Mass Of Central Supermassive Black Hole Research Articles

The Population of Massive Stars in Active Galactic Nuclei Disks

Gravitational instability in the outskirts of active galactic nuclei (AGN) disks leads to disk fragmentation and formation of ∼300 M ⊙ supermassive stars with potentially long lifetimes. Alternatively, stars can be captured ex situ and grow from gas accretion in the AGN disk. However, the number density distribution throughout the disk is limited by thermal feedback as their luminosities provide the dominant heating source. We derive equilibrium stellar surface density profiles under two limiting contexts: in the case where the stellar lifetimes are prolonged, due to the recycling of hydrogen-rich disk gas, only the fraction of gas converted into heat is removed from the disk accretion flow. Alternatively, if stellar composition recycling is inefficient and stars can evolve off the main sequence, the disk accretion rate is quenched toward smaller radii resembling a classical starburst disk, albeit the effective removal rate depends not only on the stellar lifetime, but also the mass of stellar remnants. For AGNs with central supermassive black hole masses of ∼106–108 M ⊙ accreting at ∼0.1 Eddington efficiency, we estimate a total number of 103–105 massive stars and the rate of stellar mergers to be 10−3 to 1 yr−1. We initiate the detailed study of the interaction between a swarm of massive stars through hydro and N-body simulations to provide better prescriptions of dynamical processes in AGN disks, and to constrain more accurate estimates of the stellar population.

How does the presence of bar affects the fueling of supermassive black holes? An IllustrisTNG100 perspective

ABSTRACT We conducted a statistical study of black hole masses of barred and unbarred galaxies in the IllustrisTNG100 cosmological magnetohydrodynamical simulations. This work aims to understand the role of the bars in the growth of central supermassive black hole mass and its implications on AGN fueling. Our sample consists of 1191 barred galaxies and 2738 unbarred galaxies in the IllustrisTNG100 simulations. To have an unbiased study, we perform our analysis with an equal number of barred and unbarred galaxies by using various controlled parameters like total galaxy mass, stellar mass, gas mass, dark matter halo mass, etc. Except for the stellar mass controlling, we find that the median of the black hole mass distribution for barred galaxies is higher than that of the unbarred ones, indicating that stellar mass is a key parameter influencing the black hole growth. The higher mean accretion rate of the black holes in barred galaxies, averaged since the bar forming epoch (z ∼ 2), explains the higher mean black hole masses in barred galaxies. Further, we also test that these results are unaffected by other environmental processes like minor/major merger histories and neighbouring gas density of black hole. Although the relationship between stellar mass, bar formation, and black hole growth is complex, with various mechanisms involved, our analysis suggests that bars can play a crucial role in feeding black holes, particularly in galaxies with massive stellar discs.

Modeling the Central Supermassive Black Hole Mass of Quasars via the LSTM Approach

One of the fundamental questions about quasars is related to their central supermassive black holes. The reason for the existence of these black holes with such a huge mass is still unclear, and various models have been proposed to explain them. However, there is still no comprehensive explanation that is accepted by the community. The only thing we are sure of is that these black holes were not created by the collapse of giant stars or the accretion of matter around them. Moreover, another important question is related to the mass distribution of these black holes over time. Observations have shown that if we go back through redshift, we see black holes with more mass, and after passing the peak of star formation redshift, this procedure decreases. Nevertheless, the exact redshift of this peak is still controversial. In this paper, with the help of deep learning and the LSTM algorithm, we try to find a suitable model for the mass of the central black holes of quasars over time by considering both the QUOTAS and QuasarNET data sets. Our model was built with these data reported from redshift 3 to 7 and for two redshift intervals, 0–3 and 7–10, and it predicted the mass of the quasars’ central supermassive black holes. We have also tested our model for the specified intervals with observed data from central black holes and discussed the results.

The effects of time-variable absorption due to gamma-ray bursts in active galactic nucleus accretion discs

ABSTRACT Both long and short gamma-ray bursts (GRBs) are expected to occur in the dense environments of active galactic nucleus (AGN) accretion discs. As these bursts propagate through the discs they live in, they photoionize the medium causing time-dependent opacity that results in transients with unique spectral evolution. In this paper, we use a line-of-sight radiation transfer code coupling metal and dust evolution to simulate the time-dependent absorption that occurs in the case of both long and short GRBs. Through these simulations, we investigate the parameter space in which dense environments leave a potentially observable imprint on the bursts. Our numerical investigation reveals that time-dependent spectral evolution is expected for central supermassive black hole masses between 105 and 5 × 107 solar masses in the case of long GRBs, and between 104 and 107 solar masses in the case of short GRBs. Our findings can lead to the identification of bursts exploding in AGN disc environments through their unique spectral evolution coupled with a central location. In addition, the study of the time-dependent evolution would allow for studying the disc structure, once the identification with an AGN has been established. Finally, our findings lead to insight into whether GRBs contribute to the AGN emission, and which kind, thus helping to answer the question of whether GRBs can be the cause of some of the as-of-yet unexplained AGN time variability.

TESS shines light on the origin of the ambiguous nuclear transient ASASSN-18el

ABSTRACT We analyse high-cadence data from the Transiting Exoplanet Survey Satellite (TESS) of the ambiguous nuclear transient (ANT) ASASSN-18el. The optical changing-look phenomenon in ASASSN-18el has been argued to be due to either a drastic change in the accretion rate of the existing active galactic nucleus (AGN) or the result of a tidal disruption event (TDE). Throughout the TESS observations, short-time-scale stochastic variability is seen, consistent with an AGN. We are able to fit the TESS light curve with a damped-random-walk (DRW) model and recover a rest-frame variability amplitude of $\hat{\sigma } = 0.93 \pm 0.02$ mJy and a rest-frame time-scale of $\tau _{DRW} = 20^{+15}_{-6}$ d. We find that the estimated τDRW for ASASSN-18el is broadly consistent with an apparent relationship between the DRW time-scale and central supermassive black hole mass. The large-amplitude stochastic variability of ASASSN-18el, particularly during late stages of the flare, suggests that the origin of this ANT is likely due to extreme AGN activity rather than a TDE.

Study of Variability in Long-term Multiwavelength Optical Lightcurves of Blazar AO 0235+164

We present a long-term and intraday variability study of optical multiwaveband (U BV RI) data from the blazar AO 0235+164 collected by various telescopes for ∼44 yr (1975–2019). The blazar was found to be significantly variable over the years in all wave bands with a variation of about 6 mag between its low and active states. The variations in the different wave bands are highly correlated without any time lag. We did not observe any significant trend in color variation with time, but we observed a bluer-when-brighter trend between the B − I color index and the R magnitude. Optical BV R-band spectral energy distributions always show a convex shape. Significant intraday variability was frequently seen in the quasi-simultaneous observations of AO 0235+164 made on 22 nights in the R and V bands by the CASLEO and CAHA telescopes during 1999–2019. We also estimated a central supermassive black hole mass of 7.9 × 107 M ⊙ by analyzing the broad Mg ii emission line in AO 0235+164's spectrum. We briefly explore the probable physical scenarios responsible for the observed variability.

Reverberation Mapping of IC 4329A

We present the results of a new reverberation mapping campaign for the broad-line active galactic nucleus (AGN) in the edge-on spiral IC 4329A. Monitoring of the optical continuum with V-band photometry and broad emission-line flux variability with moderate-resolution spectroscopy allowed emission-line light curves to be measured for Hβ, Hγ, and He ii λ4686. We find a time delay of days for Hβ, a similar time delay of days for Hγ, and an unresolved time delay of days for He ii. The time delay for Hβ is consistent with the predicted value from the relationship between AGN luminosity and broad-line region radius, after correction for the ∼2.4 mag of intrinsic extinction at 5100 Å. Combining the measured time delay for Hβ with the broad emission-line width and an adopted value of 〈f〉 = 4.8, we find a central supermassive black hole mass of M ⊙. Velocity-resolved time delays were measured across the broad Hβ emission-line profile and may be consistent with an “M”-like shape. Modeling of the full reverberation response of Hβ was able to provide only modest constraints on some parameters, but does exhibit agreement with the black hole mass and average time delay. The models also suggest that the AGN structure is misaligned by a large amount from the edge-on galaxy disk. This is consistent with expectations from the unified model of AGNs, in which broad emission lines are expected to be visible only for AGNs that are viewed at relatively face-on inclinations.

Conditional colour–magnitude distribution of central galaxies in galaxy formation models

ABSTRACT We investigate the conditional colour–magnitude distribution (CCMD), namely the colour–magnitude distribution at fixed halo mass, of the central galaxies in semi-analytical galaxy formation model (SAM) and hydrodynamic simulations. We analyse the CCMD of central galaxies in each halo mass bin with the Gaussian mixture model and find that it can be decomposed into red and blue components nearly orthogonal to each other, a red component narrow in colour and extended in magnitude and a blue component narrow in magnitude and extended in colour. We focus on the SAM galaxies to explore the origin of the CCMD components by studying the relation between central galaxy colour and halo or galaxy properties. Central galaxy colour is correlated with halo assembly properties for low-mass haloes and independent of them for high-mass haloes. Galaxy properties such as central supermassive black hole mass, cold gas mass, and gas specific angular momentum can all impact central galaxy colour. These results are corroborated by an alternative machine learning analysis in which we attempt to predict central galaxy colour with halo and galaxy properties. We find that the prediction for colours of central galaxies can be significantly improved using both halo and galaxy properties as input compared to using halo properties alone. With the halo and galaxy properties considered here, we find that subtle discrepancies remain between predicted and original colour distribution for low-mass haloes and that no significant determining properties are identified in massive haloes, suggesting modulations by additional stochastic processes in galaxy formation.

Infrared Surface Brightness Fluctuation Distances for MASSIVE and Type Ia Supernova Host Galaxies*

Abstract We measured high-quality surface brightness fluctuation (SBF) distances for a sample of 63 massive early-type galaxies using the WFC3/IR camera on the Hubble Space Telescope. The median uncertainty on the SBF distance measurements is 0.085 mag, or 3.9% in distance. Achieving this precision at distances of 50–100 Mpc required significant improvements to the SBF calibration and data analysis procedures for WFC3/IR data. Forty-two of the galaxies are from the MASSIVE Galaxy Survey, a complete sample of massive galaxies within ∼100 Mpc; the SBF distances for these will be used to improve the estimates of the stellar and central supermassive black hole masses in these galaxies. Twenty-four of the galaxies are Type Ia supernova hosts, useful for calibrating SN Ia distances for early-type galaxies and exploring possible systematic trends in the peak luminosities. Our results demonstrate that the SBF method is a powerful and versatile technique for measuring distances to galaxies with evolved stellar populations out to 100 Mpc and constraining the local value of the Hubble constant.

More Variable Quasars Have Stronger Emission Lines

Abstract UV/optical variation, likely driven by accretion disk turbulence, is a defining characteristic of type 1 active galactic nuclei and quasars. In this work we investigate an interesting consequence of such turbulence using quasars in Sloan Digital Sky Survey Stripe 82 for which the measurements of the UV/optical variability amplitude are available from ∼10 yr long light curves. We discover positive correlations between the UV/optical variability amplitude σ rms and equivalent widths of C iv, Mg ii, and [O iii]5007 emission lines. Such correlations remain statistically robust through partial correlation analyses, i.e., after controlling the effects of other variables including bolometric luminosity, central supermassive black hole mass, Eddington ratio, and redshift. This, for the first time, indicates a causal link between disk turbulence and emission line production. We propose two potential underlying mechanisms, both of which may be involved: (1) quasars with stronger disk turbulence have on average a bluer/harder broadband spectral energy distribution, an expected effect of the disk thermal fluctuation model; (2) stronger disk turbulence could lead to the launch of emission line regions with larger covering factors.

A Spatially Resolved Survey of Distant Quasar Host Galaxies. II. Photoionization and Kinematics of the ISM

Abstract We present detailed observations of photoionization conditions and galaxy kinematics in 11 z = 1.39–2.59 radio-loud quasar host galaxies. Data were taken with the OSIRIS integral field spectrograph and the adaptive optics system at the W. M. Keck Observatory that targeted nebular emission lines (Hβ, [O iii], Hα, [N ii]) redshifted into the near-infrared (1–2.4 μm). We detect extended ionized emission on scales ranging from 1 to 30 kpc photoionized by stars, shocks, and active galactic nuclei (AGN). Spatially resolved emission-line ratios indicate that our systems reside off the star formation and AGN-mixing sequence on the Baldwin, Phillips, & Terlevich diagram at low redshift. The dominant cause of the difference between line ratios of low-redshift galaxies and our sample is due to lower gas-phase metallicities, which are 2–5× less compared to galaxies with AGN in the nearby universe. Using gas velocity dispersion as a proxy to stellar velocity dispersion and dynamical mass measurement through inclined disk modeling, we find that the quasar host galaxies are undermassive relative to their central supermassive black hole mass, with all systems residing off the local scaling (M •–σ, M •–M *) relationship. These quasar host galaxies require substantial growth, up to an order of magnitude in stellar mass, to grow into present-day massive elliptical galaxies. Combining these results with part I of our sample paper, we find evidence for winds capable of causing feedback before the AGN host galaxies land on the local scaling relation between black hole and galaxy stellar mass, and before the enrichment of the interstellar medium to a level observed in local galaxies with AGN.

The Supermassive Black Hole Masses of Reverberation-mapped Active Galactic Nuclei

Abstract Using different kinds of velocity tracers derived from the broad Hβ profile (in the mean or rms spectrum) and the corresponding virial factors f, the central supermassive black hole masses ( ) are calculated for a compiled sample of 120 reverberation-mapped (RM) active galactic nuclei (AGNs). For its subsample of RM AGNs with measured stellar velocity dispersion ( ), the multivariate linear regression technique is used to calibrate the mean value f, as well as the variable FWHM-based f. It is found that, whether excluding the pseudobulges or not, the from the Hβ line dispersion in the mean spectrum ( ) has the smallest offset rms with respect to the relation. For the total sample excluding SDSS-RM AGNs, with respect to from or that from the Hβ line dispersion in the rms spectrum ( ), it is found that we can obtain from the with the smallest offset rms of 0.38 or 0.23 dex, respectively. It implies that, with respect to the Hβ FWHM, we prefer to calculate from the single-epoch spectrum. Using the FWHM-based f, we can improve the calculation from FWHM(Hβ) and the mean f, with a decreased offset rms from 0.52 to 0.39 dex with respect to from for the subsample of 36 AGNs with . The value of 0.39 dex is almost the same as that from and the mean f.

Origin of Ultraviolet Intermediate-width Emission Lines in Partially Obscured Quasar SDSS J151653.22+190048.2

The quasar SDSS J151653.22+190048.2 (J1516+1900) exhibits very peculiar spectral characters in the observed ultraviolet, optical, and infrared bands: the full widths at half maximum (FWHM) of its optical Hα, Hβ, and infrared Paα and Paβ emission lines are all larger than 5000km/s, and the equivalent widths of these emission lines also approach to those of normal quasars; while the ultraviolet emission lines (Lyβ, OVI, Lyα, NV, SiIV, and CIV) are dominated by intermediate-width emission lines (IELs) with a FWHM of ∼ 1700km/s. This phenomenon can be explained as the effect of partial obscuration: the broad emission lines (BELs) in the ultraviolet waveband are heavily suppressed by the dust extinction, and thus the IELs become prominent; while the dust extinction is not significant in optical and infrared bands, and the IELs can hardly be detected due to the brightness of BELs. Using the IEL width and central supermassive black hole mass MBH∼5.75×108 M⊙ of J1516+1900, and assuming that the intermediate-width emission line region (IELR) is virialized, we estimate the distance of the IEL region to the central black hole is about 1.6pc. On the other side, by combining the photoionization model calculations and observed IELs, we find that the IELR has a density of ∼1012 cm−3, and the ionization parameter of ∼10−0.65, and that its distance to the central region is ∼0.016pc, which is only one percent of the virialized distance. This contradiction can provide an important clue for studying the geometry, physical condition, and origin of the IELRs in active galactic nuclei.

Detection of a quasi-periodic oscillation in γ-ray light curve of the high redshift blazar B2 1520+31

We detected a possible quasi-periodic oscillation (QPO) of ~ 71 days in the 0.1 -- 300 GeV gamma-ray Fermi-LAT light curve of the high redshift flat spectrum radio quasar B2 1520+31. We identify and confirm that quasi-period by Lomb Scargle periodogram (LSP), and weighted wavelet z-transform (WWZ) analyses. Using this QPO period, and assuming it originates from accretion-disc fluctuations at the innermost stable circular orbit, we estimate the central supermassive black hole mass to range between ~ 5.4 * 10$^{9}$ M$_{\odot}$ for a non-rotating black hole and ~ 6.0 * 10$^{10}$ M$_{\odot}$ for a maximally rotating black hole. We briefly discuss other possible radio-loud active galactic nuclei emission models capable of producing a gamma-ray QPO of such a period in a blazar.

Exploring Possible Relations Between Optical Variability Time Scales and Broad Emission Line Shapes in AGN

Here we investigate the connection of broad emission line shapes and continuum light curve variability time scales of type-1 Active Galactic Nuclei (AGN). We developed a new model to describe optical broad emission lines as an accretion disk model of a line profile with additional ring emission. We connect ring radii with orbital time scales derived from optical light curves, and using Kepler's third law, we calculate mass of central supermassive black hole (SMBH). The obtained results for central black hole masses are in a good agreement with {other methods. This indicates that the variability time scales of AGN may not be stochastic, but rather connected to the orbital time scales which depend on the central SMBH mass.

The molecular H2 and stellar discs in the nuclear region of NGC 4258

NGC 4258 is an SABbc Seyfert galaxy, located at a distance of $7.2 \pm 0.3$ Mpc. This object is well known by its nearly edge-on molecular nuclear disc, located between 0.16 and 0.28 pc from the nucleus, whose H$_2$O maser emission allows a very precise measurement of the central supermassive black hole mass ($M_{\bullet}(maser) = 3.78 \pm 0.01 \times 10^7$ Mo). We analyse the emission line properties and the stellar kinematics in a data cube of the central region of NGC 4258, obtained, in the K band, with the Near-Infrared Integral Field Spectrograph, at the Gemini-north telescope. The nuclear spectrum, after the starlight subtraction, shows only the H$_2 \lambda 2.1218$ $\mu$m and Br$\gamma$ emission lines, the latter having a broad component with FWHM$_{Br\gamma}(broad) = 1600 \pm 29$ km s$^{-1}$. The spatial morphology and kinematics of the H$_2 \lambda 2.1218$ $\mu$m line are consistent with a rotating molecular disc around the supermassive black hole, with an upper limit for its diameter of 15.7 pc. The inner radio jet in this object is, in projection, almost perpendicular to the H$_2$ emitting disc detected in this work, and also to the H$_2$O maser emitting disc. The main features of the maps of the stellar kinematic parameters are well reproduced by a model of a thin rotating stellar circular disc. The supermassive black hole mass provided by this dynamical modelling ($M_{\bullet}(disc) = 2.8 \pm 1.0 \times 10^7$ Mo) is compatible, at 1$\sigma$ level, with the precise measurement resulting from the H$_2$O maser emission.

SUPERMASSIVE BLACK HOLES AND THEIR HOST GALAXIES. I. BULGE LUMINOSITIES FROM DEDICATED NEAR-INFRARED DATA

In an effort to secure, refine and supplement the relation between central Supermassive Black Hole masses (Mbh), and the bulge luminosities of their host galaxies, (Lbul), we obtained deep, high spatial resolution K-band images of 35 nearby galaxies with securely measured Mbh, using the wide-field WIRCam imager at the Canada-France-Hawaii-Telescope (CFHT). A dedicated data reduction and sky subtraction strategy was adopted to estimate the brightness and structure of the sky, a critical step when tracing the light distribution of extended objects in the near-infrared. From the final image product, bulge and total magnitudes were extracted via two-dimensional profile fitting. As a first order approximation, all galaxies were modeled using a simple Sersic-bulge + exponential-disk decomposition. However, we found that such models did not adequately describe the structure that we observe in a large fraction of our sample galaxies which often include cores, bars, nuclei, inner disks, spiral arms, rings and envelopes. In such cases, we adopted profile modifications and/or more complex models with additional components. The derived bulge magnitudes are very sensitive to the details and number of components used in the models, although total magnitudes remain almost unaffected. Usually, but not always, the luminosities and sizes of the bulges are overestimated when a simple bulge+disk decomposition is adopted in lieu of a more complex model. Furthermore we found that some spheroids are not well fit when the ellipticity of the Sersic model is held fixed. This paper presents the details of the image processing and analysis, while in a companion paper we discuss how model-induced biases and systematics in bulge magnitudes impact the Mbh-Lbul relation.

The relation between the Black hole mass and the Bulge mass for low redshift AGNs. Part I: Ground-based observations

Using the bulge data from AGN image decomposition with ground-based observations, we calculate the ratios of the central supermassive black hole mass(SMBH) to the Bulge mass ( M bh / M bulge ) in a sample of X-ray selected AGNs, including 15 Narrow-line Seyfert 1 galaxies (NLS1s) and 18 broad-line Seyfert 1 galaxies (BLS1s). We found that the mean value of log ( M bh / M bulge ) is - 3.81 ± 0.11 for 15 NLS1s, and - 2.91 ± 0.13 for 18 BLS1s, showing the lower M bh / M bulge in NLS1s relative to BLS1s. The calculation shows that the Bulge mass from the host image decomposition in NLS1s is statistically smaller than that from Hubble-type correction method, and a linear mass relation is suggested for NLS1s and a nonlinear mass relation for BLS1s. The studying of host galaxies with ground-based observations strongly limited by the atmospheric seeing. We need to do the decomposition of host images for NLS1s with Hubble Space Telescope observation in the future.

Confronting X‐Ray Emission Models with the Highest Redshift Kiloparsec‐Scale Jets: Thez = 3.89 Jet in Quasar 1745+624

A newly identified kiloparsec-scale X-ray jet in the high-redshift z=3.89 quasar 1745+624 is studied with multi-frequency Very Large Array, Hubble Space Telescope, and Chandra X-ray imaging data. This is only the third large-scale X-ray jet beyond z > 3 known and is further distinguished as being the most luminous relativistic jet observed at any redshift, exceeding 10{sup 45} erg/s in both the radio and X-ray bands. Apart from the jet's extreme redshift, luminosity, and high inferred equipartition magnetic field (in comparison to local analogues), its basic properties such as X-ray/radio morphology and radio polarization are similar to lower-redshift examples. Its resolved linear structure and the convex broad-band spectral energy distributions of three distinct knots are also a common feature among known powerful X-ray jets at lower-redshift. Relativistically beamed inverse Compton and ''non-standard'' synchrotron models have been considered to account for such excess X-ray emission in other jets; both models are applicable to this high-redshift example but with differing requirements for the underlying jet physical properties, such as velocity, energetics, and electron acceleration processes. One potentially very important distinguishing characteristic between the two models is their strongly diverging predictions for the X-ray/radio emission with increasing redshift. This is considered, though with the limited sample of three z > 3 jets it is apparent that future studies targeted at very high-redshift jets are required for further elucidation of this issue. Finally, from the broad-band jet emission we estimate the jet kinetic power to be no less than 10{sup 46} erg/s, which is about 10% of the Eddington luminosity corresponding to this galaxy's central supermassive black hole mass M{sub BH} {approx}> 10{sup 9} M{sub {circle_dot}} estimated here via the virial relation. The optical luminosity of the quasar core is about ten times over Eddington, hence the inferred jet power seems to be much less than that available from mass accretion. The apparent super-Eddington accretion rate may however suggest contribution of the unresolved jet emission to the observed optical flux of the nucleus.

The Relation between X-ray Spectral Index and the Eddington Ratio in AGNs

Using the Hβ linewidth, we obtained the virial central supermassive black hole masses and then the Eddington ratios in a sample of broad-line AGNs and NLS1s observed by ASCA. Combined with the data from ROSAT and Chandra observations, we found a strong correlation between hard/soft X-ray photon index and the Eddington ratio. Such a correlation can be understood by a two-zone accretion flow model, in which zone is a thin disk and the inner zone is an advection-dominated accretion flow (ADAF) disk. The relation between X-ray photon index and the Eddington ratio may account for NLS1s with not too steep X-ray photon index founded by SDSS. If this relation is directly related to the accretion disk, it may also exist in the accretion disk of different scales (such as microquasar).