scholarly journals Recent searches for continuous gravitational waves

2017 ◽  
Vol 32 (39) ◽  
pp. 1730035 ◽  
Author(s):  
Keith Riles
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Neutron Star ◽  
Gravitational Waves ◽  
Gamma Ray ◽  
Continuous Wave ◽  
New Era ◽  
Binary Neutron Star ◽  
Binary Black Hole ◽  
Bose Einstein

Gravitational wave astronomy opened dramatically in September 2015 with the LIGO discovery of a distant and massive binary black hole coalescence. The more recent discovery of a binary neutron star merger, followed by a gamma ray burst (GRB) and a kilonova, reinforces the excitement of this new era, in which we may soon see other sources of gravitational waves, including continuous, nearly monochromatic signals. Potential continuous wave (CW) sources include rapidly spinning galactic neutron stars and more exotic possibilities, such as emission from axion Bose Einstein “clouds” surrounding black holes. Recent searches in Advanced LIGO data are presented, and prospects for more sensitive future searches are discussed.

scholarly journals Could GRB170817A be really correlated to an NS–NS merging?

2018 ◽  
Vol 27 (06) ◽  
pp. 1841001 ◽  
Author(s):  
D. Fargion ◽  
M. Yu. Khlopov ◽  
P. Oliva
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Gamma Ray ◽  
Solid Angle ◽  
Open Disk ◽  
Binary Neutron Star ◽  
Binary Black Hole ◽  
Exciting Development ◽  
Soft Disk ◽  
Optical Transient

The exciting development of gravitational wave (GW) astronomy in the correlation of LIGO and VIRGO detection of GW signals makes possible to expect registration of effects of not only binary black hole (BH) coalescence but also binary neutron star (NS) merging accompanied by electromagnetic (gamma ray burst; GRB) signal. Here we consider the possibility that an NS, merging in an NS–NS or NS–BH system might be (soon) observed in correlation with any LIGO–VIRGO GWs detection. We analyze as an example the recent case of the short GRB170817A observed by Fermi and integral. The associated optical transient (OT) source in NGC4993 implies a rare near source, a consequent averaged large rate of such events (almost) compatible with expected NS–NS merging rate. However the expected beamed GRB (or short GRB) may be mostly aligned to a different direction than ours. Therefore, even soft GRB photons, spread more than hard ones, might be hardly able to shower to us. Nevertheless, a prompt spiraling electron turbine jet in largest magnetic fields, at the base of the NS–NS collapse, might shine by its tangential synchrotron radiation in spread way with its skimming photons shining in large open disk. The consequent solid angle for such soft disk gamma radiation may be large enough to be nevertheless often observed.

Reflective black holes

2021 ◽  
pp. 2150200
Author(s):  
Revaz Beradze ◽  
Merab Gogberashvili ◽  
Lasha Pantskhava
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Gravitational Waves ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Radio Bursts ◽  
Hole Model

In this paper, a brief analysis of repeated and overlapped gamma-ray bursts, fast radio bursts and gravitational waves is done. These signals may not be emitted by isolated cataclysmic events and we suggest interpreting some of them within the impenetrable black hole model, as the radiation reflected and amplified by the black hole horizons.

scholarly journals Binary Neutron Star (BNS) Merger: What We Learned from Relativistic Ejecta of GW/GRB 170817A

Physics ◽  
2019 ◽  
Vol 1 (2) ◽  
pp. 194-228 ◽  
Author(s):  
Houri Ziaeepour
Keyword(s):  
Neutron Star ◽  
Gravitational Waves ◽  
Gamma Ray ◽  
Lorentz Factor ◽  
Prompt Gamma ◽  
External Shocks ◽  
Binary Neutron Star ◽  
Tidal Forces ◽  
Relativistic Jet ◽  
Short Grbs

Gravitational Waves (GW) from coalescence of a Binary Neutron Star (BNS) and its accompanying short Gamma-Ray Burst (GRB) GW/GRB 170817A confirmed the presumed origin of these puzzling transients and opened up the way for relating properties of short GRBs to those of their progenitor stars and their surroundings. Here we review an extensive analysis of the prompt gamma-ray and late afterglows of this event. We show that a fraction of polar ejecta from the merger had been accelerated to ultra-relativistic speeds. This structured jet had an initial Lorentz factor of about 260 in our direction, which was O ( 10 ∘ ) from the jet’s axis, and was a few orders of magnitude less dense than in typical short GRBs. At the time of arrival to circum-burst material the ultra-relativistic jet had a close to Gaussian profile and a Lorentz factor ≳ 130 in its core. It had retained in some extent its internal collimation and coherence, but had extended laterally to create mildly relativistic lobes—a cocoon. Its external shocks on the far from center inhomogeneous circum-burst material and low density of colliding shells generated slowly rising afterglows, which peaked more than 100 days after the prompt gamma-ray. The circum-burst material was somehow correlated with the merger. As non-relativistic outflows or tidally ejected material during BNS merger could not have been arrived to the location of the external shocks before the relativistic jet, circum-burst material might have contained recently ejected materials from resumption of internal activities, faulting and mass loss due to deformation and breaking of stars crusts by tidal forces during latest stages of their inspiral but well before their merger. By comparing these findings with the results of relativistic Magneto-Hydro-Dynamics (MHD) simulations and observed gravitational waves we conclude that progenitor neutron stars were most probably old, had close masses and highly reduced magnetic fields.

scholarly journals Comparing the birth rate of stellar black holes in binary black hole mergers and long gamma-ray bursts

2018 ◽  
Vol 610 ◽  
pp. A58
Author(s):  
J.-L. Atteia ◽  
J.-P. Dezalay ◽  
O. Godet ◽  
A. Klotz ◽  
D. Turpin ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Birth Rate ◽  
Gamma Ray ◽  
Reference Model ◽  
Stellar Mass ◽  
Gamma Ray Bursts ◽  
Birth Rates ◽  
Binary Black Hole ◽  
History Of

Context. Gravitational wave interferometers have proven the existence of a new class of binary black hole (BBH) weighing tens of solar masses, and have provided the first reliable measurement of the rate of coalescing black holes (BHs) in the local Universe. Furthermore, long gamma-ray bursts (GRBs) detected with gamma-ray satellites are believed to be associated with the birth of stellar-mass BHs, providing a measure of the rate of these events across the history of the Universe, thanks to the measure of their cosmological redshift. These two types of sources, which are subject to different detection biases and involve BHs born in different environments with potentially different characteristics, provide complementary information on the birth rate of stellar BHs. Aims. We compare the birth rates of BHs found in BBH mergers and in long GRBs. Methods. We construct a simple model that makes reasonable assumptions on the history of GRB formation, and takes into account some major uncertainties, like the beaming angle of GRBs or the delay between the formation of BBHs and their coalescence. We use this model to evaluate the ratio of the number of stellar mass BHs formed in BBH mergers to those formed in GRBs. Results. We find that in our reference model the birth rate of stellar BHs in BBH mergers represents a significant fraction of the rate of long GRBs and that comparable birth rates are favored by models with moderate beaming angles. These numbers, however, do not consider subluminous GRBs, which may represent another population of sources associated with the birth of stellar mass BHs. We briefly discuss this result in view of our understanding of the progenitors of GRBs and BBH mergers, and we emphasize that this ratio, which will be better constrained in the coming years, can be directly compared with the prediction of stellar evolution models if a single model is used to produce GRBs and BBH mergers with the same assumptions.

scholarly journals Collimated outflows from long-lived binary neutron star merger remnants

2020 ◽  
Vol 495 (1) ◽  
pp. L66-L70 ◽  
Author(s):  
Riccardo Ciolfi
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Spin Axis ◽  
Binary Neutron Star ◽  
Physical Conditions ◽  
Massive Neutron Star ◽  
Merger Event ◽  
First Time

ABSTRACT The connection between short gamma-ray bursts (SGRBs) and binary neutron star (BNS) mergers was recently confirmed by the association of GRB 170817A with the merger event GW170817. However, no conclusive indications were obtained on whether the merger remnant that powered the SGRB jet was an accreting black hole (BH) or a long-lived massive neutron star (NS). Here, we explore the latter case via BNS merger simulations covering up to 250 ms after merger. We report, for the first time in a full merger simulation, the formation of a magnetically driven collimated outflow along the spin axis of the NS remnant. For the system at hand, the properties of such an outflow are found largely incompatible with an SGRB jet. With due consideration of the limitations and caveats of our present investigation, our results favour a BH origin for GRB 170817A and SGRBs in general. Even though this conclusion needs to be confirmed by exploring a larger variety of physical conditions, we briefly discuss possible consequences of all SGRB jets being powered by accreting BHs.

scholarly journals Gravitational waves from post-merger radially oscillating millisecond pulsars

2019 ◽  
Vol 622 ◽  
pp. A194 ◽  
Author(s):  
Z. G. Dai
Keyword(s):  
Neutron Star ◽  
Gravitational Waves ◽  
High Frequency ◽  
Gamma Ray ◽  
Magnitude Estimate ◽  
Compact Objects ◽  
Millisecond Pulsars ◽  
Binary Neutron Star ◽  
Order Of Magnitude ◽  
Negligible Contribution

Observations of short-duration gamma-ray bursts and their afterglows show that a good fraction (perhaps ≳50%) of binary neutron star mergers lead to strongly magnetized, rapidly rotating pulsars (including millisecond magnetars), no matter whether the pulsar remnants are short- or long-lived. Such compact objects are very likely to have significant radial oscillations and high interior temperatures, as indicated in recent numerical simulations. In this paper, we have investigated rotation-induced gravitational radiation from possibly existing, radially oscillating pulsars after binary neutron star mergers, and find that this mechanism can efficiently damp the radial oscillations. The resulting gravitational waves (GWs) could have a non-negligible contribution to the high-frequency spectrum. We provide an order-of-magnitude estimate of the event rate and suggest that such GW events would be detectable with the advanced LIGO/Virgo or next-generation detectors. Our discussion can also be applied to newborn, radially oscillating, millisecond pulsars formed through the other astrophysical processes.

The Direct Detection of Gravitational Waves

2018 ◽  
pp. 106-109
Author(s):  
Alvaro De Rújula
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Gravitational Waves ◽  
Direct Detection ◽  
Space Time ◽  
New Era ◽  
The Third ◽  
Perfect Storm

Gravitational waves emitted by black hole mergers. The first LIGO event: GW150917, the coalescence of two black holes of twenty nine and thirty six solar masses into one of “only” sixty two. The remaining three solar masses were emitted as energy in gravitational waves, a gigantic and perfect storm in the fabric of space-time. This is the dawn of a new era: The opening of the third “window” through which to look at the sky. Yet another triumph of general relativity. How much progress astrophysics has made since my time as a student.

scholarly journals mocca-survey Database I: Binary black hole mergers from globular clusters with intermediate mass black holes

2020 ◽  
Vol 498 (3) ◽  
pp. 4287-4294
Author(s):  
Jongsuk Hong ◽  
Abbas Askar ◽  
Mirek Giersz ◽  
Arkadiusz Hypki ◽  
Suk-Jin Yoon
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Gravitational Waves ◽  
Globular Clusters ◽  
Stellar Mass ◽  
Intermediate Mass ◽  
Binary Black Holes ◽  
Black Hole Binaries ◽  
Binary Black Hole ◽  
Intermediate Mass Black Holes

ABSTRACT The dynamical formation of black hole binaries in globular clusters that merge due to gravitational waves occurs more frequently in higher stellar density. Meanwhile, the probability to form intermediate mass black holes (IMBHs) also increases with the density. To explore the impact of the formation and growth of IMBHs on the population of stellar mass black hole binaries from globular clusters, we analyse the existing large survey of Monte Carlo globular cluster simulation data (mocca-survey Database I). We show that the number of binary black hole mergers agrees with the prediction based on clusters’ initial properties when the IMBH mass is not massive enough or the IMBH seed forms at a later time. However, binary black hole formation and subsequent merger events are significantly reduced compared to the prediction when the present-day IMBH mass is more massive than ${\sim}10^4\, \rm M_{\odot }$ or the present-day IMBH mass exceeds about 1 per cent of cluster’s initial total mass. By examining the maximum black hole mass in the system at the moment of black hole binary escaping, we find that ∼90 per cent of the merging binary black holes escape before the formation and growth of the IMBH. Furthermore, large fraction of stellar mass black holes are merged into the IMBH or escape as single black holes from globular clusters in cases of massive IMBHs, which can lead to the significant underpopulation of binary black holes merging with gravitational waves by a factor of 2 depending on the clusters’ initial distributions.

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