Shota Kisaka

Energy Sources and Light Curves of Macronovae

A macronova (kilonova) was discovered with a short gamma-ray burst, GRB 130603B, which is widely believed to be powered by the radioactivity of

X-RAY-POWERED MACRONOVAE

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Magnetic field decay with Hall drift in neutron star crusts

-process elements synthesized in the ejecta of a neutron star binary merger. As an alternative, we propose that macronovae are energized by the central engine, i.e., a black hole or neutron star, and the injected energy is emitted after the adiabatic expansion of ejecta. This engine model is motivated by extended emission of short GRBs. In order to compare the theoretical models with observations, we develop analytical formulae for the light curves of macronovae. The engine model allows a wider parameter range, especially smaller ejecta mass, and better fit to observations than the

Long-lasting Black Hole Jets in Short Gamma-Ray Bursts

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ISOTROPIC DETECTABLE X-RAY COUNTERPARTS TO GRAVITATIONAL WAVES FROM NEUTRON STAR BINARY MERGERS

-process model. Future observations of electromagnetic counterparts of gravitational waves should distinguish energy sources and constrain the activity of central engine and the

Mass-dependent evolution of the relation between the supermassive black hole mass and host spheroid mass since z∼ 1

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The correlation of black hole mass with metallicity index of host spheroid

-process nucleosynthesis.

Is the Macronova in GW170817 Powered by the Central Engine

A macronova (or kilonova) was observed as an infrared excess several days after short gamma-ray burst, GRB 130603B. Although the

Magnetar Broadband X-ray Spectra Correlated with Magnetic Fields: Suzaku Archive of SGRs and AXPs Combined with NuSTAR, Swift, and RXTE

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MULTI-WAVELENGTH EMISSION REGION OF γ-RAY EMITTING PULSARS

-process radioactivity is widely discussed as an energy source, it requires huge mass of ejecta from a neutron star (NS) binary merger. We propose a new model that the X-ray excess gives rise to the simultaneously observed infrared excess via thermal re-emission and explore what constraints this would place on the mass and velocity of the ejecta. This X-ray-powered model explains both the X-ray and infrared excesses with a single energy source by the central engine like a black hole, and allows for broader parameter region, in particular smaller ejecta mass