NuSTAR + XMM-Newton monitoring of the neutron star transient AX J1745.6-2901

Abstract

AX J1745.6-2901 is a high-inclination (eclipsing) transient neutron star (NS) Low Mass X-ray Binary (LMXB) showcasing intense ionised Fe K absorption. We present here the analysis of 11 XMM-Newton and 15 NuSTAR new data-sets (obtained between 2013-2016), therefore tripling the number of observations of AX J1745.6-2901 in outburst. Thanks to simultaneous XMM-Newton and NuSTAR spectra, we greatly improve on the fitting of the X-ray continuum. During the soft state the emission can be described by a disk black body ($kT\sim 1.1-1.2$ keV and inner disc radius $r_{DBB}\sim 14$ km), plus hot ($kT\sim 2.2-3.0$ keV) black body radiation with a small emitting radius ($r_{BB}\sim 0.5-0.8$ km) likely associated with the boundary layer or NS surface, plus a faint Comptonisation component. Imprinted on the spectra are clear absorption features created by both neutral and ionised matter. Additionally, positive residuals suggestive of an emission Fe K$\alpha$ disc line and consistent with relativistic ionised reflection are present during the soft state, while such residuals are not significant during the hard state. The hard state spectra are characterised by a hard ($\Gamma \sim 1.9-2.1$) power law, showing no evidence for a high energy cut off ($k{T}_e>60-140$ keV) and implying a small optical depth ($\tau <1.6$). The new observations confirm the previously witnessed trend of exhibiting strong Fe K absorption in the soft state, that significantly weakens during the hard state. Optical (GROND) and radio (GMRT) observations suggest for AX J1745.6-2901 a standard broad band SED as typically observed in accreting neutron stars.

arXiv commentAccepted for publication in MNRAS

References in corpus (95)

• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• On the Absorption of X-rays in the Interstellar Medium
• The European Photon Imaging Camera on XMM-Newton: The MOS Cameras
• The Nuclear Spectroscopic Telescope Array (NuSTAR) Mission
• Atomic Data for Astrophysics. II. New Analytic Fits for Photoionization Cross Sections of Atoms and Ions
• The Galaxy in Context: Structural, Kinematic and Integrated Properties
• Towards a unified model for black hole X-ray binary jets
• Modelling the behaviour of accretion flows in X-ray binaries
• A Study of the Gas-Star Formation Relation over Cosmic Time
• A Scheme to Unify Low-Power Accreting Black Holes - Jet-Dominated Accretion Flows and the Radio/X-Ray Correlation
• Broad-band gamma-ray and X-ray spectra of NGC 4151 and their implications for physical processes and geometry
• An XMM-Newton survey of broad iron lines in Seyfert galaxies
• The May 1989 outburst of the Soft X-ray Transient GS 2023+338 (V404 Cyg)
• A Unified Description of the Timing Features of Accreting X-ray Binaries
• Broad iron lines in Active Galactic Nuclei
• An Update on Monitoring Stellar Orbits in the Galactic Center
• Fluorescent iron lines as a probe of astrophysical black hole systems
• The 2013 Release of Cloudy
• Ubiquitous equatorial accretion disc winds in black hole soft states
• BlackCAT: A catalogue of stellar-mass black holes in X-ray transients
• GROND - a 7-channel imager
• WATCHDOG: A Comprehensive All-Sky Database of Galactic Black Hole X-ray Binaries
• A Global Spectral Study of Black Hole X-ray Binaries
• The broad-band power spectra of X-ray binaries
• The magnetic nature of disk accretion onto black holes
• Calibration of the NuSTAR High Energy Focusing X-ray Telescope
• A Simple Comptonization Model
• A Long, Hard Look at the Low-Hard State in Accreting Black Holes
• Line derived infrared extinction towards the Galactic Center
• NuSTAR Observations of the Bullet Cluster: Constraints on Inverse Compton Emission
• NuSTAR discovery of a 3.76-second transient magnetar near Sagittarius A*
• The 2175 A dust feature in a Gamma Ray Burst afterglow at redshift 2.45
• Hard X-ray Emission From Low Mass X-ray Binaries
• High resolution Chandra HETG and RXTE observations of GRS 1915+105 : A hot disk atmosphere & cold gas enriched in Iron and Silicon
• The Chandra HETGS and RXTE view of GRS 1915+105
• Evaluating Spectral Models and the X-ray States of Neutron-Star X-ray Transients
• Simultaneous Chandra and RXTE Spectroscopy of the Microquasar H~1743-322: Clues to Disk Wind and Jet Formation from a Variable Ionized Outflow
• Spectral States of XTE J1701-462: Link between Z and Atoll Sources
• Black hole accretion disks in the canonical low-hard state
• A systematic look at the Very High and Low/Hard state of GX 339-4: Constraining the black hole spin with a new reflection model
• Black hole-like hysteresis and accretion states in neutron star low mass X-ray binaries
• Spectral changes during dipping in low-mass X-ray binaries due to highly-ionized absorbers
• XMM-Newton study of the complex and variable spectrum of NGC 4051
• The Discovery of a State Dependent Hard Tail in the X-ray Spectrum of the Luminous Z-source GX 17+2
• Regulation of black-hole accretion by a disk wind during a violent outburst of V404 Cygni
• A powerful flare from Sgr A* confirms the synchrotron nature of the X-ray emission
• Accretion disc atmospheres and winds in low-mass X-ray binaries
• Truncation of the Inner Accretion Disk around a Black Hole at Low Luminosity
• Suzaku Results on Cygnus X-1 in the Low/Hard State
• The XMM-Newton view of the central degrees of the Milky Way
• A strongly magnetized pulsar within grasp of the Milky Way's supermassive black hole
• The variable X-ray spectrum of Markarian 766 - I. Principal components analysis
• The broad band X-ray/hard X-ray spectra of accreting neutron stars
• The X-ray spectrum of the atoll source 4U 1608-52
• A re--analysis of the iron line in the XMM-Newton data from the low/hard state in GX339--4
• The Discovery of Broad P Cygni X-ray Lines from Circinus X-1 with the Chandra High Energy Transmission Grating Spectrometer
• Fifteen years of XMM-Newton and Chandra monitoring of Sgr A*: Evidence for a recent increase in the bright flaring rate
• The truncated and evolving inner accretion disc of the black hole GX 339-4
• Measurements of accretion disc corona size in LMXB: consequences for Comptonization and LMXB models
• The behavior of subluminous X-ray transients near the Galactic center as observed using the X-ray telescope aboard Swift
• Truncated disc versus extremely broad iron line in XTE J1650-500
• Inclination and relativistic effects in the outburst evolution of black hole transients
• High Resolution Chandra HETG spectroscopy of V404 Cygni in Outburst
• A peculiar spectral state transition of 4U1705--44: when an Atoll looks like a Z
• Revealing accretion onto black holes: X-ray reflection throughout three outbursts of GX 339-4
• Timing and Flux Evolution of the Galactic Center Magnetar SGR J1745-2900
• Relativistic disc reflection in the extreme NLS1 IRAS13224-3809
• The soft component and the iron line as signatures of the disc inner radius in Galactic black hole binaries
• Regulation of Black Hole Winds and Jets Across the Mass Scale
• Discovery of narrow X-ray absorption features from the dipping low-mass X-ray binary X 1624-490 with XMM-Newton
• Results of a LMXB survey: variation in the height of the neutron star blackbody emission region
• NuSTAR Hard X-ray Survey of the Galactic Center Region II: X-ray Point Sources
• X-Ray and Near-Infrared Observations of GX 339-4 in the Low/Hard State with Suzaku and IRSF
• A Global Study of the Behaviour of Black Hole X-ray Binary Discs
• The X-ray flaring properties of Sgr A* during six years of monitoring with Swift
• Simultaneous BeppoSAX and RXTE observations of the X-ray burst sources GX 3+1 and Ser X-1
• A connection between accretion state and $\text{Fe K absorption}$ in an accreting neutron star: black hole-like soft state winds?
• Reflection spectra from an accretion disc illuminated by a neutron star X-ray burst
• Hard X-ray Morphological and Spectral Studies of The Galactic Center Molecular Cloud Sgr B2: Constraining Past Sgr A* Flaring Activity
• On the Fe K absorption - accretion state connection in the Galactic center neutron star X-ray binary AX J1745.6-2901
• The X-ray outburst of the Galactic Centre magnetar SGR J1745-2900 during the first 1.5 year
• A dichotomy between the hard state spectral properties of black hole and neutron star X-ray~binaries
• Links between quasi-periodic oscillations and accretion states in neutron star low mass X-ray binaries
• Flares, wind and nebulae: the 2015 December mini-outburst of V404 Cygni
• High ionisation absorption in low mass X-ray binaries
• The return to the hard state of GX 339-4 as seen by Suzaku
• The reverberation lag in the low mass X-ray binary H1743-322
• Is the black hole in GX 339-4 really spinning rapidly?
• Timing properties and spectral states in Aquila X-1
• Probing the Interstellar Dust towards the Galactic Centre: Dust Scattering Halo around AX J1745.6-2901
• On the Soft Excess in the X-ray Spectrum of Cir X-1: Revisitation of the Distance to Cir X-1
• The puzzling orbital period evolution of the low mass X-ray binary AX J1745.6-2901
• Photoionization instability of the Fe K absorbing plasma in the neutron star transient AX J1745.6-2901
• Suzaku spectroscopy of the neutron star transient 4U 1608-52 during its outburst decay
• Swift J174540.7-290015: a new accreting binary in the Galactic Center

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