 1) GRB 090510 the prototype of NS-NS merger leading
to a black hole (BH); 2) GRB 130603B the prototype of a NS-NS merger leading to
massive NS (MNS) with an associated kilonova; 3) GRB 060614 the prototype of a
NS-WD merger leading to a MNS with an associated kilonova candidate; 4) GRB
170817A the prototype of a WD-WD merger leading to massive WD with an
associated AT 2017gfo-like emission. None of these systems support the above
mentioned association. The clear association between GRB 170817A and AT 2017gfo
has led to introduce a new model based on on a new subfamily of GRBs
originating from WD-WD mergers. We show how this novel model is in agreement
with the exceptional observations in the optical, infrared, X- and gamma-rays
of GRB 170817A-AT 2017gfo.Comment: version accepted for publication in JCAP. Missing references adde
The newborn black hole in GRB 191014C proves that it is alive
A multi-decade theoretical effort has been devoted to finding an efficient
mechanism to use the rotational and electrodynamical extractable energy of a
Kerr-Newman black hole (BH), to power the most energetic astrophysical sources
such as gamma-ray bursts (GRBs) and active galactic nuclei (AGN). We show an
efficient general relativistic electrodynamical process which occurs in the
"inner engine" of a binary driven hypernova (BdHN). The {inner engine} is
composed of a rotating Kerr BH of mass and dimensionless spin parameter
, a magnetic field of strength aligned and parallel to the
rotation axis, and a very low-density ionized plasma. Here, we show that the
gravitomagnetic interaction between the BH and the magnetic field induces an
electric field that accelerates electrons and protons from the environment to
ultrarelativistic energies emitting synchrotron radiation. We show that in GRB
190114C the BH of mass , , and G can lead to a high-energy (GeV) luminosity of
erg s. The inner engine parameters are determined by requiring
1) that the BH extractable energy explains the GeV and ultrahigh-energy
emission energetics, 2) that the emitted photons are not subjected to
magnetic-pair production, and 3) that the synchrotron radiation timescale
agrees with the observed high-energy timescale. We find for GRB 190114C a clear
jetted emission of GeV energies with a semi-aperture angle of approximately
with respect to the BH rotation axis.Comment: Matches version to appear in A&
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