Active Galactic Nucleus Black Hole Mass Estimates in the Era of Time Domain Astronomy (original) (raw)
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Black hole mass estimation from X-ray variability measurements in active galactic nuclei
Monthly Notices of the Royal Astronomical Society, 2004
We propose a new method of estimation of the black hole masses in AGN based on the normalized excess variance, σ 2 nxs . We derive a relation between σ 2 nxs , the length of the observation, T , the light curve bin size, ∆t, and the black hole mass, assuming that (i) the power spectrum above the high frequency break, ν bf , has a slope of −2, (ii) the high frequency break scales with black hole mass, (iii) the power spectrum amplitude (in f requency × power space) is universal and (iv) σ 2 nxs is calculated from observations of length T < 1/ν bf . Values of black hole masses in AGN obtained with this method are consistent with estimates based on other techniques such as reverberation mapping or the M BH -stellar velocity dispersion relation. The method is formally equivalent to methods based on power spectrum scaling with mass but the use of σ 2 nxs has the big advantage of being applicable to relatively low quality data.
Quasar Black Hole Mass Estimates in the Era of Time Domain Astronomy
We investigate the dependence of the normalization of the high-frequency part of the X-ray and optical power spectral densities (PSD) on black hole mass for a sample of 39 active galactic nuclei (AGN) with black hole masses estimated from reverberation mapping or dynamical modeling. We obtained new Swift observations of PG 1426+015, which has the largest estimated black hole mass of the AGN in our sample. We develop a novel statistical method to estimate the PSD from a lightcurve of photon counts with arbitrary sampling, eliminating the need to bin a lightcurve to achieve Gaussian statistics, and we use this technique to estimate the X-ray variability parameters for the faint AGN in our sample. We find that the normalization of the high-frequency X-ray PSD is inversely proportional to black hole mass. We discuss how to use this scaling relationship to obtain black hole mass estimates from the short time-scale X-ray variability amplitude with precision ~ 0.38 dex. The amplitude of op...
arXiv: Astrophysics of Galaxies, 2018
Several investigations of the X-ray variability of active galactic nuclei (AGN) using the normalised excess variance (${\sigma^2_{\rm NXS}}$) parameter have shown that variability has a strong anti-correlation with black hole mass ($M_{\rm BH}$) and X-ray luminosity ($L_{\rm X}$). In this study we confirm these previous correlations and find no evidence of a redshift evolution. Using observations from XMM-Newton, we determine the sigma2rmNXS{\sigma^2_{\rm NXS}}sigma2rmNXS and LrmXL_{\rm X}LrmX for a sample of 1091 AGN drawn from the XMM-Newton Cluster Survey (XCS) - making this the largest study of X-ray spectral properties of AGNs. We created light-curves in three time-scales; 10 ks, 20 ks and 40 ks and used these to derive scaling relations between sigma2rmNXS{\sigma^2_{\rm NXS}}sigma2rmNXS, LrmXL_{\rm X}LrmX (2.0-10 keV range) and literature estimates of MrmBHM_{\rm BH}MrmBH from reverberation mapping. We confirm the anti-correlation between MrmBHM_{\rm BH}MrmBH and sigma2rmNXS{\sigma^2_{\rm NXS}}sigma2rmNXS and find a positive correlation between MrmBHM_{\rm BH}MrmBH and $...
High-frequency X-ray variability as a mass estimator of stellar and supermassive black holes
Monthly Notices of the Royal Astronomical Society, 2007
There is increasing evidence that supermassive black holes in active galactic nuclei (AGN) are scaled-up versions of Galactic black holes. We show that the amplitude of highfrequency X-ray variability in the hard spectral state is inversely proportional to the black hole mass over eight orders of magnitude. We have analyzed all available hard-state data from RXTE of seven Galactic black holes. Their power density spectra change dramatically from observation to observation, except for the high-frequency ( 10 Hz) tail, which seems to have a universal shape, roughly represented by a power law of index -2. The amplitude of the tail, C M (extrapolated to 1 Hz), remains approximately constant for a given source, regardless of the luminosity, unlike the break or QPO frequencies, which are usually strongly correlated with luminosity. Comparison with a moderate-luminosity sample of AGN shows that the amplitude of the tail is a simple function of black hole mass, C M = C/M , where C ≈ 1.25 M ⊙ Hz −1 . This makes C M a robust estimator of the black hole mass which is easy to apply to lowto moderate-luminosity supermassive black holes. The high-frequency tail with its universal shape is an invariant feature of a black hole and, possibly, an imprint of the last stable orbit.
Comparing and Calibrating Black Hole Mass Estimators for Distant Active Galactic Nuclei
The Astrophysical Journal, 2008
Black hole mass (M BH ) is a fundamental property of active galactic nuclei (AGNs). In the distant universe, M BH is commonly estimated using the MgII, Hβ, or Hα emission line widths and the optical/UV continuum or line luminosities, as proxies for the characteristic velocity and size of the broad-line region. Although they all have a common calibration in the local universe, a number of different recipes are currently used in the literature. It is important to verify the relative accuracy and consistency of the recipes, as systematic changes could mimic evolutionary trends when comparing various samples. At z = 0.36, all three lines can be observed at optical wavelengths, providing a unique opportunity to compare different empirical recipes. We use spectra from the Keck Telescope and the Sloan Digital Sky Survey to compare M BH estimators for a sample of nineteen AGNs at this redshift. We compare popular recipes available from the literature, finding that M BH estimates can differ up to 0.38 ± 0.05 dex in the mean (or 0.13 ± 0.05 dex, if the same virial coefficient is adopted). Finally, we provide a set of 30 internally self consistent recipes for determining M BH from a variety of observables. The intrinsic scatter between cross-calibrated recipes is in the range 0.1 − 0.3 dex. This should be considered as a lower limit to the uncertainty of the M BH estimators.
A near-infrared relationship for estimating black hole masses in active galactic nuclei
Monthly Notices of the Royal Astronomical Society, 2013
Black hole masses for samples of active galactic nuclei (AGN) are currently estimated from single-epoch optical spectra using scaling relations anchored in reverberation mapping results. In particular, the two quantities needed for calculating black hole masses, namely, the velocity and the radial distance of the orbiting gas are derived from the widths of the Balmer hydrogen broad emission lines and the optical continuum luminosity, respectively. We have recently presented a near-infrared (near-IR) relationship for estimating AGN black hole masses based on the widths of the Paschen hydrogen broad emission lines and the total 1 µm continuum luminosity. The near-IR offers several advantages over the optical: it suffers less from dust extinction, the AGN continuum is observed only weakly contaminated by the host galaxy and the strongest Paschen broad emission lines Paα and Paβ are unblended. Here we improve the calibration of the near-IR black hole mass relationship by increasing the sample from 14 to 23 reverberation-mapped AGN using additional spectroscopy obtained with the Gemini Near-Infrared Spectrograph (GNIRS). The additional sample improves the number statistics in particular at the high luminosity end.
Constraining black hole masses in low-accreting active galactic nuclei using X-ray spectra
Monthly Notices of the Royal Astronomical Society
In a recent work we demonstrated that a novel X-ray scaling method, originally introduced for Galactic black holes (BHs), can be reliably extended to estimate the mass of supermassive BHs accreting at a moderate to high level. Here we investigate the limits of applicability of this method to low-accreting active galactic nuclei (AGN), using a control sample with goodquality X-ray data and dynamically measured mass. For low-accreting AGN (L X /L Edd ≤ 10 −4), because the basic assumption that the photon index positively correlates with the accretion rate no longer holds the X-ray scaling method cannot be used. Nevertheless, the inverse correlation in the-L X /L Edd diagram, found in several low-accreting BHs and confirmed by this sample, can be used to constrain M BH within a factor of ∼10 from the dynamically determined values. We provide a simple recipe to determine M BH using solely X-ray spectral data, which can be used as a sanity check for M BH determination based on indirect optical methods.
On the Systematic Bias in the Estimation of Black Hole Masses in Active Galactic Nuclei
2012
In this report, we find the M BH estimated from the formalism of Wang et al. (2009)[1] are more consistent with those from the M BH -σ * relation than those from previous single-epoch mass estimators, using a large sample of AGNs. Furthermore, we examine the differences between the line widths of Hβ and Mg II in detail by comparing their line profiles. The flux around the line core and that in the wing of both Hβ and Mg II show an opposite variation tendency, which indicates the BLR is multi-componential. The contribution of the wing makes the FWHM deviate from σ line , and thus bias the M BH estimated from previous single-epoch mass estimators. Thus the correction on the formalism suggested by Wang et al. (2009)[1] is crucial to M BH estimation. Quasars, Galactic nuclei, Masses, Statistical and correlative studies of properties PACS: 98.54.Aj, 98.62.Js, 98.62.Ck, 98.62.Ve
The Astrophysical Journal, 2009
We investigate the relationship between black hole mass and bulge luminosity for AGNs with reverberationbased black hole mass measurements and bulge luminosities from two-dimensional decompositions of Hubble Space Telescope host galaxy images. We find that the slope of the relationship for AGNs is 0.76 − 0.85 with an uncertainty of ∼ 0.1, somewhat shallower than the M BH ∝ L 1.0±0.1 relationship that has been fit to nearby quiescent galaxies with dynamical black hole mass measurements. This is somewhat perplexing, as the AGN black hole masses include an overall scaling factor that brings the AGN M BH − σ ⋆ relationship into agreement with that of quiescent galaxies. We discuss biases that may be inherent to the AGN and quiescent galaxy samples and could cause the apparent inconsistency in the forms of their M BH − L bulge relationships.
Black hole masses from power density spectra: determinations and consequences
Monthly Notices of the Royal Astronomical Society, 2001
We analyze the scaling of the X-ray power density spectra with the mass of the black hole on the example of Cyg X-1 and Seyfert 1 galaxy NGC 5548.We show that the high frequency tail of the power density spectrum can be successfully used for determination of the black hole mass. We determine the masses of the black holes in 6 Broad Line Seyfert 1 galaxies, 5 Narrow Line Seyfert 1 galaxies and two QSOs using available power density spectra. The proposed scaling is clearly appropriate for other Seyfert galaxies and QSOs. In all but 1 normal Seyferts the resulting luminosity to the Eddington luminosity ratio is smaller than 0.15, with a source MCG -6-15-30 being an exception. The applicability of the same scaling to Narrow Line Seyfert 1 is less clear and there may be a systematic shift between the power spectra of NLS1 and S1 galaxies of the same mass, leading to underestimation of the black hole mass. However, both the method based on variability and the method based on spectral fitting show that those galaxies have relatively low masses and high luminosity to the Eddington luminosity ratio, supporting the view of those objects as analogs of galactic sources in their high/soft or very high state based on the overall spectral shape. Bulge masses of their host galaxies are similar to normal Seyfert galaxies so they do not follow the black hole mass -bulge mass relation for Seyfert galaxies, being evolutionary less advanced, as suggested by . The bulge mass-black hole mass relation in our sample is consistent with being linear, with black hole to bulge ratio ∼ 0.03 % , similar to and for low mass objects but significantly shifted from the relation of and . Cyg X-1 (Lin) Cyg X-1 (Cui) NGC 5548 NGC 5548 (fit) Cyg X-1 (soft) Cyg X-1 (hard) NGC 5548 (XTE) NGC 5548 (EUVE)