Ultraluminous X-ray Sources in the Chandra and XMM-Newton Era

Abstract

Ultraluminous X-ray sources (ULXs) are accreting black holes that may contain the missing population of intermediate mass black holes or reflect super-Eddington accretion physics. Ten years of Chandra and XMM-Newton observations of ULXs, integrated by multiband studies of their counterparts, have produced a wealth of observational data and phenomenological classifications. We review the properties of their host galaxies, list popular spectral models and implications for standard and supercritical accretion physics, demonstrate how X-ray timing of these objects places constraints on their masses. We also review multiwavelength studies of ULXs, including the optical emission of the binary system and nebulosity around them. We summarize that three classes of black holes could power ULXs: normal stellar mass black holes (~10 solar masses), massive stellar black holes (~< 100 solar masses), and intermediate mass black holes (10^2 - 10^4 solar masses). We collect evidence for the presence of these three types of compact objects, including caveat of each interpretation, and briefly review their formation processes.

Solicited review in New Astronomy Reviews. v2: final version for publication, 21 pages, 5 figures, references added, small revisions made, thanks to many colleagues for useful comments

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• A variable ultraluminous X-ray source in a globular cluster in NGC 4649
• Towards a dynamical mass of the ultraluminous X-ray source NGC 5408 X-1
• The Spectral and Temporal Properties of Transient Sources in Early-Type Galaxies
• Quasi-Periodic Oscillations and energy spectra from the two brightest Ultra-Luminous X-ray sources in M82
• Discovery of a Highly Variable Dipping Ultraluminous X-ray source in M94
• Searching for coherent pulsations in ultraluminous X-ray sources
• Soft Extragalactic X-Ray Binaries at the Eddington Threshold
• Spatially resolved star formation image and the ULX population in NGC2207/IC2163
• Cutoff in the hard X-ray spectra of the ultraluminous X-ray sources HoIX X-1 and M82 X-1
• An Environmental Study of the Ultraluminous X-ray Source Population in Early-type Galaxies
• Observational aspects of Outbursting Black Hole Sources - Evolution of Spectro-Temporal features and X-ray Variability
• Thick Accretion Disk Model for Ultraluminous Supersoft Sources
• A search for hyperluminous X-ray sources in the XMM-Newton source catalog
• Hunting for dark halo substructure using submilliarcsecond-scale observations of macrolensed radio jets
• Spectral variability in Swift and Chandra observations of the Ultraluminous source NGC 55 ULX1
• Modelling optical emission of Ultra-luminous X-ray Sources accreting above the Eddington limit
• Escape, capture, and levitation of matter in Eddington outbursts
• The ultraluminous X-ray source NGC 5643 ULX1: a large stellar mass black hole accreting at super-Eddington rates?
• Limits on luminosity and mass accretion rate of a radiation pressure dominated accretion disc
• Classification of X-ray Sources in the XMM-Newton Serendipitous Source Catalog: Objects of Special Interest
• The Ultraluminous X-ray sources population of the galaxy NGC 7456
• Science with the EXTraS Project: Exploring the X-ray Transient and variable Sky
• Young rotation-powered pulsars as ultra-luminous X-ray sources
• Relativistic viscous accretion flow model for ULX sources: A case study for IC 342 X-1
• Temporal evolution of long-timescale periodicities in ULX NGC 5408 X-1
• X-ray outbursts of ESO 243-49 HLX-1: comparison with Galactic low-mass X-ray binary transients
• The Magnetic Field Evolution of ULX NuSTAR J095551+6940.8 in M82--A Legacy of Accreting Magnetar
• Accreting magnetars: linking ultraluminous X-ray pulsars and the slow pulsation X-ray pulsars
• A newly discovered double-double candidate microquasar in NGC 300
• A minor merger scenario for the ultraluminous X-ray source ESO 243-49 HLX-1 - II. Constraints from photometry
• Optical counterparts of two ULXs in NGC5474 and NGC3627 (M66)
• Variability-selected low-luminosity active galactic nuclei candidates in the 7 Ms Chandra Deep Field-South
• Binary Black Hole Merger Rates Inferred from Luminosity Function of Ultra-Luminous X-ray Sources
• Super-Eddington Accretion in the Ultraluminous X-ray Source NGC1313 X-2: An Ephemeral Feast
• X-ray source population study of the starburst galaxy M83 with XMM-Newton
• A comprehensive X-ray and multiwavelength study of the Colliding Galaxy Pair NGC2207/IC2163
• Chandra and HST Observations of the Supersoft ULX in NGC 247: Candidate for Standard Disk Emission
• The influence of fallback discs on the spectral and timing properties of neutron stars
• Chandra X-ray Constraints on the Candidate Ca-rich Gap Transient SN 2016hnk
• Paving the way to simultaneous multi-wavelength astronomy
• Transition of an X-ray binary to the hard ultraluminous state in the blue compact dwarf galaxy VII Zw 403
• Constraining the dipolar magnetic field of M82 X-2 by the accretion model
• Potential Black Hole Seeding of the Spiral Galaxy NGC 4424 via an Infalling Star Cluster
• The X-ray Properties of Million Solar Mass Black Holes
• Diagnostics of Parameters for the X-ray Jets of SS 433 from High-Resolution Chandra Spectroscopy
• Optical and X-ray luminosity of expanding nebulae around ultraluminous X-ray sources
• Vibrational instability of Population III very massive main-sequence stars due to the $\epsilon$-mechanism
• Black Hole Ultra-compact X-ray Binaries: Galactic Low-Frequency Gravitational Wave Sources
• First Detection of Mid-Infrared Variability from an Ultraluminous X-Ray Source Holmberg II X-1
• The two Ultraluminous X-ray sources in the galaxy NGC 925
• ULX behaviour: the ultraluminous state, winds & interesting anomalies
• Long-term Spectral Variability of the Ultra-luminous X-ray source Holmberg IX X--1
• Jets, Arcs and Shocks: NGC 5195 at radio wavelengths
• Swift observations of the ultraluminous X-ray source XMMU J004243.6+412519 in M31
• Optical Counterparts of ULXs and Their Host Environments in NGC 4490/4485
• Weighing the IMBH candidate CO-0.40-0.22* in the Galactic Centre
• The second ULX transient in M31: Chandra, HST and XMM observations, and evidence for an extended corona
• Discovery of a second outbursting hyperluminous X-ray source
• Survey of gravitational wave memory in intermediate mass ratio binaries
• Multiwavelength Follow-up Observations of the Tidal Disruption Event Candidate 2XMMi J184725.1-631724
• Possible Periodic Dips in the Pulsating Ultraluminous X-ray Source M51 ULX-7
• X-ray variability and energy spectra from NGC5408 X-1 with XMM-Newton
• Multiwavelength Scrutiny of X-ray Sources in Dwarf Galaxies: ULXs versus AGN
• Study on the magnetic field strength of NGC 300 ULX1
• On the magnetic field of the ultraluminous X-ray pulsar M82 X-2
• NuSTAR and XMM-Newton observations of the ultraluminous X-ray source NGC 5643 X-1
• X-ray spectral and optical properties of a ULX in NGC 4258 (M106)
• NGC 7793 P9: An Ultraluminous X-Ray Source Evolved from a Canonical Black Hole X-Ray Binary
• Spitzer IRAC observations of IR excess in Holmberg IX X-1: A circumbinary disk or a variable jet?
• Central X-ray point-sources found to be abundant in low-mass, late-type galaxies predicted to contain an intermediate-mass black hole
• Disc-corona interaction in the heartbeat state of GRS 1915+105
• Discovery of a radio transient in M81
• Refining the mass estimate for the intermediate-mass black hole candidate in NGC 3319
• Swift-XRT 6-year monitoring of the ultraluminous X-ray source M33-X8
• Superbroad Component in Emission Lines of SS 433
• High Excitation Emission Line Nebula associated with an Ultra Luminous X-ray Source at $z=$ 0.027 in the \textit{AKARI} North Ecliptic Pole Deep Field
• Black holes at cosmic dawn in the redshifted 21cm signal of HI
• A Sparkler in the Fireworks Galaxy: Discovery of an Ultraluminous X-ray Transient with a Strong Oxygen Line in NGC 6946
• Measuring the black hole mass in Ultraluminous X-ray Sources with the X-ray Scaling Method
• Constraining the mass of accreting black holes in ultraluminous X-ray sources with ultrafast outflows
• Two Power-Law States of the Ultraluminous X-ray Source IC342 X-1
• High Energy Gamma Rays from Nebulae Associated with Extragalactic Microquasars and Ultra-Luminous X-ray Sources
• NuSTAR observations of the ultraluminous X-ray source M33 X-8: a black hole in a very high state?
• HI study of the environment around ESO 243-49, the host galaxy of an intermediate mass black hole
• A New Ultraluminous X-ray Source in the Nearby Edge-on Spiral NGC 891
• Transient X-ray source population in the Magellanic-type galaxy NGC 55
• Discovery of two eclipsing X-ray binaries in M51
• On the Physical Nature of the Source of Ultraluminous X-ray Pulsations
• X-ray properties of two transient ULX candidates in galaxy NGC 7090
• Revealing the nature of the ULX and X-ray population of the spiral galaxy NGC 4088
• Numerical estimates of the accretion rate onto intermediate-mass black holes
• Modelling multiwavelength emission of Ultra-luminous X-ray Sources accreting above the Eddington limit
• Ultraluminous X-ray sources with He star companions
• The Great Pretenders Among the ULX Class
• Investigation of the timing and spectral properties of an Ultra-luminous X-ray pulsar NGC 7793 P13
• Mid-Infrared and X-ray luminosity correlations of X-ray point sources in NGC 1399
• Astrophysics with the Laser Interferometer Space Antenna
• Thick-disc model to explain the spectral state transition in NGC 247
• An Intermediate-Mass Black Hole Candidate in M51?
• On the nature of high X-ray luminosities in SDSS galaxies
• Identification of a New Ultraluminous X-ray Source in NGC 1316
• Bubble in the Whale: Identifying the Optical Counterparts and Extended Nebula for the Ultraluminous X-ray Sources in NGC 4631
• Synthetic extinction maps around intermediate-mass black holes in Galactic globular clusters
• Discovery of a Large Population of Ultraluminous X-ray Sources in the Bulge-less Galaxies NGC 337 and ESO 501-23
• Exploring the Spectral Variability of the Ultra-luminous X-ray source M81 X-6 with Suzaku and XMM-Newton
• Black Hole High Mass X-ray Binary Microquasars at Cosmic Dawn
• A search for periodicities from a ULX in the LINER galaxy NGC 4736
• The restless population of bright X-ray sources of NCG 3621
• On the Black Hole Masses In Ultra-luminous X-ray Sources
• A New Characterization of the Compton Process in the ULX Spectra
• NGC 2403 XMM4: evidence for a super-Eddington neutron star with a possible transient pulsation
• A Long-term Study of Ultraluminous X-ray Sources in NGC 891
• Astrophysical black holes
• Recurrent outbursts revealed in 3XMM J031820.8-663034
• Pulsating ultraluminous X-ray sources: modeling the thermal emission and polarization properties
• Influence of irradiation-driven winds on the evolution of intermediate-mass black hole X-ray binaries
• The kilo-second variability of X-ray sources in nearby galaxies
• Optical Counterparts of Two Candidate Ultraluminous X-ray Sources in NGC 4536
• Outflows from starburst galaxies with various driving mechanisms and their X-ray properties
• Exploring the nature of an ultraluminous X-ray source in NGC 628
• Prospects for Revealing Intermediate-Mass Black Holes in NGC 1399 using SKA
• Radio Nebulæ from Hyper-Accreting X-ray Binaries as Common Envelope Precursors and Persistent Counterparts of Fast Radio Bursts
• The aperiodic variability of the Ultraluminous X-ray source in NGC 5408
• Detectability of compact intermediate-mass black hole binaries as low-frequency gravitational wave sources: the influence of dynamical friction of dark matter
• Ultraluminous X-ray sources in the group-centric elliptical galaxy NGC 5813