High-Resolution X-Ray Spectroscopy of the Bursting Pulsar GRO J1744-28

Abstract

The bursting pulsar GRO J1744-28 is a Galactic low-mass X-ray binary that distinguishes itself by displaying type-II X-ray bursts: brief, bright flashes of X-ray emission that likely arise from spasmodic accretion. Combined with its coherent 2.1 Hz X-ray pulsations and relatively high estimated magnetic field, it is a particularly interesting source to study the physics of accretion flows around neutron stars. Here we report on Chandra/HETG observations obtained near the peak of its bright 2014 accretion outburst. Spectral analysis suggests the presence of a broad iron emission line centered at E_l ~ 6.7 keV. Fits with a disk reflection model yield an inclination angle of i ~ 52 degrees and an inner disk radius of R_in ~ 85 GM/c^2, which is much further out than typically found for neutron star low-mass X-ray binaries. Assuming that the disk is truncated at the magnetospheric radius of the neutron star, we estimate a magnetic field strength of B ~ (2-6)E10 G. Furthermore, we identify an absorption feature near ~6.85 keV could correspond to blue-shifted Fe xxv and point to a fast disk wind with an outflow velocity of v_out ~ (7.5-8.2)E3 km/s (~0.025c-0.027c). If the covering fraction and filling factor are large, this wind could be energetically important and perhaps account for the fact that the companion star lost significant mass while the magnetic field of the neutron star remained strong.

arXiv commentAccepted for publication in ApJ Letters, 6 pages, 4 figures, 1 table

References in corpus (31)

• On the Absorption of X-rays in the Interstellar Medium
• Atomic Data for Astrophysics. II. New Analytic Fits for Photoionization Cross Sections of Atoms and Ions
• The Swift/BAT Hard X-ray Transient Monitor
• Ubiquitous equatorial accretion disc winds in black hole soft states
• Relativistic X-ray Lines from the Inner Accretion Disks Around Black Holes
• The magnetic nature of disk accretion onto black holes
• The Accretion Disk Wind in the Black Hole GRO J1655-40
• Relativistic Lines and Reflection from the Inner Accretion Disks Around Neutron Stars
• Simultaneous Chandra and RXTE Spectroscopy of the Microquasar H~1743-322: Clues to Disk Wind and Jet Formation from a Variable Ionized Outflow
• Evidence for "Propeller" Effects In X-ray Pulsars GX 1+4 And GROJ1744-28
• Broad relativistic iron emission line observed in SAX J1808.4-3658
• X-ray reflection in accreting stellar-mass black hole systems
• Resolving the Composite Fe K-alpha Emission Line in the Galactic Black Hole Cygnus X-1 with Chandra
• A Chandra survey of fluorescence Fe lines in X-ray Binaries at high resolution
• An Extreme X-ray Disk Wind in the Black Hole Candidate IGR J17091-3624
• XMM-Newton detects a relativistically broadened iron line in the spectrum of the ms X-ray pulsar SAX J1808.4-3658
• A highly-ionized absorber in the X-ray binary 4U 1323-62: a new explanation for the dipping phenomenon
• The Discovery of Broad P Cygni X-ray Lines from Circinus X-1 with the Chandra High Energy Transmission Grating Spectrometer
• Constraints on the Neutron Star and Inner Accretion Flow in Serpens X-1 Using NuSTAR
• Evidence of a Broad Relativistic Iron Line from the Neutron Star Low-Mass X-ray Binary Serpens X-1
• A Fast X-ray Disk Wind in the Transient Pulsar IGR J17480-2446 in Terzan 5
• Thermonuclear Burning on the Accreting X-Ray Pulsar GRO J1744-28
• The Youngest Known X-ray Binary: Circinus X-1 and its Natal Supernova Remnant
• A connection between accretion state and $\text{Fe K absorption}$ in an accreting neutron star: black hole-like soft state winds?
• Discovery of a 57-69 Hz quasi-periodic oscillation in GX13+1
• Disk reflection signatures in the spectrum of the bright Z-source GX 340+0
• Magnetic Field Upper Limits for Jet Formation
• ASCA Observations of GRO J1744-28
• GRO J1744-28, search for the counterpart: infrared photometry and spectroscopy
• Chandra grating spectroscopy of the Be/X-ray binary 1A 0535+262
• Broad iron lines in neutrons stars: dynamical broadening or wind scattering?

Cited by in corpus (35)

• Cyclotron lines in highly magnetized neutron stars
• Accretion disks and coronae in the X-ray flashlight
• A Hard Look at the Neutron Stars and Accretion Disks in 4U 1636-53, GX 17+2, and 4U 1705-44 with $\text{NuSTAR}$
• Low Mass X-ray Binaries: The Effects of the Magnetic Braking Prescription
• A new radio census of neutron star X-ray binaries
• An in-depth study of a neutron star accreting at low Eddington rate: On the possibility of a truncated disk and an outflow
• A NuSTAR observation of disk reflection from close to the neutron star in 4U 1608-52
• NuSTAR and XMM-Newton Observations of the Neutron Star X-ray Binary 1RXS J180408.9-34205
• Disk reflection and a possible disk wind during a soft X-ray state in the neutron star low-mass X-ray binary 1RXS J180408.9-342058
• GRO J1744-28: an intermediate B-field pulsar in a low mass X-ray binary
• Truncation of the Accretion Disk at One Third of the Eddington Limit in the Neutron Star Low-Mass X-ray Binary Aquila X-1
• Simultaneous NuSTAR/Chandra observations of the Bursting Pulsar GRO J1744-28 during its third reactivation
• A population study of type II bursts in the Rapid Burster
• A strongly truncated inner accretion disk in the Rapid Burster
• NuSTAR view of the Z-type neutron star low-mass X-ray binary Cygnus~X--2
• A test of the nature of the Fe K Line in the neutron star low-mass X-ray binary Serpens X-1
• Discovery of GRS 1915+105 variability patterns in the Rapid Burster
• Evidence for the radiation-pressure dominated accretion disk in bursting pulsar GRO J1744-28 using timing analysis
• Study of the accretion torque during the 2014 outburst of the X-ray pulsar GRO J1744-28
• Relativistic Disk Reflection in the Neutron Star X-ray Binary XTE J1709-267 with NuSTAR
• Spectral properties of MXB 1658-298 in the low/hard and high/soft state
• A strongly changing accretion morphology during the outburst decay of the neutron star X-ray binary 4U 1608-52
• The Evolution of X-ray Bursts in the "Bursting Pulsar" GRO J1744-28
• Discovery of radio emission from the symbiotic X-ray binary system GX 1+4
• Observations of GRO J1744-28 in quiescence with XMM-Newton
• Broad-band spectral analysis of LMXB XTE J1710-281 with Suzaku
• Quasi-Simultaneous Radio/X-ray Observations of the Candidate Transitional Millisecond Pulsar 3FGL J1544.6-1125 During its Low-Luminosity Accretion-Disc State
• Study of the reflection spectra of SAX J1748.9-2021
• AstroSat and NuSTAR observations of XTE J1739-285 during the 2019-2020 outburst
• NuSTAR observation of GRO J1744-28 at low mass accretion rate
• Discovery of hard phase lags in the pulsed emission of GRO J1744-28
• The Bursting Pulsar GRO J1744-28: the Slowest Transitional Pulsar?
• Spectral and timing analysis of the bursting pulsar GRO J1744-28 with RXTE observations
• Broad-band spectral analysis of LMXB 2S 0921-63 with Suzaku
• The X-ray bursts within the 2010 outburst of the accreting millisecond X-ray pulsar SAX J1748.9-2021