scholarly journals Electromagnetic transients and gravitational waves from white dwarf disruptions by stellar black holes in triple systems

2020 ◽  
Vol 495 (1) ◽  
pp. 1061-1072
Author(s):  
Giacomo Fragione ◽  
Brian D Metzger ◽  
Rosalba Perna ◽  
Nathan W C Leigh ◽  
Bence Kocsis
Keyword(s):  
White Dwarf ◽  
Gamma Ray ◽  
High Energy ◽  
Stellar Mass ◽  
Compact Objects ◽  
Electromagnetic Transients ◽  
Tidal Disruption ◽  
Single Star ◽  
Triple Systems ◽  
Nearby Galaxies

ABSTRACT Mergers of binaries comprising compact objects can give rise to explosive transient events, heralding the birth of exotic objects that cannot be formed through single-star evolution. Using a large number of direct N-body simulations, we explore the possibility that a white dwarf (WD) is dynamically driven to tidal disruption by a stellar-mass black hole (BH) as a consequence of the joint effects of gravitational wave (GW) emission and Lidov–Kozai oscillations imposed by the tidal field of an outer tertiary companion orbiting the inner BH–WD binary. We explore the sensitivity of our results to the distributions of natal kick velocities imparted to the BH and WD upon formation, adiabatic mass loss, semimajor axes and eccentricities of the triples, and stellar-mass ratios. We find rates of WD–tidal disruption events (TDEs) in the range 1.2 × 10−3 − 1.4 Gpc−3 yr−1 for z ≤ 0.1, rarer than stellar TDEs in triples by a factor of ∼3–30. The uncertainty in the TDE rates may be greatly reduced in the future using GW observations of Galactic binaries and triples with LISA. WD–TDEs may give rise to high-energy X-ray or gamma-ray transients of duration similar to long gamma-ray bursts but lacking the signatures of a core-collapse supernova, while being accompanied by a supernova-like optical transient that lasts for only days. WD–BH and WD–NS binaries will also emit GWs in the LISA band before the TDE. The discovery and identification of triple-induced WD–TDE events by future time domain surveys and/or GWs could enable the study of the demographics of BHs in nearby galaxies.

scholarly journals High-energy astrophysics and the search for sources of gravitational waves

2018 ◽  
Vol 376 (2120) ◽  
pp. 20170294 ◽  
Author(s):  
P. T. O'Brien ◽  
P. Evans
Keyword(s):  
Gravitational Wave ◽  
Short Duration ◽  
Gamma Ray ◽  
New Technology ◽  
High Energy ◽  
Compact Objects ◽  
Wide Field ◽  
High Energy Radiation ◽  
Energy Radiation ◽  
Binary Mergers

The dawn of the gravitational-wave (GW) era has sparked a greatly renewed interest into possible links between sources of high-energy radiation and GWs. The most luminous high-energy sources—gamma-ray bursts (GRBs)—have long been considered as very likely sources of GWs, particularly from short-duration GRBs, which are thought to originate from the merger of two compact objects such as binary neutron stars and a neutron star–black hole binary. In this paper, we discuss: (i) the high-energy emission from short-duration GRBs; (ii) what other sources of high-energy radiation may be observed from binary mergers; and (iii) how searches for high-energy electromagnetic counterparts to GW events are performed with current space facilities. While current high-energy facilities, such as Swift and Fermi, play a crucial role in the search for electromagnetic counterparts, new space missions will greatly enhance our capabilities for joint observations. We discuss why such facilities, which incorporate new technology that enables very wide-field X-ray imaging, are required if we are to truly exploit the multi-messenger era. This article is part of a discussion meeting issue ‘The promises of gravitational-wave astronomy’.

scholarly journals Time-Domain Astronomy with Swift, Fermi and Lobster

2011 ◽  
Vol 7 (S285) ◽  
pp. 41-46 ◽  
Author(s):  
Neil Gehrels ◽  
Scott D. Barthelmy ◽  
John K. Cannizzo
Keyword(s):  
Gamma Ray ◽  
Crab Nebula ◽  
High Energy ◽  
Tidal Disruption ◽  
X Ray ◽  
Order Of Magnitude ◽  
New Type ◽  
The Crab Nebula ◽  
High Energy Emission ◽  
Higher Sensitivity

AbstractThe dynamic transient gamma-ray sky is revealing many interesting results, largely due to findings by Fermi and Swift. The list includes new twists on gamma-ray bursts (GRBs), a GeV flare from a symbiotic star, GeV flares from the Crab Nebula, high-energy emission from novae and supernovae, and, within the last year, a new type of object discovered by Swift—a jetted tidal disruption event. In this review we present highlights of these exciting discoveries. A new mission concept called Lobster is also described; it would monitor the X-ray sky at order-of-magnitude higher sensitivity than current missions can.

Future prospects for y-ray astronomy

1981 ◽  
Vol 301 (1462) ◽  
pp. 693-701 ◽  
Keyword(s):  
Gamma Ray ◽  
Dynamic Pressure ◽  
High Energy ◽  
Compact Objects ◽  
Pressure Effects ◽  
Very High Energy ◽  
Order Of Magnitude ◽  
High Energy Particles ◽  
Nuclear Processes ◽  
The Universe

As y-ray astronomy moves from the discovery to the exploratory phase, the promise of y-ray astrophysics noted by theorists in the late 1940s and 1950s is beginning to be realized. In the future, satellites should carry instruments that will have over an order of magnitude greater sensitivity than those flown thus far, and, for at least some portions of the y-ray energy range, these detectors will also have substantially improved energy and angular resolution. The information to be obtained from these experiments should greatly enhance our knowledge of several astrophysical phenomena including the very energetic and nuclear processes associated with compact objects, astrophysical nucleosynthesis, solar particle acceleration, the chemical composition of the planets and other bodies of the Solar System, the structure of our Galaxy, the origin and dynamic pressure effects of the cosmic rays, high energy particles and energetic processes in other galaxies especially active ones, and the degree of matter-antimatter symmetry of the Universe. The y-ray results of the forthcoming programs such as Gamma-I, the Gamma Ray Observatory, the y-ray burst network, Solar Polar, and very high energy y-ray telescopes on the ground will almost certainly provide justification for more sophisticated telescopes. These advanced instruments might be placed on the Space Platform currently under study by N.A.S.A.

scholarly journals Very High Energy Gamma-Ray Radiation from the Stellar Mass Black Hole Binary Cygnus X-1

2007 ◽  
Vol 665 (1) ◽  
pp. L51-L54 ◽  
Author(s):  
J. Albert ◽  
E. Aliu ◽  
H. Anderhub ◽  
P. Antoranz ◽  
A. Armada ◽  
...  
Keyword(s):  
Black Hole ◽  
Gamma Ray ◽  
High Energy ◽  
Stellar Mass ◽  
High Energy Gamma ◽  
Very High Energy ◽  
Energy Gamma ◽  
Black Hole Binary ◽  
Very High

scholarly journals Magnetic fractures or reconnection of type II

2010 ◽  
Vol 6 (S274) ◽  
pp. 56-61
Author(s):  
Gerhard Haerendel
Keyword(s):  
Particle Production ◽  
Gamma Ray ◽  
Magnetic Energy ◽  
High Energy ◽  
Compact Objects ◽  
High Energy Particle ◽  
Shear Stresses ◽  
Low Density ◽  
Field Lines ◽  
Auroral Arcs

AbstractThe importance of reconnection in astrophysics has been widely recognized. It is instrumental in storing and releasing magnetic energy, the latter often in a dramatic fashion. A closely related process, playing in very low beta plasmas, is much less known. It is behind the acceleration of auroral particles in the low-density environment several 1000 km above the Earth. It involves the appearance of field-parallel voltages in presence of intense field-aligned currents. The underlying physical process is the release of magnetic shear stresses and conversion of the liberated magnetic energy into kinetic energy of the particles creating auroral arcs. In this process, field lines disconnect from the field anchored in the ionosphere and reconnect to other field lines. Because of the stiffness of the magnetic field, the process resembles mechanical fractures. It is typically active in the low-density magnetosphere of planets. However, it can also lead to significant energy conversion with high-energy particle production and subsequent gamma ray emissions in stellar magnetic fields, in particular of compact objects.

scholarly journals Studying stellar explosions with Athena

2015 ◽  
Vol 11 (A29B) ◽  
pp. 243-243
Author(s):  
P. O'Brien ◽  
P. Jonker
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Gamma Ray Bursts ◽  
Spectral Energy ◽  
Intermediate Mass ◽  
Tidal Disruption ◽  
X Ray ◽  
Cosmic Vision ◽  
Esa Cosmic Vision ◽  
Supernova Explosions

AbstractAthena is the second large mission selected in the ESA Cosmic Vision plan. With its large collecting area, high spectral-energy resolution (X-IFU instrument) and impressive grasp (WFI instrument), Athena will truly revolutionise X-ray astronomy. The most prodigious sources of high-energy photons are often transitory in nature. Athena will provide the sensitivity and spectral resolution coupled with rapid response to enable the study of the dynamic sky. Potential sources include: distant Gamma-Ray Bursts to probe the reionisation epoch and find missing baryons in the cosmic web; tidal disruption events to reveal dormant supermassive and intermediate-mass black holes; and supernova explosions to understand progenitors and their environments. We illustrate Athenas capabilities and show how it will be able to constrain the nature of explosive transients including gas metallicity and dynamics.

scholarly journals Nuclear-dominated accretion flows in two dimensions – II. Ejecta dynamics and nucleosynthesis for CO and ONe white dwarfs

2019 ◽  
Vol 488 (1) ◽  
pp. 259-279 ◽  
Author(s):  
Rodrigo Fernández ◽  
Ben Margalit ◽  
Brian D Metzger
Keyword(s):  
White Dwarf ◽  
Rotation Axis ◽  
High Energy ◽  
Two Dimensions ◽  
Electromagnetic Transients ◽  
Fusion Reactions ◽  
Global Models ◽  
Accretion Flows ◽  
Nuclear Fusion Reactions ◽  
Self Gravity

ABSTRACT We study mass ejection from accretion discs formed in the merger of a white dwarf with a neutron star or black hole. These discs are mostly radiatively inefficient and support nuclear fusion reactions, with ensuing outflows and electromagnetic transients. Here we perform time-dependent, axisymmetric hydrodynamic simulations of these discs including a physical equation of state, viscous angular momentum transport, a coupled 19-isotope nuclear network, and self-gravity. We find no detonations in any of the configurations studied. Our global models extend from the central object to radii much larger than the disc. We evolve these global models for several orbits, as well as alternate versions with an excised inner boundary to much longer times. We obtain robust outflows, with a broad velocity distribution in the range 102–104 km s−1. The outflow composition is mostly that of the initial white dwarf, with burning products mixed in at the ${\lesssim } 10\rm {-}30{{\ \rm per\ cent}}$ level by mass, including up to ∼10−2 M⊙ of 56Ni. These heavier elements (plus 4He) are ejected within ≲ 40° of the rotation axis, and should have higher average velocities than the lighter elements that make up the white dwarf. These results are in broad agreement with previous one- and two-dimensional studies, and point to these systems as progenitors of rapidly rising (∼ few day) transients. If accretion on to the central BH/NS powers a relativistic jet, these events could be accompanied by high-energy transients with peak luminosities ∼1047–1050 erg s−1 and peak durations of up to several minutes, possibly accounting for events like CDF-S XT2.

scholarly journals Can we observe neutrino flares in coincidence with explosive transients?

2017 ◽  
Vol 603 ◽  
pp. A76 ◽  
Author(s):  
Claire Guépin ◽  
Kumiko Kotera
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Photon Flux ◽  
Time Variability ◽  
Tidal Disruption ◽  
Transient Phenomena ◽  
Bolometric Luminosity ◽  
Neutrino Detection ◽  
Transient Sources ◽  
New Generation

The new generation of powerful instruments is reaching sensitivities and temporal resolutions that will allow multi-messenger astronomy of explosive transient phenomena, with high-energy neutrinos as a central figure. We derive general criteria for the detectability of neutrinos from powerful transient sources for given instrument sensitivities. In practice, we provide the minimum photon flux necessary for neutrino detection based on two main observables: the bolometric luminosity and the time variability of the emission. This limit can be compared to the observations in specified wavelengths in order to target the most promising sources for follow-ups. Our criteria can also help distinguishing false associations of neutrino events with a flaring source. We find that relativistic transient sources such as high- and low-luminosity gamma-ray bursts (GRBs), blazar flares, tidal disruption events, and magnetar flares could be observed with IceCube, as they have a good chance to occur within a detectable distance. Of the nonrelativistic transient sources, only luminous supernovae appear as promising candidates. We caution that our criterion should not be directly applied to low-luminosity GRBs and type Ibc supernovae, as these objects could have hosted a choked GRB, leading to neutrino emission without a relevant counterpart radiation. We treat a set of concrete examples and show that several transients, some of which are being monitored by IceCube, are far from meeting the criterion for detectability (e.g., Crab flares or Swift J1644+57).

scholarly journals High-energy Neutrino and Gamma-Ray Emission from Tidal Disruption Events

2020 ◽  
Vol 902 (2) ◽  
pp. 108 ◽  
Author(s):  
Kohta Murase ◽  
Shigeo S. Kimura ◽  
B. Theodore Zhang ◽  
Foteini Oikonomou ◽  
Maria Petropoulou
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Tidal Disruption ◽  
High Energy Neutrino ◽  
Energy Neutrino ◽  
Gamma Ray Emission

scholarly journals The Zadko Telescope: Exploring the Transient Universe

2017 ◽  
Vol 34 ◽  
Author(s):  
D. M. Coward ◽  
B. Gendre ◽  
P. Tanga ◽  
D. Turpin ◽  
J. Zadko ◽  
...  
Keyword(s):  
Gamma Ray ◽  
The United States ◽  
High Energy ◽  
Electromagnetic Spectrum ◽  
Science Projects ◽  
The Status ◽  
International Projects ◽  
Nearby Galaxies ◽  
Cassegrain Telescope

AbstractThe Zadko telescope is a 1 m f/4 Cassegrain telescope, situated in the state of Western Australia about 80-km north of Perth. The facility plays a niche role in Australian astronomy, as it is the only meter class facility in Australia dedicated to automated follow-up imaging of alerts or triggers received from different external instruments/detectors spanning the entire electromagnetic spectrum. Furthermore, the location of the facility at a longitude not covered by other meter class facilities provides an important resource for time critical projects. This paper reviews the status of the Zadko facility and science projects since it began robotic operations in March 2010. We report on major upgrades to the infrastructure and equipment (2012–2014) that has resulted in significantly improved robotic operations. Second, we review the core science projects, which include automated rapid follow-up of gamma ray burst (GRB) optical afterglows, imaging of neutrino counterpart candidates from the ANTARES neutrino observatory, photometry of rare (Barbarian) asteroids, supernovae searches in nearby galaxies. Finally, we discuss participation in newly commencing international projects, including the optical follow-up of gravitational wave (GW) candidates from the United States and European GW observatory network and present first tests for very low latency follow-up of fast radio bursts. In the context of these projects, we outline plans for a future upgrade that will optimise the facility for alert triggered imaging from the radio, optical, high-energy, neutrino, and GW bands.

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