Broadband pulsations from PSR B1821-24: Implications for emission models and the pulsar population of M28
We report a 5.4δ 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...
| Main Authors: | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , |
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| Format: | Journal Article |
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Institute of Physics Publishing
2013
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| Online Access: | http://hdl.handle.net/20.500.11937/26206 |
| _version_ | 1848751919752806400 |
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| author | Johnson, T. Guillemot, L. Kerr, M. Cognard, I. Ray, P. Wolff, M. Bégin, S. Janssen, G. Romani, R. Venter, C. Grove, J. Freire, P. Wood, M. Cheung, C. Casandjian, J. Stairs, I. Camilo, F. Espinoza, C. Ferrara, E. Harding, A. Johnston, S. Kramer, M. Lyne, A. Michelson, P. Ransom, S. Shannon, Ryan Smith, D. Stappers, B. Theureau, G. Thorsett, S. |
| author_facet | Johnson, T. Guillemot, L. Kerr, M. Cognard, I. Ray, P. Wolff, M. Bégin, S. Janssen, G. Romani, R. Venter, C. Grove, J. Freire, P. Wood, M. Cheung, C. Casandjian, J. Stairs, I. Camilo, F. Espinoza, C. Ferrara, E. Harding, A. Johnston, S. Kramer, M. Lyne, A. Michelson, P. Ransom, S. Shannon, Ryan Smith, D. Stappers, B. Theureau, G. Thorsett, S. |
| author_sort | Johnson, T. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | We report a 5.4δ 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. |
| first_indexed | 2025-11-14T08:00:23Z |
| format | Journal Article |
| id | curtin-20.500.11937-26206 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T08:00:23Z |
| publishDate | 2013 |
| publisher | Institute of Physics Publishing |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-262062017-09-13T15:26:24Z Broadband pulsations from PSR B1821-24: Implications for emission models and the pulsar population of M28 Johnson, T. Guillemot, L. Kerr, M. Cognard, I. Ray, P. Wolff, M. Bégin, S. Janssen, G. Romani, R. Venter, C. Grove, J. Freire, P. Wood, M. Cheung, C. Casandjian, J. Stairs, I. Camilo, F. Espinoza, C. Ferrara, E. Harding, A. Johnston, S. Kramer, M. Lyne, A. Michelson, P. Ransom, S. Shannon, Ryan Smith, D. Stappers, B. Theureau, G. Thorsett, S. We report a 5.4δ 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. 2013 Journal Article http://hdl.handle.net/20.500.11937/26206 10.1088/0004-637X/778/2/106 Institute of Physics Publishing unknown |
| spellingShingle | Johnson, T. Guillemot, L. Kerr, M. Cognard, I. Ray, P. Wolff, M. Bégin, S. Janssen, G. Romani, R. Venter, C. Grove, J. Freire, P. Wood, M. Cheung, C. Casandjian, J. Stairs, I. Camilo, F. Espinoza, C. Ferrara, E. Harding, A. Johnston, S. Kramer, M. Lyne, A. Michelson, P. Ransom, S. Shannon, Ryan Smith, D. Stappers, B. Theureau, G. Thorsett, S. Broadband pulsations from PSR B1821-24: Implications for emission models and the pulsar population of M28 |
| title | Broadband pulsations from PSR B1821-24: Implications for emission models and the pulsar population of M28 |
| title_full | Broadband pulsations from PSR B1821-24: Implications for emission models and the pulsar population of M28 |
| title_fullStr | Broadband pulsations from PSR B1821-24: Implications for emission models and the pulsar population of M28 |
| title_full_unstemmed | Broadband pulsations from PSR B1821-24: Implications for emission models and the pulsar population of M28 |
| title_short | Broadband pulsations from PSR B1821-24: Implications for emission models and the pulsar population of M28 |
| title_sort | broadband pulsations from psr b1821-24: implications for emission models and the pulsar population of m28 |
| url | http://hdl.handle.net/20.500.11937/26206 |