Tidal disruption events (TDEs) provide a means to probe the low end of the supermassive black hole (SMBH) mass distribution, as they are only observable below the Hills mass ($\lesssim 10^8$ M$_\odot$). Here we attempt to calibrate the scaling of SMBH mass with host galaxy bulge mass, enabling SMBH masses to be estimated for large TDE samples without the need for follow-up observations or extrapolations of relations based on high-mass samples. We derive host galaxy masses using Prospector fits to the UV-MIR spectral energy distributions for the hosts of 29 well-observed TDEs with BH mass estimates from MOSFiT. We then conduct detailed bulge/disk decomposition using SDSS and PanSTARRS imaging, and provide a catalog of bulge masses. We measure a positive correlation between SMBH and bulge mass for the TDE sample, with a power-law slope of 0.28 and significance $p=0.06$ (Spearmans) and $p=0.05$ (Pearsons), and an intrinsic scatter of 0.2 dex. Applying MC resampling and bootstrapping, we find a more conservative estimate of the slope is $0.18\pm0.11$, dominated by the systematic errors from Prospector and MOSFiT. This is shallower than the slope at high SMBH mass, which may be due to a bias in the TDE sample towards lower mass BHs that can more easily disrupt low-mass stars outside of the event horizon. When combining the TDE sample with that of the high mass regime, we find that TDEs are successful in extending the SMBH - stellar mass relationship further down the mass spectrum and provide a relationship across the full range of SMBH masses.
Recent studies of Tidal Disruption Events (TDEs) have revealed unexpected correlations between the TDE rate and the large-scale properties of the host galaxies. In this review, we present the host galaxy properties of all TDE candidates known to date and quantify their distributions. We consider throughout the differences between observationally-identified types of TDEs and differences from spectroscopic control samples of galaxies. We focus here on the black hole and stellar masses of TDE host galaxies, their star formation histories and stellar populations, the concentration and morphology o…
We study the properties of the galaxies hosting the first 19 tidal disruption events (TDEs) detected with the Zwicky Transient Facility (ZTF) within the context of a carefully constructed, representative host galaxy sample. We find that the ZTF sample of TDE hosts is dominated by compact "green valley" galaxies. After we restrict the comparison sample to galaxies with a similar concentration, as measured by Sersic index, we find this green valley over representation is even larger. That is, concentrated red sequence galaxies are not producing TDEs at elevated levels. We present host galaxy spe…
We study the properties of tidal disruption event (TDE) host galaxies in the context of a catalog of ~500,000 galaxies from the Sloan Digital Sky Survey. We explore whether selection effects can account for the overrepresentation of TDEs in E+A/post-starburst galaxies by creating matched galaxy samples. Accounting for possible selection effects due to black hole (BH) mass, redshift completeness, strong AGN presence, bulge colors, and surface brightness can reduce the apparent overrepresentation of TDEs in E+A host galaxies by a factor of ~4 (from ~$\times$100-190 to ~$\times$25-48), but cannot…
Merger Driven or Internal Evolution? A New Morphological Study of Tidal Disruption Event Host Galaxies
The University of Hong Kong（香港大学）；The Hong Kong Institute for Astronomy and Astrophysics, The University of Hong Kong（香港大学天文及天体物理研究所）；International Centre for Radio Astronomy Research, University of Western Australia（西澳大利亚大学国际射电天文研究中心）；Tata Institute of Fundamental Research（塔塔基础研究所）；Tsinghua University（清华大学）；The Chinese University of Hong Kong（香港中文大学）；CUHK Shenzhen Research Institute（香港中文大学（深圳）研究院）；University of Victoria（维多利亚大学）；University of Nottingham（诺丁汉大学）；University of Hawaii（夏威夷大学）
We explore the galaxy structure of four tidal disruption event (TDE) host galaxies on 30 pc to kpc scales using HST WFC3 multi-band imaging. The star formation histories of these hosts are diverse, including one post-starburst galaxy (ASASSN-14li), two hosts with recent weak starbursts (ASASSN-14ae and iPTF15af), and one early type (PTF09ge). Compared to early type galaxies of similar stellar masses, the TDE hosts have higher central surface brightnesses and stellar mass surface densities on 30-100 pc scales. The TDE hosts do not show the large, kpc-scale tidal disruptions seen in some post-st…
The mass of the central black hole in a galaxy that hosted a tidal disruption event (TDE) is an important parameter in understanding its energetics and dynamics. We present the first homogeneously measured black hole masses of a complete sample of 12 optically/UV selected TDE host galaxies (down to $g_{host}$$\leq$22 mag and $z$=0.37) in the Northern sky. The mass estimates are based on velocity dispersion measurements, performed on late time optical spectroscopic observations. We find black hole masses in the range 3$\times$10$^5$ M$_{\odot}$$\leq$M$_{\rm BH}$$\leq$2$\times$10$^7$ M$_{\odot}$…
We report European Very Long Baseline Interferometry Network (EVN) radio continuum observations of ASASSN-14li, one of the best studied tidal disruption events (TDEs) to date. At 1.7 GHz with ~12x6mas resolution, the emission is unresolved. At 5.0 GHz with ~3x2mas resolution, the radio emission shows an extended structure that can be modeled with two components: a core-like component and a fainter, possibly elongated source 4.3mas (~2pc) away. Our observations are not conclusive as to the nature of the components, but three scenarios are discussed. One possibility is a core-jet/outflow morphol…
We constrain the recent star formation histories of the host galaxies of eight optical/UV-detected tidal disruption events (TDEs). Six hosts had quick starbursts of <200 Myr duration that ended 10 to 1000 Myr ago, indicating that TDEs arise at different times in their host's post-starburst evolution. If the disrupted star formed in the burst or before, the post-burst age constrains its mass, generally excluding O, most B, and highly massive A stars. If the starburst arose from a galaxy merger, the time since the starburst began limits the coalescence timescale and thus the merger mass ratio to…
The rate of tidal disruption events (TDEs), $R_\text{TDE}$, is predicted to depend on stellar conditions near the super-massive black hole (SMBH), which are on difficult-to-measure sub-parsec scales. We test whether $R_\text{TDE}$ depends on kpc-scale global galaxy properties, which are observable. We concentrate on stellar surface mass density, $Σ_{M_\star}$, and velocity dispersion, $σ_v$, which correlate with the stellar density and velocity dispersion of the stars around the SMBH. We consider 35 TDE candidates, with and without known X-ray emission. The hosts range from star-forming to qui…
Resolving the sub-parsec circumnuclear density profiles of quiescent galaxies: Evidence for Bondi accretion flows in tidal disruption event hosts
International Centre for Radio Astronomy Research – Curtin University（国际射电天文中心 - 科廷大学）；School of Natural Sciences, Institute for Advanced Study（自然科学与高级研究院）
eROSITA-RU Tidal Disruption Events with Keck-I/LRIS: Sample Selection, Optical Properties, and Host Galaxy Demographics
University of California, Berkeley（加州大学伯克利分校）；Sichuan University（四川大学）；Miller Institute for Basic Research in Science（米勒基础科学研究学院）；Berkeley Center for Multi-messenger Research on Astrophysical Transients and Outreach (Multi-RAPTOR)（伯克利多信使天体物理瞬变现象研究与外展中心（Multi-RAPTOR））；Space Research Institute (IKI), Russian Academy of Sciences（俄罗斯科学院空间研究所）；Max-Planck-Institut für Astrophysik（马克斯·普朗克天体物理学研究所）
Time domain optical surveys have discovered roughly a dozen candidate stellar tidal disruption flares in the last five years, and future surveys like the {\it Large Synoptic Survey Telescope} will likely find hundreds to thousands more. These tidal disruption events (TDEs) present an interesting puzzle: a majority of the current TDE sample is hosted by rare post-starburst galaxies, and tens of percent are hosted in even rarer E+A galaxies, which make up $\sim 0.1\%$ of all galaxies in the local universe. E+As are therefore overrepresented among TDE hosts by 1-2 orders of magnitude, a discrepan…
There is a strong decrease in scatter in the black hole mass versus bulge luminosity relationship with increasing luminosity and very little scatter for the most luminous galaxies. It is shown that this is a natural consequence of the substantial initial dispersion in the ratio of black hole mass to total stellar mass and of subsequent galaxy growth through hierarchical mergers. "Fine-tuning" through feedback between black hole growth and bulge growth is neither necessary nor desirable.
CSS100217 was a nuclear, rapid and luminous flare in a Narrow-Line Seyfert 1 galaxy, whose initial interpretation as a supernova is now debated between variability of the active galactic nucleus (AGN) or a tidal disruption event (TDE). In this paper, we present and discuss new evidence in favour of a TDE or extreme flaring episode scenario. After the decay of the flare, the galaxy entered a long-term low luminosity state, 0.4 magnitudes lower than the pre-outburst emission in the V band. We attribute this to the creation of a cavity in the accretion disk after the tidal disruption of a star in…
In November 2020, the Swift team announced an update to the UltraViolet and Optical Telescope calibration to correct for the loss of sensitivity over time. This correction affects observations in the three near ultraviolet (UV) filters, by up to 0.3 mag in some cases. As UV photometry is critical to characterizing tidal disruption events (TDEs) and other peculiar nuclear outbursts, we re-computed published Swift data for TDEs and other singular nuclear outbursts with Swift photometry in 2015 or later, as a service to the community. Using archival UV, optical, and infrared photometry we ran hos…
We present and analyse a new tidal disruption event (TDE), AT2017eqx at redshift z=0.1089, discovered by Pan-STARRS and ATLAS. The position of the transient is consistent with the nucleus of its host galaxy; it peaks at a luminosity of $L \approx 10^{44}$ erg s$^{-1}$; and the spectrum shows a persistent blackbody temperature $T \gtrsim 20,000$ K with broad H I and He II emission. The lines are initially centered at zero velocity, but by 100 days the H I lines disappear while the He II develops a blueshift of $\gtrsim 5,000$ km s$^{-1}$. Both the early- and late-time morphologies have been see…
Stars passing too close to a super massive black hole (SMBH) can produce tidal disruption events (TDEs). Since the resulting stellar debris can produce an electromagnetic flare, TDEs are believed to probe the presence of single SMBHs in galactic nuclei, which otherwise remain dark. In this paper, we show how stars orbiting an IMBH secondary are perturbed by an SMBH primary. We find that the evolution of the stellar orbits are severely affected by the primary SMBH due to secular effects and stars orbiting with high inclinations with respect to the SMBH-IMBH orbital plane end their lives as TDEs…
A tidal disruption event (TDE) occurs when a star is destroyed by the strong tidal shear of a massive black hole (MBH). The accumulation of TDE observations over the last years has revealed that post-starburst galaxies are significantly overrepresented in the sample of TDE hosts. Here we address the post-starburst preference by investigating the decline of TDE rates in a Milky-Way like nuclear stellar cluster featuring either a monochromatic (1 M$\odot$) or a complete, evolved stellar mass function. In the former case, the decline of TDE rates with time is very mild, and generally up to a fact…
An unexpected population of quenched galaxies harbouring under-massive SMBHs revealed by tidal disruption events
School of Physics and Astronomy, University of Birmingham（伯明翰大学物理与天文学学院）；Astrophysics Research Centre, School of Mathematics and Physics, Queens University Belfast（贝尔法斯特女王大学数学与物理学院天体物理学研究中心）；Institute for Gravitational Wave Astronomy, University of Birmingham（伯明翰大学引力波天文研究所）
Recent claimed detections of tidal disruption events (TDEs) in multi-wavelength data have opened potential new windows into the evolution and properties of otherwise dormant supermassive black holes (SMBHs) in the centres of galaxies. At present, there are several dozen TDE candidates, which share some properties and differ in others. The range in properties is broad enough to overlap other transient types, such as active galactic nuclei (AGN) and supernovae (SNe), which can make TDE classification ambiguous. A further complication is that "TDE signatures" have not been uniformly observed to s…
We present results of our analysis of spectra of the host galaxies of the candidate Tidal Disruption Events (TDEs) XMMSL1 J111527.3+180638 and PTF09axc to determine the nature of these transients. We subtract the starlight component from the host galaxy spectra to determine the origin of the nuclear emission lines. Using a Baldwin-Phillips-Terlevich (BPT) diagram we conclude that the host galaxy of XMMSL1 J111527.3+180638 is classified as a Seyfert galaxy, suggesting this transient is likely to be caused by (extreme) variability in the active galactic nucleus. We find that the host of PTF09axc…
Tidal disruption events (TDEs) are valuable probes of the demographics of supermassive black holes as well as the dynamics and population of stars in the centers of galaxies. In this Letter, we focus on studying how the debris disk formation and circularization processes can impact the possibility of observing prompt flares in TDEs. First, we investigate how the efficiency of disk formation is determined by the key parameters, namely, the black hole mass $M_{BH}$, the stellar mass $m_\star$, and the orbital penetration parameter $β$ that quantifies how close the disrupted star would orbit arou…
The ePESSTO+ census of ZTF nuclear transients. I. What flares in galactic nuclei?
Technical University of Denmark（丹麦技术大学）；University of Belgrade（贝尔格莱德大学）；University of Warsaw（华沙大学）；University of Turku（图尔库大学）；Institute of Space Sciences (ICE, CSIC)（空间科学研究所（ICE，CSIC））；Isaac Newton Group of Telescopes（艾萨克·牛顿望远镜组）；Queens University Belfast（贝尔法斯特女王大学）；National Centre for Nuclear Research（国家核研究中心）；University of Southampton（南安普顿大学）；National Central University（中央大学）；Sorbonne University（索邦大学）
JWST and Keck observations of the off-nuclear tidal disruption event TDE 2025abcr: An evolving reprocessing layer
UC Santa Cruz（加州大学圣克鲁兹分校）；University of California Observatories（加州大学天文台）；University of California, Berkeley（加州大学伯克利分校）；University of Illinois at Urbana-Champaign（伊利诺伊大学厄巴纳-香槟分校）；Center for Astrophysics | Harvard & Smithsonian（哈佛史密森尼天体物理中心）；University of Texas Austin（德克萨斯大学奥斯汀分校）
We present the discovery and first three months of follow-up observations of a currently on-going unusual transient detected by the OGLE-IV survey, located in the centre of a galaxy at redshift z=0.1655. The long rise to absolute magnitude of -20.5 mag, slow decline, very broad He and H spectral features make OGLE16aaa similar to other optical/UV Tidal Disruption Events (TDEs). Weak narrow emission lines in the spectrum and archival photometric observations suggest the host galaxy is a weak-line Active Galactic Nucleus (AGN), which has been accreting at higher rate in the past. OGLE16aaa, alon…
The deep connection between galaxies and their supermassive black holes is central to modern astrophysics and cosmology. The observed correlation between galaxy and black hole mass is usually attributed to the contribution of major mergers to both. We make use of a sample of galaxies whose disk-dominated morphologies indicate a major-merger-free history and show that such systems are capable of growing supermassive black holes at rates similar to quasars. Comparing black hole masses to conservative upper limits on bulge masses, we show that the black holes in the sample are typically larger th…
Stars passing too close to a black hole can produce tidal disruption events (TDEs), when the tidal force across the star exceeds the gravitational force that binds it. TDEs have usually been discussed in relation to massive black holes that reside in the centres of galaxies or lurk in star clusters. In this paper, we investigate the possibility that triple stars hosting a stellar black hole (SBH) may be sources of TDEs. We start from a triple system made up of three main sequence (MS) stars and model the supernova (SN) kick event that led to the production of an inner binary comprised of a SBH…
We investigate the scaling relations between the supermassive black holes mass (M_bh) and the host bulge mass in elliptical galaxies, classical bulges, and pseudo-bulges. We use two-dimensional image analysis software BUDDA to obtain the structural parameters of 57 galaxies with dynamical M_bh measurement, and determine the bulge K-band luminosities (L_bul,K), stellar masses (M_s), and dynamical masses (M_d). The updated M_bh-L_bul,K, M_bh-M_s, and M_bh-M_d correlations for elliptical galaxies and classical bulges give M_bh~0.006M_s or 0.003M_d. The most tight relationship is log(M_bh/M_sun)=a…
We report the results of ultraviolet (UV) and optical photometric and spectroscopic analysis of the tidal disruption event (TDE) AT2019qiz. Our follow-up observations started $<$10 days after the source began to brighten in the optical and lasted for a period of six months. Our late-time host-dominated spectrum indicates that the host galaxy likely harbors a weak active galactic nucleus. The initial {\it Hubble Space Telescope (HST)} spectrum of AT2019qiz exhibits an iron and low-ionization broad absorption line (FeLoBAL) system that is seen for the first time in a TDE. This spectrum also bear…
TDE 2025abcr: A Tidal Disruption Event in the Outskirts of a Massive Galaxy
University of Maryland（马里兰大学）；NASA Goddard Space Flight Center（NASA戈达德太空飞行中心）；University of North Carolina at Chapel Hill（北卡罗来纳大学教堂山分校）；The Pennsylvania State University（宾夕法尼亚州立大学）；University of California, Berkeley（加州大学伯克利分校）
Tidal disruption events (TDEs), apart from producing luminous electromagnetic (EM) flares, can generate potentially detectable gravitational wave (GW) burst signals by future space-borne GW detectors. In this Letter, we propose a methodology to constrain the Hubble constant $H_0$ by incorporating the TDE parameters measured by EM observations (e.g., stellar mass, black hole (BH) mass and spin, and other orbital parameters) into the observed TDE GW waveforms. We argue that an accurate knowledge of the BH spin could help constrain the orbital inclination angle, hence alleviating the well-known d…
Rates of tidal disruption events from constrained cosmological simulations of the local Universe: population properties and implications for transient surveys
Ludwig-Maximilians Universität（路德维希-马克西米利安大学）；University of Oxford（牛津大学）；Max-Planck-Institut für Astrophysik（马克斯·普朗克天体物理学研究所）
It is commonly accepted that radio-loud active galactic nuclei are hosted exclusively by giant elliptical galaxies. We analyze high-resolution optical Hubble Space Telescope images of a sample of radio galaxies with extended double-lobed structures associated with disk-like optical counterparts. After systematically evaluating the probability of chance alignment between the radio lobes and the optical counterparts, we obtain a sample of 18 objects likely to have genuine associations. The host galaxies have unambiguous late-type morphologies, including spiral arms, large-scale dust lanes among …
AT 2022csn: A Photometrically Peculiar Optical/UV Tidal Disruption Event in a Type II AGN
Tel Aviv University（特拉维夫大学）；University of Texas at Austin（德克萨斯大学奥斯汀分校）；University of Florida（佛罗里达大学）；Stanford University（斯坦福大学）；Kavli Institute for Particle Astrophysics & Cosmology, Stanford University（斯坦福大学卡弗里粒子天体物理与宇宙学研究所）；Center for Decoding the Universe, Stanford University（斯坦福大学解码宇宙中心）；NASA Goddard Space Flight Center（美国国家航空航天局戈达德太空飞行中心）
本研究报道了II型AGN中一颗测光特殊的光学/紫外TDE AT 2022csn，其为遥远且明亮的TDE，或属于低温高半径TDE新子群，提出TDE与AGN吸积盘相互作用等场景解释其特性。
We present a feedback mechanism for supermassive black holes and their host bulges that operates during epochs of radio-loud quasar activity. In the radio cores of relativistic quasar jets, internal shocks convert a fraction of ordered bulk kinetic energy into randomized relativistic ions, or in other words cosmic rays. By employing a phenomenologically-motivated jet model, we show that enough 1-100 GeV cosmic rays escape the radio core into the host galaxy to break the Eddington limit in cosmic rays. As a result, hydrostatic balance is lost and a cosmic ray momentum-driven wind develops, expe…
Numerous tidal disruption event (TDE) candidates originating from galactic centres have been detected (e.g., by ${\it Swift}$ and ASASSN). Some of their host galaxies show typical characteristics of a weak active galactic nucleus (AGN), indicative of a pre-existing accretion disc around the supermassive black hole (SMBH). In this work, we develop an analytic model to study how a pre-existing accretion disc affects a TDE. We assume the density of the disc $ρ\propto R^{-λ}$, $R$ being the radial distance from the SMBH and $λ$ varying between $0.5$ and $1.5$. Interactions between the pre-existing…
Tidal disruption events (TDEs) provide a unique opportunity to probe the stellar populations around supermassive black holes (SMBHs). By combining light curve modeling with spectral line information and knowledge about the stellar populations in the host galaxies, we are able to constrain the properties of the disrupted star for three TDEs. The TDEs in our sample have UV spectra, and measurements of the UV N III to C III line ratios enabled estimates of the nitrogen-to-carbon abundance ratios for these events. We show that the measured nitrogen line widths are consistent with originating from …
As the sensitivity of gravitational wave (GW) instruments improves and new networks start operating, hundreds of merging stellar-mass black holes (SBHs) and intermediate-mass black holes (IMBHs) are expected to be observed in the next few years. The origin and distribution of SBH and IMBH binaries in various dynamical environments is a fundamental scientific question in GW astronomy. In this paper, we discuss ways tidal disruption events (TDEs) may provide a unique electromagnetic window into the assembly and merger of binary SBHs and IMBHs in nuclear star clusters (NSCs). We discuss how the h…
Can tidal disruption event models reliably measure black hole masses?
Queen’s University Belfast（贝尔法斯特女王大学）；University of Birmingham（伯明翰大学）；University of Cambridge（剑桥大学）；The Observatories of the Carnegie Institute for Science（卡内基科学研究所天文台）；University of California, Davis（加州大学戴维斯分校）；University of California, Berkeley（加州大学伯克利分校）；University of Maryland, College Park（马里兰大学帕克分校）
AT2019cmw: A highly luminous, cooling featureless TDE candidate from the disruption of a high mass star in an early-type galaxy
Liverpool John Moores University（利物浦约翰摩尔斯大学）；Stockholm University（斯德哥尔摩大学）；Kyoto University（京都大学）；the University of Tokyo（东京大学）；University of California, Berkeley（加州大学伯克利分校）
