13 research outputs found
Off-axis short GRBs from structured jets as counterparts to GW events
Binary neutron star mergers are considered to be the most favorable sources
that produce electromagnetic (EM) signals associated with gravitational waves
(GWs). These mergers are the likely progenitors of short duration gamma-ray
bursts (GRBs). The brief gamma-ray emission (the "prompt GRB" emission) is
produced by ultra-relativistic jets, as a result, this emission is strongly
beamed over a small solid angle along the jet. It is estimated to be a decade
or more before a short GRB jet within the LIGO volume points along our line of
sight. For this reason, the study of the prompt signal as an EM counterpart to
GW events has been sparse. We argue that for a realistic jet model, one whose
luminosity and Lorentz factor vary smoothly with angle, the prompt signal can
be detected for a significantly broader range of viewing angles. This can lead
to a new type of EM counterpart, an "off-axis" short GRB. Our estimates and
simulations show that it is feasible to detect these signals with the aid of
the temporal coincidence from a LIGO trigger, even if the observer is
substantially misaligned with respect to the jet.Comment: 6 pages, 4 figures, accepted to MNRAS Letter
Multi-Messenger Astronomy with Extremely Large Telescopes
The field of time-domain astrophysics has entered the era of Multi-messenger
Astronomy (MMA). One key science goal for the next decade (and beyond) will be
to characterize gravitational wave (GW) and neutrino sources using the next
generation of Extremely Large Telescopes (ELTs). These studies will have a
broad impact across astrophysics, informing our knowledge of the production and
enrichment history of the heaviest chemical elements, constrain the dense
matter equation of state, provide independent constraints on cosmology,
increase our understanding of particle acceleration in shocks and jets, and
study the lives of black holes in the universe. Future GW detectors will
greatly improve their sensitivity during the coming decade, as will
near-infrared telescopes capable of independently finding kilonovae from
neutron star mergers. However, the electromagnetic counterparts to
high-frequency (LIGO/Virgo band) GW sources will be distant and faint and thus
demand ELT capabilities for characterization. ELTs will be important and
necessary contributors to an advanced and complete multi-messenger network.Comment: White paper submitted to the Astro2020 Decadal Surve
Multi-Messenger Astronomy with Extremely Large Telescopes
The field of time-domain astrophysics has entered the era of Multi-messenger Astronomy (MMA). One key science goal for the next decade (and beyond) will be to characterize gravitational wave (GW) and neutrino sources using the next generation of Extremely Large Telescopes (ELTs). These studies will have a broad impact across astrophysics, informing our knowledge of the production and enrichment history of the heaviest chemical elements, constrain the dense matter equation of state, provide independent constraints on cosmology, increase our understanding of particle acceleration in shocks and jets, and study the lives of black holes in the universe. Future GW detectors will greatly improve their sensitivity during the coming decade, as will near-infrared telescopes capable of independently finding kilonovae from neutron star mergers. However, the electromagnetic counterparts to high-frequency (LIGO/Virgo band) GW sources will be distant and faint and thus demand ELT capabilities for characterization. ELTs will be important and necessary contributors to an advanced and complete multi-messenger network
Transients from Rare, Violent Stellar Deaths
Some of the brightest and most energetic events in the Universe are associated with the death of stars. These stellar deaths power transient electromagnetic emission which are routinely observed on Earth. This dissertation presents our research on various such transients. Its topics includes, supernova remnants, kilonovae, gammaray bursts (GRBs): The “long” type produced from core-collapse supernovae and the “short” type associated with neutron star merger events. It also focuses on the disruption of stars by the tidal forces of supermassive black holes i.e., tidal disruption events (TDEs). We model the emission from these transients and compare them to observations in order to draw a number of conclusions and make predictions for future detections. For example, we find that the non-thermal emission from supernovae and kilonovae associated with GRBs can produce long term emission which may be detected as a re-brightening in the overall emission. The sharp cut off observed in some TDE flares can be caused by a pre-existing accretion disk present around a supermassive black hole, which is expected in active galactic nuclei. Our work successfully predicted the nature of the very first electromagnetic detection from a neutron star merger, and was able to reproduce the emission that had been observed for more than one hundred days after the merger. This dissertation also provides frameworks on how the observable features of these transients can be leveraged to probe the properties of the progenitor system and their environment