The Effect of Radiation Pressure on Virial Black Hole Mass Estimates and the Case of Narrow-Line Seyfert 1 Galaxies

By A. Marconi, D. Axon, R. Maiolino, Tohru Nagao, G. Pastorini, P. Pietrini, A. Robinson, G. Torricelli. 2008

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We consider the effect of radiation pressure from ionizing photons on black hole (BH) mass estimates based on the application of the virial theorem to broad emission lines in AGN spectra. BH masses based only on the virial product Δ V2R and neglecting the effect of radiation pressure can be severely underestimated, especially in objects close to the Eddington limit. We provide an empirical calibration of the correction for radiation pressure, and we show that it is consistent with a simple physical model in which BLR clouds are optically thick to ionizing radiation and have average column densities of NH ∼ 1023 cm −2. This value is remarkably similar to what is required in standard BLR photoionization models to explain observed spectra. With the inclusion of radiation pressure, the discrepancy between virial BH masses based on single-epoch spectra and on reverberation mapping data drops from 0.4 to 0.2 dex rms. The use of single-epoch observations as surrogates of reverberation mapping campaigns can thus provide more accurate BH masses than previously thought. Finally, we show that narrow-line Seyfert 1 (NLS1) galaxies have apparently low BH masses because they are radiating close to their Eddington limit. After the radiation pressure correction, NLS1 galaxies have BH masses similar to other broad-line AGNs and follow the same MBH − σe/Lsph relations as other active and normal galaxies. Radiation forces arising from ionizing photon momentum deposition constitute an important physical effect which must be taken into account when computing virial BH masses.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/e8ae76863726cd00010e2602ee1b87ae3ef020c5

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Citations in the corpus

EDDINGTON-LIMITED ACCRETION AND THE BLACK HOLE MASS FUNCTION AT REDSHIFT 6 (2010, background): “…by Di Matteo et al. (2008) peaks at λ = 0.04 and has a negligible fraction of the distribution at λ > 0.3, which is clearly inconsistent with our distribution, unless our black hole masses are biased low by radiation pressure effects (Marconi et al. 2008), which we argue later is unlikely.”
A CATALOG OF QUASAR PROPERTIES FROM SLOAN DIGITAL SKY SURVEY DATA RELEASE 7 (2010, background): “…dex) associated with these estimates and the systematics involved in the calibration and usage, which will potentially lead to significant biases of these BH mass estimates (e.g., Collin et al. 2006; Shen et al. 2008b; Marconi et al. 2008; Denney et al. 2009; Kelly et al. 2009; Shen & Kelly 2010).”
The quasar relation through cosmic time – II. Evidence for evolution from z = 3 to the present age (2009, background): “Marconi et al. (2008, 2009) suggest that the virial estimates of MBH may yield lower limits to the true BH mass, as the radiation pressure is not taken into account.”
Simultaneous X-ray/optical/UV snapshots of active galactic nuclei from XMM–Newton: spectral energy distributions for the reverberation mapped sample (2008, methodology): “Marconi et al. (2008) calculate λLλ(5100Å) more accurately by subtracting the host galaxy following the approach of Bentz et al. (2006), and find a similar average value for the whole sample, MnewBH /M old BH ∼ 1.25 (obtained via private communication with the author).”
REVERBERATION MAPPING MEASUREMENTS OF BLACK HOLE MASSES IN SIX LOCAL SEYFERT GALAXIES (2010, methodology): “…note here that there has been some debate in the literature as to the importance of radiation pressure on black hole masses calculated using virial assumptions, since the outward radiation force has the same radial dependence as gravity (see Marconi et al. 2008; Netzer 2009; Marconi et al. 2009).”
CAIXA: a catalogue of AGN in the XMM-Newton archive - II. Multiwavelength correlations (2009, background): “…be in CAIXA, must be luminous and, likely, with a large BH mass. Note that, at each redshift, narrow-line objects invariably have the smallest BH masses: this is well known and some authors believe that the masses in these objects are underestimated (e.g. Decarli et al. 2008; Marconi et al. 2008).”
THE SIMULTANEOUS OPTICAL-TO-X-RAY SPECTRAL ENERGY DISTRIBUTION OF SOFT X-RAY SELECTED ACTIVE GALACTIC NUCLEI OBSERVED BY SWIFT (2010, background): “…be the case; especially, since few NLS1 galaxies have been reverberation-mapped, since radiation-pressure corrections may be relevant in some cases (Marconi et al. 2008), and since other processes might affect the Broad Line Region kinematics in individual galaxies (e.g., jet-cloud interactions).”
AN ALTERNATIVE APPROACH TO MEASURING REVERBERATION LAGS IN ACTIVE GALACTIC NUCLEI (2010, background): “We note in passing that there is currently an active debate about the relative importance of radiation pressure on the BLR gas and how this affects reverberation-based mass measurements (Marconi et al. 2008; Netzer 2009; Marconi et al. 2009; Netzer & Marziani 2010).”
THE SLOAN DIGITAL SKY SURVEY REVERBERATION MAPPING PROJECT: TECHNICAL OVERVIEW (2014, background): “Moreover, over much of its history, RM has 28 The possible role of radiation pressure, also an inverse square force, remains a source of systematic uncertainty (Marconi et al. 2008; Netzer & Marziani 2010). been regarded as a technique that is still in an experimental and developmental state.”
Galaxy Zoo Green Peas: discovery of a class of compact extremely star-forming galaxies (2009, background): “However, the [OIII] line is known to often exhibit a blue wing that is associated with gas outflow and this can affect mass determinations (Marconi et al. 2008).”
Measuring the Masses of Supermassive Black Holes (2014, background): “In closing this section, it is noted that an unresolved issue is whether or not radiation pressure plays a sufficiently important role in the BLR dynamics that it affects black hole mass measurement (Marconi et al. 2008; Netzer & Marziani 2010).”
An expanded Mbh–σ diagram, and a new calibration of active galactic nuclei masses (2010, background): “…may reside below the Mbh–σ relation (Wandel 2002; Mathur & Grupe 2005; Wu 2009; but see Botte et al. 2005; Komossa & Xu 2007; Decarli et al. 2008a), Marconi et al. (2008) point out that the apparent offset of the NLS1 galaxies relative to the broadline AGN may be due to past underestimates of…”
ESTIMATING BLACK HOLE MASSES IN ACTIVE GALACTIC NUCLEI USING THE Mg ii λ2800 EMISSION LINE (2009, background): “Furthermore, because Mg ii originates only from optically thick clouds, radiation pressure force cannot act on them very significantly (cf. Marconi et al. 2008, 2009; Dong et al. 2009a, 2009b), and thus Mg ii suffers little from nonvirial motion.”
Accretion and star formation rates in low‐redshift type II active galactic nuclei (2009, background): “Complications due to the effect of radiation pressure force on the motion of the BLR gas (Marconi et al. 2008) are probably not very impor- ⋆ E-mail: netzer@wise.tau.ac.il tant, at least for low redshift low luminosity AGN (Netzer 2009, hereafter N09; see also Marconi et al. 2009).”
Accretion-driven evolution of black holes: Eddington ratios, duty cycles and active galaxy fractions (2011, background): “…observational noise, and intrinsic scatter in black hole mass estimators can all have strong effects on the apparent distribution of Eddington ratios (e.g., Lamastra et al. 2006; Lauer et al. 2007; Marconi et al. 2008; Shen et al. 2008; Netzer 2009; Shen & Kelly 2010; Rafiee & Hall 2011).”
CONSTRAINTS ON BLACK HOLE GROWTH, QUASAR LIFETIMES, AND EDDINGTON RATIO DISTRIBUTIONS FROM THE SDSS BROAD-LINE QUASAR BLACK HOLE MASS FUNCTION (2010, background): “We do not make any attempt to correct for radiation pressure on the broad emission line clouds (Marconi et al. 2008), as its importance and effects are currently poorly understood (e.g., for a discussion see Vestergaard & Osmer 2009).”