Fainter harder brighter softer: a correlation between ${\alpha }_{\mathrm{ox}}$ , X-ray spectral state and Eddington ratio in tidal disruption events

Abstract

We explore the accretion states of tidal disruption events (TDEs) using a sample of 7 X- ray bright sources. To this end, we estimate the relative contribution of the disk and corona to the observed X-ray emission through spectral modeling, and assess the X-ray brightness (through $\alpha$_ox, L${}_{2keV}$ and f${}_{Edd,X}$) as a function of the Eddington ratio. We report strong positive correlations between $\alpha$_ox and f${}_{Edd,bol}$; f${}_{Edd,X}$ and f${}_{Edd,UV}$ ; and an anti-correlation for L${}_{2keV}$ and f${}_{Edd,UV}$. TDEs at high f${}_{Edd,bol}$ have thermal dominated X-ray spectra and high (soft) $\alpha$_ox, whereas those at low f${}_{Edd,bol}$ show a significant power-law contribution and low (hard) $\alpha$_ox. Similar to X-ray binaries and active galactic nuclei, the transition between X-ray spectral states occurs around f${}_{Edd,bol}$ $\approx$ 0.03, although the uncertainty is large due to the small sample size. Our results suggest that X-ray surveys are more likely to discover TDEs at low f${}_{Edd,bol}$, whereas optical surveys are more sensitive to TDEs at high Eddington ratios. The X-ray and optical selected TDEs have different UV and X-ray properties, which should be taken into account when deriving rates, luminosity and black hole mass functions. TDEs around the most massive supermassive black holes are observed in the hard state; this could indicate that TDE evolution is faster around more massive BHs.

arXiv commentMNRAS Letters, in press

References in corpus (39)

• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• X-ray Properties of Black-Hole Binaries
• Methods and results of an automatic analysis of a complete sample of Swift-XRT observations of GRBs
• HI4PI: A full-sky HI survey based on EBHIS and GASS
• On the Black Hole Mass - Bulge Mass Relation
• The M-sigma and M-L Relations in Galactic Bulges and Determinations of their Intrinsic Scatter
• Improving the full spectrum fitting method: accurate convolution with Gauss-Hermite functions
• Some Aspects of Measurement Error in Linear Regression of Astronomical Data
• Optimal Techniques in Two-dimensional Spectroscopy: Background Subtraction for the 21st Century
• Foundations of Black Hole Accretion Disk Theory
• Intrinsic disc emission and the Soft X-ray Excess in AGN
• The X-ray-to-Optical Properties of Optically-Selected Active Galaxies Over Wide Luminosity and Redshift Ranges
• Piecing Together the X-ray Background: Bolometric Corrections for Active Galactic Nuclei
• The X-ray to optical-UV luminosity ratio of X-ray selected Type 1 AGN in XMM-COSMOS
• Do X-ray Binary Spectral State Transition Luminosities Vary?
• Six Months of Multi-Wavelength Follow-up of the Tidal Disruption Candidate ASASSN-14li and Implied TDE Rates from ASAS-SN
• General Relativistic Hydrodynamic Simulation of Accretion Flow from a Stellar Tidal Disruption
• New physical insights about Tidal Disruption Events from a comprehensive observational inventory at X-ray wavelengths
• A physical model of the broadband continuum of AGN and its implications for the UV/X relation and optical variability
• The tight relation between X-ray and ultraviolet luminosity of quasars
• Disc formation from tidal disruptions of stars on eccentric orbits by Schwarzschild black holes
• A Dark Year for Tidal Disruption Events
• The Connection Between Radio Quiet AGN and the High/Soft State of X-Ray Binaries
• A Huge Drop in X-ray Luminosity of the Non-Active Galaxy RXJ1242.6-1119A, and First Post-Flare Spectrum - Testing the Tidal Disruption Scenario
• Black hole masses of tidal disruption event host galaxies
• Evidence for rapid disk formation and reprocessing in the X-ray bright tidal disruption event AT 2018fyk
• Late-time UV observations of tidal disruption flares reveal unobscured, compact accretion disks
• X-ray Brightening and UV Fading of Tidal Disruption Event ASASSN-15oi
• The Host Galaxies of Tidal Disruption Events
• The Analogous Structure of Accretion Flows in Supermassive and Stellar Mass Black Holes: New Insights from Faded Changing-Look Quasars
• Black hole masses of tidal disruption event host galaxies II
• The spectral evolution of disc dominated tidal disruption events
• XMMSL1 J074008.2-853927: a tidal disruption event with thermal and non-thermal components
• Implications from Late-Time X-ray Detections of Optically Selected Tidal Disruption Events: State Changes, Unification, and Detection Rates
• RBS 1032: A Tidal Disruption Event in Another Dwarf Galaxy?
• What can we learn about quasars from alpha_OX measurements in galactic black hole binaries?
• Testing the disk-corona interplay in radiatively-efficient broad-line AGN
• Examining a Peak-Luminosity/Decline-Rate Relationship for Tidal Disruption Events
• XMMSL2 J144605.0+685735 : a slow tidal disruption event

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