BH Mass Research Articles

A 3.8 yr optical quasi-periodic oscillations in blue quasar SDSS J132144+033055 through combined light curves from CSS and ZTF

ABSTRACT In the manuscript, a 3.8 yr optical quasi-periodic oscillations (QPOs) is reported in blue quasar SDSS J132144+033055 (= SDSS J1321) at z = 0.269, based on 16.3yr-long light curve from both CSS and ZTF directly described by a sinusoidal function. The 3.8 yr QPOs can be confirmed through the Generalized Lomb–Scargle periodogram with confidence level higher than 5σ, through properties of the phase-folded light curve and the WWZ technique. Moreover, the collected Pan-STARRS light curves well follow the sinusoidal function described best fitting results to the Catalina Sky Survey (CSS) and Catalina Sky Survey (ZTF) light curves. The optical QPOs strongly indicate a central binary black hole (BBH) system in SDSS J1321, with expected space separation smaller than 0.018 pc, through the estimated upper limit of total BH mass 3.3 × 109 M⊙ through the correlation between BH mass and continuum luminosity. Meanwhile, we check disc precession applied to explain the optical QPOs. However, under the disc precession assumption, the determined optical emission regions from central BH have sizes about 37RG similar as the sizes 35RG of the expected NUV emission regions through the correlation between disc size and BH mass, indicating the disc precession is not preferred. And due to undetected radio emissions, jet precession can be ruled out. Furthermore, only 0.1 per cent probability can determined as the QPOs mis-detected through CAR process randomly created light curves related to intrinsic AGN activities, re-confirming the optical QPOs with significance level higher than 3σ. Therefore, combining long-term light curves from CSS and ZTF can lead to more QPOs candidates in the near future.

Hydrodynamical evolution of black-hole binaries embedded in AGN discs

ABSTRACT Stellar-mass binary black holes (BBHs) embedded in active galactic nucleus (AGN) discs are possible progenitors of black hole mergers detected in gravitational waves by LIGO/VIRGO. To better understand the hydrodynamical evolution of BBHs interacting with the disc gas, we perform a suite of high-resolution 2D simulations of binaries in local disc (shearing-box) models, considering various binary mass ratios, eccentricities and background disc properties. We use the γ-law equation of state and adopt a robust post-processing treatment to evaluate the mass accretion rate, torque and energy transfer rate on the binary to determine its long-term orbital evolution. We find that circular comparable-mass binaries contract, with an orbital decay rate of a few times the mass doubling rate. Eccentric binaries always experience eccentricity damping. Prograde binaries with higher eccentricities or smaller mass ratios generally have slower orbital decay rates, with some extreme cases exhibiting orbital expansion. The averaged binary mass accretion rate depends on the physical size of the accretor. The accretion flows are highly variable, and the dominant variability frequency is the apparent binary orbital frequency (in the rotating frame around the central massive BH) for circular binaries but gradually shifts to the radial epicyclic frequency as the binary eccentricity increases. Our findings demonstrate that the dynamics of BBHs embedded in AGN discs is quite different from that of isolated binaries in their own circumbinary discs. Furthermore, our results suggest that the hardening time-scales of the binaries are much shorter than their migration time-scales in the disc, for all reasonable binary and disc parameters.

The structure of the ultrarelativistic prompt emission phase and the properties of the black hole in GRB 180720B

In analogy with GRB 190114C, we here analyze the ultrarelativistic prompt emission (UPE) of GRB 180720B observed in the rest-frame time interval t_{mathrm{rf}}=4.84–10.89 s by Fermi-GBM. We reveal the UPE hierarchical structure from the time-resolved spectral analysis performed in time sub-intervals: the spectrum in each shorter time interval is always fitted by a composite blackbody plus cutoff power-law model. We explain this structure with the inner engine of binary-driven hypernova (BdHN) model operating in a quantum electrodynamics (QED) regime. In this regime, the electric field induced by the gravitomagnetic interaction of the newborn Kerr BH with the surrounding magnetic field is overcritical, i.e., |mathbf{E}|ge E_c, where E_c=m_e^2 c^3/(ehbar ). The overcritical field polarizes the vacuum leading to an e^+~e^- pair plasma that loads baryons from the surroundings during its expansion. We calculate the dynamics of the self-acceleration of the pair-electromagnetic-baryon (PEMB) pulses to their point of transparency. We characterize the quantum vacuum polarization process in the sequences of decreasing time bins of the UPE by determining the radiation timescale, Lorentz factors, and transparency radius of the PEMB pulses. We also estimate the strength of the surrounding magnetic field sim 10^{14} G, and obtain a lower limit to the BH mass, M=2.4~M_odot , and correspondingly an upper limit to the spin, alpha = 0.6, from the conditions that the UPE is powered by the Kerr BH extractable energy and its mass is bound from below by the NS critical mass.

Variability-selected Intermediate-mass Black Hole Candidates in Dwarf Galaxies from ZTF and WISE

While it is difficult to observe the first black hole seeds in the early universe, we can study intermediate-mass black holes (IMBHs) in local dwarf galaxies for clues about their origins. In this paper we present a sample of variability-selected active galactic nuclei (AGN) in dwarf galaxies using optical photometry from the Zwicky Transient Facility (ZTF) and forward-modeled mid-IR photometry of time-resolved Wide-field Infrared Survey Explorer (WISE) co-added images. We found that 44 out of 25,714 dwarf galaxies had optically variable AGN candidates and 148 out of 79,879 dwarf galaxies had mid-IR variable AGN candidates, corresponding to active fractions of 0.17% ± 0.03% and 0.19% ± 0.02%, respectively. We found that spectroscopic approaches to AGN identification would have missed 81% of our ZTF IMBH candidates and 69% of our WISE IMBH candidates. Only nine candidates have been detected previously in radio, X-ray, and variability searches for dwarf galaxy AGN. The ZTF and WISE dwarf galaxy AGN with broad Balmer lines have virial masses of 105 M ⊙ < M BH < 107 M ⊙, but for the rest of the sample, BH masses predicted from host galaxy mass range between 105.2 M ⊙ < M BH < 107.25 M ⊙. We found that only 5 of 152 previously reported variability-selected AGN candidates from the Palomar Transient Factory in common with our parent sample were variable in ZTF. We also determined a nuclear supernova fraction of 0.05% ± 0.01% yr−1 for dwarf galaxies in ZTF. Our ZTF and WISE IMBH candidates show the promise of variability searches for the discovery of otherwise hidden low-mass AGN.

Black hole and host galaxy growth in an isolated z ∼ 6 QSO observed with ALMA

The outstanding mass growth of supermassive black holes (SMBHs) at the epoch of reionisation and its relation to the concurrent growth of their host galaxies poses challenges to theoretical models aimed at explaining how these systems formed on short timescales (&lt; 1 Gyr). To trace the average evolutionary paths of quasi-stellar objects (QSOs) and their host galaxies in the plane of BH mass to host mass (Mdyn), we compare the star formation rate (SFR), derived from the accurate estimate of the dust temperature and the dust mass (Tdust, Mdust) based on infrared and sub-millimeter (sub-mm) spectral energy distribution (SED), with the BH accretion rate, derived from Lbol based on X-ray and optical and ultraviolet SED. To this aim, we analysed a deep ALMA observation of the sub-mm continuum, [CII], and H2O of the z ∼ 6 QSO J2310+1855 with a resolution of 900 pc, which enabled a detailed study of dust properties and cold gas kinematics. We performed an accurate SED analysis obtaining a dust temperature of Tdust = 71 ± 4 K, dust mass Mdust = (4.4 ± 0.7)×108 M⊙, and total far-infrared luminosity of LTIR = 2.5−0.5+0.6 × 1013 L⊙. The implied active galactic nuclei (AGN) – corrected SFR = 1240−260+310 M⊙ yr−1 is a factor of 2 lower than previously reported for this QSO. We measured a gas-to-dust ratio of GDR = 101 ± 20. The dust continuum and [CII] surface brightness profiles are spatially extended out to r ∼ 6.7 kpc and r ∼ 5 kpc, respectively, with half-light radii of 0.9 and 1.1 kpc for the dust and gas, respectively. The derived gas surface density, Σgas, and star formation rate density, ΣSFR, place the J2310+1855 host galaxy above the Kennicutt-Schmidt relation. We derived a best estimate of the dynamical mass Mdyn = 5.2 × 1010 M⊙ within r = 1.7 kpc based on a dynamical model of the system with a rotating disk inclined at i = 25 deg. The Toomre parameter profile across the disk is Qgas ∼ 3 and implies that the disk is unstable. We found that SFR/Mdyn &gt; ṀBH/MBH, suggesting that AGN feedback might be efficiently acting to slow down the SMBH accretion, while stellar mass assembly is still vigorously taking place in the host galaxy. In addition, we were also able to detect high-velocity emission on the red and blue sides of the [CII] emission line that is not consistent with disk rotation and traces a gaseous outflow. We derived an outflow mass Mout = 3.5 × 108 M⊙, and a mass outflow rate in the range Ṁout = 1800 − 4500 M⊙ yr−1. The implied Ėout ∼ 0.0005 − 0.001 Lbol is in agreement with the values observed for ionised winds. For the first time, we mapped a spatially resolved water vapour disk through the H2O v = 0 3(2, 2) − 3(1, 3) emission line detected at νobs = 274.074 GHz, whose kinematic properties and size are broadly consistent with those of the [CII] disk. The luminosity ratio LH2O/LTIR = 1.4 × 10−5 is consistent with line excitation by dust-reprocessed star formation in the interstellar medium of the host galaxy.

Cosmological 21-cm line observations to test scenarios of super-Eddington accretion on to black holes being seeds of high-redshifted supermassive black holes

In this paper, we study scenarios of the super-Eddington accretion onto black holes at high redshifts $z > 10$, which are expected to be seeds to evolve to supermassive black holes until redshift $z \sim 7$. For an initial mass, $M_{\rm BH, ini} \lesssim 2 \times 10^{3} M_{\odot}$ of a seed BH, we definitely need the super-Eddington accretion, which can be applicable to both astrophysical and primordial origins. Such an accretion disk inevitably emitted high-energy photons which had heated the cosmological plasma of the inter-galactic medium continuously from high redshifts. In this case, the cosmic history of cosmological gas temperature is modified, by which the absorption feature of the cosmological 21 cm lines is suppressed. By comparing theoretical predictions of the 21cm line absorption with the observational data at $z\sim17$, we obtain a cosmological upper bound on the mass-accretion rate as a function of the seed BH masses. In order to realize $M_{\rm BH} \sim 10^9 M_{\odot}$ at $z \sim 7$ by a continuous mass-accretion on to a seed BH, to be consistent with the cosmological 21cm line absorption at $z \sim 17$, we obtained an severe upper bound on the initial mass of the seed BH to be $M_{\rm BH, ini} \lesssim 10^2 M_{\odot}$ ($M_{\rm BH, ini} \lesssim 10^6 M_{\odot}$) when we assume a seed BH with its comoving number density $n_{\rm seed,0} \sim 10^{-3} {\rm Mpc}^{-3}$ ($n_{\rm seed,0} \sim 10^{-7} {\rm Mpc}^{-3}$). We also discuss some implications for application to primordial black holes as the seed black holes.

Turbulent cold flows gave birth to the first quasars.

How quasars powered by supermassive black holes formed less than a billion years after the Big Bang is still one of the outstanding problems in astrophysics, 20 years after their discovery1-4. Cosmological simulations suggest that rare cold flows converging on primordial haloes in low-shear environments could have created these quasars if they were 104-105 solar masses at birth, but could not resolve their formation5-8. Semi-analytical studies of the progenitor halo of a primordial quasar found that it favours the formation of such seeds, but could not verify if one actually appeared9. Here we show that a halo at the rare convergence of strong, cold accretion flows creates massive black holes seeds without the need for ultraviolet backgrounds, supersonic streaming motions or even atomic cooling. Cold flows drive violent, supersonic turbulence in the halo, which prevents star formation until it reaches a mass that triggers sudden, catastrophic baryon collapse that forms 31,000 and 40,000 solar-mass stars. This simple, robust process ensures that haloes capable of forming quasars by a redshift of z > 6 produce massive seeds. The first quasars were thus a natural consequence of structure formation in cold dark matter cosmologies, and not exotic, finely tuned environments as previously thought10-14.

The bulge masses of TDE host galaxies and their scaling with black hole mass

ABSTRACT Tidal disruption events (TDEs) provide a means to probe the low end of the supermassive black hole (SMBH) mass distribution, as they are only observable below the Hills mass (≲ 108 M⊙). Here, we attempt to calibrate the scaling of SMBH mass with host galaxy bulge mass, enabling SMBH masses to be estimated for large TDE samples without the need for follow-up observations or extrapolations of relations based on high-mass samples. We derive host galaxy masses using prospector fits to the UV-MIR spectral energy distributions for the hosts of 29 well-observed TDEs with BH mass estimates from mosfit. We then conduct detailed bulge/disc decomposition using SDSS and PanSTARRS imaging, and provide a catalogue of bulge masses. We measure a positive correlation between SMBH and bulge mass for the TDE sample, with a power-law slope of 0.28 and significance p = 0.06 (Spearmans) and p = 0.05 (Pearsons), and an intrinsic scatter of 0.2 dex. Applying MC resampling and bootstrapping, we find a more conservative estimate of the slope is 0.18 ± 0.11, dominated by the systematic errors from prospector and mosfit. This is shallower than the slope at high SMBH mass, which may be due to a bias in the TDE sample towards lower mass BHs that can more easily disrupt low-mass stars outside of the event horizon. When combining the TDE sample with that of the high-mass regime, we find that TDEs are successful in extending the SMBH – stellar mass relationship further down the mass spectrum and provide a relationship across the full range of SMBH masses.

The formation of the first quasars: the black hole seeds, accretion, and feedback models

ABSTRACT Supermassive black holes (SMBHs) of $\sim 10^9\, \rm M_{\odot }$ are generally believed to be the central engines of the luminous quasars observed at z ≳ 6, but their astrophysical origin remains elusive. To investigate the formation of these distant quasars, we perform a suite of zoom-in simulations on a favourable halo, with a mass of $\sim 10^{13}\, \rm M_{\odot }$ at z = 6 and a history of multiple major mergers, ideal for BH growth. We test BH seeds of $10 {\!-\!} 10^6\, \rm M_{\odot }$, and various accretion and feedback models, including thin-disc and slim-disc accretion. We find that abundant gas supply and efficient angular momentum transport by gravitational torques are critical to BH accretion, and that the final BH mass depends strongly on the seed mass and radiative efficiency which in turn depends on feedback model. In our simulations, heavy seeds of $\gtrsim 10^4\, \rm M_{\odot }$ can grow rapidly to SMBHs of $10^8 {\!-\!} 10^9\, \rm M_{\odot }$ by z ∼6 in both thin and slim disc accretion models, provided that the duty cycle of near-Eddington accretion with an Eddington ratio λEdd ≳ 0.6 is maintained at $\gtrsim 40{{\ \rm per\ cent}}$. In particular, for a $10^5\, \rm M_{\odot }$ seed, both our fiducial model and the supercritical accretion model with no spin produce bright quasars with SMBHs of $\sim 10^9\, \rm M_{\odot }$ at z ∼ 7.5. On the other hand, the light seeds of $\lesssim 10^3\, \rm M_{\odot }$ failed to grow to $10^8\, \rm M_{\odot }$ by z ∼ 6 in our simulations. We caution that the results are inconclusive due to limitations of our numerical methods and physical models, and we stress the need for further investigations on the growth of BH seeds with more advanced methods.

Spin-induced scalarization and magnetic fields

In the presence of certain non-minimal couplings between a scalar field and the Gauss-Bonnet curvature invariant, Kerr black holes can scalarize, as long as they are spinning fast enough. This provides a distinctive violation of the Kerr hypothesis, occurring only for some high spin range. In this paper we assess if strong magnetic fields, that may exist in the vicinity of astrophysical black holes, could facilitate this distinctive effect, by bringing down the spin threshold for scalarization. This inquiry is motivated by the fact that self-gravitating magnetic fields, by themselves, can also promote “spin-induced” scalarization. Nonetheless, we show that in the vicinity of the horizon the effect of the magnetic field B on a BH of mass M, up to BM≲1, works against spin-induced scalarization, requiring a larger dimensionless spin j from the black hole. A geometric interpretation for this result is suggested, in terms of the effects of rotation vs. magnetic fields on the horizon geometry.

The Redshift Evolution of the Binary Black Hole Merger Rate: A Weighty Matter

Gravitational-wave detectors are starting to reveal the redshift evolution of the binary black hole (BBH) merger rate, R BBH(z). We make predictions for R BBH(z) as a function of black hole mass for systems originating from isolated binaries. To this end, we investigate correlations between the delay time and black hole mass by means of the suite of binary population synthesis simulations, COMPAS. We distinguish two channels: the common envelope (CE), and the stable Roche-lobe overflow (RLOF) channel, characterized by whether the system has experienced a common envelope or not. We find that the CE channel preferentially produces BHs with masses below about 30 M ⊙ and short delay times (t delay ≲ 1 Gyr), while the stable RLOF channel primarily forms systems with BH masses above 30 M ⊙ and long delay times (t delay ≳ 1 Gyr). We provide a new fit for the metallicity-dependent specific star formation rate density based on the Illustris TNG simulations, and use this to convert the delay time distributions into a prediction of R BBH(z). This leads to a distinct redshift evolution of R BBH(z) for high and low primary BH masses. We furthermore find that, at high redshift, R BBH(z) is dominated by the CE channel, while at low redshift, it contains a large contribution (∼40%) from the stable RLOF channel. Our results predict that, for increasing redshifts, BBHs with component masses above 30 M ⊙ will become increasingly scarce relative to less massive BBH systems. Evidence of this distinct evolution of R BBH(z) for different BH masses can be tested with future detectors.

A Near-infrared Look at AGN Feedback in Bulgeless Galaxies

While it is generally believed that supermassive black holes (SMBHs) lie in most galaxies with bulges, few SMBHs have been confirmed in bulgeless galaxies. Identifying such a population could provide important insights to the BH seed population and secular BH growth. To this end, we obtained near-infrared (NIR) spectroscopic observations of a sample of low-redshift bulgeless galaxies with mid-infrared colors suggestive of active galactic nuclei (AGNs). We find additional evidence of AGN activity (such as coronal lines and broad permitted lines) in 69% (9/13) of the sample, demonstrating that mid-infrared selection is a powerful tool to detect AGNs. More than half of the galaxies with confirmed AGN activity show fast outflows in [O iii] in the optical and/or [Si vi] in the NIR, with the latter generally having much faster velocities that are also correlated to their spatial extent. We are also able to obtain virial BH masses for some targets and find they fall within the scatter of other late-type galaxies in the M BH–M stellar relation. The fact that they lack a significant bulge component indicates that secular processes, likely independent of major mergers, grew these BHs to supermassive sizes. Finally, we analyze the rotational gas kinematics and find two notable exceptions: two AGN hosts with outflows that appear to be rotating faster than expected. There is an indication that these two galaxies have stellar masses significantly lower than expected from their dark matter halo masses. This, combined with the observed AGN activity and strong gas outflows, may be evidence of the effects of AGN feedback.

Stable Mass Transfer Can Explain Massive Binary Black Hole Mergers with a High-spin Component

Recent gravitational-wave observations showed that binary black hole (BBH) mergers with massive components are more likely to have high effective spins. In the model of isolated binary evolution, BH spins mainly originate from the angular momenta of the collapsing cores before BH formation. Both observations and theories indicate that BHs tend to possess relatively low spins; the origin of fast-spinning BHs remains a puzzle. We investigate an alternative process that stable Case A mass transfer may significantly increase BH spins during the evolution of massive BH binaries. We present detailed binary evolution calculations and find that this process can explain the observed high spins of some massive BBH mergers under the assumption of mildly super-Eddington accretion.

Population Properties of Gravitational-wave Neutron Star–Black Hole Mergers

Abstract Over the course of the third observing run of the LIGO–Virgo–KAGRA Collaboration, several gravitational-wave (GW) neutron star–black hole (NSBH) candidates have been announced. By assuming that these candidates are real signals with astrophysical origins, we analyze the population properties of the mass and spin distributions for GW NSBH mergers. We find that the primary BH mass distribution of NSBH systems, whose shape is consistent with that inferred from the GW binary BH (BBH) primaries, can be well described as a power law with an index of α = 4.8 − 2.8 + 4.5 plus a high-mass Gaussian component peaking at ∼ 33 − 9 + 14 M ⊙ . The NS mass spectrum could be shaped as a nearly flat distribution between ∼1.0 and 2.1 M ⊙. The constrained NS maximum mass agrees with that inferred from NSs in our Galaxy. If GW190814 and GW200210 are NSBH mergers, the posterior results of the NS maximum mass would be always larger than ∼2.5 M ⊙ and significantly deviate from that inferred in Galactic NSs. The effective inspiral spin and effective precession spin of GW NSBH mergers are measured to potentially have near-zero distributions. The negligible spins for GW NSBH mergers imply that most events in the universe should be plunging events, which support the standard isolated formation channel of NSBH binaries. More NSBH mergers to be discovered in the fourth observing run would help to more precisely model the population properties of cosmological NSBH mergers.

Quasiperiodic oscillations from noncommutative inspired black holes

We investigate the dynamics of test particles in the spacetime of noncommutative inspired black holes (NCi BHs). In this context, we first analyse spacetime properties of the NCi BHs together with innermost stable circular orbits (ISCOs) for the particles. It is observed that whereas the ISCO radius does not depend on the NC parameter, the frequencies of the Keplerian orbits and harmonic oscillations are NC parameter dependent. As an application, we consider quasiperiodic oscillations (QPOs) to test effects of the NC gravity around the BHs using twin-peak QPOs frequencies. It is found that the frequency changes even in the presence of the critical NC parameter are smaller than the error in the frequency measurements. The method developed for testing gravity using data from twin peak QPOs may also be applied to other alternate theories of gravity to obtain restrictions on the central BH parameters. We show that the orbits of QPOs lie near ISCO. This assumption may be helpful in solving the ISCO measurement problems in astrophysical observations. In addition, we determine the mass of the central BH in microquasar GRS 1915-105 and the QPO orbit in both the relativistic precession and warped disk models. It is shown that these parameters do not depend on the quantum corrections in the NC gravity. Lastly, we investigate the gravitational capture cross-section for photons and show that the effect of the NC parameter is also less than the error in shadow measurements of the supermassive BH (SMBH) Messier 87 (M87).

On the polytropic Bondi accretion in two-component galaxy models with a central massive BH

ABSTRACT In many investigations involving accretion on a central point mass, ranging from observational studies to cosmological simulations, including semi-analytical modelling, the classical Bondi accretion theory is the standard tool widely adopted. Previous works generalized the theory to include the effects of the gravitational field of the galaxy hosting a central black hole and of electron scattering in the optically thin limit. Here, we apply this extended Bondi problem, in the general polytropic case, to a class of new two-component galaxy models recently presented. In these models, a Jaffe stellar density profile is embedded in a dark matter halo such that the total density distribution follows a r−3 profile at large radii; the stellar dynamical quantities can be expressed in a fully analytical way. The hydrodynamical properties of the flow are set by imposing that the gas temperature at infinity is proportional to the virial temperature of the stellar component. The isothermal and adiabatic (monoatomic) cases can be solved analytically; in the other cases, we explore the accretion solution numerically. As non-adiabatic accretion inevitably leads to an exchange of heat with the ambient, we also discuss some important thermodynamical properties of the polytropic Bondi accretion and provide the expressions needed to compute the amount of heat exchanged with the environment as a function of radius. The results can be useful for the subgrid treatment of accretion in numerical simulations, as well as for the interpretation of observational data.

Relativistic Coulomb screening in pulsational pair instability supernovae

Context.Pulsational pair-instability supernovae (PPISNe) and pair instability supernovae (PISNe) are the result of a thermonuclear runaway in the presence of a background electron-positron pair plasma. As such, their evolution and resultant black hole masses could possibly be affected by screening corrections due to the electron pair plasma.Aims.The sensitivity of PISNe and PPISNe to relativistic weak screening has been explored.Methods.In this paper a weak screening model that includes effects from relativistic pair production has been developed and applied at temperatures approaching and exceeding the threshold for pair production. This screening model replaces “classical” screening commonly used in astrophysics. Modifications to the weak screening electron Debye length were incorporated in a computationally tractable analytic form.Results.In PPISNe the BH masses were found to increase somewhat at high temperatures, though this increase is small. The BH collapse is also found to occur at earlier times, and the pulsational morphology also changes. In addition to the resultant BH mass, the sensitivity to the screening model of the pulsational period, the pulse structure, the PPISN-to-PISN transition, and the shift in the BH mass gap has been analyzed. The dependence of the composition of the ejected mass was also examined.

Quantum gravity evolution in the Hawking radiation of a rotating regular Hayward black hole

In this paper, we study two different phenomena (the Newman-Janis algorithm and the semiclassical Hamilton-Jacobi method) to analyze the Hawking temperature ($T_H$) for massive $4$-dimensional regular Hayward BH with spin parameter. First of all, we compute the rotating regular Hayward black hole solution by taking the Newman-Janis algorithmic rule. We derive the $T_H$ for rotating regular Hayward BH with the help of surface gravity. We have also analyzed the effects of spin parameter $a$ and free parameter $l$ on $T_H$ with the help of graphs. Moreover, we investigate the quantum corrected Hawking temperature ($T'_H$) for rotating regular Hayward black hole. To do so, we utilize the Lagrangian filed equation in the background of GUP within the concept of WKB approximation and semiclassical Hamilton-Jacobi method. The $T'_H$ of rotating regular Hayward BH depends upon correction parameter $\beta$, BH mass $m$, spin parameter $a$, free parameter $l$ and BH radius $r_+$. We also study the graphical behavior of $T'_H$ versus event horizon $r_+$ for rotating regular Hayward BH and check the influences of quantum gravity parameter $\beta$, spin parameter $a$ and free parameter $l$ on the stability of corresponding black hole. Moreover, we study the significance's of logarithmic entropy correction for regular rotating Hayward BH.

Multimessenger Constraints on Magnetic Fields in Merging Black Hole–Neutron Star Binaries

Abstract The LIGO–Virgo–KAGRA Collaboration recently detected gravitational waves (GWs) from the merger of black hole–neutron star (BHNS) binary systems GW200105 and GW200115. No coincident electromagnetic (EM) counterparts were detected. While the mass ratio and BH spin in both systems were not sufficient to tidally disrupt the NS outside the BH event horizon, other, magnetospheric mechanisms for EM emission exist in this regime and depend sensitively on the NS magnetic field strength. Combining GW measurements with EM flux upper limits, we place upper limits on the NS surface magnetic field strength above which magnetospheric emission models would have generated an observable EM counterpart. We consider fireball models powered by the black hole battery mechanism, where energy is output in gamma rays over ≲1 s. Consistency with no detection by Fermi-GBM or INTEGRAL SPI-ACS constrains the NS surface magnetic field to ≲1015 G. Hence, joint GW detection and EM upper limits rule out the theoretical possibility that the NSs in GW200105 and GW200115, and the putative NS in GW190814, retain dipolar magnetic fields ≳1015 G until merger. They also rule out formation scenarios where strongly magnetized magnetars quickly merge with BHs. We alternatively rule out operation of the BH-battery-powered fireball mechanism in these systems. This is the first multimessenger constraint on NS magnetic fields in BHNS systems and a novel approach to probe fields at this point in NS evolution. This demonstrates the constraining power that multimessenger analyses of BHNS mergers have on BHNS formation scenarios, NS magnetic field evolution, and the physics of BHNS magnetospheric interactions.

A 6.4-yr optical quasi-periodic oscillations in SDSS J075217.84+193542.2: a new candidate for central binary black hole system

ABSTRACT In this manuscript, a 6.4-yr optical quasi-periodic oscillations (QPOs) is detected in the quasar SDSS J075217.84+193542.2 (=+SDSS J0752) at a redshift 0.117, of which 13.6-yr-long light curve from Catalina Sky Survey and All-Sky Automated Survey for Supernovae is directly described by a sinusoidal function with a periodicity 6.4 yr. The 6.4-yr QPOs can be further confirmed through the generalized Lomb–Scargle periodogram with confidence level higher than 99.99 per cent, and through the autocorrelation analysis results, and through the weighted wavelet z-transformation technique. The optical QPOs strongly indicate a central binary black hole (BBH) system in SDSS J0752. The determined two broad Gaussian components in the broad H α can lead to the BBH system with expected space separation about 0.02 pc between the expected two central BHs with determined virial BH masses about 8.8 × 107 and 1.04 × 109 M⊙. Meanwhile, we check the disc precessions applied to explain the optical QPOs. However, under the disc precession assumption, the determined optical emission regions from central BH have sizes about 40RG two times smaller than sizes of the expected Near UltraViolet (NUV) emission regions through the correlation between disc size and BH mass, indicating the disc precessions are not preferred. And due to the lower radio loudness around 0.28, jet precessions can be also totally ruled out. Furthermore, only 0.08 per cent probability can determined as the QPOs misdetected through light curves randomly created by the continuous autoregressive process, reconfirming the reported optical QPOs.