The mass distribution of Galactic double neutron stars: constraints on the gravitational-wave sources like GW170817

2019 ◽  
Vol 488 (4) ◽  
pp. 5020-5028 ◽  
Author(s):  
Jianwei Zhang ◽  
Yiyan Yang ◽  
Chengmin Zhang ◽  
Wuming Yang ◽  
Di Li ◽  
...  
Keyword(s):  
Neutron Star ◽  
Gravitational Wave ◽  
Mass Distribution ◽  
Mass Ratio ◽  
Important Indicator ◽  
Distribution Ranges ◽  
The Galaxy ◽  
Merger Event ◽  
Credible Intervals ◽  
First Time

ABSTRACT The merger event of double neutron star (DNS) system (GW170817) was detected by the gravitational-wave (GW) detectors (Advanced LIGO and Advanced Virgo) in 2017 for the first time, so their mass distribution has become a significant topic with the new round GW hunting (O3) in 2019. A few models (e.g. Gaussian, two-Gaussian, or mixture-Gaussian) were adopted to draw the mass distribution of observed Galactic DNS systems, however, there is no a confirmed model now due to the small size of DNS samples (N < 20). Here we focus on determining the most probable distribution ranges of DNS masses without model selection by assuming the neutron star masses to be uniformly distributed between the lower and upper bounds. We apply a Bayesian analysis and Markov chain Monte Carlo simulation to 15 Galactic DNS systems, and obtain that the component masses of DNS systems should mainly fall in the range of 1.165–1.590 M⊙, and the predominant ranges for the total mass, mass ratio, and chirp mass lie in 2.535–2.867 M⊙, 0.741–0.995, and 1.115–1.237 M⊙, respectively. Our results are in agreement with the properties of DNS in GW170817, whose 90 per cent credible intervals for the component masses, total masses, mass ratio, and chirp masses are 1.16–1.60 M⊙, $2.73_{-0.01}^{+0.04}\, \mathrm{ M}_\odot$, 0.73–1.00, and $1.186_{-0.001}^{+0.001}\, \mathrm{ M}_\odot$, respectively. The above similarity is an important indicator that reveals the source of GW170817 to be a DNS system from the galaxy NGC 4993, and our results can be tested by the forthcoming GW hunting O3.

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 Detecting the Hadron-Quark Phase Transition with Gravitational Waves

Universe ◽  
2019 ◽  
Vol 5 (6) ◽  
pp. 156 ◽  
Author(s):  
Matthias Hanauske ◽  
Luke Bovard ◽  
Elias Most ◽  
Jens Papenfort ◽  
Jan Steinheimer ◽  
...  
Keyword(s):  
Phase Transition ◽  
Neutron Star ◽  
Equation Of State ◽  
Gravitational Wave ◽  
Compact Star ◽  
Binary Neutron Star ◽  
Interesting Part ◽  
Merger Event ◽  
Tidal Deformations ◽  
Quark Phase

The long-awaited detection of a gravitational wave from the merger of a binary neutron star in August 2017 (GW170817) marks the beginning of the new field of multi-messenger gravitational wave astronomy. By exploiting the extracted tidal deformations of the two neutron stars from the late inspiral phase of GW170817, it is now possible to constrain several global properties of the equation of state of neutron star matter. However, the most interesting part of the high density and temperature regime of the equation of state is solely imprinted in the post-merger gravitational wave emission from the remnant hypermassive/supramassive neutron star. This regime was not observed in GW170817, but will possibly be detected in forthcoming events within the current observing run of the LIGO/VIRGO collaboration. Numerous numerical-relativity simulations of merging neutron star binaries have been performed during the last decades, and the emitted gravitational wave profiles and the interior structure of the generated remnants have been analysed in detail. The consequences of a potential appearance of a hadron-quark phase transition in the interior region of the produced hypermassive neutron star and the evolution of its underlying matter in the phase diagram of quantum cromo dynamics will be in the focus of this article. It will be shown that the different density/temperature regions of the equation of state can be severely constrained by a measurement of the spectral properties of the emitted post-merger gravitational wave signal from a future binary compact star merger event.

scholarly journals The effect of differential accretion on the gravitational wave background and the present-day MBH binary population

2020 ◽  
Vol 498 (1) ◽  
pp. 537-547 ◽  
Author(s):  
Magdalena S Siwek ◽  
Luke Zoltan Kelley ◽  
Lars Hernquist
Keyword(s):  
Gravitational Wave ◽  
Analytical Models ◽  
Galaxy Mergers ◽  
Mass Ratio ◽  
Massive Black Hole ◽  
Black Hole Binaries ◽  
Pulsar Timing ◽  
Coalescence Rate ◽  
Gravitational Wave Background ◽  
First Time

ABSTRACT Massive black hole binaries (MBHBs) form as a consequence of galaxy mergers. However, it is still unclear whether they typically merge within a Hubble time, and how accretion may affect their evolution. These questions will be addressed by pulsar timing arrays (PTAs), which aim to detect the gravitational wave (GW) background (GWB) emitted by MBHBs during the last Myr of inspiral. Here, we investigate the influence of differential accretion on MBHB merger rates, chirp masses, and the resulting GWB spectrum. We evolve an MBHB sample from the Illustris hydrodynamic cosmological simulation using semi-analytical models and for the first time self-consistently evolve their masses with binary accretion models. In all models, MBHBs coalesce with median total masses up to 1.5 × 108 M⊙, up to 3−4 times larger than in models neglecting accretion. In our model with the largest plausible impact, the median mass ratio of coalescing MBHBs increases by a factor 3.6, the coalescence rate by $52.3{{\ \rm per\ cent}}$, and the GWB amplitude by a factor 4.0, yielding a dimensionless GWB strain $A_{yr^{-1}} = 1 \times 10^{-15}$. Our model that favours accretion on to the primary MBH reduces the median mass ratio of coalescing MBHBs by a factor of 2.9, and yields a GWB amplitude $A_{yr^{-1}} = 3.1 \times 10^{-16}$. This is nearly indistinguishable from our model neglecting accretion, despite higher MBHB masses at coalescence. We further predict binary separation and mass ratio distributions of stalled MBHBs in the low-redshift Universe, and find that these depend sensitively on binary accretion models. This presents the potential for combined electromagnetic and GW observational constraints on merger rates and accretion models of MBHB populations.

scholarly journals The heavier the better: how to constrain mass ratios and spins of high-mass neutron star mergers

2020 ◽  
Vol 496 (1) ◽  
pp. L16-L21 ◽  
Author(s):  
Elias R Most ◽  
Lukas R Weih ◽  
Luciano Rezzolla
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Lower Bound ◽  
Equations Of State ◽  
High Mass ◽  
Maximum Mass ◽  
Mass Ratio ◽  
Effective Spin ◽  
Binary Neutron Star ◽  
Merger Event

ABSTRACT The first binary neutron star merger event, GW170817, and its bright electromagnetic counterpart have provided a remarkable amount of information. By contrast, the second event, GW190425, with $M_{\rm tot}=3.4^{+0.3}_{-0.1}\, \mathrm{ M}_{\odot }$ and the lack of an electromagnetic counterpart, has hardly improved our understanding of neutron star physics. While GW190425 is compatible with a scenario in which the merger has led to a prompt collapse to a black hole and little ejected matter to power a counterpart, determining the mass ratio and the effective spin $\tilde{\chi }$ of the binary remains difficult. This is because gravitational waveforms cannot yet well constrain the component spins of the binary. However, since the mass of GW190425 is significantly larger than the maximum mass for non-rotating neutron stars, $M_{_{\rm TOV}}$, the mass ratio q cannot be too small, as the heavier star would not be gravitationally stable. Making use of universal relations and a large number of equations of state, we provide limits in the $(\tilde{\chi },q)$ plane for GW190425, namely qmin ≥ 0.38 and $\tilde{\chi }_{\rm max}\le 0.20$, assuming $M_\mathrm{tot} \simeq 3.4\, \mathrm{ M}_\odot$. Finally, we show how future observations of high-mass binaries can provide a lower bound on $M_{_{\rm TOV}}$.

scholarly journals Hottest Superfluid and Superconductor in the Universe: Lessons from the Cooling of the Cassiopeia A Neutron Star

2011 ◽  
Vol 7 (S285) ◽  
pp. 337-339
Author(s):  
Wynn C. G. Ho ◽  
Craig O. Heinke ◽  
Daniel J. Patnaude ◽  
Peter S. Shternin ◽  
Dmitry G. Yakovlev
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Cooling Rate ◽  
Recent Onset ◽  
Cassiopeia A ◽  
Protons And Neutrons ◽  
The Galaxy ◽  
Rapid Temperature ◽  
First Time ◽  
The Universe

AbstractThe cooling rate of young neutron stars gives direct insight into their internal makeup. Using Chandra observations of the 330-year-old Cassiopeia A supernova remnant, we find that the temperature of the youngest-known neutron star in the Galaxy has declined by 4% over the last 10 years. The decline is explained naturally by superconductivity and superfluidity of the protons and neutrons in the stellar core. The protons became superconducting early in the life of the star and suppressed the early cooling rate; the neutron star thus remained hot before the (recent) onset of neutron superfluidity. Once the neutrons became superfluid, the Cooper pair-formation process produced a splash of neutrino emission which accelerated the cooling and resulted in the observed rapid temperature decline. This is the first time a young neutron star has been seen to cool in real time, and is the first direct evidence, from cooling observations, of superfluidity and superconductivity in the core of neutron stars.

Simulation of chirp mass distribution of neutron star and black hole merger events for gravitational-wave radiation

2020 ◽  
Vol 101 (4) ◽  
Author(s):  
Jianwei Zhang ◽  
Chengmin Zhang ◽  
Wuming Yang ◽  
Yiyan Yang ◽  
Di Li ◽  
...  
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Gravitational Wave ◽  
Mass Distribution ◽  
Wave Radiation

scholarly journals Future merger of the Milky Way with the Andromeda galaxy and the fate of their supermassive black holes

2020 ◽  
Vol 642 ◽  
pp. A30
Author(s):  
Riccardo Schiavi ◽  
Roberto Capuzzo-Dolcetta ◽  
Manuel Arca-Sedda ◽  
Mario Spera
Keyword(s):  
Black Holes ◽  
Gravitational Wave ◽  
Relative Motion ◽  
Milky Way ◽  
Close Approach ◽  
Supermassive Black Holes ◽  
Andromeda Galaxy ◽  
The Galaxy ◽  
Inner Region ◽  
First Time

Our Galaxy and the nearby Andromeda galaxy (M 31) are the most massive members of the Local Group, and they seem to be a bound pair, despite the uncertainties on the relative motion of the two galaxies. A number of studies have shown that the two galaxies will likely undergo a close approach in the next 4−5 Gyr. We used direct N-body simulations to model this interaction to shed light on the future of the Milky Way – Andromeda system and for the first time explore the fate of the two supermassive black holes (SMBHs) that are located at their centers. We investigated how the uncertainties on the relative motion of the two galaxies, linked with the initial velocities and the density of the diffuse environment in which they move, affect the estimate of the time they need to merge and form “Milkomeda”. After the galaxy merger, we follow the evolution of their two SMBHs up to their close pairing and fusion. Upon the fiducial set of parameters, we find that Milky Way and Andromeda will have their closest approach in the next 4.3 Gyr and merge over a span of 10 Gyr. Although the time of the first encounter is consistent with other predictions, we find that the merger occurs later than previously estimated. We also show that the two SMBHs will spiral in the inner region of Milkomeda and coalesce in less than 16.6 Myr after the merger of the two galaxies. Finally, we evaluate the gravitational-wave emission caused by the inspiral of the SMBHs, and we discuss the detectability of similar SMBH mergers in the nearby Universe (z ≤ 2) through next-generation gravitational-wave detectors.

scholarly journals The New Astronomy: Observing Our Universe With Light and Gravity

2019 ◽  
Vol 7 ◽  
Author(s):  
Joey Shapiro Key ◽  
LIGO Scientific Collaboration
Keyword(s):  
Black Holes ◽  
South America ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Gamma Ray ◽  
Distant Galaxy ◽  
The World ◽  
The Galaxy ◽  
First Time

On a summer day in 2017, astronomers around the world received a message about an exciting collision of two stars far, far away. The message was sent by a team of astronomers from the LIGO and Virgo observatories. These new observatories are very different from the telescopes we have used to study our Universe up until now. LIGO and Virgo are gravitational wave observatories, listening for quiet ripples in spacetime created by the collisions of distant black holes and neutron stars. On August 17, 2017 LIGO and Virgo detected a signal that astronomers named GW170817, from the collision of two neutron stars. Less than two seconds later, NASA's Fermi satellite caught a signal, known as a gamma-ray burst, and within minutes, telescopes around the world began searching the sky. Telescopes in South America found the location of the collision in a distant galaxy known as NGC 4993. For the weeks and months that followed, astronomers watched the galaxy and the fading light from the collision. This is a new kind of multi-messenger astronomy where, for the first time, the same event was observed by both gravitational waves and light.

scholarly journals Inward bound: the incredible journey of massive black holes as they pair and merge – I. The effect of mass ratio in flattened rotating galactic nuclei

2019 ◽  
Vol 492 (1) ◽  
pp. 256-267 ◽  
Author(s):  
Fazeel Mahmood Khan ◽  
Muhammad Awais Mirza ◽  
Kelly Holley-Bockelmann
Keyword(s):  
Black Holes ◽  
Gravitational Wave ◽  
Galactic Nuclei ◽  
Orbital Plane ◽  
Host Galaxy ◽  
Mass Ratio ◽  
Binary Forms ◽  
Wave Source ◽  
Rotating Systems ◽  
The Galaxy

ABSTRACT Understanding how supermassive black holes (SMBHs) pair and merge helps to inform predictions of off-centre, dual, and binary active galactic nuclei (AGNs), and provides key insights into how SMBHs grow and co-evolve with their galaxy hosts. As the loudest known gravitational wave source, binary SMBH mergers also hold centrestage for the Laser Interferometer Space Antenna (LISA), a joint ESA/NASA gravitational wave observatory set to launch in 2034. Here, we continue our work to characterize SMBH binary formation and evolution through increasingly more realistic high-resolution direct N-body simulations, focusing on the effect of SMBH mass ratio, orientation, and eccentricity within a rotating and flattened stellar host. During the dynamical friction phase, we found a prolonged orbital decay for retrograde SMBHs and swift pairing time-scales for prograde SMBHs compared to their counterparts in non-rotating models, an effect that becomes more pronounced for smaller mass ratios Msec/Mprim = q. During this pairing phase, the eccentricity dramatically increases for retrograde configurations, but as the binary forms, the orbital plane flips so that it is almost perfectly prograde, which stifles the rapid eccentricity growth. In prograde configurations, SMBH binaries form and remain at comparatively low eccentricities. As in our prior work, we note that the centre of mass of a prograde SMBH binary itself settles into an orbit about the centre of the galaxy. Since even the initially retrograde binaries flip their orbital plane, we expect few binaries in rotating systems to reside at rest in the dynamic centre of the host galaxy, though this effect becomes smaller as q decreases.

scholarly journals Biotransformation of Timosaponin BII into Seven Characteristic Metabolites by the Gut Microbiota

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3861
Author(s):  
Guo-Ming Dong ◽  
Hang Yu ◽  
Li-Bin Pan ◽  
Shu-Rong Ma ◽  
Hui Xu ◽  
...  
Keyword(s):  
Gut Microbiota ◽  
Rat Liver ◽  
Pharmacological Activity ◽  
Liver Homogenate ◽  
Intestinal Flora ◽  
Important Indicator ◽  
Metabolic Characteristics ◽  
Metabolic Behavior ◽  
First Time ◽  
Rat Liver Microsome

Timosaponin BII is one of the most abundant Anemarrhena saponins and is in a phase II clinical trial for the treatment of dementia. However, the pharmacological activity of timosaponin BII does not match its low bioavailability. In this study, we aimed to determine the effects of gut microbiota on timosaponin BII metabolism. We found that intestinal flora had a strong metabolic effect on timosaponin BII by HPLC-MS/MS. At the same time, seven potential metabolites (M1-M7) produced by rat intestinal flora were identified using HPLC/MS-Q-TOF. Among them, three structures identified are reported in gut microbiota for the first time. A comparison of rat liver homogenate and a rat liver microsome incubation system revealed that the metabolic behavior of timosaponin BII was unique to the gut microbiota system. Finally, a quantitative method for the three representative metabolites was established by HPLC-MS/MS, and the temporal relationship among the metabolites was initially clarified. In summary, it is suggested that the metabolic characteristics of gut microbiota may be an important indicator of the pharmacological activity of timosaponin BII, which can be applied to guide its application and clinical use in the future.

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