27 research outputs found
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
GRB 190829A -- A Showcase of Binary Late Evolution
GRB 190829A is the fourth closest gamma-ray burst (GRB) to date ().
Owing to its wide range of radio, optical, X-ray, and the very-high-energy
(VHE) observations by H.E.S.S., it has become an essential new source examined
by various models with complementary approaches. We here show in GRB 190829A
the double-prompt pulses and the three-multiwavelength afterglows are
consistent with the type II binary-driven hypernova (BdHN II) model. The
progenitor is a binary composed of a carbon-oxygen (CO) star and a neutron star
(NS) companion. The gravitational collapse of the iron core of the CO star
produces a supernova (SN) explosion and leaves behind a new neutron star
(NS) at its center. The accretion of the SN ejecta onto the NS companion
and onto the NS via matter fallback spins up the NSs and produces the
double-peak prompt emission. The synchrotron emission from the expanding SN
ejecta with the energy injection from the rapidly spinning NS and its
subsequently spin-down leads to the afterglow in the radio, optical, and X-ray.
We model the sequence of physical and related radiation processes in BdHNe and
focus on individuating the binary properties that play the relevant roles.Comment: 14 pages, 6 figures. Accepted for publication in Ap
The binary progenitors of short and long GRBs and their gravitational-wave emission
We have sub-classified short and long-duration gamma-ray bursts (GRBs) into seven families according to the binary nature of their progenitors. Short GRBs are produced in mergers of neutron-star binaries (NS-NS) or neutron star-black hole binaries (NS-BH). Long GRBs are produced via the induced gravitational collapse (IGC) scenario occurring in a tight binary system composed of a carbon-oxygen core (COcore) and a NS companion. The COcore explodes as type Ic supernova (SN) leading to a hypercritical accretion process onto the NS: if the accretion is sufficiently high the NS reaches the critical mass and collapses forming a BH, otherwise a massive NS is formed. Therefore long GRBs can lead either to NS-BH or to NS-NS binaries depending on the entity of the accretion. We discuss for the above compact-object binaries: 1) the role of the NS structure and the nuclear equation of state; 2) the occurrence rates obtained from X and gamma-rays observations; 3) the predicted annual number of detections by the Advanced LIGO interferometer of their gravitational-wave emission
GRB-SN Association within the Binary-Driven Hypernova Model
The observations of supernovae (SNe) Ic occurring after the prompt emission
of long gamma-ray bursts (GRBs) are addressed within the binary-driven
hypernova (BdHN) model where GRBs originate from a binary composed of a
carbon-oxygen (CO) star and a neutron star (NS). The CO core
collapse gives the trigger, leading to a hypernova with a fast-spinning newborn
NS (NS) at its center. The evolution depends strongly on the binary
period, . For min, BdHNe I occur with energies
--erg. The accretion of SN ejecta onto the NS leads to its
collapse, forming a black hole (BH) originating the MeV/GeV radiation. For
min, BdHNe II occur with energies --erg
and for hours, BdHN III occurs with energies below
erg. {In BdHNe II and III,} no BH is formed. The --ms NS
originates, in all BdHNe, the X-ray-optical-radio afterglows by synchrotron
emission. The hypernova follows an independent evolution, becoming an SN Ic,
powered by nickel decay, observable after the GRB prompt emission. We report
SNe Ic associated with BdHNe. Their optical peak luminosity and time of
occurrence are similar and independent of the associated GRBs. {From previously
identified BdHN I comprising redshifts up to , we analyze} four
examples with their associated hypernovae. By multiwavelength extragalactic
observations, we identify seven new Episodes, theoretically explained,
fortunately not yet detected in galactic sources, opening new research areas.
Refinement of population synthesis simulations is needed to map the progenitors
of such short-lived binary systems inside our galaxy.Comment: Accepted for publication in The Astrophysical Journa