IS CALVERA A GAMMA-RAY PULSAR?
- Astronomy Department, Columbia University, 550 West 120th Street, New York, NY 10027-6601 (United States)
Originally selected as a neutron star (NS) candidate in the ROSAT All-Sky Survey, 1RXS J141256.0+792204 ('Calvera') was discovered to be a 59 ms X-ray pulsar in a pair of XMM-Newton observations by Zane et al. Surprisingly, their claimed detection of this pulsar in Fermi {gamma}-ray data requires no period derivative, severely restricting its dipole magnetic field strength, spin-down luminosity, and distance to small values. This implies that the cooling age of Calvera is much younger than its characteristic spin-down age. If so, it could be a mildly recycled pulsar, or the first 'orphaned' central compact object (CCO). Here we show that the published Fermi ephemeris fails to align the pulse phases of the two X-ray observations with each other, which indicates that the Fermi detection is almost certainly spurious. Analysis of additional Fermi data also does not confirm the {gamma}-ray detection. This leaves the spin-down rate of Calvera less constrained, and its place among the families of NSs uncertain. It could still be either an ordinary pulsar, a mildly recycled pulsar, or an orphaned CCO.
- OSTI ID:
- 21562540
- Journal Information:
- Astrophysical Journal Letters, Vol. 736, Issue 1; Other Information: DOI: 10.1088/2041-8205/736/1/L3; ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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