Hard X-ray flares and spectral variability in NGC 4395 ULX1

Abstract

We report the detection of flaring events in NGC 4395 ULX1, a nearby ultraluminous X-ray source (ULX), for the first time, using recent XMM-NEWTON observations. The flaring episodes are spectrally harder than the steady emission intervals, resulting in higher fractional variability in the high energy regime. A thin Keplerian and a slim accretion disk provide the best-fit continuum for XMM-NEWTON spectra. All observations show a broad hump-like feature around $\sim 0.9$ keV, which can be associated with a collection of blended emission lines, and suggests the presence of a wind/outflow in this ULX through comparison with other ULXs that show a similar feature. The flaring spectra correspond to higher slim disk temperatures due to higher mass accretion rate under an advection-dominated accretion scenario. The luminosity-temperature (L-T) values in different flux states show a positive trend. When characterized with a powerlaw relation, the L-T profile is broadly consistent with both $L\propto T^2$ and $L\propto T^4$ relations for the analysed data. The empirical predictions for a slim accretion disk in the case of super-Eddington accretion onto a stellar-mass compact object is $L\propto T^2$ which is a possible scenario in ULX1. The origin of the flaring events is understood as an intrinsic change of accretion rate or presence of variable clumpy wind in the inner region of the accretion disk.

arXiv comment15 pages, 5 figures, accepted for publication in ApJ

References in corpus (63)

• On the Absorption of X-rays in the Interstellar Medium
• X-ray Properties of Black-Hole Binaries
• Atomic Data for Astrophysics. II. New Analytic Fits for Photoionization Cross Sections of Atoms and Ions
• HI4PI: A full-sky HI survey based on EBHIS and GASS
• On characterising the variability properties of X-ray light curves from active galaxies
• An Ultraluminous X-ray Source Powered by An Accreting Neutron Star
• Super-critically accreting stellar-mass black holes as ultraluminous X-ray sources
• Ultraluminous X-Ray Sources
• An accreting pulsar with extreme properties drives an ultraluminous x-ray source in NGC 5907
• X-ray Spectral Variability and Rapid Variability of the Soft X-ray Spectrum Seyfert 1 Galaxies Ark 564 and Ton S180
• Discovery of a 0.42-s pulsar in the ultraluminous X-ray source NGC 7793 P13
• The flux-dependent amplitude of broadband noise variability in X-ray binaries and active galaxies
• Discovery of coherent pulsations from the Ultraluminous X-ray Source NGC 7793 P13
• Discovery of pulsations from NGC 300 ULX1 and its fast period evolution
• Stingray: A Modern Python Library For Spectral Timing
• The ultraluminous state revisited: fractional variability and spectral shape as diagnostics of super-Eddington accretion
• Resolved atomic lines reveal outflows in two ultraluminous X-ray sources
• Masses, Beaming and Eddington Ratios in Ultraluminous X-ray Sources
• A spectral-timing model for ULXs in the super-critical regime
• The Three Spectral Regimes Found in the Stellar Black Hole XTE J1550--564 in its High/Soft State
• The ultraluminous X-ray sources NGC 1313 X-1 and X-2: a broadband study with NuSTAR and XMM-Newton
• The discovery of weak coherent pulsations in the ultraluminous X-ray source NGC 1313 X-2
• Ultra-luminous X-ray Sources in nearby galaxies from ROSAT HRI observations I. data analysis
• Discovery of a 2.8 s pulsar in a 2 d orbit High-Mass X-ray Binary powering the Ultraluminous X-ray source ULX-7 in M51
• NICER and Fermi GBM Observations of the First Galactic Ultraluminous X-ray Pulsar Swift J0243.6+6124
• Evidence for a Variable Ultrafast Outflow in the Newly Discovered Ultraluminous Pulsar NGC 300 ULX-1
• From ultraluminous X-ray sources to ultraluminous supersoft sources: NGC 55 ULX, the missing link
• Magnetic field strength of a neutron-star-powered ultraluminous X-ray source
• Diagnosing the accretion flow in ultraluminous X-ray sources using soft X-ray atomic features
• Broad absorption features in wind-dominated ULXs?
• Pulsing ULXs: tip of the iceberg?
• Broadband X-ray Spectra of the Ultraluminous X-ray Source Holmberg IX X-1 observed with NuSTAR, XMM-Newton and Suzaku
• ULXs: Neutron Stars vs Black Holes
• Optically thick outflows in ultraluminous supersoft sources
• A Fourier Domain "Jerk" Search for Binary Pulsars
• An Extremely Luminous and Variable Ultraluminous X-ray Source in the Outskirts of Circinus Observed with NuSTAR
• Optically thick envelopes around ULXs powered by accreating neutron stars
• An Iron K Component to the Ultrafast Outflow in NGC 1313 X-1
• Spectral Changes in the Hyperluminous Pulsar in NGC 5907 as a Function of Super-Orbital Phase
• The Broadband XMM-Newton and NuSTAR X-ray Spectra of Two Ultraluminous X-ray Sources in the Galaxy IC 342
• Searching for Outflows in Ultraluminous X-ray Sources Through High-Resolution X-ray Spectroscopy
• XMM-Newton campaign on the ultraluminous X-ray source NGC 247 ULX-1: outflows
• Study of Recent outburst in the Be/X-ray binary RX J0209.6-7427 with AstroSat: A new ultraluminous X-ray pulsar in the Magellanic Bridge?
• Long-term X-ray spectral evolution of Ultraluminous X-ray sources: implications on the accretion flow geometry and the nature of the accretor
• The 2019 super-Eddington outburst of RX J0209.6-7427: Detection of pulsations and constraints on the magnetic field strength
• X-Ray Monitoring of Ultraluminous X-Ray Sources
• NuSTAR, XMM-Newton and Suzaku Observations of the Ultraluminous X-ray Source Holmberg II X-1
• NuSTAR and XMM-Newton observations of the extreme ultraluminous X-ray source NGC 5907 ULX1: A Vanishing Act
• The Unusual Broadband X-ray Spectral Variability of NGC 1313 X-1 seen with XMM$-$Newton, Chandra and NuSTAR
• A Hard X-Ray Study of Ultraluminous X-ray Source NGC 5204 X-1 with NuSTAR and XMM-Newton
• XMM-Newton Campaign On Ultraluminous X-ray Source NGC 1313 X-1: Wind vs. State Variability
• Ionised Emission and Absorption in a Large Sample of Ultraluminous X-ray Sources
• On Black Hole Mass Estimation from X-ray Spectra of Ultraluminous X-ray Sources
• A broadband X-ray spectral study of the intermediate-mass black hole candidate M82 X-1 with NuSTAR, Chandra and Swift
• Discovery of a recurrent spectral evolutionary cycle in the ultra-luminous X-ray sources Holmberg II X-1 and NGC 5204 X-1
• Discovery of a soft X-ray lag in the Ultraluminous X-ray Source NGC 1313 X-1
• The slim-disk state of the ultraluminous X-ray source in M83
• A broadband look at the old and new ULXs of NGC 6946
• Soft Extragalactic X-Ray Binaries at the Eddington Threshold
• The slow heartbeats of an ultra-luminous X-ray source in NGC 3621
• The rare X-ray flaring activity of the Ultraluminous X-ray source NGC 4559 X7
• The Ultraluminous X-ray sources population of the galaxy NGC 7456
• In-depth studies of the NGC 253 ULXs with XMM-Newton: remarkable variability in ULX1, and evidence for extended coronae

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