2 research outputs found
Science with the Daksha High Energy Transients Mission
We present the science case for the proposed Daksha high energy transients
mission. Daksha will comprise of two satellites covering the entire sky from
1~keV to ~MeV. The primary objectives of the mission are to discover and
characterize electromagnetic counterparts to gravitational wave source; and to
study Gamma Ray Bursts (GRBs). Daksha is a versatile all-sky monitor that can
address a wide variety of science cases. With its broadband spectral response,
high sensitivity, and continuous all-sky coverage, it will discover fainter and
rarer sources than any other existing or proposed mission. Daksha can make key
strides in GRB research with polarization studies, prompt soft spectroscopy,
and fine time-resolved spectral studies. Daksha will provide continuous
monitoring of X-ray pulsars. It will detect magnetar outbursts and high energy
counterparts to Fast Radio Bursts. Using Earth occultation to measure source
fluxes, the two satellites together will obtain daily flux measurements of
bright hard X-ray sources including active galactic nuclei, X-ray binaries, and
slow transients like Novae. Correlation studies between the two satellites can
be used to probe primordial black holes through lensing. Daksha will have a set
of detectors continuously pointing towards the Sun, providing excellent hard
X-ray monitoring data. Closer to home, the high sensitivity and time resolution
of Daksha can be leveraged for the characterization of Terrestrial Gamma-ray
Flashes.Comment: 19 pages, 7 figures. Submitted to ApJ. More details about the mission
at https://www.dakshasat.in
Prospects of measuring Gamma-ray Burst Polarisation with the Daksha mission
The proposed Daksha mission comprises of a pair of highly sensitive space
telescopes for detecting and characterising high-energy transients such as
electromagnetic counterparts of gravitational wave events and gamma-ray bursts
(GRBs). Along with spectral and timing analysis, Daksha can also undertake
polarisation studies of these transients, providing data crucial for
understanding the source geometry and physical processes governing high-energy
emission. Each Daksha satellite will have 340 pixelated Cadmium Zinc Telluride
(CZT) detectors arranged in a quasi-hemispherical configuration without any
field-of-view collimation (open detectors). These CZT detectors are good
polarimeters in the energy range 100 -- 400 keV, and their ability to measure
polarisation has been successfully demonstrated by the Cadmium Zinc Telluride
Imager (CZTI) onboard AstroSat. Here we demonstrate the hard X-ray polarisation
measurement capabilities of Daksha and estimate the polarisation measurement
sensitivity (in terms of the Minimum Detectable Polarisation: MDP) using
extensive simulations. We find that Daksha will have MDP of~ for a
fluence threshold of erg cm (in 10 -- 1000 keV). We estimate that
with this sensitivity, if GRBs are highly polarised, Daksha can measure the
polarisation of about five GRBs per year.Comment: Submitted to Journal of Astronomical Telescopes, Instruments, and
Systems (JATIS