scholarly journals Detection of Periodic Radio Signal from the Blazar J1043+2408

Galaxies ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 136 ◽  
Author(s):  
Gopal Bhatta
Keyword(s):  
Black Hole ◽  
Radio Signal ◽  
Field Configuration ◽  
Periodic Signal ◽  
Magnetic Field Configuration ◽  
Supermassive Black Hole ◽  
Central Engine ◽  
Direct View ◽  
Periodic Signals ◽  
Periodic Changes

The search for periodic signals from blazars has become a widely discussed topic in recent years. In the scenario that such periodic changes originate from the innermost regions of blazars, the signals bear imprints of the processes occurring near the central engine, which are mostly inaccessible to our direct view. Such signals provide insights into various aspect of blazar studies, including disk-jet connection, magnetic-field configuration and, more importantly, strong gravity near the supermassive black holes and release of gravitational waves from binary supermassive-black-hole systems. In this work, we report the detection of a periodic signal in the radio light curve of blazar J1043+2408 spanning ∼10.5 years. We performed multiple methods of time-series analysis, namely, epoch folding, Lomb–Scargle periodogram, and discrete autocorrelation function. All three methods consistently revealed a repeating signal with a periodicity of ∼560 days. To robustly account for the red-noise processes usually dominant in the blazar variability and other possible artefacts, a large number of Monte Carlo simulations were performed. This allowed us to estimate high significance (99.9% local and 99.4% global) against possible spurious detection. As possible explanations, we discuss a number of scenarios, including binary supermassive-black-hole systems, Lense–Thirring precession, and jet precession.

scholarly journals Detection of Periodic Radio Signal from the Blazar J1043+2408

2018 ◽  
Author(s):  
Gopal Bhatta
Keyword(s):  
Black Hole ◽  
Radio Signal ◽  
Field Configuration ◽  
Light Curves ◽  
Periodic Signal ◽  
Magnetic Field Configuration ◽  
Auto Correlation ◽  
Direct View ◽  
Auto Correlation Function ◽  
Periodic Signals

Search for periodic signals from blazars has become widely discussed topic in recent years. This is because periodic signals bear imprints of the processes occurring near the innermost regions of blazars which are mostly inaccessible to our direct view. Such signals provide insights into various aspect of blazar studies including disk-jet connection, magnetic field configuration and, more importantly, strong gravity near the supermassive black holes and release of gravitational waves from the binary supermassvie black hole systems. In this work, we report detection of a periodic signal in the radio light curves of the blazar J1043+2408 spanning ~10.5 years. We performed multiple methods of time series analysis, namely, epoch folding, Lomb-Scargle periodogram, and discrete auto-correlation function. All three methods consistently reveal a repeating signal with a periodicity of ~563 days. To robustly account for the red-noise processes usually dominant in the blazar variability and other possible artifacts, a large number of Monte Carlo simulations were performed. This allowed us to estimate a high significance (99.9% local and 99.4% global) against possible spurious detection. As possible explanations, we discuss a number of scenarios including binary supermassive black hole system, Lense-Thirring precession, and jet swing and precession.

scholarly journals Studying the Galactic Central Engine from Space Observatories

1990 ◽  
Vol 123 ◽  
pp. 559-561
Author(s):  
Howard D. Greyber
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
Field Configuration ◽  
Energy Output ◽  
Current Loop ◽  
Central Engine ◽  
Dipole Magnetic Field ◽  
The Galaxy ◽  
Magnetic Field Model ◽  
Space Observatories

Three general models have been constructed for the fantastically powerful “central engine” that powers the enormous energy output from quasars and active galactic nuclei (AGN). One model assumes a rapidly rotating accretion disk around a central black hole (however the disks, thick or thin, are subject to violent instabilities). Another assumes that in some postulated circuitry energy is extracted from the rotational portion of the deepest potential hole known, a black hole. Both models appear implausible.The third model is the STRONG MAGNETIC FIELD MODEL (SMF) in which an extremely strong gravitationally bound current loop (GBCL) is formed during the gravitational collapse that forms the galaxy or quasar, producing a very intense dipole magnetic field anchored in the nucleus. SMF, first published in 1962, thus predicted the vertical magnetic field configuration seen today at our own galactic nucleus; to some the radio arcs observed suggest a dipole magnetic field there, just as SMF predicts.

scholarly journals Study of Periodic Signals from Blazars

Proceedings ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 15
Author(s):  
Gopal Bhatta
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Gamma Ray ◽  
Supermassive Black Holes ◽  
Light Curves ◽  
Supermassive Black Hole ◽  
Transient Nature ◽  
Time Series Analyses ◽  
Periodic Signals

The search for periodic signals from blazars has become an actively pursued field of research in recent years. This is because periodic signals bring us information about the processes occurring near the innermost regions of blazars, which are mostly inaccessible to our direct view. Such signals provide insights into some of the extreme conditions that take place in the vicinity of supermassive black holes that lead to the launch of the relativistic jets. In addition, studies of characteristic timescales in blazar light curves shed light on some of the challenging issues in blazar physics that include disk-jet connection, strong gravity near fast-rotating supermassive black holes and release of gravitational waves from binary supermassive black hole systems. However, a number of issues associated with the search for quasi-periodic oscillations (QPOs) in blazars e.g., red-noise dominance, modest significance of the detection, periodic modulation lasting for only a couple of cycles and their transient nature, make it difficult to estimate the true significance of the detection. Consequently, it also becomes difficult to make meaningful inferences about the nature of the on-going processes. In this proceedings, results of study focused on searching for QPOs in a number of blazar multi-frequency light curves are summarized. The time series analyses of long term observations of the blazars revealed the presence of year-timescale QPOs in the sources including OJ 287 (optical), Mrk 501 (gamma-ray), J1043+2408 (radio) and PKS 0219-164 (radio). A likely explanations, we discuss a number of scenarios including binary supermassive black hole systems, lense-thirring precession, and jet precession.

scholarly journals Black Hole Masses and Unification of Seyferts

1999 ◽  
Vol 194 ◽  
pp. 311-312
Author(s):  
R. Bachev ◽  
G. T. Petrov ◽  
L. Slavcheva ◽  
B. Mihov
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Power Source ◽  
Active Galaxies ◽  
Supermassive Black Hole ◽  
Central Engine ◽  
Internal Structures ◽  
Accretion Rates ◽  
Black Hole Masses

The most commonly invoked power source of Active Galactic Nuclei (AGN) is accretion of galactic gas (probably through a disk) onto a supermassive black hole in the center of the nucleus (Rees 1984). As is well known, a black hole is completely defined by its mass and angular momentum. The unification scheme of active galaxies assumes that two known Seyfert types (Sy1 and Sy2) are not intrinsically different, i. e. their black hole masses, accretion rates and the whole internal structures are identical (Antonucci 1993) and observed differences are due just to a different orientation to the observer of the axisymmetrical central structure (central engine, BLR and thick torus, shadowing broad lines from some directions).

scholarly journals Hydrodynamics Near the Central Engine

1986 ◽  
Vol 89 ◽  
pp. 369-383
Author(s):  
John F. Hawley
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Disk Formation ◽  
Accretion Flows ◽  
Supermassive Black Hole ◽  
Central Engine ◽  
Accretion Rates ◽  
Considerable Work ◽  
Black Hole Masses

AbstractThe “central engine” of quasars and active galactic nuclei Is most likely powered by accretion into a supermassive black hole. A menagerie of steady state accretion flows have been developed, and these are briefly reviewed. Several examples from recent numerical calculations of axisymmetric accretion flows provide disk formation scenarios from which one can calculate plasma densities, and other values of interest for a range of accretion rates and black hole masses. These results can be compared with the well studied, but physically unrealistic case of radial accretion. Although a reasonable conceptual picture of the central engine has been developed, considerable work remains to be done.

Central kiloparsec of NGC 1326 observed with SINFONI

2020 ◽  
Vol 638 ◽  
pp. A53
Author(s):  
Nastaran Fazeli ◽  
Gerold Busch ◽  
Andreas Eckart ◽  
Françoise Combes ◽  
Persis Misquitta ◽  
...  
Keyword(s):  
Black Hole ◽  
Galaxy Evolution ◽  
Near Infrared ◽  
Velocity Fields ◽  
Molecular Gas ◽  
Nearby Galaxy ◽  
Stellar Content ◽  
Stellar Rotation ◽  
Supermassive Black Hole ◽  
Integral Field Spectrograph

Gas inflow processes in the vicinity of galactic nuclei play a crucial role in galaxy evolution and supermassive black hole growth. Exploring the central kiloparsec of galaxies is essential to shed more light on this subject. We present near-infrared H- and K-band results of the nuclear region of the nearby galaxy NGC 1326, observed with the integral-field spectrograph SINFONI mounted on the Very Large Telescope. The field of view covers 9″ × 9″ (650 × 650 pc2). Our work is concentrated on excitation conditions, morphology, and stellar content. The nucleus of NGC 1326 was classified as a LINER, however in our data we observed an absence of ionised gas emission in the central r ∼ 3″. We studied the morphology by analysing the distribution of ionised and molecular gas, and thereby detected an elliptically shaped, circum-nuclear star-forming ring at a mean radius of 300 pc. We estimate the starburst regions in the ring to be young with dominating ages of < 10 Myr. The molecular gas distribution also reveals an elongated east to west central structure about 3″ in radius, where gas is excited by slow or mild shock mechanisms. We calculate the ionised gas mass of 8 × 105 M⊙ completely concentrated in the nuclear ring and the warm molecular gas mass of 187 M⊙, from which half is concentrated in the ring and the other half in the elongated central structure. The stellar velocity fields show pure rotation in the plane of the galaxy. The gas velocity fields show similar rotation in the ring, but in the central elongated H2 structure they show much higher amplitudes and indications of further deviation from the stellar rotation in the central 1″ aperture. We suggest that the central 6″ elongated H2 structure might be a fast-rotating central disc. The CO(3–2) emission observations with the Atacama Large Millimeter/submillimeter Array reveal a central 1″ torus. In the central 1″ of the H2 velocity field and residual maps, we find indications for a further decoupled structure closer to a nuclear disc, which could be identified with the torus surrounding the supermassive black hole.

scholarly journals WISDOM project – VII. Molecular gas measurement of the supermassive black hole mass in the elliptical galaxy NGC 7052

2021 ◽  
Vol 503 (4) ◽  
pp. 5984-5996
Author(s):  
Mark D Smith ◽  
Martin Bureau ◽  
Timothy A Davis ◽  
Michele Cappellari ◽  
Lijie Liu ◽  
...  
Keyword(s):  
Black Hole ◽  
Hubble Space Telescope ◽  
Elliptical Galaxy ◽  
Continuum Emission ◽  
Molecular Gas ◽  
Supermassive Black Hole ◽  
Gas Kinematics ◽  
Long Baseline ◽  
Gas Measurement ◽  
Strong Gradient

ABSTRACT Supermassive black hole (SMBH) masses can be measured by resolving the dynamical influences of the SMBHs on tracers of the central potentials. Modern long-baseline interferometers have enabled the use of molecular gas as such a tracer. We present here Atacama Large Millimeter/submillimeter Array observations of the elliptical galaxy NGC 7052 at 0${^{\prime\prime}_{.}}$11 ($37\,$pc) resolution in the 12CO(2-1) line and $1.3\,$ mm continuum emission. This resolution is sufficient to resolve the region in which the potential is dominated by the SMBH. We forward model these observations, using a multi-Gaussian expansion of a Hubble Space Telescope F814W image and a spatially constant mass-to-light ratio to model the stellar mass distribution. We infer an SMBH mass of $2.5\pm 0.3\times 10^{9}\, \mathrm{M_\odot }$ and a stellar I-band mass-to-light ratio of $4.6\pm 0.2\, \mathrm{M_\odot /L_{\odot ,I}}$ (3σ confidence intervals). This SMBH mass is significantly larger than that derived using ionized gas kinematics, which however appears significantly more kinematically disturbed than the molecular gas. We also show that a central molecular gas deficit is likely to be the result of tidal disruption of molecular gas clouds due to the strong gradient in the central gravitational potential.

scholarly journals Morphological evolution of supermassive black hole merger hosts and multimessenger signatures

2021 ◽  
Vol 503 (3) ◽  
pp. 3629-3642
Author(s):  
Colin DeGraf ◽  
Debora Sijacki ◽  
Tiziana Di Matteo ◽  
Kelly Holley-Bockelmann ◽  
Greg Snyder ◽  
...  
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Star Formation ◽  
Morphological Evolution ◽  
Full Range ◽  
High Mass ◽  
Morphological Evidence ◽  
Galaxy Mergers ◽  
Host Galaxies ◽  
Supermassive Black Hole

ABSTRACT With projects such as Laser Interferometer Space Antenna (LISA) and Pulsar Timing Arrays (PTAs) expected to detect gravitational waves from supermassive black hole mergers in the near future, it is key that we understand what we expect those detections to be, and maximize what we can learn from them. To address this, we study the mergers of supermassive black holes in the Illustris simulation, the overall rate of mergers, and the correlation between merging black holes and their host galaxies. We find these mergers occur in typical galaxies along the MBH−M* relation, and that between LISA and PTAs we expect to probe the full range of galaxy masses. As galaxy mergers can trigger star formation, we find that galaxies hosting low-mass black hole mergers tend to show a slight increase in star formation rates compared to a mass-matched sample. However, high-mass merger hosts have typical star formation rates, due to a combination of low gas fractions and powerful active galactic nucleus feedback. Although minor black hole mergers do not correlate with disturbed morphologies, major mergers (especially at high-masses) tend to show morphological evidence of recent galaxy mergers which survive for ∼500 Myr. This is on the same scale as the infall/hardening time of merging black holes, suggesting that electromagnetic follow-ups to gravitational wave signals may not be able to observe this correlation. We further find that incorporating a realistic time-scale delay for the black hole mergers could shift the merger distribution towards higher masses, decreasing the rate of LISA detections while increasing the rate of PTA detections.

Sign in / Sign up

Export Citation Format

Share Document