Abstract
We have analysed archival HST/WFPC2 images in both the F555W & F814W bands of the core field of the globular cluster M 28 in an attempt to identify the optical counterpart of the magnetospherically active millisecond pulsar PSR B1821-24. Examination of the radio derived error circle yielded several potential candidates, down to a magnitude of V ∼ 24.5 (V0 ∼ 23.0). Each were further investigated, both in the context of the CMD of M 28, and also with regard to phenomenological models of pulsar magnetospheric emission. The latter was based on both luminosity-spindown correlations and known spectral flux density behaviour in this regime from the small population of optical pulsars observed to date. None of the potential candidates exhibited emission expected from a magnetospherically active pulsar. The fact that the magnetic field & spin coupling for PSR B1821-24 is of a similar magnitude to that of the Crab pulsar in the vicinity of the light cylinder has suggested that the millisecond pulsar may well be an efficient nonthermal emitter. ASCA's detection of a strong synchrotron-dominated X-ray pulse fraction encourages such a viewpoint. We argue that only future dedicated 2-d high speed photometry observations of the radio error-circle can finally resolve this matter.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 198-204 |
| Number of pages | 7 |
| Journal | Astronomy and Astrophysics |
| Volume | 371 |
| Issue number | 1 |
| State | Published - May 2001 |
| Externally published | Yes |
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Keywords
- Astrometry
- Globular clusters: general
- Globular clusters: individual M 28/NGC 6626
- Pulsars: general
- Pulsars: individual PSR B1821-24
- Techniques: image processing
ASJC Scopus subject areas
- Space and Planetary Science
Cite this
A search for the optical counterpart to PSR B1821-24 in M 28. / Golden, A.; Butler, R. F.; Shearer, A.
In: Astronomy and Astrophysics, Vol. 371, No. 1, 05.2001, p. 198-204.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - A search for the optical counterpart to PSR B1821-24 in M 28
AU - Golden, A.
AU - Butler, R. F.
AU - Shearer, A.
PY - 2001/5
Y1 - 2001/5
N2 - We have analysed archival HST/WFPC2 images in both the F555W & F814W bands of the core field of the globular cluster M 28 in an attempt to identify the optical counterpart of the magnetospherically active millisecond pulsar PSR B1821-24. Examination of the radio derived error circle yielded several potential candidates, down to a magnitude of V ∼ 24.5 (V0 ∼ 23.0). Each were further investigated, both in the context of the CMD of M 28, and also with regard to phenomenological models of pulsar magnetospheric emission. The latter was based on both luminosity-spindown correlations and known spectral flux density behaviour in this regime from the small population of optical pulsars observed to date. None of the potential candidates exhibited emission expected from a magnetospherically active pulsar. The fact that the magnetic field & spin coupling for PSR B1821-24 is of a similar magnitude to that of the Crab pulsar in the vicinity of the light cylinder has suggested that the millisecond pulsar may well be an efficient nonthermal emitter. ASCA's detection of a strong synchrotron-dominated X-ray pulse fraction encourages such a viewpoint. We argue that only future dedicated 2-d high speed photometry observations of the radio error-circle can finally resolve this matter.
AB - We have analysed archival HST/WFPC2 images in both the F555W & F814W bands of the core field of the globular cluster M 28 in an attempt to identify the optical counterpart of the magnetospherically active millisecond pulsar PSR B1821-24. Examination of the radio derived error circle yielded several potential candidates, down to a magnitude of V ∼ 24.5 (V0 ∼ 23.0). Each were further investigated, both in the context of the CMD of M 28, and also with regard to phenomenological models of pulsar magnetospheric emission. The latter was based on both luminosity-spindown correlations and known spectral flux density behaviour in this regime from the small population of optical pulsars observed to date. None of the potential candidates exhibited emission expected from a magnetospherically active pulsar. The fact that the magnetic field & spin coupling for PSR B1821-24 is of a similar magnitude to that of the Crab pulsar in the vicinity of the light cylinder has suggested that the millisecond pulsar may well be an efficient nonthermal emitter. ASCA's detection of a strong synchrotron-dominated X-ray pulse fraction encourages such a viewpoint. We argue that only future dedicated 2-d high speed photometry observations of the radio error-circle can finally resolve this matter.
KW - Astrometry
KW - Globular clusters: general
KW - Globular clusters: individual M 28/NGC 6626
KW - Pulsars: general
KW - Pulsars: individual PSR B1821-24
KW - Techniques: image processing
UR - http://www.scopus.com/inward/record.url?scp=0035325478&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0035325478&partnerID=8YFLogxK
M3 - Article
AN - SCOPUS:0035325478
VL - 371
SP - 198
EP - 204
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
SN - 0004-6361
IS - 1
ER -