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Title: A state change in the missing link binary pulsar system PSR J1023+0038

Abstract

We present radio and γ-ray observations, which, along with concurrent X-ray observations, reveal that the binary millisecond pulsar (MSP)/low-mass X-ray binary transition system PSR J1023+0038 has undergone a transformation in state. Whereas until recently the system harbored a bright millisecond radio pulsar, the radio pulsations at frequencies between 300 to 5000 MHz have now become undetectable. Concurrent with this radio disappearance, the γ-ray flux of the system has quintupled. We conclude that, though the radio pulsar is currently not detectable, the pulsar mechanism is still active and the pulsar wind, as well as a newly formed accretion disk, are together providing the necessary conditions to create the γ-ray increase. This system is the first example of a compact, low-mass binary which has shown significant state changes accompanied by large changes in γ-ray flux; it will continue to provide an exceptional test bed for better understanding the formation of MSPs as well as accretion onto neutron stars in general.

Authors:
;  [1]; ; ; ;  [2];  [3];  [4];  [5];  [6]; ;  [7]
  1. Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL (United Kingdom)
  2. ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA Dwingeloo (Netherlands)
  3. Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, NY 10027 (United States)
  4. McGill University, 3600 University Street, Montreal, QC H3A 2T8 (Canada)
  5. Leiden Observatory, Leiden University, PO Box 9513, NL-2300 RA Leiden (Netherlands)
  6. Space Radiation Laboratory, California Institute of Technology, 1200 East California Boulevard, MC 249-17, Pasadena, CA 91125 (United States)
  7. W. W. Hansen Experimental Physics Laboratory, KIPAC, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States)
Publication Date:
OSTI Identifier:
22365593
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 790; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; BINARY STARS; COSMIC GAMMA SOURCES; COSMIC RADIO SOURCES; ECLIPSE; MASS; NEUTRON STARS; PULSARS; STELLAR WINDS; TRANSFORMATIONS; X RADIATION

Citation Formats

Stappers, B. W., Lyne, A. G., Archibald, A. M., Hessels, J. W. T., Bassa, C. G., Janssen, G. H., Bogdanov, S., Kaspi, V. M., Patruno, A., Tendulkar, S., Hill, A. B., and Glanzman, T. A state change in the missing link binary pulsar system PSR J1023+0038. United States: N. p., 2014. Web. doi:10.1088/0004-637X/790/1/39.
Stappers, B. W., Lyne, A. G., Archibald, A. M., Hessels, J. W. T., Bassa, C. G., Janssen, G. H., Bogdanov, S., Kaspi, V. M., Patruno, A., Tendulkar, S., Hill, A. B., & Glanzman, T. A state change in the missing link binary pulsar system PSR J1023+0038. United States. doi:10.1088/0004-637X/790/1/39.
Stappers, B. W., Lyne, A. G., Archibald, A. M., Hessels, J. W. T., Bassa, C. G., Janssen, G. H., Bogdanov, S., Kaspi, V. M., Patruno, A., Tendulkar, S., Hill, A. B., and Glanzman, T. Sun . "A state change in the missing link binary pulsar system PSR J1023+0038". United States. doi:10.1088/0004-637X/790/1/39.
@article{osti_22365593,
title = {A state change in the missing link binary pulsar system PSR J1023+0038},
author = {Stappers, B. W. and Lyne, A. G. and Archibald, A. M. and Hessels, J. W. T. and Bassa, C. G. and Janssen, G. H. and Bogdanov, S. and Kaspi, V. M. and Patruno, A. and Tendulkar, S. and Hill, A. B. and Glanzman, T.},
abstractNote = {We present radio and γ-ray observations, which, along with concurrent X-ray observations, reveal that the binary millisecond pulsar (MSP)/low-mass X-ray binary transition system PSR J1023+0038 has undergone a transformation in state. Whereas until recently the system harbored a bright millisecond radio pulsar, the radio pulsations at frequencies between 300 to 5000 MHz have now become undetectable. Concurrent with this radio disappearance, the γ-ray flux of the system has quintupled. We conclude that, though the radio pulsar is currently not detectable, the pulsar mechanism is still active and the pulsar wind, as well as a newly formed accretion disk, are together providing the necessary conditions to create the γ-ray increase. This system is the first example of a compact, low-mass binary which has shown significant state changes accompanied by large changes in γ-ray flux; it will continue to provide an exceptional test bed for better understanding the formation of MSPs as well as accretion onto neutron stars in general.},
doi = {10.1088/0004-637X/790/1/39},
journal = {Astrophysical Journal},
number = 1,
volume = 790,
place = {United States},
year = {Sun Jul 20 00:00:00 EDT 2014},
month = {Sun Jul 20 00:00:00 EDT 2014}
}
  • We present radio, X-ray, and γ-ray observations which reveal that the binary millisecond pulsar / low-mass X-ray binary transition system PSR J1023+0038 has undergone a transformation in state. Whereas until recently the system harbored a bright millisecond radio pulsar, the radio pulsations at frequencies between 300 to 5000MHz have now become undetectable. Concurrent with this radio disappearance, the γ-ray flux of the system has quintupled. We conclude that, though the radio pulsar is currently not detectable, the pulsar mechanism is still active and the pulsar wind, as well as a newly formed accretion disk, are together providing the necessary conditionsmore » to create the γ-ray increase. The system is the first example of a transient, compact, low-mass γ-ray binary and will continue to provide an exceptional test bed for better understanding the formation of millisecond pulsars as well as accretion onto neutron stars in general.« less
  • PSR J1023+0038 is an exceptional system for understanding how slowly rotating neutron stars are spun up to millisecond rotational periods through accretion from a companion star. Observed as a radio pulsar from 2007-2013, optical data showed that the system had an accretion disk in 2000/2001. Starting at the end of 2013 June, the radio pulsar has become undetectable, suggesting a return to the previous accretion-disk state, where the system more closely resembles an X-ray binary. In this Letter we report the first targeted X-ray observations ever performed of the active phase and complement them with UV/optical and radio observations collectedmore » in 2013 October. We find strong evidence that indeed an accretion disk has recently formed in the system and we report the detection of fast X-ray changes spanning about two orders of magnitude in luminosity. No radio pulsations are seen during low flux states in the X-ray light curve or at any other times.« less
  • The binary millisecond radio pulsar PSR J1023+0038 exhibits many characteristics similar to the gamma-ray binary system PSR B1259–63/LS 2883, making it an ideal candidate for the study of high-energy nonthermal emission. It has been the subject of multiwavelength campaigns following the disappearance of the pulsed radio emission in 2013 June, which revealed the appearance of an accretion disk around the neutron star. We present the results of very high energy (VHE) gamma-ray observations carried out by the Very Energetic Radiation Imaging Telescope Array System before and after this change of state. Searches for steady and pulsed emission of both datamore » sets yield no significant gamma-ray signal above 100 GeV, and upper limits are given for both a steady and pulsed gamma-ray flux. These upper limits are used to constrain the magnetic field strength in the shock region of the PSR J1023+0038 system. Assuming that VHE gamma rays are produced via an inverse Compton mechanism in the shock region, we constrain the shock magnetic field to be greater than ∼2 G before the disappearance of the radio pulsar and greater than ∼10 G afterward.« less
  • Recent observations strongly suggest that the millisecond pulsar binary PSR J1023+0038 has developed an accretion disk since 2013 June. We present a multi-wavelength analysis of PSR J1023+0038, which reveals that (1) its gamma-rays suddenly brightened within a few days in 2013 June/July and has remained at a high gamma-ray state for several months; (2) both UV and X-ray fluxes have increased by roughly an order of magnitude; and (3) the spectral energy distribution has changed significantly after the gamma-ray sudden flux change. Time variabilities associated with UV and X-rays are on the order of 100-500 s and 50-100 s, respectively.more » Our model suggests that a newly formed accretion disk, due to the sudden increase of the stellar wind, could explain the changes of all these observed features. The increase of UV is emitted from the disk, and a new component in gamma-rays is produced by inverse Compton scattering between the new UV component and pulsar wind. The increase of X-rays results from the enhancement of injection pulsar wind energy into the intra-binary shock due to the increase of the stellar wind. We also predict that the radio pulses may be blocked by the evaporated winds from the disk, and the pulsar is still powered by rotation.« less
  • We report NuSTAR observations of the millisecond pulsar-low-mass X-ray binary (LMXB) transition system PSR J1023+0038 from 2013 June and October, before and after the formation of an accretion disk around the neutron star. Between June 10 and 12, a few days to two weeks before the radio disappearance of the pulsar, the 3-79 keV X-ray spectrum was well fit by a simple power law with a photon index of Γ=1.17{sub −0.07}{sup +0.08} (at 90% confidence) with a 3-79 keV luminosity of 7.4 ± 0.4 × 10{sup 32} erg s{sup –1}. Significant orbital modulation was observed with a modulation fraction ofmore » 36% ± 10%. During the October 19-21 observation, the spectrum is described by a softer power law (Γ=1.66{sub −0.05}{sup +0.06}) with an average luminosity of 5.8 ± 0.2 × 10{sup 33} erg s{sup –1} and a peak luminosity of ≈1.2 × 10{sup 34} erg s{sup –1} observed during a flare. No significant orbital modulation was detected. The spectral observations are consistent with previous and current multiwavelength observations and show the hard X-ray power law extending to 79 keV without a spectral break. Sharp-edged, flat-bottomed dips are observed with widths between 30 and 1000 s and ingress and egress timescales of 30-60 s. No change in hardness ratio was observed during the dips. Consecutive dip separations are log-normal in distribution with a typical separation of approximately 400 s. These dips are distinct from dipping activity observed in LMXBs. We compare and contrast these dips to observations of dips and state changes in the similar transition systems PSR J1824–2452I and XSS J1227.0–4859 and discuss possible interpretations based on the transitions in the inner disk.« less