Starbursts and black hole masses in X-shaped radio galaxies: Signatures of a merger event?

Mezcua, Mar; Chavushyan, V.; Lobanov, A. P.

doi:10.1051/0004-6361/201117724

Cited by 21 publications

(32 citation statements)

References 47 publications

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“…In the upper panel of Figure 5 we compare the SMBH mass distribution determined for the XRGs and for the control sample of 388 FRII radio galaxies. In this comparison, we have also included the 41 XRGs known earlier for which stellar velocity dispersions are available in Mezcua et al (2011Mezcua et al ( , 2012. The average M BH for the FRII radio sources is found to be M BH = 9.07M ⊙ , which is slightly higher than the average M BH = 8.81M ⊙ estimated for the 67 XRGs (see also, Kuźmicz et al 2017).…”

Section: Masses Of the Central Black Holesmentioning

confidence: 94%

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X-shaped Radio Galaxies: Optical Properties, Large-scale Environment, and Relationship to Radio Structure

Joshi

Krishna

Yang

et al. 2019

ApJ

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In order to find clues to the origin of the "winged" or X-shaped radio galaxies (XRGs) we investigate here the parent galaxies of a large sample of 106 XRGs for optical-radio axes alignment, interstellar medium, black hole mass, and large-scale environment. For 41 of the XRGs it was possible to determine the optical major axis and the primary radio axis and the strong tendency for the two axes to be fairly close is confirmed. However, several counter-examples were also found and these could challenge the widely discussed backflow diversion model for the origin of the radio wings. Comparison with a welldefined large sample of normal FR II radio galaxies has revealed that: (i) XRGs possess slightly less massive central black holes than the normal radio galaxies (average masses being logM BH ∼ 8.81 M ⊙ and 9.07 M ⊙ , respectively); (ii) a much higher fraction of XRGs (∼ 80%) exhibits red mid-IR colors (W 2 − W 3 > 1.5), indicating a population of young stars and/or an enhanced dust mass, probably due to relatively recent galaxy merger(s). A comparison of the large-scale environment (i.e., within ∼ 1 Mpc) shows that both XRGs and FRII radio galaxies inhabit similarly poor galaxy clustering environments (medium richness being 8.94 and 11.87, respectively). Overall, the origin of XRGs seems difficult to reconcile with a single dominant physical mechanism and competing mechanisms seem prevalent.

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Section: Masses Of the Central Black Holesmentioning

confidence: 94%

“…Clearly, a satisfactory resolution of this issue would need deeper radio imaging at meter wavelengths. Mezcua et al (2011Mezcua et al ( , 2012) (open stars) and for the 388 FRII radio galaxies (circles). Upper panel: Distribution of MBH found here for the 67 XRGs and 388 FRII radio galaxies.…”

Section: Optical Versus Radio Structural Alignmentmentioning

confidence: 99%

X-shaped Radio Galaxies: Optical Properties, Large-scale Environment, and Relationship to Radio Structure

Joshi

Krishna

Yang

et al. 2019

ApJ

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“…Here we posit the hypothesis that the former option is correct, and moreover that it applies to other X-shape radio galaxies as well. That is, we propose that the X-shape radio morphology forms in post-merger systems that are rich in cold molecular gas, which assures an efficient accretion (see Mezcua et al 2012), with large net magnetic flux accumulated in central regions of the accretion flow that only host, however, slowly spinning supermassive black holes (likely in close binary systems with others, less massive black holes; Liu 2004). Tilted accretion disks naturally formed in these systems, along with the postulated low values of black hole spins, enable a rapid realignment of the jet axis, leading to the formation of winged radio morphologies.…”

Section: X-shaped Radio Morphologymentioning

confidence: 99%

Dynamical analysis of the complex radio structure in 3C 293: clues on a rapid jet realignment in X-shaped radio galaxies

Machalski

Jamrozy

Stawarz

et al. 2016

A&A

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Context. Radio galaxies classified as X-shaped/winged, are characterised by two pairs of extended and misaligned lobes, which suggest a rapid realignment of the jet axis, for which a potential cause (including binary supermassive black holes, a black hole merger, or a Lense-Thirring precession) is still under debate. Aims. Here we analyse the complex radio structure of 3C 293 winged source hosted by the post-merger galaxy UGC 8782, which uniquely displays a significant asymmetry between the sizes (and therefore the ages) of the two pairs of lobes, indicating that an episode of jet realignment took place only very recently. This allows us to tightly constrain the corresponding timescales, and therefore to discriminate between different models proposed for the formation of X-shaped radio galaxies in general.Methods. Based on all the available and carefully re-analysed radio data for 3C 293, we have performed a detailed spectral modelling for the older and younger lobes in the system, using the existing evolutionary DYNAGE algorithm. In this way we derived the lobes' ages and jet energetics, which we then compared to the accretion power in the source. Results. We found that the 200 kpc-scale outer lobes of 3C 293 are ∼ 60 Myr old and, until very recently, have been supplied with fresh electrons and magnetic field by the jets, i.e., jet activity related to the formation of the outer lobes ceased within the last Myr. Meanwhile, the inner 4 kpc-scale lobes, tilted by ∼ 40• with respect to the outer ones, are only about ∼ 0.3 Myr old. Interestingly, the best model fits also return identical values of the jet power supplying the outer and the inner structures. This power, moreover, is of the order of the maximum kinetic luminosity of a Blandford-Znajek jet for a given black hole mass and accretion rate, but only in the case of relatively low values of a black hole spin, a ∼ 0.2. Conclusions. The derived jet energetics and timescales, along with the presence of two optical nuclei in UGC 8782, all provide a strong support to the Lense-Thirring precession model in which the supermassive black hole spin, and therefore the jet axis, flips rapidly owing to the interactions with the tilted accretion disk in a new tidal interaction episode of the merging process. We further speculate that, in general, X-shape radio morphology forms in post-merger systems that are rich in cold molecular gas, and only host slowly spinning supermassive black holes.

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“…If these systems launch radio jets, jet formation will be temporarily interrupted, too, and this may explain the presence of double-double radio galaxies (Liu et al 2003). If the hole's spin direction changes after coalescence, the jet will be launched in a new direction, and this is one possibility to account for the structure of X-shaped radio galaxies (Merritt & Ekers 2002;see Gopal-Krishna et al 2012 for a recent overview; see also Mezcua et al 2012). If the newly formed single SMBH receives a significant kick velocity after coalescence, it will appear spatially or kinematically off-set from its host galaxy, and several candidate recoiling SMBHs have emerged in recent years (review by Komossa 2012).…”

Section: Post-coalescence Candidatesmentioning

confidence: 99%

Compact object mergers: observations of supermassive binary black holes and stellar tidal disruption events

Komossa

Zensus

2014

Proc. IAU

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Abstract. The capture and disruption of stars by supermassive black holes (SMBHs), and the formation and coalescence of binaries, are inevitable consequences of the presence of SMBHs at the cores of galaxies. Pairs of active galactic nuclei (AGN) and binary SMBHs are important stages in the evolution of galaxy mergers, and an intense search for these systems is currently ongoing. In the early and advanced stages of galaxy merging, observations of the triggering of accretion onto one or both BHs inform us about feedback processes and BH growth. Identification of the compact binary SMBHs at parsec and sub-parsec scales provides us with important constraints on the interaction processes that govern the shrinkage of the binary beyond the "final parsec". Coalescing binary SMBHs are among the most powerful sources of gravitational waves (GWs) in the universe. Stellar tidal disruption events (TDEs) appear as luminous, transient, accretion flares when part of the stellar material is accreted by the SMBH. About 30 events have been identified by multi-wavelength observations by now, and they will be detected in the thousands in future ground-based or space-based transient surveys. The study of TDEs provides us with a variety of new astrophysical tools and applications, related to fundamental physics or astrophysics. Here, we provide a review of the current status of observations of SMBH pairs and binaries, and TDEs, and discuss astrophysical implications.

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Starbursts and black hole masses in X-shaped radio galaxies: Signatures of a merger event?

Cited by 21 publications

References 47 publications

X-shaped Radio Galaxies: Optical Properties, Large-scale Environment, and Relationship to Radio Structure

X-shaped Radio Galaxies: Optical Properties, Large-scale Environment, and Relationship to Radio Structure

Dynamical analysis of the complex radio structure in 3C 293: clues on a rapid jet realignment in X-shaped radio galaxies

Compact object mergers: observations of supermassive binary black holes and stellar tidal disruption events

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