The bars associated with each point represent the 1 standard deviation of the measurement. (2015) suggested that there may be no strong flux deficit in the continuum emission of a BBH-disk accretion system by considering the emission from the infalling streams. These Fe absorption features are quite similar to a 1.6-timescale up of the FeLoBAL absorption features of SDSS 1125+0029 shown in Figure 4(a) of Hall et al. is supported by the NSF grant AST-1413056. In this work, he advanced this method by considering both the amplitude and the phase of the function which describes the response of ionized gas under radiation. From top to bottom, the first panel: the green curve represents the observations as that in Figure 2. This site uses cookies. 2014; Graham et al. The numerical simulations suggest that the accretion rate onto the primary SMBH is smaller than that onto the secondary SMBH for a BBH-disk accretion system with a mass ratio of a few to 25% (e.g., Farris et al. Numerical simulations suggest that the continuum emission from a BBHdisk accretion system may vary periodically due to the change of the material infalling rate from the circumbinary disk to the inner mini-disk(s) (e.g., Hayasaki et al. While every effort has been made to follow citation style rules, there may be some discrepancies. All rights reserved. By alternatively setting \mathrm{cos}i=0.5, the best fit obtained from the MCMC fitting suggests \mathrm{log}({M}_{\bullet }/{M}_{\odot })={8.5}_{-0.2}^{+0.2}, \mathrm{log}q={-1.9}_{-0.2}^{+0.2}, \mathrm{log}{f}_{\mathrm{Edd},{\rm{c}}}={-0.5}_{-0.4}^{+0.3}, \mathrm{log}{f}_{\mathrm{Edd},{\rm{s}}}={-0.3}_{-0.2}^{+0.2}, \mathrm{log}({a}_{\mathrm{BBH}}/{R}_{{\rm{g}}})={2.5}_{-0.2}^{+0.2}, \mathrm{log}{f}_{{\rm{r}},{\rm{s}}}={-0.5}_{-0.3}^{+0.3}, and {E}_{{\rm{B}}-{\rm{V}}}={0.07}_{-0.02}^{+0.02}. A small ionization parameter is compatible with the best-fit parameters of the BBHdisk accretion system, since the broad line emission region is bound to the primary SMBH, much more massive than the secondary SMBH, while the ionizing photons are provided by the mini-disk around the secondary SMBH. We neglect this slight difference for now and will discuss this in the Appendix. Here c is the speed of light. Let us know if you have suggestions to improve this article (requires login). 2008; Boroson & Lauer 2009; Tsalmantza et al. 2015). 2013; Leighly et al. 2006; Bogdanovic et al. Thus, an unusual complex geometric structure for the extinction material surrounding the disk must be designed (Veilleux et al. Such a high level of optical Fe line emission suggests a significant amount of Fe line emission at the UV band; however, it is not visible in the observed UV spectrum (Veilleux et al. Click here to sign in with Two-dimensional probability contours for different parameters of the BBH. Recently, Gltekin & Miller (2012) proposed that the continuum emission from a BBH-disk accretion system, with unique observable signatures between 2000 and 2 m because of a gap or a hole in the inner part, can be used to diagnose BBHs (see Sesana et al. Fourth, the hard X-ray emission of Mrk 231 is extremely weak. Optical-to-UV spectrum of Mrk 231 and the model spectrum. A self-similar solution can be obtained for the evolution of the circumbinary disk once the initial separation of the BBH is given [i.e., {a}_{\mathrm{BBH}}(t=0)={a}_{\mathrm{BBH},\ 0}]. The flat optical and UV continua are mainly emitted from a circumbinary disk and a mini-disk around the secondary black hole (BH), respectively; and the observed sharp drop off and flux deficit at 40002500 is due to a gap (or hole) opened by the secondary BH migrating within the circumbinary disk. The emission from the mini-disk around the secondary SMBH is determined by q, {f}_{\mathrm{Edd},{\rm{s}}}, and {f}_{{\rm{r}},{\rm{s}}}, for which q and {f}_{\mathrm{Edd},{\rm{s}}} are also degenerate with each other. 2008; Graham et al. While in the second model, a small fraction of FUV emission is leaked through the obscuring material, and the UV variability will depend on the stability of the leaking holes. Volume 809, For simplicity, we consider three species, i.e., Fe i, Fe ii, and Mg ii, and assume a temperature of 10000 K, minimum velocity {v}_{\mathrm{min}}=1000\;\mathrm{km}\;{{\rm{s}}}^{-1}, and maximum velocity {v}_{\mathrm{max}}=8000\;\mathrm{km}\;{{\rm{s}}}^{-1}. 1995). or, by University of Science and Technology of China. where {t}_{\mathrm{GW}}=[5{(1+q)}^{2}/64q]({R}_{{\rm{g}}}/c){({a}_{\mathrm{BBH}}/{R}_{{\rm{g}}})}^{4} is the gravitation wave radiation timescale Peters (1964), {R}_{{\rm{g}}}={{GM}}_{\bullet }/{c}^{2} is the gravitational radius, and {t}_{{\rm{J}}}\equiv {L}_{\mathrm{BBH}}/2{F}_{J} is the characteristic timescale for the BBH orbit shrinking due to the coupling to the circumbinary disk. The solution of this equation can be obtained by the standard approach introduced in Lynden-Bell & Pringle (1974), if the inner boundary condition (IBC) is assumed to be torque free. The constraints on these three parameters can be substantially improved if observations at EUV (e.g., \lesssim 1000 ) are available. The farthest galaxies and quasars have distances on the order of about 4,000 megaparsecs, or 13,000,000,000 light-years. 2012; Farris et al.

However, only a specific case with a mass ratio of 1 is considered in Farris et al. Neither your address nor the recipient's address will be used for any other purpose. Below we show that the above first feature, the anomalous UV continuum, is a distinct prediction of a BBHdisk accretion system as shown in Figure 1. The red curve represents the best-fit continuum spectrum, a combination of the continuum emissions from the circumbinary disk, the mini-disk around the secondary SMBH, and the pseudo continuum by Fe emissions. Those previous investigations only focus on theoretical predictions, and the paper is the first attempt to apply this method to fit real observations. If confirmed by future observations, this BBH will provide a unique laboratory to study the interplay between BBHs and accretion flows onto them. The fitting windows adopted are 11401152, 12601300, 13401400, 15001650, 18602000, 30903145, 37403800, 44004700, 50805600, 60606350, and 67506850 . Schematic diagram for a BBHdisk accretion system. 11273004 (Q.Y. RIS.

Homer L. Dodge Department of Physics and Astronomy, The University of Oklahoma, Norman OK, 73019, USA, 3 The accretion onto each of the two SMBHs may be highly variable (Hayasaki et al. In the standard thin accretion disk model, the emission from an annulus r-{dr}/2\to r+{dr}/2 of the disk is approximated by a blackbody radiation with an effective temperature of, where G is the gravitation constant, {\sigma }_{{\rm{B}}} is the StefanBoltzmann constant, {\dot{M}}_{\mathrm{acc}} is the accretion rate of the SMBH, and {r}_{\mathrm{in}} is the radius of the disk's inner edge. 2012). Figure 3. This article was most recently revised and updated by, https://www.britannica.com/science/parsec, Wolfram Research - Eric Weisstein's World of Astronomy - Parsec. The content is provided for information purposes only. The emission from the mini-disk around the primary SMBH is insignificant for a BBH system with a small mass ratio (roughly in the range of a few percent to 0.25) due to its low accretion rate as suggested by the state of the art numerical simulations (Roedig et al. Considering that all those simulations are quite idealized, it is also not clear whether the accretion onto the central BBH is really significantly suppressed or not. Figure 5.

2008; Roedig et al. Currently it is not clear whether such a small infalling rate can be realized in BBHdisk accretion systems. Subtracting the best-fit continuum from the observed spectrum from 4700 to 5800 , we obtain {{\rm{H}}}_{\beta } luminosity by integrating the residual spectrum. 2008; Valtonen et al. 1995). Several UV observations of Mrk 231 have been obtained by Hubble Space Telescope (HST) over the years. Considering a BBH system resulting from a gas rich merger, the BBH is probably surrounded by a circumbinary disk, and each of the two SMBHs is associated with a mini-disk (see Figure 1). 2012; Roedig et al. 2014), the periodical variations (e.g., Valtonen et al.

2006). The cyan curves represent 1, 2, and 3 confidence contours from the inside to the outside, respectively. Please refer to the appropriate style manual or other sources if you have any questions. 2014). Thank you for taking time to provide your feedback to the editors. 2013). 2008; Graham et al. He developed a new approach based on his previous studies. 2014). 2014, but Farris et al. In this paper, we show that various unique features in the optical-to-UV spectrum and the intrinsic X-ray weakness of Mrk 231 can all be well explained, if a pair of SMBHs exists in the core of Mrk 231, with the masses of the primary and the secondary SMBHs as \sim 1.5\times {10}^{8}{M}_{\odot } and 4.5\times {10}^{6}{M}_{\odot }, respectively. Our analysis of Mrk 231 demonstrates the feasibility of finding BBH systems by searching for the deficits in the optical-to-UV emission among the spectra of quasars, a new method proposed by a number of authors (Gltekin & Miller 2012; Sesana et al. googletag.cmd.push(function() { googletag.display('div-gpt-ad-1449240174198-2'); }); According to modern theories on galactic formation and evolution, the mechanism of Active Galactic Nuclei (AGN) feedback suggests that the gigantic black hole at a galactic center modulates its evolution by blowing ionized gas, namely the quasar outflow, preventing a potential oversized growth of black hole. Export citation and abstract Only 50,000 points (black) out of 50,000,000 simulations are plotted. 2014). 2013; Liu et al. Under this approach, {f}_{\mathrm{Edd},{\rm{s}}}=\chi {f}_{\mathrm{Edd},{\rm{c}}}/q. As seen from Figure 6, earlier observations by IUE (Hutchings & Neff 1987) show that the continuum (\lambda {L}_{\lambda }) levels of Mrk 231 at 1300 \sim \;2.30,3.20, and 3.21\times {10}^{-12}\;\;\mathrm{erg}\;{\mathrm{cm}}^{-2}\ {{\rm{s}}}^{-1} at three different epochs, and later on they are about 1.85 and 1.77\times {10}^{-12}\;\mathrm{erg}\;{\mathrm{cm}}^{-2}\ {{\rm{s}}}^{-1} measured by the HST COS (Veilleux et al. is article data? Your feedback is important to us. First, the flux spectrum ({F}_{\lambda }) drops dramatically by a factor of 10 at the near-UV band (from wavelength \lambda \sim 4000 to 2500 ), while it is flat at 10002500 and at 400010000 . Using the above equation, we find {\rm{\Omega }}/4\pi \sim 0.29, which is fully consistent with the typical range of for AGNs/quasars and suggests that the ionizing photon emission from the mini-disk around the secondary SMBH is sufficient to produce the optical broad emission lines, such as H and H. We find that the total flux of the UV Fe emission ({I}_{\mathrm{Fe},\mathrm{UV}}) to the total flux of the optical Fe emission ({I}_{\mathrm{Fe},\mathrm{opt}}) generated from the CLOUDY model (3) is similar to that of I Zw 1 if the ionization parameter is sufficiently small (0.001). (2014) with consideration of the shock heating hot-spot on the inner mini-disk(s), one new simulation by Farris et al. 2008), though the variation for those systems with small mass ratios (less than a few percent) may not be significant (e.g., Farris et al. Physics Forums | Science Articles, Homework Help, Discussion, Science X Daily and the Weekly Email Newsletter are free features that allow you to receive your favorite sci-tech news updates in your email inbox. According to the best-fit model, the circumbinary disk dominates the emission of Mrk 231 in the optical band; the mini-disk dominates the FUV emission; the sharp drop off at 40002500 is mainly due to the cut off of the circumbinary disk and the gap (or hole) opened by the secondary SMBH, but not an extremely high extinction (see the top panel of Figure 3). Supermassive binary black holes (BBHs) are unavoidable products of galaxy mergers and are expected to exist in the cores of many quasars. This type of geometric configurations for the BBHdisk accretion systems has been revealed by many numerical simulations and analysis (Artymowicz & Lubow 1996; Escala et al. 2015) because (1) the total number of the observations is small; and (2) the intervals between some of these observations are too large compared with the expected orbital period. and Terms of Use. The continuum shows a sharp drop off at \lambda \sim 4000-2500 and deficit of flux at \lambda \sim 4000-1000 . It has been shown that the polarization fraction of the optical-to-UV continuum of Mrk 231 depends on frequency and the peak of the polarization is around the wavelengths 3000 (Smith et al. Number 2 The red dotted vertical line in each panel represents the value of the best fit adopted in Figures 2 and 3 to produce the model spectrum. The maximum velocity is on the same order of the escape velocity at {a}_{\mathrm{BBH}}. However, the evidence for BBHs at the sub-parsec scale is still elusive (e.g., Popovi 2012), which raises a challenge to our understanding of the BBH merger process and the formation and evolution of SMBHs and galaxies. 2013; Farris et al. What does a barometer measure? The parameters included in the continuum model are the total mass ({M}_{\bullet }), mass ratio (q), semimajor axis ({a}_{\mathrm{BBH}}) of the BBH, the Eddington ratios of the outer circumbinary disk ({f}_{\mathrm{Edd},{\rm{c}}}) and the inner mini-disk ({f}_{\mathrm{Edd},{\rm{s}}}), the ratio of the outer boundary of the inner mini-disk to the mean Roche radius ({f}_{{\rm{r}},{\rm{s}}}), the scale factor {A}_{{\rm{s}}} and convolution width {\mathrm{FWHM}}_{\ \mathrm{conv}} of the Fe emission lines, and the extinction {E}_{{\rm{B}}-{\rm{V}}} due to the interstellar medium in Mrk 231. 2007, or the simple arguments by Rafikov 2013). We first adopt those nine parameters ({M}_{\bullet }, q, {a}_{\mathrm{BBH}}, {f}_{\mathrm{Edd},{\rm{c}}}, {f}_{\mathrm{Edd},{\rm{s}}}, {f}_{{\rm{r}},{\rm{s}}}, {A}_{{\rm{s}}}, {\mathrm{FWHM}}_{\mathrm{conv}}, {E}_{{\rm{B}}-{\rm{V}}}) to fit the spectrum and obtain the best fit, and then fix the two parameters {A}_{{\rm{s}}} and {\mathrm{FWHM}}_{\mathrm{conv}}(\sim 3000\;\mathrm{km}\;{{\rm{s}}}^{-1}) at their best-fit values and obtain constraints on the other seven parameters ({M}_{\bullet }, q, {a}_{\mathrm{BBH}}, {f}_{\mathrm{Edd},{\rm{c}}}, {f}_{\mathrm{Edd},{\rm{s}}}, {f}_{{\rm{r}},{\rm{s}}}, {E}_{{\rm{B}}-{\rm{V}}}). Figures 4 and 5 show the two-dimensional probability contours and one-dimensional marginalized probability distributions for the model parameters obtained from the MCMC fitting, respectively. He proposed that BAL variation could be a powerful tool in probing outflows. The orbit of such a BBH system decays on a timescale of a few times of 105 years due to gravitational wave radiation and the torque of the circumbinary disk (Haiman et al. More from Physics Forums | Science Articles, Homework Help, Discussion. The second panel: the green curve represents the observational spectrum of Mrk 231. 2014), thus its emission can be neglected. According to the best fit, the infalling rate from the circumbinary disk to the inner disk(s) is smaller than the accretion rate of the circumbinary disk by a factor of 30. A number of BBH candidates in quasars have been proposed according to various spectral or other features, such as the double-peaked, asymmetric, or offset broad line emission (e.g., Boroson & Lauer 2009; Tsalmantza et al. Note that the best fit value of {f}_{\mathrm{Edd},{\rm{s}}}=0.6 means that the secondary SMBH accretes via a rate close to the Eddington limit. The top panel of Figure 3 shows the best-fit model to the continuum emission from the BBH-disk accretion system. Provided by 2015), which are omitted in this study, may also introduce some errors to the fitting. The distance to the Andromeda Galaxy (Messier 31) is about 0.76 megaparsec. In this paper, we report a BBH candidate in the core of Mrk 231, the nearest quasar with a redshift z = 0.0422, according to its unique optical-UV spectrum. Different points are obtained from the UV spectra obtained by IUE and HST at different epochs as marked in the figure, smoothed over a wavelength range of 20 around 1300 at the rest frame. Molecular outflow identified in the galaxy NGC 1482, Study shows that skyrmions and antiskyrmions can coexist at different temperatures, Mangrove forest found living in freshwater, Wasps able to tell the difference between 'same' and 'different', Highly collimated radio jets discovered around galaxy NGC 2663, A unique stone-skipping-like trajectory of asteroid Aletai, LQG Legend Writes Paper Claiming GR Explains Dark Matter Phenomena. Note that the periodical variation of the BBH candidate PG 1302-102 (Graham et al. Other best-fit parameters are {M}_{\bullet }={10}^{8.2}{M}_{\odot }, {f}_{\mathrm{Edd},{\rm{c}}}=0.4, q = 0.02, \chi =0.04 (corresponding to {f}_{\mathrm{Edd},{\rm{s}}}=0.7), {a}_{\mathrm{BBH}}=343{R}_{{\rm{g}}}\sim 540 AU (corresponding to {r}_{\mathrm{in},{\rm{c}}}=402{R}_{{\rm{g}}}, {f}_{{\rm{r}},{\rm{s}}}=0.12), and {E}_{{\rm{B}}-{\rm{V}}}=0.14. The Sun is at a distance of 8.3 kiloparsecs from the centre of the Milky Way system. In the optical band, the Fe template is constructed according to the list of the Fe lines for I Zw 1 given in Vron-Cetty et al. Omissions? This dependence is probably due to the scattering clouds distributed asymmetrically about the illuminating source (Smith et al. The width of the gap (or hole) is roughly determined by the Hill radius {R}_{{\rm{H}}} [\sim {a}_{\mathrm{BBH}}{({M}_{\bullet ,{\rm{s}}}/3{M}_{\bullet ,{\rm{p}}})}^{1/3}\simeq 0.69{q}^{1/3}{a}_{\mathrm{BBH}}], where q is the mass ratio, and the inner boundary of the circumbinary disk can be approximated as {r}_{\mathrm{in},{\rm{c}}}\sim {a}_{\mathrm{BBH}}/(1+q)+{R}_{{\rm{H}}}. It has been shown that there are extremely strong Fe ii emission lines in the optical spectrum of Mrk 231. In between the circumbinary disk and the inner mini-disks, a gap (or hole) is opened by the secondary SMBH, which is probably the most distinct feature of a BBHdisk accretion system, in analogy to a system in which a gap or hole is opened by a planet migrating in the planetary disk around a star (Lin et al.

We choose a standard thin disk to approximate the temperature profile of the circumbinary disk. As shown in the Appendix, we adopt the model by Rafikov (2013) to fit the continuum, in which both the internal viscosity and the external torque by the BBH on the circumbinary disk are considered, and we find that there are no significant differences in the constraints on the model parameters. It has a worldwide membership of around 50 000 comprising physicists from all sectors, as well as those with an interest in physics. parsec, unit for expressing distances to stars and galaxies, used by professional astronomers. 2012; Rafikov 2013; Roedig et al. 2005; Hayasaki et al. Our result also demonstrates a new method to find sub-parsec scale BBHs by searching for deficits in the optical-to-UV continuum among the spectra of quasars. The deficit of intrinsic UV emission will lead to substantially weaker broad line emissions compared with those of normal quasars. The FOS data is scaled up by a factor of 2 to match the COS data (see Veilleux et al. All rights reserved. They obtained the kinetic information regarding quasar outflows, and discovered the acceleration at a scale of tens of parsecs for the first time, which far exceeded that predicted by the traditional accretion disk wind model. The parameters {M}_{\bullet }, {f}_{\mathrm{Edd}}, and {a}_{\mathrm{BBH}} mainly determine the emission from the circumbinary disk and they are strongly degenerate with each other. It appears that the main absorption features seen in the residuals can be roughly modeled, though there are still some discrepancies in details. According to Rafikov (2013), the evolution of the circumbinary disk under the actions of both the internal viscosity and the external torque can be described by a simple equation, Here t is the evolution time, is the external torque per unit mass of the disk due to the central BBH, , , and r are the surface density, kinematic viscosity, and radius of the disk, respectively, and l={\rm{\Omega }}(r){r}^{2} is the specific angular momentum of gas material on a circular orbit with a radius r. At each radius, the accretion disk properties can be characterized by the viscous angular momentum flux. We find that a slight change of \mathrm{cos}i does not affect our results significantly. For general inquiries, please use our contact form. Updates? The structure and spectral energy distribution (SED) of the circumbinary disk may be different from that of a standard thin disk, especially at the region close to the inner edge, since the torque raised by the central BBH may lead to gas accumulation there. The X-ray emission of AGNs and quasars is normally emitted from a corona structure above the inner disk area in the standard diskcorona model (Haardt & Maraschi 1993; Dai et al. However, the expected corresponding absorption features at the UV and FUV bands are not evident. 2014; Farris et al. 2010; Comerford et al.

Evidence has been accumulated for SMBH pairs in active galactic nuclei (AGNs) and quasars with perturbed galaxy morphologies or other merger features (e.g., Komossa et al. Dr. Copyright 2022 IOP The third panel: the green curve represents the residuals of the best fit continuum to the observations. Note these values for the model parameters are somewhat different from those from the best fit with minimum {\chi }^{2}-value. The third panel of Figure 3 shows the residuals of the model spectrum at 20003200 which reveals strong Fe absorption lines. The total number of {{\rm{H}}}_{\beta } photons is directly related to the number of ionizing photons as {L}_{{{\rm{H}}}_{\beta }}=\displaystyle \frac{{\rm{\Omega }}}{4\pi }\displaystyle \frac{{\alpha }_{{{\rm{H}}}_{\beta }}^{\mathrm{eff}}({{\rm{H}}}^{0},T)}{{\alpha }_{{\rm{B}}}({{\rm{H}}}^{0},T)}h{\nu }_{{{\rm{H}}}_{\beta }}{\displaystyle \int }_{{\nu }_{0}}^{\infty }\frac{{L}_{\nu }}{h\nu }d\nu , where {\rm{\Omega }}/4\pi is the covering factor, {\alpha }_{{{\rm{H}}}_{\beta }}^{\mathrm{eff}}/{\alpha }_{{\rm{B}}}\sim 1/8.5 is the number of {{\rm{H}}}_{\beta } photons produced per hydrogen recombination, and {\nu }_{0}=c/912 , {\nu }_{{{\rm{H}}}_{\beta }}=c/4861 (Osterbrock et al. With the solution of {F}_{J}(r,t), the effective temperature of the disk can be obtained as, By integrating the multi-color blackbody emission over the whole circumbinary disk, we obtain the continuum flux as, Here h is the Planck constant, {k}_{{\rm{B}}} is the Boltzmann constant, {r}_{\mathrm{in},{\rm{c}}}={a}_{\mathrm{BBH}}(t)/(1+q)+{R}_{{\rm{H}}}, {r}_{\mathrm{out},{\rm{c}}} is set to be {10}^{5}{{GM}}_{\bullet }/{c}^{2}, and {a}_{\mathrm{BBH}}(t) is the semimajor axis of the BBH at time t. The evolution of {a}_{\mathrm{BBH}}(t) is controlled by. Apart from any fair dealing for the purpose of private study or research, no Such a BBH emits gravitational wave on tens of nanohertz, and the change rate of its orbital period due to gravitational wave radiation is about 40 s per orbit. 2014).

For close BBHdisk accretion systems, a number of simulations and analyses suggested that the infalling rate into the gap or the central cavity is substantially smaller than the accretion rate at the outer boundary of the circumbinary disk because of the tidal barrier by the central BBH (e.g., the 1D simulations by Milosavljevi & Phinney 2005, the 3D simulations by Hayasaki et al. By this setting, \dot{M}({r}_{\mathrm{in}}) can be substantially smaller than {\dot{M}}_{\infty }, and disk material may gradually accumulate near the inner boundary if \chi \lt 1. A detailed dynamical model for the broadening and the shift of individual Fe emission lines is beyond the scope of our paper. You can unsubscribe at any time and we'll never share your details to third parties. Rayleigh scattering -- What is the true reason for the color of the sky? The BBH is surrounded by a circumbinary disk, connecting with the mini-disk around each component of the BBH by streams. With this BBH configuration, the orbital period is {1.6}_{-0.2}^{+0.3} years and {\rm{\Omega }}/4\pi \simeq 0.5. 1995; Veilleux et al. (2014), likewise, also provided qualitative explanations on these polarization measurements in their competing models. Figure 2. It is also not a necessity to have different extinctions in different bands to explain the sharp drop off. 2010). Thousands of Fe emission lines from the broad line emission region blending together can form a pseudo-continuum. The total flux of the Fe emission, {I}_{\mathrm{Fe}}, is equal to {A}_{{\rm{s}}} multiplied by the total flux of the template; the FWHM of the Fe lines can be expressed as {\mathrm{FWHM}}_{\ \mathrm{Fe}}=\sqrt{{\mathrm{FWHM}}_{\mathrm{IZw}1}^{2}+{\mathrm{FWHM}}_{\mathrm{conv}}^{2}}. 2012), and the temperature structure of each of the two mini-disks may be affected by the torque from the other SMBH component, the outer circumbinary disk (Farris et al. The inclination angle of the disk in Mrk 231 could be larger, e.g., \mathrm{cos}i\sim 0.5, since Mrk 231 is an FeLoBAL (though not a normal FeLoBAL in the BBHdisk accretion scenario) and FeLoBALs were suggested to have a larger i and a smaller \mathrm{cos}i (Goodrich & Miller 2005). 1994). The outer boundary of the mini-disk surrounding the secondary SMBH ({r}_{\mathrm{out},{\rm{s}}}) is assumed to be a fraction ({f}_{{\rm{r}},{\rm{s}}}) of the mean Roche radius, {R}_{\mathrm{RL}}(q)\simeq 0.49{a}_{\mathrm{BBH}}{q}^{2/3}/[0.6{q}^{2/3}+\mathrm{ln}(1+{q}^{1/2})] (Eggleton 1983), i.e., {r}_{\mathrm{out},{\rm{s}}}={f}_{{\rm{r}},{\rm{s}}}{R}_{\mathrm{RL}}(q), considering that the mini-disk may not fill the whole Roche lobe (the red dashed circle). Great effort has been made during the past several decades to search for BBHs among quasars; however, observational evidence for BBHs remains elusive and ambiguous, which is difficult to reconcile with theoretical expectations. (Note that the secondary SMBH is rather low in mass; however, it should be able to sink down to the center because the stars initially associated with it enhance the dynamical friction see Yu 2002.) In the observed UV spectrum, however, there appear no strong Fe emission lines (Veilleux et al.

However, we do not guarantee individual replies due to the high volume of messages. The UV continuum of the HST COS observations by Veilleux et al. However, little was known about the outflow of active galaxies, for a key factor, the scale of outflows was mainly deduced from spectroscopic blueshifted adsorption lines (BAL). We set the accretion rate at the outer boundary as {\dot{M}}_{\infty }. (2013) and Leighly et al. Veilleux et al. 2015), in addition to those current practices by searching for the kinematic and image signatures of BBHs among AGNs/quasars (Gaskell 1996; Rodriguez et al. Roedig et al. The locations of the emission lines H, H, and Ly are also marked in the figure. Dr. (1995). In the first model, the FUV emission is dominated by the young star burst with an age of 100 Myr and therefore would have no significant short time-scale variations, which appears inconsistent with the observations. 2012; Yan et al. The obtained results were not reliable enough due to its heavy reliance on models. The ratio of the H flux to the H flux is roughly 3, consistent with those of normal quasars. Receive alerts on all new research papers in American Astronomical Society Their paper was published in Science Advances By using our site, you acknowledge that you have read and understand our Privacy Policy The red stars represent the best-fit parameter values.

However, only a specific case with a mass ratio of 1 is considered in Farris et al. Neither your address nor the recipient's address will be used for any other purpose. Below we show that the above first feature, the anomalous UV continuum, is a distinct prediction of a BBHdisk accretion system as shown in Figure 1. The red curve represents the best-fit continuum spectrum, a combination of the continuum emissions from the circumbinary disk, the mini-disk around the secondary SMBH, and the pseudo continuum by Fe emissions. Those previous investigations only focus on theoretical predictions, and the paper is the first attempt to apply this method to fit real observations. If confirmed by future observations, this BBH will provide a unique laboratory to study the interplay between BBHs and accretion flows onto them. The fitting windows adopted are 11401152, 12601300, 13401400, 15001650, 18602000, 30903145, 37403800, 44004700, 50805600, 60606350, and 67506850 . Schematic diagram for a BBHdisk accretion system. 11273004 (Q.Y. RIS.

Homer L. Dodge Department of Physics and Astronomy, The University of Oklahoma, Norman OK, 73019, USA, 3 The accretion onto each of the two SMBHs may be highly variable (Hayasaki et al. In the standard thin accretion disk model, the emission from an annulus r-{dr}/2\to r+{dr}/2 of the disk is approximated by a blackbody radiation with an effective temperature of, where G is the gravitation constant, {\sigma }_{{\rm{B}}} is the StefanBoltzmann constant, {\dot{M}}_{\mathrm{acc}} is the accretion rate of the SMBH, and {r}_{\mathrm{in}} is the radius of the disk's inner edge. 2012). Figure 3. This article was most recently revised and updated by, https://www.britannica.com/science/parsec, Wolfram Research - Eric Weisstein's World of Astronomy - Parsec. The content is provided for information purposes only. The emission from the mini-disk around the primary SMBH is insignificant for a BBH system with a small mass ratio (roughly in the range of a few percent to 0.25) due to its low accretion rate as suggested by the state of the art numerical simulations (Roedig et al. Considering that all those simulations are quite idealized, it is also not clear whether the accretion onto the central BBH is really significantly suppressed or not. Figure 5.

2008; Roedig et al. Currently it is not clear whether such a small infalling rate can be realized in BBHdisk accretion systems. Subtracting the best-fit continuum from the observed spectrum from 4700 to 5800 , we obtain {{\rm{H}}}_{\beta } luminosity by integrating the residual spectrum. 2008; Valtonen et al. 1995). Several UV observations of Mrk 231 have been obtained by Hubble Space Telescope (HST) over the years. Considering a BBH system resulting from a gas rich merger, the BBH is probably surrounded by a circumbinary disk, and each of the two SMBHs is associated with a mini-disk (see Figure 1). 2012; Roedig et al. 2014), the periodical variations (e.g., Valtonen et al.

2006). The cyan curves represent 1, 2, and 3 confidence contours from the inside to the outside, respectively. Please refer to the appropriate style manual or other sources if you have any questions. 2014). Thank you for taking time to provide your feedback to the editors. 2013). 2008; Graham et al. He developed a new approach based on his previous studies. 2014). 2014, but Farris et al. In this paper, we show that various unique features in the optical-to-UV spectrum and the intrinsic X-ray weakness of Mrk 231 can all be well explained, if a pair of SMBHs exists in the core of Mrk 231, with the masses of the primary and the secondary SMBHs as \sim 1.5\times {10}^{8}{M}_{\odot } and 4.5\times {10}^{6}{M}_{\odot }, respectively. Our analysis of Mrk 231 demonstrates the feasibility of finding BBH systems by searching for the deficits in the optical-to-UV emission among the spectra of quasars, a new method proposed by a number of authors (Gltekin & Miller 2012; Sesana et al. googletag.cmd.push(function() { googletag.display('div-gpt-ad-1449240174198-2'); }); According to modern theories on galactic formation and evolution, the mechanism of Active Galactic Nuclei (AGN) feedback suggests that the gigantic black hole at a galactic center modulates its evolution by blowing ionized gas, namely the quasar outflow, preventing a potential oversized growth of black hole. Export citation and abstract Only 50,000 points (black) out of 50,000,000 simulations are plotted. 2014). 2013; Liu et al. Under this approach, {f}_{\mathrm{Edd},{\rm{s}}}=\chi {f}_{\mathrm{Edd},{\rm{c}}}/q. As seen from Figure 6, earlier observations by IUE (Hutchings & Neff 1987) show that the continuum (\lambda {L}_{\lambda }) levels of Mrk 231 at 1300 \sim \;2.30,3.20, and 3.21\times {10}^{-12}\;\;\mathrm{erg}\;{\mathrm{cm}}^{-2}\ {{\rm{s}}}^{-1} at three different epochs, and later on they are about 1.85 and 1.77\times {10}^{-12}\;\mathrm{erg}\;{\mathrm{cm}}^{-2}\ {{\rm{s}}}^{-1} measured by the HST COS (Veilleux et al. is article data? Your feedback is important to us. First, the flux spectrum ({F}_{\lambda }) drops dramatically by a factor of 10 at the near-UV band (from wavelength \lambda \sim 4000 to 2500 ), while it is flat at 10002500 and at 400010000 . Using the above equation, we find {\rm{\Omega }}/4\pi \sim 0.29, which is fully consistent with the typical range of for AGNs/quasars and suggests that the ionizing photon emission from the mini-disk around the secondary SMBH is sufficient to produce the optical broad emission lines, such as H and H. We find that the total flux of the UV Fe emission ({I}_{\mathrm{Fe},\mathrm{UV}}) to the total flux of the optical Fe emission ({I}_{\mathrm{Fe},\mathrm{opt}}) generated from the CLOUDY model (3) is similar to that of I Zw 1 if the ionization parameter is sufficiently small (0.001). (2014) with consideration of the shock heating hot-spot on the inner mini-disk(s), one new simulation by Farris et al. 2008), though the variation for those systems with small mass ratios (less than a few percent) may not be significant (e.g., Farris et al. Physics Forums | Science Articles, Homework Help, Discussion, Science X Daily and the Weekly Email Newsletter are free features that allow you to receive your favorite sci-tech news updates in your email inbox. According to the best-fit model, the circumbinary disk dominates the emission of Mrk 231 in the optical band; the mini-disk dominates the FUV emission; the sharp drop off at 40002500 is mainly due to the cut off of the circumbinary disk and the gap (or hole) opened by the secondary SMBH, but not an extremely high extinction (see the top panel of Figure 3). Supermassive binary black holes (BBHs) are unavoidable products of galaxy mergers and are expected to exist in the cores of many quasars. This type of geometric configurations for the BBHdisk accretion systems has been revealed by many numerical simulations and analysis (Artymowicz & Lubow 1996; Escala et al. 2015) because (1) the total number of the observations is small; and (2) the intervals between some of these observations are too large compared with the expected orbital period. and Terms of Use. The continuum shows a sharp drop off at \lambda \sim 4000-2500 and deficit of flux at \lambda \sim 4000-1000 . It has been shown that the polarization fraction of the optical-to-UV continuum of Mrk 231 depends on frequency and the peak of the polarization is around the wavelengths 3000 (Smith et al. Number 2 The red dotted vertical line in each panel represents the value of the best fit adopted in Figures 2 and 3 to produce the model spectrum. The maximum velocity is on the same order of the escape velocity at {a}_{\mathrm{BBH}}. However, the evidence for BBHs at the sub-parsec scale is still elusive (e.g., Popovi 2012), which raises a challenge to our understanding of the BBH merger process and the formation and evolution of SMBHs and galaxies. 2013; Farris et al. What does a barometer measure? The parameters included in the continuum model are the total mass ({M}_{\bullet }), mass ratio (q), semimajor axis ({a}_{\mathrm{BBH}}) of the BBH, the Eddington ratios of the outer circumbinary disk ({f}_{\mathrm{Edd},{\rm{c}}}) and the inner mini-disk ({f}_{\mathrm{Edd},{\rm{s}}}), the ratio of the outer boundary of the inner mini-disk to the mean Roche radius ({f}_{{\rm{r}},{\rm{s}}}), the scale factor {A}_{{\rm{s}}} and convolution width {\mathrm{FWHM}}_{\ \mathrm{conv}} of the Fe emission lines, and the extinction {E}_{{\rm{B}}-{\rm{V}}} due to the interstellar medium in Mrk 231. 2007, or the simple arguments by Rafikov 2013). We first adopt those nine parameters ({M}_{\bullet }, q, {a}_{\mathrm{BBH}}, {f}_{\mathrm{Edd},{\rm{c}}}, {f}_{\mathrm{Edd},{\rm{s}}}, {f}_{{\rm{r}},{\rm{s}}}, {A}_{{\rm{s}}}, {\mathrm{FWHM}}_{\mathrm{conv}}, {E}_{{\rm{B}}-{\rm{V}}}) to fit the spectrum and obtain the best fit, and then fix the two parameters {A}_{{\rm{s}}} and {\mathrm{FWHM}}_{\mathrm{conv}}(\sim 3000\;\mathrm{km}\;{{\rm{s}}}^{-1}) at their best-fit values and obtain constraints on the other seven parameters ({M}_{\bullet }, q, {a}_{\mathrm{BBH}}, {f}_{\mathrm{Edd},{\rm{c}}}, {f}_{\mathrm{Edd},{\rm{s}}}, {f}_{{\rm{r}},{\rm{s}}}, {E}_{{\rm{B}}-{\rm{V}}}). Figures 4 and 5 show the two-dimensional probability contours and one-dimensional marginalized probability distributions for the model parameters obtained from the MCMC fitting, respectively. He proposed that BAL variation could be a powerful tool in probing outflows. The orbit of such a BBH system decays on a timescale of a few times of 105 years due to gravitational wave radiation and the torque of the circumbinary disk (Haiman et al. More from Physics Forums | Science Articles, Homework Help, Discussion. The second panel: the green curve represents the observational spectrum of Mrk 231. 2014), thus its emission can be neglected. According to the best fit, the infalling rate from the circumbinary disk to the inner disk(s) is smaller than the accretion rate of the circumbinary disk by a factor of 30. A number of BBH candidates in quasars have been proposed according to various spectral or other features, such as the double-peaked, asymmetric, or offset broad line emission (e.g., Boroson & Lauer 2009; Tsalmantza et al. Note that the best fit value of {f}_{\mathrm{Edd},{\rm{s}}}=0.6 means that the secondary SMBH accretes via a rate close to the Eddington limit. The top panel of Figure 3 shows the best-fit model to the continuum emission from the BBH-disk accretion system. Provided by 2015), which are omitted in this study, may also introduce some errors to the fitting. The distance to the Andromeda Galaxy (Messier 31) is about 0.76 megaparsec. In this paper, we report a BBH candidate in the core of Mrk 231, the nearest quasar with a redshift z = 0.0422, according to its unique optical-UV spectrum. Different points are obtained from the UV spectra obtained by IUE and HST at different epochs as marked in the figure, smoothed over a wavelength range of 20 around 1300 at the rest frame. Molecular outflow identified in the galaxy NGC 1482, Study shows that skyrmions and antiskyrmions can coexist at different temperatures, Mangrove forest found living in freshwater, Wasps able to tell the difference between 'same' and 'different', Highly collimated radio jets discovered around galaxy NGC 2663, A unique stone-skipping-like trajectory of asteroid Aletai, LQG Legend Writes Paper Claiming GR Explains Dark Matter Phenomena. Note that the periodical variation of the BBH candidate PG 1302-102 (Graham et al. Other best-fit parameters are {M}_{\bullet }={10}^{8.2}{M}_{\odot }, {f}_{\mathrm{Edd},{\rm{c}}}=0.4, q = 0.02, \chi =0.04 (corresponding to {f}_{\mathrm{Edd},{\rm{s}}}=0.7), {a}_{\mathrm{BBH}}=343{R}_{{\rm{g}}}\sim 540 AU (corresponding to {r}_{\mathrm{in},{\rm{c}}}=402{R}_{{\rm{g}}}, {f}_{{\rm{r}},{\rm{s}}}=0.12), and {E}_{{\rm{B}}-{\rm{V}}}=0.14. The Sun is at a distance of 8.3 kiloparsecs from the centre of the Milky Way system. In the optical band, the Fe template is constructed according to the list of the Fe lines for I Zw 1 given in Vron-Cetty et al. Omissions? This dependence is probably due to the scattering clouds distributed asymmetrically about the illuminating source (Smith et al. The width of the gap (or hole) is roughly determined by the Hill radius {R}_{{\rm{H}}} [\sim {a}_{\mathrm{BBH}}{({M}_{\bullet ,{\rm{s}}}/3{M}_{\bullet ,{\rm{p}}})}^{1/3}\simeq 0.69{q}^{1/3}{a}_{\mathrm{BBH}}], where q is the mass ratio, and the inner boundary of the circumbinary disk can be approximated as {r}_{\mathrm{in},{\rm{c}}}\sim {a}_{\mathrm{BBH}}/(1+q)+{R}_{{\rm{H}}}. It has been shown that there are extremely strong Fe ii emission lines in the optical spectrum of Mrk 231. In between the circumbinary disk and the inner mini-disks, a gap (or hole) is opened by the secondary SMBH, which is probably the most distinct feature of a BBHdisk accretion system, in analogy to a system in which a gap or hole is opened by a planet migrating in the planetary disk around a star (Lin et al.

We choose a standard thin disk to approximate the temperature profile of the circumbinary disk. As shown in the Appendix, we adopt the model by Rafikov (2013) to fit the continuum, in which both the internal viscosity and the external torque by the BBH on the circumbinary disk are considered, and we find that there are no significant differences in the constraints on the model parameters. It has a worldwide membership of around 50 000 comprising physicists from all sectors, as well as those with an interest in physics. parsec, unit for expressing distances to stars and galaxies, used by professional astronomers. 2012; Rafikov 2013; Roedig et al. 2005; Hayasaki et al. Our result also demonstrates a new method to find sub-parsec scale BBHs by searching for deficits in the optical-to-UV continuum among the spectra of quasars. The deficit of intrinsic UV emission will lead to substantially weaker broad line emissions compared with those of normal quasars. The FOS data is scaled up by a factor of 2 to match the COS data (see Veilleux et al. All rights reserved. They obtained the kinetic information regarding quasar outflows, and discovered the acceleration at a scale of tens of parsecs for the first time, which far exceeded that predicted by the traditional accretion disk wind model. The parameters {M}_{\bullet }, {f}_{\mathrm{Edd}}, and {a}_{\mathrm{BBH}} mainly determine the emission from the circumbinary disk and they are strongly degenerate with each other. It appears that the main absorption features seen in the residuals can be roughly modeled, though there are still some discrepancies in details. According to Rafikov (2013), the evolution of the circumbinary disk under the actions of both the internal viscosity and the external torque can be described by a simple equation, Here t is the evolution time, is the external torque per unit mass of the disk due to the central BBH, , , and r are the surface density, kinematic viscosity, and radius of the disk, respectively, and l={\rm{\Omega }}(r){r}^{2} is the specific angular momentum of gas material on a circular orbit with a radius r. At each radius, the accretion disk properties can be characterized by the viscous angular momentum flux. We find that a slight change of \mathrm{cos}i does not affect our results significantly. For general inquiries, please use our contact form. Updates? The structure and spectral energy distribution (SED) of the circumbinary disk may be different from that of a standard thin disk, especially at the region close to the inner edge, since the torque raised by the central BBH may lead to gas accumulation there. The X-ray emission of AGNs and quasars is normally emitted from a corona structure above the inner disk area in the standard diskcorona model (Haardt & Maraschi 1993; Dai et al. However, the expected corresponding absorption features at the UV and FUV bands are not evident. 2014; Farris et al. 2010; Comerford et al.

Evidence has been accumulated for SMBH pairs in active galactic nuclei (AGNs) and quasars with perturbed galaxy morphologies or other merger features (e.g., Komossa et al. Dr. Copyright 2022 IOP The third panel: the green curve represents the residuals of the best fit continuum to the observations. Note these values for the model parameters are somewhat different from those from the best fit with minimum {\chi }^{2}-value. The third panel of Figure 3 shows the residuals of the model spectrum at 20003200 which reveals strong Fe absorption lines. The total number of {{\rm{H}}}_{\beta } photons is directly related to the number of ionizing photons as {L}_{{{\rm{H}}}_{\beta }}=\displaystyle \frac{{\rm{\Omega }}}{4\pi }\displaystyle \frac{{\alpha }_{{{\rm{H}}}_{\beta }}^{\mathrm{eff}}({{\rm{H}}}^{0},T)}{{\alpha }_{{\rm{B}}}({{\rm{H}}}^{0},T)}h{\nu }_{{{\rm{H}}}_{\beta }}{\displaystyle \int }_{{\nu }_{0}}^{\infty }\frac{{L}_{\nu }}{h\nu }d\nu , where {\rm{\Omega }}/4\pi is the covering factor, {\alpha }_{{{\rm{H}}}_{\beta }}^{\mathrm{eff}}/{\alpha }_{{\rm{B}}}\sim 1/8.5 is the number of {{\rm{H}}}_{\beta } photons produced per hydrogen recombination, and {\nu }_{0}=c/912 , {\nu }_{{{\rm{H}}}_{\beta }}=c/4861 (Osterbrock et al. With the solution of {F}_{J}(r,t), the effective temperature of the disk can be obtained as, By integrating the multi-color blackbody emission over the whole circumbinary disk, we obtain the continuum flux as, Here h is the Planck constant, {k}_{{\rm{B}}} is the Boltzmann constant, {r}_{\mathrm{in},{\rm{c}}}={a}_{\mathrm{BBH}}(t)/(1+q)+{R}_{{\rm{H}}}, {r}_{\mathrm{out},{\rm{c}}} is set to be {10}^{5}{{GM}}_{\bullet }/{c}^{2}, and {a}_{\mathrm{BBH}}(t) is the semimajor axis of the BBH at time t. The evolution of {a}_{\mathrm{BBH}}(t) is controlled by. Apart from any fair dealing for the purpose of private study or research, no Such a BBH emits gravitational wave on tens of nanohertz, and the change rate of its orbital period due to gravitational wave radiation is about 40 s per orbit. 2014).

For close BBHdisk accretion systems, a number of simulations and analyses suggested that the infalling rate into the gap or the central cavity is substantially smaller than the accretion rate at the outer boundary of the circumbinary disk because of the tidal barrier by the central BBH (e.g., the 1D simulations by Milosavljevi & Phinney 2005, the 3D simulations by Hayasaki et al. By this setting, \dot{M}({r}_{\mathrm{in}}) can be substantially smaller than {\dot{M}}_{\infty }, and disk material may gradually accumulate near the inner boundary if \chi \lt 1. A detailed dynamical model for the broadening and the shift of individual Fe emission lines is beyond the scope of our paper. You can unsubscribe at any time and we'll never share your details to third parties. Rayleigh scattering -- What is the true reason for the color of the sky? The BBH is surrounded by a circumbinary disk, connecting with the mini-disk around each component of the BBH by streams. With this BBH configuration, the orbital period is {1.6}_{-0.2}^{+0.3} years and {\rm{\Omega }}/4\pi \simeq 0.5. 1995; Veilleux et al. (2014), likewise, also provided qualitative explanations on these polarization measurements in their competing models. Figure 2. It is also not a necessity to have different extinctions in different bands to explain the sharp drop off. 2010). Thousands of Fe emission lines from the broad line emission region blending together can form a pseudo-continuum. The total flux of the Fe emission, {I}_{\mathrm{Fe}}, is equal to {A}_{{\rm{s}}} multiplied by the total flux of the template; the FWHM of the Fe lines can be expressed as {\mathrm{FWHM}}_{\ \mathrm{Fe}}=\sqrt{{\mathrm{FWHM}}_{\mathrm{IZw}1}^{2}+{\mathrm{FWHM}}_{\mathrm{conv}}^{2}}. 2012), and the temperature structure of each of the two mini-disks may be affected by the torque from the other SMBH component, the outer circumbinary disk (Farris et al. The inclination angle of the disk in Mrk 231 could be larger, e.g., \mathrm{cos}i\sim 0.5, since Mrk 231 is an FeLoBAL (though not a normal FeLoBAL in the BBHdisk accretion scenario) and FeLoBALs were suggested to have a larger i and a smaller \mathrm{cos}i (Goodrich & Miller 2005). 1994). The outer boundary of the mini-disk surrounding the secondary SMBH ({r}_{\mathrm{out},{\rm{s}}}) is assumed to be a fraction ({f}_{{\rm{r}},{\rm{s}}}) of the mean Roche radius, {R}_{\mathrm{RL}}(q)\simeq 0.49{a}_{\mathrm{BBH}}{q}^{2/3}/[0.6{q}^{2/3}+\mathrm{ln}(1+{q}^{1/2})] (Eggleton 1983), i.e., {r}_{\mathrm{out},{\rm{s}}}={f}_{{\rm{r}},{\rm{s}}}{R}_{\mathrm{RL}}(q), considering that the mini-disk may not fill the whole Roche lobe (the red dashed circle). Great effort has been made during the past several decades to search for BBHs among quasars; however, observational evidence for BBHs remains elusive and ambiguous, which is difficult to reconcile with theoretical expectations. (Note that the secondary SMBH is rather low in mass; however, it should be able to sink down to the center because the stars initially associated with it enhance the dynamical friction see Yu 2002.) In the observed UV spectrum, however, there appear no strong Fe emission lines (Veilleux et al.

However, we do not guarantee individual replies due to the high volume of messages. The UV continuum of the HST COS observations by Veilleux et al. However, little was known about the outflow of active galaxies, for a key factor, the scale of outflows was mainly deduced from spectroscopic blueshifted adsorption lines (BAL). We set the accretion rate at the outer boundary as {\dot{M}}_{\infty }. (2013) and Leighly et al. Veilleux et al. 2015), in addition to those current practices by searching for the kinematic and image signatures of BBHs among AGNs/quasars (Gaskell 1996; Rodriguez et al. Roedig et al. The locations of the emission lines H, H, and Ly are also marked in the figure. Dr. (1995). In the first model, the FUV emission is dominated by the young star burst with an age of 100 Myr and therefore would have no significant short time-scale variations, which appears inconsistent with the observations. 2012; Yan et al. The obtained results were not reliable enough due to its heavy reliance on models. The ratio of the H flux to the H flux is roughly 3, consistent with those of normal quasars. Receive alerts on all new research papers in American Astronomical Society Their paper was published in Science Advances By using our site, you acknowledge that you have read and understand our Privacy Policy The red stars represent the best-fit parameter values.