140 research outputs found
Update on the GRB universal scaling E-E-E with ten years of data
From a comprehensive statistical analysis of X-ray light-curves of
gamma-ray bursts (GRBs) collected from December 2004 to the end of 2010, we
found a three-parameter correlation between the isotropic energy emitted in the
rest frame 1-10 keV energy band during the prompt emission
(E), the rest frame peak of the prompt emission energy
spectrum (E), and the X-ray energy emitted in the rest frame 0.3-30
keV observed energy band (E), computed excluding the
contribution of the flares. In this paper, we update this correlation with the
data collected until June 2014, expanding the sample size with 35% more
objects, where the number of short GRBs doubled. With this larger sample we
confirm the existence of a universal correlation that connects the prompt and
afterglow properties of long and short GRBs. We show that this correlation does
not depend on the X-ray light-curve morphology and that further analysis is
necessary to firmly exclude possible biases derived by redshift measurements.
In addition we discuss about the behavior of the peculiar objects as ultra-long
GRBs and we propose the existence of an intermediate group between long and
short GRBs. Interestingly, two GRBs with uncertain classification fall into
this category. Finally, we discuss the physics underlying this correlation, in
the contest of the efficiency of conversion of the prompt -ray emission
energy into the kinetic energy of the afterglow, the photosferic model, and the
cannonball model.Comment: 11 pages, 5 figures, accepted for publication in MNRA
High-Energy Emission from Interacting Supernovae: New Constraints on Cosmic-Ray Acceleration in Dense Circumstellar Environments
Supernovae (SNe) with strong interactions with circumstellar material (CSM)
are promising candidate sources of high-energy neutrinos and gamma rays, and
have been suggested as an important contributor to Galactic cosmic rays beyond
1 PeV. Taking into account the shock dissipation by a fast velocity component
of SN ejecta, we present comprehensive calculations of the non-thermal emission
from SNe powered by shock interactions with a dense wind or CSM. Remarkably, we
consider electromagnetic cascades in the radiation zone and subsequent
attenuation in the pre-shock CSM. A new time-dependent phenomenological
prescription provided by this work enables us to calculate gamma-ray, hard
X-ray, radio, and neutrino signals, which originate from cosmic rays
accelerated by the diffusive shock acceleration mechanism. We apply our results
to SN IIn 2010jl and SN Ib/IIn 2014C, for which the model parameters can be
determined from the multi-wavelength data. For SN 2010jl, the more promising
case, by using the the latest Fermi Large Area Telescope (LAT) Pass 8 data
release, we derive new constraints on the cosmic-ray energy fraction,
<0.05-0.1. We also find that the late-time radio data of these interacting SNe
are consistent with our model. Further multi-messenger and multi-wavelength
observations of nearby interacting SNe should give us new insights into the
diffusive shock acceleration in dense environments as well as pre-SN mass-loss
mechanisms.Comment: 16 pages, 10 figures, 3 tables, accepted for publication in ApJ.
Results and conclusions unchange
Unveiling the Engines of Fast Radio Bursts, Super-Luminous Supernovae, and Gamma-Ray Bursts
Young, rapidly spinning magnetars are invoked as central engines behind a
diverse set of transient astrophysical phenomena, including gamma-ray bursts
(GRB), super-luminous supernovae (SLSNe), fast radio bursts (FRB), and binary
neutron star (NS) mergers. However, a barrier to direct confirmation of the
magnetar hypothesis is the challenge of directly observing non-thermal emission
from the central engine at early times (when it is most powerful and thus
detectable) due to the dense surrounding ejecta. We present CLOUDY calculations
of the time-dependent evolution of the temperature and ionization structure of
expanding supernova or merger ejecta due to photo-ionization by a magnetar
engine, in order to study the escape of X-rays (absorbed by neutral gas) and
radio waves (absorbed by ionized gas), as well as to assess the evolution of
the local dispersion measure due to photo-ionization. We find that ionization
breakout does not occur if the engine's ionizing luminosity decays rapidly, and
that X-rays typically escape the oxygen-rich ejecta of SLSNe only on timescales, consistent with current X-ray non-detections. We apply
these results to constrain engine-driven models for the binary NS merger
GW170817 and the luminous transient ASASSN-15lh. In terms of radio transparency
and dispersion measure constraints, the repeating FRB 121102 is consistent with
originating from a young, , magnetar similar to
those inferred to power SLSNe. We further show that its high rotation measure
can be produced within the same nebula that is proposed to power the quiescent
radio source observed co-located with FRB 121102. Our results strengthen
previous work suggesting that at least some FRBs may be produced by young
magnetars, and motivate further study of engine powered transients.Comment: submitted to MNRAS; comments welcom
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