skip to main content

DOE PAGESDOE PAGES

Title: Broadband pulsations from PSR B1821-24: Implications for emission models and the pulsar population of M28

Here, we report a 5.4σ detection of pulsed gamma rays from PSR B1821–24 in the globular cluster M28 using ~44 months of Fermi Large Area Telescope (LAT) data that have been reprocessed with improved instrument calibration constants. We constructed a phase-coherent ephemeris, with post-fit residual rms of 3 μs, using radio data spanning ~23.2 yr, enabling measurements of the multi-wavelength light-curve properties of PSR B1821–24 at the milliperiod level. We fold RXTE observations of PSR B1821–24 from 1996 to 2007 and discuss implications on the emission zones. The gamma-ray light curve consists of two peaks separated by 0.41 ± 0.02 in phase, with the first gamma-ray peak lagging behind the first radio peak by 0.05 ± 0.02 in phase, consistent with the phase of giant radio pulses. We observe significant emission in the off-peak interval of PSR B1821–24 with a best-fit LAT position inconsistent with the core of M28. We do not detect significant gamma-ray pulsations at the spin or orbital periods from any other known pulsar in M28, and we place limits on the number of energetic pulsars in the cluster. The derived gamma-ray efficiency, ~2%, is typical of other gamma-ray pulsars with comparable spin-down power, suggesting that themore » measured spin-down rate (2.2 × 10 36 erg s –1) is not appreciably distorted by acceleration in the cluster potential. This confirms PSR B1821–24 as the second very energetic millisecond pulsar in a globular cluster and raises the question of whether these represent a separate class of objects that only form in regions of very high stellar density.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [5] ;  [6] ;  [7] ;  [3] ;  [8] ;  [5] ;  [2] ;  [3] ;  [5] ;  [9] ;  [10] ;  [11] ;  [12] ;  [13] ;  [13] more »;  [14] ;  [15] ;  [7] ;  [3] ;  [16] ;  [14] ;  [17] ;  [7] ;  [18] ;  [19] « less
  1. National Academy of Sciences, Washington, D.C. (United States); Naval Research Lab., Washington, D.C. (United States)
  2. Max-Planck-Institut fur Radioastronomie, Bonn (Germany)
  3. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
  4. Lab. de Physique et Chimie de l'Environnement, Orleans Cedex (France); Observatoire de Paris, Nancay (France)
  5. Naval Research Lab., Washington, D.C. (United States)
  6. Univ. Laval, Quebec (Canada)
  7. The Univ. of Manchester, Manchester (United Kingdom)
  8. North-West Univ., Potchefstroom (South Africa)
  9. CEA-IRFU/CNRS/Univ. Paris Diderot, Gif sur Yvette (France)
  10. Univ. of British Columbia, Vancouver, BC (Canada)
  11. Columbia Univ., New York, NY (United States); Arecibo Observatory, Arecibo, Puerto Rico (United States)
  12. The Univ. of Manchester, Manchester (United Kingdom); Pontificia Univ. Catolica de Chile, Santiago (Chile)
  13. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
  14. Australia Telescope National Facility, Epping, NSW (Australia)
  15. Max-Planck-Institut fur Radioastronomie, Bonn (Germany); The Univ. of Manchester, Manchester (United Kingdom)
  16. National Radio Astronomy Observatory (NRAO), Charlottesville, VA (United States)
  17. Univ. Bordeaux, Gradignan Cedex (France)
  18. Lab. de Physique et Chimie de l'Environnement, Orleans Cedex (France)
  19. Willamette Univ., Salem, OR (United States)
Publication Date:
Grant/Contract Number:
AC02-76SF00515
Type:
Accepted Manuscript
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 778; Journal Issue: 2; Journal ID: ISSN 0004-637X
Publisher:
Institute of Physics (IOP)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; gamma rays: stars; globular clusters: individual (M28); pulsars: individual (B1821–24)
OSTI Identifier:
1356550

Johnson, Tyrel J., Guillemot, L., Kerr, M., Cognard, I., Ray, Paul S., Wolff, M. T., Bégin, S., Janssen, G. H., Romani, R. W., Venter, C., Grove, J. E., Freire, P. C. C., Wood, M., Cheung, C. C., Casandjian, J. M., Stairs, I. H., Camilo, F., Espinoza, C. M., Ferrara, E. C., Harding, A. K., Johnston, S., Kramer, M., Lyne, A. G., Michelson, P. F., Ransom, S. M., Shannon, R., Smith, D. A., Stappers, B. W., Theureau, G., and Thorsett, S. E.. Broadband pulsations from PSR B1821-24: Implications for emission models and the pulsar population of M28. United States: N. p., Web. doi:10.1088/0004-637X/778/2/106.
Johnson, Tyrel J., Guillemot, L., Kerr, M., Cognard, I., Ray, Paul S., Wolff, M. T., Bégin, S., Janssen, G. H., Romani, R. W., Venter, C., Grove, J. E., Freire, P. C. C., Wood, M., Cheung, C. C., Casandjian, J. M., Stairs, I. H., Camilo, F., Espinoza, C. M., Ferrara, E. C., Harding, A. K., Johnston, S., Kramer, M., Lyne, A. G., Michelson, P. F., Ransom, S. M., Shannon, R., Smith, D. A., Stappers, B. W., Theureau, G., & Thorsett, S. E.. Broadband pulsations from PSR B1821-24: Implications for emission models and the pulsar population of M28. United States. doi:10.1088/0004-637X/778/2/106.
Johnson, Tyrel J., Guillemot, L., Kerr, M., Cognard, I., Ray, Paul S., Wolff, M. T., Bégin, S., Janssen, G. H., Romani, R. W., Venter, C., Grove, J. E., Freire, P. C. C., Wood, M., Cheung, C. C., Casandjian, J. M., Stairs, I. H., Camilo, F., Espinoza, C. M., Ferrara, E. C., Harding, A. K., Johnston, S., Kramer, M., Lyne, A. G., Michelson, P. F., Ransom, S. M., Shannon, R., Smith, D. A., Stappers, B. W., Theureau, G., and Thorsett, S. E.. 2013. "Broadband pulsations from PSR B1821-24: Implications for emission models and the pulsar population of M28". United States. doi:10.1088/0004-637X/778/2/106. https://www.osti.gov/servlets/purl/1356550.
@article{osti_1356550,
title = {Broadband pulsations from PSR B1821-24: Implications for emission models and the pulsar population of M28},
author = {Johnson, Tyrel J. and Guillemot, L. and Kerr, M. and Cognard, I. and Ray, Paul S. and Wolff, M. T. and Bégin, S. and Janssen, G. H. and Romani, R. W. and Venter, C. and Grove, J. E. and Freire, P. C. C. and Wood, M. and Cheung, C. C. and Casandjian, J. M. and Stairs, I. H. and Camilo, F. and Espinoza, C. M. and Ferrara, E. C. and Harding, A. K. and Johnston, S. and Kramer, M. and Lyne, A. G. and Michelson, P. F. and Ransom, S. M. and Shannon, R. and Smith, D. A. and Stappers, B. W. and Theureau, G. and Thorsett, S. E.},
abstractNote = {Here, we report a 5.4σ detection of pulsed gamma rays from PSR B1821–24 in the globular cluster M28 using ~44 months of Fermi Large Area Telescope (LAT) data that have been reprocessed with improved instrument calibration constants. We constructed a phase-coherent ephemeris, with post-fit residual rms of 3 μs, using radio data spanning ~23.2 yr, enabling measurements of the multi-wavelength light-curve properties of PSR B1821–24 at the milliperiod level. We fold RXTE observations of PSR B1821–24 from 1996 to 2007 and discuss implications on the emission zones. The gamma-ray light curve consists of two peaks separated by 0.41 ± 0.02 in phase, with the first gamma-ray peak lagging behind the first radio peak by 0.05 ± 0.02 in phase, consistent with the phase of giant radio pulses. We observe significant emission in the off-peak interval of PSR B1821–24 with a best-fit LAT position inconsistent with the core of M28. We do not detect significant gamma-ray pulsations at the spin or orbital periods from any other known pulsar in M28, and we place limits on the number of energetic pulsars in the cluster. The derived gamma-ray efficiency, ~2%, is typical of other gamma-ray pulsars with comparable spin-down power, suggesting that the measured spin-down rate (2.2 × 1036 erg s–1) is not appreciably distorted by acceleration in the cluster potential. This confirms PSR B1821–24 as the second very energetic millisecond pulsar in a globular cluster and raises the question of whether these represent a separate class of objects that only form in regions of very high stellar density.},
doi = {10.1088/0004-637X/778/2/106},
journal = {Astrophysical Journal},
number = 2,
volume = 778,
place = {United States},
year = {2013},
month = {11}
}