A broadband look of the Accreting Millisecond X-ray Pulsar SAX J1748.9-2021 using AstroSat and XMM-Newton

Abstract

SAX J1748.9-2021 is a transient accretion powered millisecond X-ray pulsar located in the Globular cluster NGC 6440. We report on the spectral and timing analysis of SAX J1748.9-2021 performed on AstroSat data taken during its faint and short outburst of 2017. We derived the best-fitting orbital solution for the 2017 outburst and obtained an average local spin frequency of 442.361098(3) Hz. The pulse profile obtained from 3-7 keV and 7-20 keV energy bands suggest constant fractional amplitude ~0.5% for fundamental component, contrary to previously observed energy pulse profile dependence. Our AstroSat observations revealed the source to be in a hard spectral state. The 1-50 keV spectrum from SXT and LAXPC on-board AstroSat can be well described with a single temperature blackbody and thermal Comptonization. Moreover, we found that the combined spectra from XMM-Newton (EPIC-PN) and AstroSat (SXT+LAXPC) indicated the presence of reflection features in the form of iron (Fe K$\alpha$) line that we modeled with the reflection model xillvercp. One of the two X-ray burst observed during the AstroSat/LAXPC observation showed hard X-ray emission (>30 keV) due to Compton up-scattering of thermal photons by the hot corona. Time resolved analysis performed on the bursts revealed complex evolution in emission radius of blackbody for second burst suggestive of mild photospheric radius expansion.

arXiv comment9 pages, 8 figures. Accepted for publication in MNRAS

References in corpus (57)

• On the Absorption of X-rays in the Interstellar Medium
• The European Photon Imaging Camera on XMM-Newton: The MOS Cameras
• Atomic Data for Astrophysics. II. New Analytic Fits for Photoionization Cross Sections of Atoms and Ions
• An online repository of Swift/XRT light curves of GRBs
• The MAXI Mission on the ISS: Science and Instruments for Monitoring All Sky X-Ray Images
• Broad-band gamma-ray and X-ray spectra of NGC 4151 and their implications for physical processes and geometry
• Thermonuclear (type-I) X-ray bursts observed by the Rossi X-ray Timing Explorer
• The May 1989 outburst of the Soft X-ray Transient GS 2023+338 (V404 Cyg)
• X-ray reflected spectra from accretion disk models. III. A complete grid of ionized reflection calculations
• Swings between rotation and accretion power in a millisecond binary pulsar
• Photospheric radius expansion X-ray bursts as standard candles
• X-ray reflected spectra from accretion disk models. I. Constant density atmospheres
• The two-hour orbit of a binary millisecond X-ray pulsar
• Calibration of the Large Area X-ray Proportional Counter (LAXPC) instrument on-board AstroSat
• Gas Slit Camera (GSC) onboard MAXI on ISS
• Discovery of a Second Millisecond Accreting Pulsar: XTE J1751-305
• Discovery of a High-Latitude Accreting Millisecond Pulsar in an Ultracompact Binary
• Near-IR properties of 24 Globular Clusters in the Galactic Bulge
• Broad relativistic iron emission line observed in SAX J1808.4-3658
• Intermittent millisecond X-ray pulsations from the neutron-star X-ray transient SAX J1748.9-2021 in the globular cluster NGC 6440
• INTEGRAL and RXTE observations of accreting millisecond pulsar IGR J00291+5934 in outburst
• XMM-Newton detects a relativistically broadened iron line in the spectrum of the ms X-ray pulsar SAX J1808.4-3658
• Physics of accretion in the millisecond pulsar XTE J1751-305
• The mass and the radius of the neutron star in the transient low mass X-ray binary SAX J1748.9-2021
• Chandra Observation of the Globular Cluster NGC 6440 and the Nature of Cluster X-ray Luminosity Functions
• The magnetic field strengths of accreting millisecond pulsars
• AstroSat view of MAXI J1535-571: broadband spectro-temporal features
• The X-ray spectrum of the newly discovered accreting millisecond pulsar IGR J17511-3057
• The accretion flow to the intermittent accreting ms pulsar, HETE J1900.1-2455, as observed by XMM-Newton and RXTE
• Identification of the optical and quiescent counterparts to the bright X-ray transient in NGC 6440
• Discovery of 105 Hz coherent pulsations in the ultracompact binary IGR J16597-3704
• "Hiccup" accretion in the swinging pulsar IGR J18245-2452
• Timing an Accreting Millisecond Pulsar: Measuring the Accretion Torque in IGR J00291+5934
• Phase-coherent timing of the accreting millisecond pulsar SAX J1748.9-2021
• Timing an Accreting Millisecond Pulsar: Measuring the Accretion Torque in IGR J00291+5934
• Broad-band spectral analysis of the accreting millisecond X-ray pulsar SAX J1748.9-2021
• Timing of the accreting millisecond pulsar SAX J1748.9-2021 during its 2015 outburst
• NuSTAR and XMM-Newton broad-band spectrum of SAX J1808.4-3658 during its latest outburst in 2015
• Accreting pulsars: mixing-up accretion phases in transitional systems
• NuSTAR and NICER reveal IGR J17591-2342 as a new accreting millisecond X-ray pulsar
• Discovery of 442-Hz Pulsations from an X-ray Source in the Globular Cluster NGC 6440
• Truncation of the Accretion Disk at One Third of the Eddington Limit in the Neutron Star Low-Mass X-ray Binary Aquila X-1
• Secular spin-down of the AMP XTE J1751-305
• Indications of non-conservative mass-transfer in AMXPs
• Testing Rate Dependent corrections on timing mode EPIC-pn spectra of the accreting Neutron Star GX 13+1
• Probing the effects of a thermonuclear X-ray burst on the neutron star accretion flow with NuSTAR
• Discovery of X-Ray Burst Oscillations from a Neutron-Star X-Ray Transient in the Globular Cluster NGC 6440
• XMM-Newton detection of the 2.1 ms coherent pulsations from IGR J17379-3747
• The Optical Counterpart to the Accreting Millisecond X-ray Pulsar SAX J1748.9-2021 in the Globular Cluster NGC 6440
• SWIFT J1756.9-2508: spectral and timing properties of its 2018 outburst
• Thermonuclear X-ray bursts in rapid succession in 4U 1636-536 with AstroSat-LAXPC
• Pulse-phase resolved spectroscopy of continuum and reflection in SAX J1808.4-3658
• Mixed H/He bursts in SAX J1748.9-2021 during the spectral change of its 2015 outburst
• Study of the reflection spectra of SAX J1748.9-2021
• A faint outburst of the accreting millisecond X-ray pulsar SAX J1748.9-2021 in NGC 6440
• Temperature Measurement during Thermonuclear X-ray Bursts with BeppoSAX
• The X-ray bursts within the 2010 outburst of the accreting millisecond X-ray pulsar SAX J1748.9-2021

Cited by in corpus (15)

• Search for continuous gravitational waves from 20 accreting millisecond X-ray pulsars in O3 LIGO data
• Large Area X-ray Proportional Counter (LAXPC) in Orbit Performance : Calibration, background, analysis software
• AstroSat Observations of the first Galactic ULX Pulsar Swift J0243.6+6124
• Thermonuclear X-ray bursts from LMXB 4U 1636$-$536 observed with AstroSat
• Broadband mHz QPOs and spectral study of LMC X$-$4 with AstroSat
• The AstroSat observation of accreting millisecond X-ray pulsar SAX J1808.4-3658 during its 2019 outburst
• Broad-band spectral analysis of LMXB XTE J1710-281 with Suzaku
• AstroSat and NuSTAR observations of XTE J1739-285 during the 2019-2020 outburst
• Eclipse Timings of the LMXB XTE J1710-281 : Discovery of a third orbital period glitch
• Science with the $AstroSat$ Soft X-ray Telescope: an overview
• Sidebands to mHz QPOs in 4U 1626$-$67 in the second spin-down state
• X-ray spectral properties of the accreting millisecond pulsar IGR J17498-2921 during its 2023 outburst
• LAXPC instrument onboard AstroSat: Five exciting years of new scientific results specially on X-ray Binaries
• Change in spin-down rate and detection of emission line in HMXB 4U 2206+54 with AstroSat observation
• AstroSat observation of the magnetar SGR J1830$-$0645 during its first detected X-ray outburst