Abstract
Under the hypothesis of gravitational redshift induced by the central supermassive black hole and based on line widths and shifts of redward-shifted Hβ and Hα broad emission lines for more than 8000 Sloan Digital Sky Survey DR7 active galactic nuclei (AGNs), we measure the virial factor in determining supermassive black hole masses. The virial factor had been believed to be independent of accretion radiation pressure on gas clouds in broad-line regions (BLRs) and only dependent on the inclination effects of BLRs. The virial factor measured spans a very large range. For the vast majority of AGNs (>96%) in our samples, the virial factor is larger than the f = 1 usually used in the literature. The f-correction makes the percent of high-accreting AGNs decrease by about 100 times. There are positive correlations of f with the dimensionless accretion rate and Eddington ratio. The redward shifts of Hβ and Hα are mainly of gravitational origin, confirmed by a negative correlation between the redward shift and the dimensionless radius of the BLR. Our results show that radiation pressure force is a significant contributor to the measured virial factor, containing the inclination effects of the BLR. The usually used values of f should be corrected for high-accreting AGNs, especially high-redshift quasars. The f-correction increases their masses by 1–2 orders of magnitude, which will make it more challenging to explain the formation and growth of supermassive black holes at high redshifts.
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1. Introduction
Black hole mass, M•, is an important fundamental parameter of black holes. Reliable measurement of M• is always a key issue of black hole–related research. For active galactic nuclei (AGNs), the reverberation mapping (RM) method or the relevant secondary methods based on single-epoch spectra were widely used to measure M• by a virial mass when clouds in the broad-line region (BLR) are in virialized motion, where f is the virial factor, vFWHM is the full width at half-maximum of the broad emission line, rBLR is the radius of the BLR, and G is the gravitational constant (e.g., Peterson et al. 2004). However, f is very uncertain due to the unclear kinematics and geometry of the BLR (e.g., Peterson et al. 2004; Woo et al. 2015). f is commonly considered to be the main source of uncertainty in MRM. The reverberation-based masses are themselves uncertain, typically by a factor of ∼2.9 (Onken et al. 2004), and the absolute uncertainties in MRM given by the secondary methods are typically around a factor of 4 (Vestergaard & Peterson 2006). If vFWHM is replaced with the line width σline, the second moment of emission line, f becomes fσ . Based on the photoionization assumption (e.g., Blandford & McKee 1982; Peterson 1993), rBLR = τob c/(1 + z), where c is the speed of light, z is the cosmological redshift of the source, and τob is the observed time lag of the broad-line variations relative to the continuum ones. For non-RM AGNs studied by the secondary methods, rBLR can be estimated with the empirical rBLR–L5100 relation for the Hβ emission line of the RM AGNs, where L5100 is the AGN continuum luminosity at rest-frame wavelength 5100 Å (e.g., Kaspi et al. 2000; Bentz et al. 2013; Du et al. 2018b; Du & Wang 2019; Yu et al. 2020).
RM surveys have been carried out (e.g., Shen et al. 2015a, 2015b, 2016, 2019; King et al. 2015; Grier et al. 2017; Hoormann et al. 2019). Nonsurvey RM observation research has been done for more than 100 AGNs over the last several decades (e.g., Kaspi & Netzer 1999; Kaspi et al. 2000, 2007; Peterson et al. 2005; Bentz et al. 2006,2010, 2016, 2021, 2022, 2023; Denney et al. 2010; Barth et al. 2011, 2015; Haas et al. 2011; Pozo Nuñez et al. 2012; Du et al. 2014, 2015, 2016, 2018a, 2018b; Pei et al. 2014, 2017; Wang et al. 2014; Hu et al. 2015, 2020, 2021; Lu et al. 2016, 2021; Xiao et al. 2018a, 2018b; Zhang et al. 2019; Feng et al. 2021a, 2021b; Li et al. 2021, 2022). The single-epoch spectra had been widely used to estimate MRM in studies of high-z quasars (e.g., Willott et al. 2010; Wu et al. 2015; Wang et al. 2019; Eilers et al. 2023) and on statistics of AGNs, such as the Sloan Digital Sky Survey (SDSS) quasars (e.g., Hu et al. 2008; Liu et al. 2019). Based on the M•–σ* relation for the low-z inactive and quiescent galaxies, where σ* is the stellar velocity dispersion of the galaxy bulge (e.g., Tremaine et al. 2002; Onken et al. 2004; Piotrovich et al. 2015; Woo et al. 2015), these derived averages of 〈f〉 ≈ 1 and/or 〈fσ 〉 ≈ 5 were usually used to estimate MRM by the RM and/or single-epoch spectra of AGNs. Therefore, measuring f and/or fσ independently by a new method for individual AGNs is necessary and important to understand the physics of the BLR and the issues related to the masses of the supermassive black holes (SMBHs), e.g., the formation and growth of SMBHs at z ≳ 6 (e.g., Wu et al. 2015; Fan et al. 2023), the coevolution (or not) of SMBHs and host galaxies (e.g., Tremaine et al. 2002; Kormendy & Ho 2013; Woo et al. 2013; Caglar et al. 2020), etc.
Some efforts have been made on an object-by-object basis for small samples of AGNs using high-fidelity RM techniques (e.g., Pancoast et al. 2014a, 2014b) or by using spectral fitting methods (Mejía-Restrepo et al. 2018 and references therein). Liu et al. (2017) proposed a new method to measure f based on the widths and shifts of redward-shifted broad emission lines for the RM AGNs. Based on SDSS DR5 quasars with redward-shifted Hβ and Fe ii broad emission lines, Liu et al. (2022) made further efforts toward researching f and fσ . The Fe iii λ λ2039–2113 UV line blend comes from an inner region of the BLR (Mediavilla et al. 2018; Mediavilla & Jiménez-Vicente 2021), and for 10 lensed quasars of higher Eddington ratio, the redward-shifted Fe iii blend was used to estimate f with 〈f〉 = 14.3 much larger than 〈f〉 ≈ 1 (Mediavilla et al. 2020). However, the origins of broad emission lines and BLRs are yet unclear for AGNs (e.g., Wang et al. 2017). Thus, the origin of redward shifts of broad emission lines is unclear. The redward shifts of broad emission lines are commonly believed to be from inflow (e.g., Hu et al. 2008). Inflow can generate the redward shifts of broad absorption lines, but the broad absorption and emission lines may be from different gas regions due to their distinct velocities (Zhou et al. 2019).
RM observations of Mrk 817 suggest that the redward shifts of broad emission lines do not originate from inflow because of their redward asymmetric velocity-resolved lag maps (Lu et al. 2021), which are not consistent with the blueward asymmetric maps expected from inflow. Redward shifts of broad emission lines in the RM observations of Mrk 110 follow the gravitational redshift prediction (Kollatschny 2003). The gravitational interpretation of the redward shift of the Fe iii blend is preferred over alternative explanations, such as inflow, that will need additional physics to explain the observed correlation between the width and redward shift of the blend (Mediavilla et al. 2018). A sign of the gravitational redshift zg was found in a statistical sense for broad Hβ in the single-epoch spectra of SDSS DR7 quasars (Tremaine et al. 2014). Based on the widths and asymmetries of Hα and Hβ broad emission line profiles in a sample of type 1 AGNs taken from SDSS DR16, Rakić (2022) showed that the BLR gas seems to be virialized. The velocity-resolved lag maps of the Hβ broad emission lines for Mrk 50 and SBS 1518+593 show characteristics of Keplerian disks or virialized motion (Barth et al. 2011; Du et al. 2018a). Thus, it is likely that the redward shifts of broad emission lines originate from the gravity of the central black hole.
Radiation pressure from the accretion disk has a significant influence on the stability and dynamics of clouds in the BLR (e.g., Marconi et al. 2008; Netzer & Marziani 2010; Krause et al. 2011, 2012; Naddaf et al. 2021). The dynamics of clouds can determine the three-dimensional geometry of the BLR (Naddaf et al. 2021). However, radiation pressure was not considered in estimating MRM, and the virial factor was believed to be only from the geometric effect of the BLR. Lu et al. (2016) found that the BLR of NGC 5548 could be jointly controlled by the radiation pressure force from the accretion disk and the gravity of the central black hole. Krause et al. (2011) found that stable orbits of clouds in the BLR exist for very sub-Keplerian rotation, for which the radiation pressure force contributes substantially to the force budget. Thus, the radiation pressure force may result in significant influence on the virial factor. Based on redward-shifted Hβ and Fe ii broad emission lines for a sample of 1973 z < 0.8 SDSS DR5 quasars, Liu et al. (2022) found a positive correlation of the virial factor with the dimensionless accretion rate or the Eddington ratio. They suggested that the radiation pressure force is a significant contributor to the virial factor, and that the redward shift of the Hβ broad emission line is mainly from the gravity of the black hole. In this work, more than 8000 SDSS DR7 AGNs with redward-shifted Hβ and Hα broad emission lines from Table 2 in Liu et al. (2019) will be adopted to investigate the virial factor, the relations of the virial factor with other physical quantities, the origin of the redward shifts of the broad Balmer emission lines, and the implications of the f-correction.
The structure is as follows. Section 2 presents the method. Section 3 describes the sample selection. Section 4 presents the analysis and results. Section 5 is the potential influence on quasars at z ≳ 6. Section 6 is the potential influence on the M•–σ* map of AGNs. Section 7 presents the discussion, and Section 8 is the conclusion. Throughout this paper, we assume a standard cosmology with H0 = 70 km s−1 Mpc−1, ΩM = 0.3, and ΩΛ = 0.7 (Spergel et al. 2007).
2. Method
A BLR cloud is subject to the gravity of the black hole, Fg, and radiation pressure force, Fr, due to central continuum radiation. The total mechanical energy and angular momentum are conserved for the BLR clouds because Fg and Fr are central forces. Under various assumptions, Fr can be calculated for more than hundreds of thousands of lines, with detailed photoionization, radiative transfer, and energy balance calculations (e.g., Dannen et al. 2019). In principle, M• could be estimated by the BLR cloud motions when the numerical calculation methods give Fr. However, the various assumptions may significantly influence the reliability of Fr, especially the many unknown physical parameters that likely vary for different AGNs. Thus, a new method was proposed to measure f and then MRM, avoiding the use of the averages of the virial factor or the numerical calculation of Fr (Liu et al. 2017, 2022).
The virial factor formula in Liu et al. (2022) was derived from the Schwarzschild metric for clouds in the virialized motion,
where the gravitational and transverse Doppler shifts are taken into account. If vFWHM is replaced with σline, f becomes fσ . As zg ≪ 1 or rg/rBLR ≪ 1 for broad emission lines (the gravitational radius rg = GM•/c2), we have
Mediavilla & Jiménez-Vicente (2021) pinpointed that the observed redward shift of the Fe iii λ λ2039–2113 emission line blend in quasars originates from the gravity of the black hole, while these Fe iii λ λ2039–2113 emission lines are broad emission lines. Furthermore, their redward shifts and line widths follow the gravitational redshift prediction (see Figure 4 in Mediavilla et al. 2018). So, the broad emission line position and width should be determined not only by the kinematics of the BLR but also by the gravity of the black hole. The virialized assumption in measuring MRM will ensure that the line position should be governed by the gravity of the black hole for the redward-shifted broad emission lines in AGNs (this will be tested in the next section). The same method as in Liu et al. (2017, 2022) was used to estimate the virial factor in Mediavilla et al. (2018; see their Equation 5). Thus, the method in this work, evolved from Liu et al. (2017), is reliable, and the assumption of the gravitational redshift is reasonable.
The Schwarzschild metric is valid at the optical BLR scales, and Equation (1) is valid for a disklike BLR (see Liu et al. 2022). The disklike BLR is preferred by some RM observations of AGNs, e.g., NGC 3516 (e.g., Denney et al. 2010; Feng et al. 2021a) and the VLTI instrument GRAVITY observations of quasar 3C 273 (Sturm et al. 2018). For rapidly rotating BLR clouds, the relativistic beaming effect can give rise to a profile asymmetry with an enhanced blue side in broad emission lines, i.e., blueshifts of broad emission lines (Mediavilla & Insertis 1989). Thus, the relativistic beaming effect should be neglected for the redward-shifted broad emission lines, which should be dominated by the gravitational redshift and transverse Doppler effects. The reliability of the redward shift method was confirmed by the consistent masses estimated from Equations (4) and (7) based on four broad emission lines for Mrk 110 (see Figure 2 of Liu et al. 2017). Hereafter, MRM denotes M• measured with the RM method and/or the relevant secondary methods, fg denotes 〈f〉 = 1 for vFWHM or 〈fσ 〉 = 5.5 for σline, MRM ≡ MRM(fg = 1), the Eddington luminosity LEdd ≡ LEdd(fg = 1), the Eddington ratio Lbol/LEdd ≡ Lbol/LEdd(fg = 1), and rg ≡ rg(fg = 1).
3. Sample Selection
Liu et al. (2019) reported a comprehensive and uniform sample of 14,584 broad-line AGNs with z < 0.35 from the SDSS DR7. The stellar continuum was properly removed for each spectrum with significant host absorption line features, and careful analyses of emission line spectra, particularly in the Hα and Hβ wave bands, were carried out. The line widths and line centroid wavelengths of the Hα, Hβ, and [O iii] spectra are given in Table 2 of Liu et al. (2019). The redward shifts of the broad emission lines Hβ and Hα are defined as
where λb is the centroid wavelength of the broad emission line corrected by the cosmological redshift zSDSS given by the SDSS site (Liu et al. 2019), λn is the centroid wavelength of the narrow emission line corrected by zSDSS, and λ0 is the vacuum wavelength of the spectrum line (λ0 = 4862.68 Å for Hβ, λ0 = 6564.61 Å for Hα, and λ0 = 5008.24 Å for [O iii] λ5007). 5
Because of the absence of the uncertainty of λn for Hβ in Table 2 of Liu et al. (2019), and in order to unify the standard of estimating zg for the broad Hβ and Hα, the [O iii] λ5007 line is used in Equation (3). First, one of the choice criteria is the AGN's flag = 0, which means no emission lines with multiple peaks (Liu et al. 2019), because the multiple peaks of the emisson lines may be from dual AGNs (e.g., Wang et al. 2009). Second, AGNs are selected on the basis of zg > 0 and zg − σ(zg) > 0 for the broad Hβ and Hα, where σ(zg) is the uncertainty of zg. Third, AGNs are selected on the basis of vFWHM > 0 and vFWHM − σ(vFWHM) > 0 for the broad Hβ and Hα, where σ(vFWHM) is the uncertainty of vFWHM. The selection conditions of zg > 0 and zg − σ(zg) > 0 make sure that the shifts of the broad emission lines are redward within 1σ uncertainties. Because the empirical rBLR–L5100 relation is established for broad emission line Hβ, the relevant research on the virial factor is made with the broad Hβ and Hα in this work. A total of 9185 AGNs are selected out of the 14,584 AGNs as sample 1 only for the broad Hβ. A total of 9271 AGNs are selected out of the 14,584 AGNs as sample 2 only for the broad Hα. The cross-identified AGNs in samples 1 and 2 are used as sample 3, which contains 8169 AGNs with the zg of the broad Hβ and Hα.
Some physical quantities are taken or estimated from Table 2 in Liu et al. (2019), including vFWHM(Hβ), vFWHM(Hα), zg(Hβ), zg(Hα), L5100, MRM, Lbol/LEdd, and the dimensionless accretion rate . The bolometric luminosity Lbol was estimated in Liu et al. (2019) using Lbol = 9.8L5100 (McLure & Dunlop 2004). The details of samples are listed in Tables 1–3. The virial factors, f(Hβ) and f(Hα), are estimated by Equation (1) for the broad Hβ and Hα (see Tables 1–3). , where η is the efficiency of converting rest-mass energy to radiation. Hereafter, in addition to a special statement, we adopt η = 0.038 (Du et al. 2015).
Table 1. The Relevant Parameters for 9185 AGNs in SDSS DR7 for Sample 1
Designation | zg(Hβ) | f(Hβ) | RFe II | |||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) | (11) | (12) | (13) |
J000048.16−095404.0 | 2132.9 ± 71.0 | 0.00089 ± 0.00005 | 43.39 ± 0.00 | 7.26 | −1.086 | 11.7 ± 0.8 | 0.334 | 15,381.3 | −999 | −999 | −999 | −999 |
J000102.19−102326.9 | 4695.0 ± 69.2 | 0.00062 ± 0.00049 | 44.36 ± 0.00 | 8.46 | −1.356 | 1.7 ± 0.0 | 0.064 | 3191.6 | 0.188 | 8.49 | 3191.7 | 0.037 |
J000154.29+000732.5 | 1813.8 ± 98.9 | 0.00046 ± 0.00023 | 43.48 ± 0.00 | 7.14 | −0.972 | 8.4 ± 0.9 | 0.448 | 22,644.5 | 0.115 | 7.27 | 22,645.3 | 0.322 |
Note. Column (1): object name. Column (2): vFWHM of Hβ broad emission line. Column (3): redward shift of Hβ. Column (4): logarithm of L5100 in units of erg s−1. Column (5): logarithm of MRM in units of M⊙. Column (6): logarithm of Lbol/LEdd. Column (7): f estimated from vFWHM of Hβ. Column (8): logarithm of . Column (9): rBLR in units of rg, where lt-day with L44 = L5100/(1044 erg s−1). Column (10): RFe II is the line ratio of Fe ii to Hβ. Columns (2)–(6) and (10) are taken from Table 2 of Liu et al. (2019) or converted from the relevant quantities in Table 2 of Liu et al. (2019). An amount of −999 denotes no data of R(Fe ii), which results in no data for the latter three quantities. † denotes the values estimated from Equations (6) and (7).
Only a portion of this table is shown here to demonstrate its form and content. A machine-readable version of the full table is available.
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Table 2. The Relevant Parameters for 9271 AGNs in SDSS DR7 for Sample 2
Designation | zg(Hα) | zg(Hα)(b-n) | f(Hα) | f(Hα)(b-n) | ||||||
---|---|---|---|---|---|---|---|---|---|---|
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) | (11) |
J000048.16−095404.0 | 2132.9 ± 282.9 | 0.00089 ± 0.00022 | 0.00063 ± 0.00022 | 43.39 ± 0.00 | 7.26 | −1.086 | 11.7 ± 3.1 | 8.3 ± 2.2 | 0.334 | 15,381.3 |
J000102.19−102326.9 | 4695.0 ± 172.5 | 0.00062 ± 0.00050 | 0.00073 ± 0.00050 | 44.36 ± 0.00 | 8.46 | −1.356 | 1.7 ± 0.1 | 2.0 ± 0.1 | 0.064 | 3191.6 |
J000111.15−100155.5 | 1937.4 ± 84.2 | 0.00015 ± 0.00012 | 0.00013 ± 0.00012 | 43.15 ± 0.04 | 6.37 | −0.327 | 2.4 ± 0.2 | 2.1 ± 0.2 | 1.093 | 88,935.0 |
Note. Column (1): object name. Column (2): vFWHM of Hα broad emission line. Column (3): redward shift of broad Hα with respect to [O iii] λ5007. Column (4): redward shift of broad Hα with respect to narrow Hα. Column (5): logarithm of L5100 in units of ergs−1. Column (6): logarithm of MRM in units of M⊙. Column (7): logarithm of Lbol/LEdd. Column (8): virial factor estimated from vFWHM of broad Hα and zg(Hα). Column (9): virial factor estimated from vFWHM of broad Hα and zg(Hα)(b-n). Column (10): logarithm of . Column (11): rBLR in units of rg, where lt-day with L44 = L5100/(1044 erg s−1). Columns (2)–(7) are taken from Table 2 of Liu et al. (2019) or converted from the relevant quantities in Table 2 of Liu et al. (2019). An amount of -999 indicates a null value in columns (4) and (9).
Only a portion of this table is shown here to demonstrate its form and content. A machine-readable version of the full table is available.
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Table 3. The Relevant Parameters for 8169 AGNs in SDSS DR7 for Sample 3
Designation | zg(Hβ) | zg(Hα) | f(Hβ) | f(Hα) | RFe II | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) | (11) | (12) | (13) | (14) | (15) | (16) |
J000048.16–095404.0 | 2132.9 ± 71.0 | 0.00089 ± 0.00005 | 2132.9 ± 282.9 | 0.00089 ± 0.00022 | 43.39 ± 0.00 | 7.26 | −1.086 | 11.7 ± 0.8 | 11.7 ± 3.1 | 0.334 | 15,381.3 | −999 | –999 | −999 | –999 |
J000102.19–102326.9 | 4695.0 ± 69.2 | 0.00062 ± 0.00049 | 4695.0 ± 172.5 | 0.00062 ± 0.00050 | 44.36 ± 0.00 | 8.46 | −1.356 | 1.7 ± 0.0 | 1.7 ± 0.1 | 0.064 | 3191.6 | 0.188 | 8.49 | 6663.8 | 0.037 |
J000154.29+000732.5 | 1813.8 ± 98.9 | 0.00046 ± 0.00023 | 1813.8 ± 178.9 | 0.00046 ± 0.00023 | 43.48 ± 0.00 | 7.14 | −0.972 | 8.4 ± 0.9 | 8.4 ± 1.7 | 0.448 | 22,644.5 | 0.115 | 7.27 | 52,991.6 | 0.322 |
Note. Column (1): object name. Column (2): vFWHM of Hβ broad emission line. Column (3): redward shift of Hβ. Column (4): vFWHM of Hα broad emission line. Column (5): redward shift of Hα. Column (6): logarithm of L5100 in units of erg s−1. Column (7): logarithm of MRM in units of M⊙. Column (8): logarithm of Lbol/LEdd. Column (9): f estimated from vFWHM of Hβ. Column (10): f estimated from vFWHM of Hα. Column (11): logarithm of . Column (12): rBLR in units of rg, where lt-day with L44 = L5100/(1044 erg s−1). Column (13): RFe II is the line ratio of Fe ii to Hβ. Columns (2)–(8) and (13) are taken from Table 2 of Liu et al. (2019) or converted from the relevant quantities in Table 2 of Liu et al. (2019). The number −999 and † are the same as in Table 1.
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For our selected AGNs, L5100 spans 4 orders of magnitude, MRM spans more than 4 orders of magnitude, and Lbol/LEdd spans more than 3 orders of magnitude. These parameters are at least 1 order of magnitude wider than those in Liu et al. (2022). The measured values of f span more than 3 orders of magnitude, which are at least 1 order of magnitude wider than those in Liu et al. (2022). These much wider parameters can ensure that this work is feasible.
4. Analysis and Results
In order to study the correlation between f, , L5100, and vFWHM, as well as zg and rBLR/rg, we will perform the Spearman's rank test and/or the Pearson's correlation analysis. The bisector linear regression (Isobe et al. 1990) is performed to obtain the slope and intercept coefficients of y = a + bx in fitting our samples, if needed for some quantities. The partial correlation analysis is used to further verify the presence of a correlation between f and . All correlation analyses are calculated in log-space. The SPEAR (Press et al. 1992) is used to calculate the Spearman's rank correlation coefficient rs and the p-value Ps of the hypothesis test. The PEARSN (Press et al. 1992) is used to give the Pearson's correlation coefficient r and the p-value P of the hypothesis test.
The Spearman's rank correlation test is run for samples 1–3, and the analysis results are listed in Table 4. There are positive correlations between the virial factor and or Lbol/LEdd for samples 1–3 (see Figure 1 and Table 4). The results from the Pearson's correlation analysis are listed in Table 5. The bisector regression fit can give a and b, as well as their uncertainties Δa and Δb, but it does not take into account the obervational errors of the data (Isobe et al. 1990). So, based on Monte Carlo simulated data sets from the obervational values and errors, we calculate the best parameters using the bisector regression and repeat this procedure 104 times to generate the distributions of aMC, bMC, ΔaMC, and ΔbMC. The means of the aMC and bMC distributions are taken to be the final best parameters of a and b, respectively. The corresponding uncertainties are given by the combinations of the means of the ΔaMC and ΔbMC distributions with the standard deviations of the aMC and bMC distributions, respectively. The bisector regression is run for , and the fitting results are
where the p-values of the hypothesis test are <10−40, and in the fittings, the uncertainty of is taken to be 0.4, determined by the uncertainty of 0.4 dex usually used in MRM. Equations (4a–d) correspond to the best fits to the data sets (f,) for Hβ in sample 1, Hα in sample 2, Hβ in sample 3, and Hα in sample 3, respectively. It is clear that , and then .
Table 4. Spearman's Rank Analysis Results
X | Y | Line | rs | Ps | Sample |
---|---|---|---|---|---|
Hβ | 0.615 | <10−40 | 1 | ||
Hα | 0.578 | <10−40 | 2 | ||
Hβ | 0.626 | <10−40 | 3 | ||
Hα | 0.590 | <10−40 | 3 | ||
Hβ | 0.089 | 1.0 × 10−17 | 1 | ||
Hα | 0.047 | 6.0 × 10−6 | 2 | ||
Hβ | 0.113 | 8.3 × 10−25 | 3 | ||
Hα | 0.044 | 5.8 × 10−5 | 3 | ||
Hβ | −0.440 | <10−40 | 1 | ||
Hα | −0.318 | <10−40 | 2 | ||
Hβ | −0.447 | <10−40 | 3 | ||
Hα | −0.335 | <10−40 | 3 | ||
Hβ | 0.654 | <10−40 | 1 | ||
Hα | 0.647 | <10−40 | 2 | ||
Hβ | 0.662 | <10−40 | 3 | ||
Hα | 0.658 | <10−40 | 3 |
Note. X and Y are the relevant quantities presented in samples 1–3. The first part: and η = 0.038. The last part: and .
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Table 5. Pearson's Analysis Results
X | Y | Line | r | P | Sample |
---|---|---|---|---|---|
Hβ | 0.601 | <10−40 | 1 | ||
Hα | 0.568 | <10−40 | 2 | ||
Hβ | 0.618 | <10−40 | 3 | ||
Hα | 0.588 | <10−40 | 3 | ||
Hβ | 0.236 | <10−40 | 1 | ||
Hα | 0.265 | <10−40 | 2 | ||
Hβ | 0.247 | <10−40 | 3 | ||
Hα | 0.247 | <10−40 | 3 | ||
Hβ | −0.747 | <10−40 | 1 | ||
Hα | −0.757 | <10−40 | 2 | ||
Hβ | −0.753 | <10−40 | 3 | ||
Hα | −0.787 | <10−40 | 3 | ||
Hβ | 0.072 | 5.4 × 10−12 | 1 | ||
Hα | 0.032 | 2.1 × 10−3 | 2 | ||
Hβ | 0.096 | 4.6 × 10−18 | 3 | ||
Hα | 0.028 | 1.0 × 10−2 | 3 | ||
Hβ | 0.133 | 1.5 × 10−37 | 1 | ||
Hα | 0.073 | 2.7 × 10−12 | 2 | ||
Hβ | 0.117 | 3.9 × 10−26 | 3 | ||
Hα | 0.090 | 3.3 × 10−16 | 3 | ||
Hβ | −0.647 | <10−40 | 1 | ||
Hα | −0.686 | <10−40 | 2 | ||
Hβ | −0.666 | <10−40 | 3 | ||
Hα | −0.693 | <10−40 | 3 |
Note. X and Y are the relevant quantities presented in samples 1–3. and η = 0.038.
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Since f may be affected by Fr, it is possible that f is correlated with L5100. In fact, there are weak correlations between f and L5100 (see Tables 4 and 5). Also, the dependence of f and on vFWHM may result in a false correlation. Thus, the partial correlation analysis is needed to test the – correlation when excluding the influence of vFWHM and/or L5100. Based on the Pearson's correlation coefficients in Table 5, the first-order partial correlation analysis gives a confidence level of >99.99% for the – correlation when excluding the dependence on L5100 or vFWHM (see Table 6). The second-order partial correlation analysis gives a confidence level of >99.99% for the – correlation when excluding the dependence on vFWHM and L5100, except for the broad Hα in sample 3 at a confidence level of 99.84% (see Table 6). Thus, a positive correlation exists between f and . This positive correlation is qualitatively consistent with the logical expectation when the overall effect of Fr on the BLR clouds is taken into account to estimate MRM. In addition, f > fg = 1 for Hβ and Hα in most of the AGNs (see Figure 1): >96.5% for Hβ in sample 1, >97.2% for Hα in sample 2, and >97.7% for Hβ and >97.4% for Hα in sample 3.
Table 6. Partial Correlation Analysis Results
Name | Order | Line | rp | Pp | Sample |
---|---|---|---|---|---|
1 | Hβ | 0.603 | <10−4 | 1 | |
1 | Hβ | 0.232 | <10−4 | 1 | |
2 | Hβ | 0.151 | <10−4 | 1 | |
1 | Hα | 0.581 | <10−4 | 2 | |
1 | Hα | 0.102 | <10−4 | 2 | |
2 | Hα | 0.055 | <10−4 | 2 | |
1 | Hβ | 0.616 | <10−4 | 3 | |
1 | Hβ | 0.237 | <10−4 | 3 | |
2 | Hβ | 0.141 | <10−4 | 3 | |
1 | Hα | 0.600 | <10−4 | 3 | |
1 | Hα | 0.096 | <10−4 | 3 | |
2 | Hα | 0.035 | 1.6 × 10−3 | 3 |
Note. Based on the Pearson's correlation coefficient r in Table 5, the partial correlation coefficient rp and the p-value Pp of the hypothesis test are estimated using the website for Statistical Computation (http://vassarstats.net/index.html). Orders 1 and 2 denote the first- and second-order partial correlation coefficients, respectively. and η = 0.038.
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In order to test the gravitational origin of the redward shift of the broad emission line, we compare zg to rBLR/rg, the dimensionless radius of the BLR in units of rg. The Spearman's rank correlation test shows a negative correlation between zg and rBLR/rg (see Table 4). This negative correlation is qualitatively consistent with the expectation that zg is mainly from the gravity of the central black hole, because MRM cannot be corrected individually for each AGN due to the absence of the individual virial factor that is independent of zg. So, we can make the overall correction of MRM to be MRM/〈f〉, where 〈f〉 is the average of f in samples 1–3 (see Figure 2). This overall correction is equivalent to the parallel shift of the data point in Figure 2. The negative correlation expectation is basically consistent with the trend between zg and rBLR/rg/〈f〉 in Figure 2. This indicates that zg is dominated by the gravity of the central black hole. In addition, rg/rBLR ≲ 0.01 ≪ 1 and 〈f〉rg/rBLR < 0.1 for AGNs in Tables 1–3. 〈f〉rg/rBLR ≲ 0.01 for >96% of AGNs in sample 1, >97% of AGNs in sample 2, and >96% of AGNs in sample 3. Thus, the Schwarzschild metric is valid and matches the weak-field limit at the optical BLR scales of AGNs in our samples, which are conditions on the validity of Equation (1) (see Liu et al. 2022).
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Standard image High-resolution imageSince f > 1 for most of the SDSS AGNs in samples 1–3, the f-correction might result in substantial influence on MRM and . We choose 8169 AGNs in sample 3 to illustrate this influence. On average, the corrected MRM becomes larger by 1 order of magnitude than MRM, and the corrected decreases by about 10 times (see Figure 3). The substantial increase of MRM will significantly impact the black hole mass function of these SDSS AGNs, e.g., leading to more AGNs with higher masses. The substantial decrease of loosens the requirement for the accretion rate of the accretion disk and might make the distinction between high- and low-accreting sources less obvious. If Lbol/LEdd ≥ 0.1, i.e., , for high-accreting sources, the percent of AGNs with is 31.4%, but the percent of AGNs with is only 0.3% (see Figure 3). The percent of high-accreting sources is decreased by about 100 times due to the f-correction. In a sense, the f-correction blurs the distinction between high- and low-accreting sources.
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Standard image High-resolution imageThe virial factor of Hβ is consistent with that of Hα for 8169 AGNs in sample 3 (see Figure 4). The Hα lags are consistent with or (slightly) larger than the Hβ lags for RM AGNs (e.g., Kaspi et al. 2000; Bentz et al. 2010; Grier et al. 2017). Because the Hα optical depth is larger than the Hβ optical depth, the optical depth effects may result in the larger Hα lags that cause the Hα emission line to seemingly appear at larger distances than Hβ (see Bentz et al. 2010), even though the Hβ and Hα broad emission lines are from the same region. Thus, it seems that rBLR(Hβ) ≈ rBLR(Hα). For broad emission lines with different rBLR, there will be (α > 0) as Fr is considered and the BLR clouds are in the virialized motion for a given AGN (Liu et al. 2017). The Hβ and Hα BLRs have similar virialized kinematics for type 1 AGNs in SDSS DR16 (Rakić 2022). If rBLR(Hβ) ≈ rBLR(Hα) and , it will be expected that f(Hβ) is on the whole consistent with f(Hα) for AGNs in sample 3, as shown in Figure 4.
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Standard image High-resolution image5. Potential Influence on Quasars at z ≳ 6
Quasars at z ≳ 6 can probe the formation and growth of SMBHs in the Universe within the first billion years after the Big Bang. The quasars, with MRM ≳ 109 M⊙ at z ≳ 7 and MRM ≳ 1010 M⊙ at z ≳ 6, make the formation and growth of SMBHs ever more challenging (e.g., Wu et al. 2015; Fan et al. 2023). These SMBHs will need a combination of massive early black hole seeds with highly efficient and sustained accretion (e.g., Fan et al. 2023). However, the single-epoch spectrum method had been widely used to estimate the MRM of the high-z quasars (e.g., Willott et al. 2010; Wu et al. 2015; Wang et al. 2019; Eilers et al. 2023), and this may result in underestimation of MRM, overestimation of Lbol/LEdd, and significant influence on the formation and growth of SMBHs in the early Universe. Based on Equation (4), we will use to estimate f and study its influence for quasars at z ≳ 6.
There are 113 quasars at 6 ≲ z ≲ 8 with reliable Mg ii–based black hole mass estimates (Fan et al. 2023). These 113 quasars have 〈f〉 = 78 (f = 12–189), , , and 〈Lbol/LEdd/f〉 = 0.01 (see Table7). The f-correction makes MRM increase by 1–2 orders of magnitude. Also, the substantially reduced Lbol/LEdd/f =0.007–0.014 will make these 113 quasars accrete at well below the Eddington limit, although likely in the radiatively efficient regime via a geometrically thin, optically thick accretion disk (Shakura & Sunyaev 1973). Based on Equation (7) in Fan et al. (2023), , the growth times of SMBHs in these quasars will increase by a factor of 2.5–5.2 due to the f-correction. Thus, the black hole seeds do not seem to have enough time to grow up for SMBHs in quasars at z ≳ 6, and this gives more strong constraints on the formation and growth of the black hole seeds. Thus, the f-correction will make it more difficult to explain the formation and growth of SMBHs at z ≳ 6; e.g., larger masses of SMBHs need more massive early black hole seeds and/or longer growth times. Bogdán et al. (2024) found evidence for the heavy-seed origin of early SMBHs from a z ≈ 10 X-ray quasar. Our results of corrected masses support heavy-seed origin scenarios of early SMBHs.
Table 7. Quasars at z ≳ 6
Name | Redshift | f | |||||
---|---|---|---|---|---|---|---|
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) |
J000825.77−062604.42 | 5.930 | 8.72 | 46.32 | 1.626 | 127.4 | 10.82 | 0.013 |
J002031.47−365341.82 | 6.834 | 9.23 | 46.42 | 0.633 | 59.8 | 11.01 | 0.011 |
J002429.77+391318.97 | 6.621 | 8.43 | 46.18 | 2.293 | 167.7 | 10.66 | 0.014 |
Note. Lbol = 5.15L3000, where L3000 is the UV quasar continuum luminosity at rest-frame wavelength 3000 Å (Fan et al. 2023). f is estimated by , where is estimated by Lbol/LEdd/η and η = 0.038.
Only a portion of this table is shown here to demonstrate its form and content. A machine-readable version of the full table is available.
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The highest-redshift quasar, J031343.84−180636.40, at z = 7.6423, has , , and Lbol/LEdd/f = 0.01. Quasar J0100+2802, the most luminous quasar known at z > 6, has and Lbol/LEdd ∼ 0.8 (Wu et al. 2015). So, J0100+2802 has and Lbol/LEdd/f ∼ 0.01. Quasar J140821.67+025733.2, at z = 2.055, has a black hole mass of 1011.3 M⊙ with an uncertainty of 0.4 dex (Kozłowski 2017). It seems reasonable that J0100+2802 has with an uncertainty of 0.4. Recently, Kokorev et al. (2023) found an AGN at z = 8.50 with an Hβ-based mass of and Lbol/LEdd ∼ 0.33. We have and Lbol/LEdd/f ∼ 0.01 for this AGN. In addition, samples 1–3 each have 〈Lbol/LEdd/f〉 = 0.01. It is interesting that 〈Lbol/LEdd/f〉 =0.01 exists for quasars/AGNs at z < 0.35 and ≳6, and perhaps it is a coincidence.
6. Potential Influence on the M•–σ* Map of AGNs
It is not determined whether or not the SMBHs coevolve with their host galaxies (e.g., Kormendy & Ho 2013), especially the SMBHs in AGNs with high accretion rates. Coevolution had been supported by the M•–σ* relations of local quiescent galaxies. For 31 nearby galaxies, Tremaine et al. (2002) obtained with σ0 = 200 km s−1. McConnell & Ma (2013) presented a revised scaling relation of for dynamical measurements of M• at the centers of 72 nearby galaxies. For 72 nearby quiescent galaxies with dynamical measurements of M•, Woo et al. (2013) obtained . For 19 local luminous AGNs at z < 0.01, Caglar et al. (2020) obtained.
We collect σ* from Table 1 in Woo et al. (2015) for AGNs in our samples and MRM, σ*, L5100, etc. for other SDSS quasars from Table 1 in Shen et al. (2015b). There are 62 AGNs and 88 quasars collected (see Tables 8 and 9). The 62 AGNs are at z = 0.013–0.100 with 〈z〉 = 0.063, which is beyond the local Universe. The 88 quasars are at z = 0.116–0.997 with 〈z〉 = 0.581, which is well beyond the local Universe. The significant difference of redshift might influence whether these 150 sources follow the same M•–σ* relationship as the local sources. The (MRM, σ*) data of these 150 soures do not roughly follow the four local M•–σ* relations, and the deviation of the 88 quasars is more obvious (see Figure 5). When studying the coevolution of SMBHs, the local M•–σ* relation is basically equivalent to the local black hole–galaxy bulge mass relation. Quasars at z ∼ 6 are above the local mass relation (e.g., Fan et al. 2023). So, the quasars at z ∼ 6 should be above the local M•–σ* relation. Thus, these z ≳ 6 quasars using fMRM might be above the local M•–σ* relations.
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Standard image High-resolution imageTable 8. 62 SDSS AGNs in M•–σ* Map Research
Name | Redshift | f | ||||
---|---|---|---|---|---|---|
(1) | (2) | (3) | (4) | (5) | (6) | (7) |
J010409.16+000843.7 | 0.071 | 6.78 | 0.065 | 6.4 | 66 ± 16 | 7.59 |
J030417.78+002827.4 | 0.045 | 6.54 | 0.147 | 25.9 | 88 ± 8 | 7.95 |
J073106.87+392644.7 | 0.048 | 6.39 | 0.120 | 29.8 | 72 ± 14 | 7.86 |
Note. The σ* of the 62 AGNs in our samples are taken from Table 1 in Woo et al. (2015).
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Table 9. 88 SDSS Quasars in M•–σ* Map Research
Name | Redshift | f | |||||
---|---|---|---|---|---|---|---|
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) |
141359.51+531049.3 | 0.8982 | 7.94 | 44.11 | 0.117 | 15.6 | 121 ± 31 | 9.13 |
141324.28+530527.0 | 0.4559 | 8.36 | 43.91 | 0.028 | 4.9 | 191 ± 4 | 9.05 |
141323.27+531034.3 | 0.8492 | 8.93 | 44.28 | 0.017 | 3.4 | 166 ± 20 | 9.46 |
Note. The 88 SDSS quasars are taken from Table 1 in Shen et al. (2015b). Lbol = 9.8L5100. f is estimated by , where is estimated by Lbol/LEdd/η and η = 0.038.
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The local luminous AGNs in Caglar et al. (2020) have 〈Lbol/LEdd〉 = 0.07, which corresponds to f = 10, indicating that the M•–σ* relation of Caglar et al. (2020) should be corrected by moving vertically upward by an order of magnitude in the M•–σ* map. Though the (fMRM, σ*) data of these 150 sources deviate from (are above) these local M•–σ* relations, they roughly follow the corrected M•–σ* relation (see Figure 5). This deviation implies requirements of more massive black hole seeds, longer growth times, larger AGN duty cycles, and/or higher mass accretion rates in the long-term accretion history for them. Also, it seems that the agreement of the (fMRM, σ*) data with the corrected M•–σ* relation is better than the agreement of the (MRM, σ*) data with the local M•–σ* relations (see Figure 5). These results might shed light on the possible redshift evolution in the M•–σ* relationship. The formation and growth of the local SMBHs and host galaxies might be different from those of the SMBHs in higher-redshift AGNs/quasars and host galaxies.
7. Discussion
The redward shift zg can also be estimated by the λb and λn of the Hβ and Hα lines (see Equation (3)). Because of the absence of the uncertainty of λn for Hβ in Table 2 of Liu et al. (2019), zg is estimated by the λb and λn of Hα for 7552 AGNs in sample 2, zg(Hα)(b-n). zg(Hα)(b-n) is roughly consistent with the [O iii] λ5007–based zg(Hα) (see Figure 6). Considering the uncertainties of zg(Hα) and zg(Hα)(b-n) (see columns (3) and (4) in Table 2), they are consistent with each other. Thus, the results of zg(Hα) are reliable. Based on zg(Hα) and zg(Hα)(b-n), the virial factors of f(Hα) and f(Hα)(b-n) are estimated and compared to test their reliabilities. Figure 6 shows that f(Hα) and f(Hα)(b-n) are basically consistent. Considering the uncertainties, which have a mean of 2.0 and median of 0.8 for f(Hα) and a mean of 1.6 and median of 0.7 for f(Hα)(b-n) (see columns (8) and (9) in Table 2), f(Hα) is consistent with f(Hα)(b-n). Thus, the selection of [O iii] λ5007 as a reference to estimate zg in Equation (3) will not influence our results.
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Standard image High-resolution imageIt is very difficult to get a real individual value of η to estimate for a large sample of AGNs, because η is closely related to the difficultly measured spin of a black hole. Usually, the Eddington ratio is regarded as a proxy of the accretion rate of the black hole. Even though these correlations of with f are likely influenced by the unknown individual value of η, there are still correlations of the Eddington ratio with f, because a difference of only 0.038 exists between and Lbol/LEdd in Tables 1–3. Davis & Laor (2011) found a strong correlation of for a sample of 80 Palomar–Green quasars, where M8 is the black hole mass in units of 108 M⊙ and η was estimated from the mass accretion rate and Lbol. This empirical relation is used to estimate η in order to test the influence of using η = 0.038 on these correlations of with f. Correlation analyses are made for and f in Figure 1, with to be reestimated by Lbol/LEdd in Tables 1–3 and the estimated η. There are still correlations very similar to those found in Figure 1 when using these new dimensionless accretion rates (see Figure 7 and Table 4). Thus, the –f correlations found in this work do not result from using the fixed value of η = 0.038.
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Standard image High-resolution imageEquation (2) can give for vFWHM, f, and zg
which is similar to Equation (6) in Mediavilla et al. (2018). Mediavilla et al. (2018) found a tight correlation between the widths and redward shifts of the Fe iii λ λ2039–2113 blend for lensed quasars, which supports the gravitational interpretation of the Fe iii λ λ2039–2113 redward shifts. A series of lines based on Equation (4) with different f are compared to the observational data points (see Figure 8). From top to bottom, the corresponding f increases. Because of the codependence among the Eddington ratio, dimensionless accretion rate, and vFWHM, the large ranges of the former two quantities may lead to the large span in the direction roughly perpendicular to these lines (see Figure 8). These lines with f = 1–100 recover the observational data in Figure 8, and this indicates the gravitational origin of zg. At the same time, the internal physical processes, e.g., the microturbulence, within the BLR cloud can broaden and smooth the line profles (Bottorff & Ferland 2000). Also, the turbulence velocity of the BLR cloud can influence the widths of the line profiles. These turbulence processes will influence vFWHM and then f for different AGNs. The combination of the column density of the BLR cloud, the metallicity of the BLR cloud, internal physical processes within the BLR cloud, etc., may decrease these correlations in Figure 1 (e.g., Liu et al. 2022).
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Standard image High-resolution imageThere are the various outflows at accretion disk, BLR, NLR, and kiloparsec scales, driven by Fr from AGNs (Dyda & Proga 2018; Kang & Woo 2018; Dannen et al. 2019; Mas-Ribas & Mauland 2019; Nomura et al. 2020; Meena et al. 2021; Singha et al. 2021). Thus, Fr is prevalent and may contribute to the force budget for inflow, e.g., Fr decelerates inflow (Ferland et al. 2009). RM observations of PG 0026+129 indicate a decelerating inflow if zg originates from inflow. If the decelerating inflow is prevalent, zg will increase with the increasing rBLR/rg, but this expectation is not consistent with the negative trend found in Figure 2. Thus, the inflow seems not to be the origin of zg. In RM observations, the asymmetric lag maps and shifts of broad emission lines for AGNs usually differ from the theoretical expectation that inflow will generate the redward-shifted broad emission lines with the blueward asymmetric lag maps (e.g., Denney et al. 2010; Zhang et al. 2019; Hu et al. 2020; Feng et al. 2021a, 2021b). This kind of broad emission line may originate from an elliptical disklike BLR (Kovačević et al. 2020; Feng et al. 2021a). Therefore, the redward-shifted broad emission lines in AGNs do not necessarily originate from inflow.
Mejía-Restrepo et al. (2018) determined the virial factor in a smaller set of sources using a different method than proposed here and found a relation whereby f ∝ 1/vFWHM, which is attributed to inclination effects, but without excluding the possibility of radiation pressure effects over a wide luminosity range. Their sources have ≈ 3.2–4.0, which are much narrower than the ≈ 2.7–4.4 in our samples. Also, their sources have 7.5–9.7 and = 44.3–46.2, which are much narrower than the ≈5.2–9.7 and = 40.6–45.6 in our samples, respectively. There are positive correlations between zg and vFWHM for our samples, (see Figure 9). Based on and Equation (2), with vFWHM partly contributed by inclination effects, we have , which is qualitatively consistent with but shallower than f ∝ 1/vFWHM. This discrepancy might be generated by our consideration of radiation pressure and the estimation of M• using standard thin accretion disk models for sources with the narrower parameter coverage (Mejía-Restrepo et al. 2018). In this sense, the results and interpretations promoted here are consistent with Mejía-Restrepo et al. (2018).
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Standard image High-resolution imageThe AGNs with high accretion rates show shorter time lags by factors of a few compared to the predictions from the rBLR–L5100 relationship (Du et al. 2015). Du & Wang (2019) found that accretion rate is the main driver for the shortened lags and established a new scaling relation,
where rBLR(Hβ) is rBLR in units of light-days for Hβ, L44 = L5100/(1044 erg s−1), and RFe II is the line ratio of Fe ii to Hβ. Replacing with Equation (6), the mass of the black hole is given by
which is used to estimate the dimensionless accretion rate, . Samples 1 and 3 are used to investigate the influence of Equation (6) on the f– relation. RFe II is estimated by equivalent widths of Hβ and Fe ii taken from Table 2 of Liu et al. (2019) for 5997 AGNs in sample 1 and 5365 AGNs in sample 3. First, is overall consistent with the original (see Figure 10). Second, f is well correlated with (see Figure 10), and Equation (6) has a slight impact on the f– relation. Also, rBLR(RFe II )/rg(RFe II ) is estimated, and there exists the anticorrelation trend between zg and rBLR(RFe II )/rg(RFe II )/〈f〉 (see Figure 11), same as in Figure 2. The potential effect of , especially at the high mass accretion rate end (Du et al. 2015), does not lead to qualitatively different results of rBLR/rg.
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Standard image High-resolution image8. Conclusion
Based on the assumption of a gravitational origin for the redward shifts of the broad emission lines Hβ and Hα and their widths and redward shifts for more than 8000 SDSS DR7 AGNs with z < 0.35, we measured the virial factor in MRM, estimated by the RM method and/or the relevant secondary methods. The measured virial factor contains the overall effect of Fr from accretion disk radiation and the geometric effect of the BLR. Our findings can be summarized as follows.
- 1.There are positive correlations of f with and Lbol/LEdd, which are a combined effect of several physical mechanisms, such as the Doppler effect, the gravitational redshift, the gravity of the black hole, the radiation pressure force, etc. f spans a large range, and f > 1 for >96% of AGNs in samples 1–3. The f-correction makes the percent of high-accreting AGNs decrease by about 100 times and blurs the distinction between high- and low-accreting sources.
- 2.zg is anticorrelated with rBLR/rg. zg and rBLR/rg/〈f〉 marginally follow the 1:1 line. A series of lines with different f basically reproduce the vFWHM–zg distribution for the broad Hβ and Hα. These results suggest that the redward shifts of the broad Hβ and Hα are governed by the gravity of the central SMBHs.
- 3.For quasars at z ≳ 6, the f-correction changes them from near-Eddington accreting sources to low-accreting sources, likely in the radiatively efficient regime via a geometrically thin, optically thick accretion disk. The f-corrected masses indicate that quasars at z ≳ 6 have more massive early black hole seeds and longer growth times, supporting the heavy-seed origin scenarios of early SMBHs. These results will make it more challenging to explain the formation and growth of SMBHs at z ≳ 6.
- 4.A total of 62 AGNs and 88 quasars beyond the local Universe do not follow the local M•–σ* relations. After the f-correction, these 150 sources are above the local M•–σ* relations, but they roughly follow the f-corrected M•–σ* relation of the local luminous AGNs in Caglar et al. (2020). These results might shed light on possible redshift evolution in the M•–σ* relationship.
Our results show that radiation pressure force should be considered in estimating the virial masses of SMBHs. The usually used values of f should be corrected for high-accreting AGNs, especially quasars at z ≳ 6. The f-correction to MRM will make the coevolution (or not) of SMBHs and host galaxies more complex for local and higher-redshift sources. Positive correlations of f with and Lbol/LEdd need to be further tested by the redward-shifted broad emission lines of the RM AGNs without the signatures of inflow and outflow in the BLR, which can be picked out by the velocity-resolved time lag maps.
Acknowledgments
We are grateful to the anonymous referee for constructive comments and suggestions that significantly improved this manuscript. We are thankful for the financial support of the National Key R&D Program of China (grant No. 2021YFA1600404), the National Natural Science Foundation of China (grants Nos. 12373018, 12303022, 12203096, 12063005, and 11991051), Yunnan Fundamental Research Projects (grant Nos. 202301AT070358 and 202301AT070339), Yunnan Postdoctoral Research Foundation Funding Project, Special Research Assistant Funding Project of Chinese Academy of Sciences, and the science research grants from the China Manned Space Project with grant No. CMS-CSST-2021-A06. We acknowledge the Program for Innovative Research Team (in Science and Technology) in University of Yunnan Province (IRTSTYN).