scholarly journals An improved test of the binary black hole hypothesis for quasars with double-peaked broad Balmer lines

2019 ◽  
Vol 491 (1) ◽  
pp. 1104-1126 ◽  
Author(s):  
Anh Doan ◽  
Michael Eracleous ◽  
Jessie C Runnoe ◽  
Jia Liu ◽  
Gavin Mathes ◽  
...  

ABSTRACT Velocity offsets in the broad Balmer lines of quasars and their temporal variations serve as indirect evidence for bound supermassive black hole binaries (SBHBs) at sub-parsec separations. In this work, we test the SBHB hypothesis for 14 quasars with double-peaked broad emission lines using their long-term (14–41 yr) radial velocity curves. We improve on the previous work by (i) using elliptical instead of circular orbits for the SBHBs, (ii) adopting a statistical model for radial velocity jitter, (iii) employing a Markov chain Monte Carlo method to explore the orbital parameter space efficiently and build posterior distributions of physical parameters, and (iv) incorporating new observations. We determine empirically that jitter comprises approximately Gaussian distributed fluctuations about the smooth radial velocity curves that are larger than the measurement errors by factors of a few. We initially treat jitter by enlarging the effective error bars and then verify this approach via a variety of Gaussian process models for it. We find lower mass limits for the hypothesized SBHBs in the range 108–1011 M⊙. For seven objects, the SBHB scenario appears unlikely based on goodness-of-fit tests. For two additional objects, the minimum SBHB masses are unreasonably large (>1010 M⊙), strongly disfavouring the SBHB scenario. Using constraints on the orbital inclination angle (which requires some assumptions) makes the minimum masses of four more objects unreasonably large. We also cite physical and observational arguments against the SBHB hypothesis for nine objects. We conclude that the SBHB explanation is not the favoured explanation of double-peaked broad emission lines.

2006 ◽  
Vol 2 (S238) ◽  
pp. 475-476
Author(s):  
Alexander F. Zakharov

AbstractRecent X-ray observations of microquasars and Seyfert galaxies reveal broad emission lines in their spectra, which can arise in the innermost parts of accretion disks. Recently Müller & Camenzind (2004) classified different types of spectral line shapes and described their origin. Zakharov (2006b) clarified their conclusions about an origin of doubled peaked and double horned line shapes in the framework of a radiating annulus model and discussed s possibility to evaluate black hole parameters analyzing spectral line shapes.


2006 ◽  
pp. 1-11 ◽  
Author(s):  
L.C. Popovic

In this paper a discussion of kinematics and physics of the Broad Line Region (BLR) is given. The possible physical conditions in the BLR and problems in determination of the physical parameters (electron temperature and density) are considered. Moreover, one analyses the geometry of the BLR and the probability that (at least) a fraction of the radiation in the Broad Emission Lines (BELs) originates from a relativistic accretion disk.


2019 ◽  
Vol 880 (2) ◽  
pp. 96 ◽  
Author(s):  
E. Mediavilla ◽  
J. Jiménez-vicente ◽  
J. Mejía-restrepo ◽  
V. Motta ◽  
E. Falco ◽  
...  

1991 ◽  
Vol 143 ◽  
pp. 147-154
Author(s):  
C. Robert ◽  
A. F. J. Moffat ◽  
W. Seggewiss

Time-resolved spectroscopy has revealed small, systematically varying features superimposed on the broad emission lines of WR stars. We believe that these structures are due to inhomogeneities of emitting wind material propagating with the general wind. Here we suggest a common, but still unknown, origin for the intrinsic variations observed in WR stars.


2020 ◽  
Vol 498 (3) ◽  
pp. 4119-4133 ◽  
Author(s):  
P Short ◽  
M Nicholl ◽  
A Lawrence ◽  
S Gomez ◽  
I Arcavi ◽  
...  

ABSTRACT We present results from spectroscopic observations of AT 2018hyz, a transient discovered by the All-Sky Automated Survey for Supernova survey at an absolute magnitude of MV ∼ −20.2 mag, in the nucleus of a quiescent galaxy with strong Balmer absorption lines. AT 2018hyz shows a blue spectral continuum and broad emission lines, consistent with previous TDE candidates. High cadence follow-up spectra show broad Balmer lines and He i in early spectra, with He ii making an appearance after ∼70–100 d. The Balmer lines evolve from a smooth broad profile, through a boxy, asymmetric double-peaked phase consistent with accretion disc emission, and back to smooth at late times. The Balmer lines are unlike typical active galactic nucleus in that they show a flat Balmer decrement (Hα/Hβ ∼ 1.5), suggesting the lines are collisionally excited rather than being produced via photoionization. The flat Balmer decrement together with the complex profiles suggests that the emission lines originate in a disc chromosphere, analogous to those seen in cataclysmic variables. The low optical depth of material due to a possible partial disruption may be what allows us to observe these double-peaked, collisionally excited lines. The late appearance of He ii may be due to an expanding photosphere or outflow, or late-time shocks in debris collisions.


2012 ◽  
Vol 8 (S290) ◽  
pp. 21-24
Author(s):  
Bozena Czerny ◽  
Krzysztof Hryniewicz ◽  
Janusz Kaluzny ◽  
Ishita Maity

AbstractThe most characteristic property of active galaxies, including quasars, are prominent broad emission lines. I will discuss an interesting possibility that dust is responsible for this phenomenon. The dust is known to be present in quasars in the form of a dusty/molecular torus which results in complexity of the appearance of active galaxies. However, this dust is located further from the black hole than the Broad Line Region. We propose that the dust is present also closer in and it is actually responsible for formation of the broad emission lines. The argument is based on determination of the temperature of the disk atmosphere underlying the Broad Line Region: it is close to 1000 K, independently from the black hole mass and accretion rate of the object. The mechanism is simple and universal but leads to a considerable complexity of the active nucleus surrounding. The understanding the formation of BLR opens a way to use it reliably - in combination with reverberation measurement of its size - as standard candles in cosmology.


2021 ◽  
Vol 502 (3) ◽  
pp. 3312-3328
Author(s):  
Eduardo O Schmidt ◽  
Laura D Baravalle ◽  
Adriana R Rodríguez-Kamenetzky

ABSTRACT The spectra of active galactic nuclei usually exhibit wings in some emission lines, such as [O iii]λλ5007, 4959, with these wings generally being blueshifted and related to strong winds and outflows. The aim of this work was to analyse the [O iii] emission lines in broad-line Seyfert 1 (BLS1) galaxies in order to detect the presence of wings, and to study the [O iii] line properties and their possible connection with the central engine. In addition, we attempted to compare the black hole mass distribution in both BLS1 galaxies with symmetric and blue-asymmetric [O iii] profiles. For this purpose, we carried out a spectroscopic study of a sample of 45 nearby southern BLS1 galaxies from the Six Degree Field Galaxy survey. The [O iii] emission lines were well-fitted using a single Gaussian function in 23 galaxies, while 22 objects presented a wing component and required a double-Gaussian decomposition. By computing the radial velocity difference between the wing and core centroids (i.e. Δv), we found 18 galaxies exhibiting blueshifted wings, 2 objects presenting red wings, and 2 galaxies showing symmetric wings (Δv = 0). Moreover, Δv was slightly correlated with the black hole mass. In addition, we computed the radial velocity difference of the blue-side full extension of the wing relative to the centroid of the core component through the blue emission parameter, which revealed a correlation with black hole mass, in agreement with previous results reported for narrow-line galaxies. Finally, in our sample, similar black hole mass distributions were observed in both BLS1 galaxies with symmetric and blueshifted asymmetric [O iii] profiles.


2015 ◽  
Author(s):  
Francesca Onori ◽  
Fabio La Franca ◽  
Federica Ricci ◽  
Marcella Brusa ◽  
Eleonora Sani ◽  
...  

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