skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Broad-line region geometry from multiple emission lines in a single-epoch spectrum
The broad-line region (BLR) of active galactic nuclei (AGNs) traces gas close to the central supermassive black hole (BH). Recent reverberation mapping (RM) and interferometric spectro-astrometry data have enabled detailed investigations of the BLR structure and dynamics as well as estimates of the BH mass. These exciting developments have motivated comparative investigations of BLR structures using different broad emission lines. In this work, we have developed a method to simultaneously model multiple broad lines of the BLR from a single-epoch spectrum. We applied this method to the five strongest broad emission lines (Hα, Hβ, Hγ, Paβ, and He Iλ5876) in the UV-to-near-IR spectrum of NGC 3783, a nearby Type I AGN that has been well studied by RM and interferometric observations. Fixing the BH mass to the published value, we fit these line profiles simultaneously to constrain the BLR structure. We find that the differences between line profiles can be explained almost entirely as being due to different radial distributions of the line emission. We find that using multiple lines in this way also enables one to measure some important physical parameters, such as the inclination angle and virial factor of the BLR. The ratios of the derived BLR time lags are consistent with the expectation of theoretical model calculations and RM measurements.  more » « less
Award ID(s):
1909711
PAR ID:
10611457
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
Publisher / Repository:
Astronomy & Astrophysics
Date Published:
Journal Name:
Astronomy & Astrophysics
Volume:
684
ISSN:
0004-6361
Page Range / eLocation ID:
A52
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; (, The Astrophysical Journal)
    Abstract Fast empirical models of the broad emission line region (BLR) are a powerful tool to interpret velocity-resolved reverberation mapping (RM) data, estimate the mass of the supermassive black holes, and gain insight into its geometry and kinematics. Much of the effort so far has been devoted to describing the emissivity of one emission line at a time. We present here an alternative approach aimed at describing the underlying BLR gas distribution, by exploiting simple numerical recipes to connect it with emissivity. This approach is a step toward describing multiple emission lines originating from the same gas and allows us to clarify some issues related to the interpretation of RM data. We illustrate this approach—implemented in the codeCARAMEL-gas—using three data sets covering the Hβemission line (Mrk 50, Mrk 1511, Arp 151) that have been modeled using the emissivity-based version of the code. As expected, we find differences in the parameters describing the BLR gas and emissivity distribution, but the emissivity-weighted lag measurements and all other model parameters including black hole mass and overall BLR morphology and kinematics are consistent with the previous measurements. We also model the Hαemission line for Arp 151 using both the gas- and emissivity-based BLR models. We find ionization stratification in the BLR with Hαarising at larger radii than Hβ, while all other model parameters are consistent within the uncertainties. 
    more » « less
  2. ; ; ; ; ; ; ; ; ; ; et al (, Astronomy & Astrophysics)
    By using the GRAVITY instrument with the near-infrared (NIR) Very Large Telescope Interferometer (VLTI), the structure of the broad (emission-)line region (BLR) in active galactic nuclei (AGNs) can be spatially resolved, allowing the central black hole (BH) mass to be determined. This work reports new NIR VLTI/GRAVITY interferometric spectra for four type 1 AGNs (Mrk 509, PDS 456, Mrk 1239, and IC 4329A) with resolved broad-line emission. Dynamical modelling of interferometric data constrains the BLR radius and central BH mass measurements for our targets and reveals outflow-dominated BLRs for Mrk 509 and PDS 456. We present an updated radius-luminosity (R-L) relation independent of that derived with reverberation mapping (RM) measurements using all the GRAVITY-observed AGNs. We find our R-L relation to be largely consistent with that derived from RM measurements except at high luminosity, where BLR radii seem to be smaller than predicted. This is consistent with RM-based claims that high Eddington ratio AGNs show consistently smaller BLR sizes. The BH masses of our targets are also consistent with the standardMBH-σ*relation. Model-independent photocentre fitting shows spatial offsets between the hot dust continuum and the BLR photocentres (ranging from ∼17 μas to 140 μas) that are generally perpendicular to the alignment of the red- and blueshifted BLR photocentres. These offsets are found to be related to the AGN luminosity and could be caused by asymmetricK-band emission of the hot dust, shifting the dust photocentre. We discuss various possible scenarios that can explain this phenomenon. 
    more » « less
  3. ; ; ; ; ; ; ; ; ; ; et al (, The Astrophysical Journal)
    Abstract The most reliable single-epoch supermassive black hole mass (MBH) estimates in quasars are obtained by using the velocity widths of low-ionization emission lines, typically the Hβλ4861 line. Unfortunately, this line is redshifted out of the optical band atz≈ 1, leavingMBHestimates to rely on proxy rest-frame ultraviolet (UV) emission lines, such as Civλ1549 or Mgiiλ2800, which contain intrinsic challenges when measuring, resulting in uncertainMBHestimates. In this work, we aim at correctingMBHestimates derived from the Civand Mgiiemission lines based on estimates derived from the Hβemission line. We find that employing the equivalent width of Civin derivingMBHestimates based on Mgiiand Civprovides values that are closest to those obtained from Hβ. We also provide prescriptions to estimateMBHvalues when only Civ, only Mgii, and both Civand Mgiiare measurable. We find that utilizing both emission lines, where available, reduces the scatter of UV-basedMBHestimates by ∼15% when compared to previous studies. Lastly, we discuss the potential of our prescriptions to provide more accurate and precise estimates ofMBHgiven a much larger sample of quasars at 3.20 ≲z≲ 3.50, where both Mgiiand Hβcan be measured in the same near-infrared spectrum. 
    more » « less
  4. ; ; ; ; ; ; ; ; ; ; et al (, Astronomy & Astrophysics)
    We present JWST/NIRSpec integral field data of the quasar PJ308-21 atz = 6.2342. As shown by previous ALMA and HST imaging, the quasar has two companion sources, interacting with the quasar host galaxy. The high-resolution G395H/290LP NIRSpec spectrum covers the 2.87 − 5.27 μm wavelength range and shows the rest-frame optical emission of the quasar with exquisite quality (signal-to-noise ratio ∼100 − 400 per spectral element). Based on the Hβline from the broad line region, we obtain an estimate of the black hole massMBH, Hβ ∼ 2.7 × 109 M⊙. This value is within a factor ≲1.5 of the Hα-based black hole mass from the same spectrum (MBH, Hα ∼ 1.93 × 109 M⊙) and is consistent with a previous estimate relying on the Mg IIλ2799 line (MBH, MgII ∼ 2.65 × 109 M⊙). All theseMBHestimates are within the ∼0.5 dex intrinsic scatter of the adopted mass calibrations. The high Eddington ratio of PJ308-21λEdd, Hβ ∼ 0.67 (λEdd, Hα ∼ 0.96) is in line with the overall quasar population atz ≳ 6. The relative strengths of the [O III], Fe II, and Hβlines are consistent with the empirical “Eigenvector 1” correlations as observed for low redshift quasars. We find evidence for blueshifted [O III]λ5007 emission with a velocity offset Δv[O III] = −1922 ± 39 km s−1from the systemic velocity and a full width at half maximum (FWHM)FWHM([O III]) = 2776−74+75km s−1. This may be the signature of outflowing gas from the nuclear region, despite the true values of Δv[O III]andFWHM([O III]) likely being more uncertain due to the blending with Hβand Fe IIlines. Our study demonstrates the unique capabilities of NIRSpec in capturing quasar spectra at cosmic dawn and studying their properties in unprecedented detail. 
    more » « less
  5. ; ; ; ; ; ; ; ; ; ; et al (, Astronomy & Astrophysics)
    This work focuses on active galactic nuclei (AGNs) and on the relation between the sizes of the hot dust continuum and the broad-line region (BLR). We find that the continuum size measured using optical/near-infrared interferometry (OI) is roughly twice that measured by reverberation mapping (RM). Both OI and RM continuum sizes show a tight relation with the H β BLR size, with only an intrinsic scatter of 0.25 dex. The masses of supermassive black holes (BHs) can hence simply be derived from a dust size in combination with a broad line width and virial factor. Since the primary uncertainty of these BH masses comes from the virial factor, the accuracy of the continuum-based BH masses is close to those based on the RM measurement of the broad emission line. Moreover, the necessary continuum measurements can be obtained on a much shorter timescale than those required monitoring for RM, and they are also more time efficient than those needed to resolve the BLR with OI. The primary goal of this work is to demonstrate a measuring of the BH mass based on the dust-continuum size with our first calibration of the R BLR – R d relation. The current limitation and caveats are discussed in detail. Future GRAVITY observations are expected to improve the continuum-based method and have the potential of measuring BH masses for a large sample of AGNs in the low-redshift Universe. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email