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Title: Discovery of millisecond pulsars in radio searches of southern Fermi Large Area Telescope sources

Abstract

Using the Parkes Radio Telescope, we have carried out deep observations of 11 unassociated gamma-ray sources. Periodicity searches of these data have discovered two millisecond pulsars, PSR J1103–5403 (1FGL J1103.9–5355) and PSR J2241–5236 (1FGL J2241.9–5236), and a long-period pulsar, PSR J1604–44 (1FGL J1604.7–4443). In addition, we searched for but did not detect any radio pulsations from six gamma-ray pulsars discovered by the Fermi satellite to a level of ~0.04 mJy (for pulsars with a 10 per cent duty cycle). The timing of the millisecond pulsar PSR J1103–5403 has shown that its position is 9 arcmin from the centroid of the gamma-ray source. Since these observations were carried out, independent evidence has shown that 1FGL J1103.9–5355 is associated with the flat spectrum radio source PKS 1101–536. It appears certain that the pulsar is not associated with the gamma-ray source, despite the seemingly low probability of a chance detection of a radio millisecond pulsar. We consider that PSR J1604–44 is a chance discovery of a weak, long-period pulsar and is unlikely to be associated with 1FGL J1604.7–4443. PSR J2241–5236 has a spin period of 2.2 ms and orbits a very low mass companion with a 3.5-h orbital period. The relatively high fluxmore » density and low dispersion measure of PSR J2241–5236 make it an excellent candidate for high precision timing experiments. The gamma rays of 1FGL J2241.9–5236 have a spectrum that is well modelled by a power law with an exponential cut-off, and phase binning with the radio ephemeris results in a multipeaked gamma-ray pulse profile. Furthermore, observations with Chandra have identified a coincident X-ray source within 0.1 arcsec of the position of the pulsar obtained by radio timing.« less

Authors:
 [1];  [1];  [2];  [3];  [4];  [5];  [6];  [7];  [8];  [8];  [9];  [10];  [10];  [3];  [11];  [12];  [13];  [12];  [14];  [3] more »;  [15];  [2] « less
  1. Australia Telescope National Facility, Epping, NSW (Australia)
  2. Naval Research Lab., Washington, D.C. (United States)
  3. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States)
  4. Univ. of California, Santa Cruz, CA (United States)
  5. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); Univ. of Maryland Baltimore County (UMBC), Baltimore, MD (United States)
  6. Univ. of California, Santa Cruz, CA (United States); INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica, Milano (Italy); Univ. di Pavia, Pavia (Italy)
  7. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); Univ. of Maryland, College Park, MD (United States)
  8. National Academy of Sciences, Washington, D.C. (United States); Naval Research Lab., Washington, D.C. (United States)
  9. Columbia Univ., New York, NY (United States)
  10. Max-Planck-Institut fur Radioastronomie, Bonn (Germany)
  11. Max-Planck-Institut fur Radioastronomie, Bonn (Germany); The Univ. of Manchester, Manchester (United Kingdom)
  12. Stanford Univ., Stanford, CA (United States)
  13. National Radio Astronomy Observatory (NRAO), Charlottesville, VA (United States)
  14. Univ. Bordeaux, Gradignan (France)
  15. The Univ. of Manchester, Manchester (United Kingdom)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1357255
Grant/Contract Number:
AC02-76SF00515
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Monthly Notices of the Royal Astronomical Society
Additional Journal Information:
Journal Volume: 414; Journal Issue: 2; Journal ID: ISSN 0035-8711
Publisher:
Royal Astronomical Society
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; pulsars: general; pulsars: individual: J2241−5236

Citation Formats

Keith, M. J., Johnston, S., Ray, P. S., Ferrara, E. C., Saz Parkinson, P. M., Çelik, Ö., Belfiore, A., Donato, D., Cheung, C. C., Abdo, A. A., Camilo, F., Freire, P. C. C., Guillemot, L., Harding, A. K., Kramer, M., Michelson, P. F., Ransom, S. M., Romani, R. W., Smith, D. A., Thompson, D. J., Weltevrede, P., and Wood, K. S.. Discovery of millisecond pulsars in radio searches of southern Fermi Large Area Telescope sources. United States: N. p., 2011. Web. doi:10.1111/j.1365-2966.2011.18464.x.
Keith, M. J., Johnston, S., Ray, P. S., Ferrara, E. C., Saz Parkinson, P. M., Çelik, Ö., Belfiore, A., Donato, D., Cheung, C. C., Abdo, A. A., Camilo, F., Freire, P. C. C., Guillemot, L., Harding, A. K., Kramer, M., Michelson, P. F., Ransom, S. M., Romani, R. W., Smith, D. A., Thompson, D. J., Weltevrede, P., & Wood, K. S.. Discovery of millisecond pulsars in radio searches of southern Fermi Large Area Telescope sources. United States. doi:10.1111/j.1365-2966.2011.18464.x.
Keith, M. J., Johnston, S., Ray, P. S., Ferrara, E. C., Saz Parkinson, P. M., Çelik, Ö., Belfiore, A., Donato, D., Cheung, C. C., Abdo, A. A., Camilo, F., Freire, P. C. C., Guillemot, L., Harding, A. K., Kramer, M., Michelson, P. F., Ransom, S. M., Romani, R. W., Smith, D. A., Thompson, D. J., Weltevrede, P., and Wood, K. S.. Wed . "Discovery of millisecond pulsars in radio searches of southern Fermi Large Area Telescope sources". United States. doi:10.1111/j.1365-2966.2011.18464.x. https://www.osti.gov/servlets/purl/1357255.
@article{osti_1357255,
title = {Discovery of millisecond pulsars in radio searches of southern Fermi Large Area Telescope sources},
author = {Keith, M. J. and Johnston, S. and Ray, P. S. and Ferrara, E. C. and Saz Parkinson, P. M. and Çelik, Ö. and Belfiore, A. and Donato, D. and Cheung, C. C. and Abdo, A. A. and Camilo, F. and Freire, P. C. C. and Guillemot, L. and Harding, A. K. and Kramer, M. and Michelson, P. F. and Ransom, S. M. and Romani, R. W. and Smith, D. A. and Thompson, D. J. and Weltevrede, P. and Wood, K. S.},
abstractNote = {Using the Parkes Radio Telescope, we have carried out deep observations of 11 unassociated gamma-ray sources. Periodicity searches of these data have discovered two millisecond pulsars, PSR J1103–5403 (1FGL J1103.9–5355) and PSR J2241–5236 (1FGL J2241.9–5236), and a long-period pulsar, PSR J1604–44 (1FGL J1604.7–4443). In addition, we searched for but did not detect any radio pulsations from six gamma-ray pulsars discovered by the Fermi satellite to a level of ~0.04 mJy (for pulsars with a 10 per cent duty cycle). The timing of the millisecond pulsar PSR J1103–5403 has shown that its position is 9 arcmin from the centroid of the gamma-ray source. Since these observations were carried out, independent evidence has shown that 1FGL J1103.9–5355 is associated with the flat spectrum radio source PKS 1101–536. It appears certain that the pulsar is not associated with the gamma-ray source, despite the seemingly low probability of a chance detection of a radio millisecond pulsar. We consider that PSR J1604–44 is a chance discovery of a weak, long-period pulsar and is unlikely to be associated with 1FGL J1604.7–4443. PSR J2241–5236 has a spin period of 2.2 ms and orbits a very low mass companion with a 3.5-h orbital period. The relatively high flux density and low dispersion measure of PSR J2241–5236 make it an excellent candidate for high precision timing experiments. The gamma rays of 1FGL J2241.9–5236 have a spectrum that is well modelled by a power law with an exponential cut-off, and phase binning with the radio ephemeris results in a multipeaked gamma-ray pulse profile. Furthermore, observations with Chandra have identified a coincident X-ray source within 0.1 arcsec of the position of the pulsar obtained by radio timing.},
doi = {10.1111/j.1365-2966.2011.18464.x},
journal = {Monthly Notices of the Royal Astronomical Society},
number = 2,
volume = 414,
place = {United States},
year = {Wed Jun 08 00:00:00 EDT 2011},
month = {Wed Jun 08 00:00:00 EDT 2011}
}

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  • Here, we report the discovery of two millisecond pulsars in a search for radio pulsations at the positions of Fermi-Large Area Telescope sources with no previously known counterparts, using the Nançay Radio Telescope. The two millisecond pulsars, PSRs J2017+0603 and J2302+4442, have rotational periods of 2.896 and 5.192 ms and are both in binary systems with low-eccentricity orbits and orbital periods of 2.2 and 125.9 days, respectively, suggesting long recycling processes. Gamma-ray pulsations were subsequently detected for both objects, indicating that they power the associated Fermi sources in which they were found. The gamma-ray light curves and spectral properties aremore » similar to those of previously detected gamma-ray millisecond pulsars. Detailed modeling of the observed radio and gamma-ray light curves shows that the gamma-ray emission seems to originate at high altitudes in their magnetospheres. Additionally, X-ray observations revealed the presence of an X-ray source at the position of PSR J2302+4442, consistent with thermal emission from a neutron star. These discoveries along with the numerous detections of radio-loud millisecond pulsars in gamma rays suggest that many Fermi sources with no known counterpart could be unknown millisecond pulsars.« less
  • In this work, we report on the discovery of gamma-ray pulsations from five millisecond pulsars (MSPs) using the Fermi Large Area Telescope (LAT) and timing ephemerides provided by various radio observatories. We also present confirmation of the gamma-ray pulsations from a sixth source, PSR J2051-0827. Five of these six MSPs are in binary systems: PSRs J1713+0747, J1741+1351, J1600-3053 and the two black widow binary pulsars PSRs J0610-2100 and J2051-0827. The only isolated MSP is the nearby PSR J1024-0719, which is also known to emit X-rays. We present X-ray observations in the direction of PSRs J1600-3053 and J2051-0827. While PSR J2051-0827more » is firmly detected, we can only give upper limits for the X-ray flux of PSR J1600-3053. There are no dedicated X-ray observations available for the other three objects. The MSPs mentioned above, together with most of the MSPs detected by Fermi, are used to put together a sample of 30 gamma-ray MSPs. This sample is used to study the morphology and phase connection of radio and gamma-ray pulse profiles. We show that MSPs with pulsed gamma-ray emission which is phase-aligned with the radio emission present the steepest radio spectra and the largest magnetic fields at the light cylinder among all MSPs. Also, we observe a trend towards very low, or undetectable, radio linear polarization levels. These properties could be attributed to caustic radio emission produced at a range of different altitudes in the magnetosphere. In conclusion, we note that most of these characteristics are also observed in the Crab pulsar, the only other radio pulsar known to exhibit phase-aligned radio and gamma-ray emission.« less
  • We report the discovery of two millisecond pulsars in a search for radio pulsations at the positions of Fermi-Large Area Telescope sources with no previously known counterparts, using the Nancay Radio Telescope. The two millisecond pulsars, PSRs J2017+0603 and J2302+4442, have rotational periods of 2.896 and 5.192 ms and are both in binary systems with low-eccentricity orbits and orbital periods of 2.2 and 125.9 days, respectively, suggesting long recycling processes. Gamma-ray pulsations were subsequently detected for both objects, indicating that they power the associated Fermi sources in which they were found. The gamma-ray light curves and spectral properties are similarmore » to those of previously detected gamma-ray millisecond pulsars. Detailed modeling of the observed radio and gamma-ray light curves shows that the gamma-ray emission seems to originate at high altitudes in their magnetospheres. Additionally, X-ray observations revealed the presence of an X-ray source at the position of PSR J2302+4442, consistent with thermal emission from a neutron star. These discoveries along with the numerous detections of radio-loud millisecond pulsars in gamma rays suggest that many Fermi sources with no known counterpart could be unknown millisecond pulsars.« less
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  • We have discovered six radio millisecond pulsars (MSPs) in a search with the Arecibo telescope of 34 unidentified gamma-ray sources from the Fermi Large Area Telescope (LAT) 4-year point source catalog. Among the 34 sources, we also detected two MSPs previously discovered elsewhere. Each source was observed at a center frequency of 327 MHz, typically at three epochs with individual integration times of 15 minutes. The new MSP spin periods range from 1.99 to 4.66 ms. Five of the six pulsars are in interacting compact binaries (period ≤ 8.1 hr), while the sixth is a more typical neutron star-white dwarfmore » binary with an 83-day orbital period. This is a higher proportion of interacting binaries than for equivalent Fermi-LAT searches elsewhere. The reason is that Arecibo’s large gain afforded us the opportunity to limit integration times to 15 minutes, which significantly increased our sensitivity to these highly accelerated systems. Seventeen of the remaining 26 gamma-ray sources are still categorized as strong MSP candidates, and will be re-searched.« less