A Search for Millisecond-pulsar Radio Emission from the Faint Quiescent Soft X-Ray Transient 1H 1905+000
Abstract
Transitional millisecond pulsars (tMSPs) switch between an accretion-powered state without radio pulsations and a rotation-powered state with radio pulsations. In the former state, tMSPs are X-ray bright, while in the latter state, they are X-ray dim. Soft X-ray transients (SXTs) undergo similar switches in X-ray, between “high” states with bright X-ray outbursts and “low” states of quiescence. The upper limit on the quiescent X-ray luminosity of SXT 1H 1905+000 suggests that its luminosity might be similar to that of the known tMSPs. A detection of radio pulsations would link SXTs more strongly with tMSPs; and thus, e.g., put stricter constraints on tMSP transitional timescales through the connection with the well-known SXT periods of quiescence. A nondetection allows us, based on the telescope sensitivity, to estimate how likely these sources are to pulsate in radio. Over a 10-year span, 2006-2015, we carried out targeted radio observations at 400/800 MHz with Arecibo, and searched for radio pulsations from the quiescent SXT 1H 1905+000. None of the observations have revealed radio pulsations from the targeted SXT. For a 1 ms pulsar, our flux density upper limit is 10.3 μJy. At an assumed distance of 10 kpc this translates to a pseudo-luminosity upper limit of 1.0 mJy kpc2, which makes our search complete to ∼85% of the known MSP population. Given the high sensitivity, and the generally large beaming fraction of millisecond pulsars, we conclude that SXT 1H 1905+000 is unlikely to emit in radio as a tMSP.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 2017
- DOI:
- 10.3847/1538-4357/aa696a
- arXiv:
- arXiv:1703.09491
- Bibcode:
- 2017ApJ...840....9M
- Keywords:
-
- pulsars: general;
- stars: individual: 1H 1905+000;
- stars: neutron;
- X-rays: binaries;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 8 pages, 5 figures, 3 tables, accepted for publication in the Astrophysical Journal