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Your search keyword '"Combi , L."' showing total 3 results
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3 results on '"Combi , L."'

1. Non-thermal radiation from dual jet interactions in supermassive black hole binaries

Author

Gutiérrez, E. M., Combi, L., Romero, G. E., and Campanelli, M.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Supermassive black hole binaries (SMBHBs) are natural by-products of galaxy mergers and are expected to be powerful multi-messenger sources. They can be powered by the accretion of matter and then radiate across the electromagnetic spectrum, much like normal active galactic nuclei (AGNs). Current electromagnetic observatories have a good chance of detecting and identifying these systems in the near future. However, precise observational indicators are needed to distinguish individual AGNs from SMBHBs. In this paper, we propose a novel electromagnetic signature from SMBHBs: non-thermal emission produced by the interaction between the jets ejected by the black holes. We study close SMBHBs, which accrete matter from a circumbinary disc and the mini-discs formed around each hole. Each black hole ejects a magnetically dominated jet in the direction of its spin through the Blandford--Znajeck mechanism. We argue that in such a situation, the interaction between the jets can trigger strong magnetic reconnection events, where particles are accelerated and emit non-thermal radiation. Depending on whether the jets are aligned or misaligned, this radiation can have different periodicities. We model the evolution of the particles accelerated during the dual jet interaction and calculate their radiative output, obtaining spectra and providing estimates for the variability timescales. We finally discuss how this emission compares with that of normal AGNs., Comment: 11 pages, 5 figures. Accepted to be published in MNRAS

Published
2023

2. Flares from dual jets in supermassive black hole binaries

Author

Gutiérrez, E. M., Combi, L., Romero, G. E., Campanelli, M., Gutiérrez, E. M., Combi, L., Romero, G. E., and Campanelli, M.

Abstract

Supermassive black hole binaries (SMBHBs) are natural by-products of galaxy mergers and are expected to be powerful multi-messenger sources. They can be powered by the accretion of matter and shine throughout the electromagnetic spectrum similarly to normal active galactic nuclei (AGNs). Current electromagnetic observatories have good chances to detect and identify these systems in the near future, but we need precise observational indicators to distinguish single AGNs from SMBHBs. In this work, we propose a novel electromagnetic signature from SMBHBs: periodic flares caused by the interaction between the jets launched by the black holes. We investigate close black hole binaries accreting matter from a circumbinary disc and the mini-discs formed around each hole, and launching magnetically-dominated jets in the direction of their spin through the Blandfor--Znajeck mechanism. If the spins are slightly inclined, the two jets will encounter each other once per orbit. We argue that this interaction may trigger strong magnetic reconnection events where particles are accelerated and form plasmoids that emit non-thermal radiation. We model the evolution of these particles and calculate the radiative output obtaining spectra and light curves at different wavelengths. We show that these flares can significantly shine in radio, soft X-rays, and \gamma rays, providing a periodic multi-wavelength electromagnetic signature for SMBHBs., Comment: 14 pages, 12 figures, submitted to MNRAS

Published
2023

3. Jets from Neutron-Star Merger Remnants and Massive Blue Kilonovae.

Author

Combi L and Siegel DM

Abstract

We perform three-dimensional general-relativistic magnetohydrodynamic simulations with weak interactions of binary neutron-star (BNS) mergers resulting in a long-lived remnant neutron star, with properties typical of galactic BNS and consistent with those inferred for the first observed BNS merger GW170817. We demonstrate self-consistently that within ≲30  ms postmerger magnetized (σ∼5-10) incipient jets emerge with asymptotic Lorentz factor Γ∼5-10, which successfully break out from the merger debris within ≲20  ms. A fast (v≲0.6c), magnetized (σ∼0.1) wind surrounds the jet core and generates a UV/blue kilonova precursor on timescales of hours, similar to the precursor signal due to free neutron decay in fast dynamical ejecta. Postmerger ejecta are quickly dominated by magnetohydrodynamically driven outflows from an accretion disk. We demonstrate that, within only 50 ms postmerger, ≳2×10^{-2}M_{⊙} of lanthanide-free, quasispherical ejecta with velocities ∼0.1-0.2c is launched, yielding a kilonova signal consistent with GW170817 on timescales of ≲5  d.

Published
2023
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