PRECISE γ-RAY TIMING AND RADIO OBSERVATIONS OF 17 FERMI γ-RAY PULSARS

Abstract

We present precise phase-connected pulse timing solutions for 16 γ -ray-selected pulsars recently discovered using the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope plus one very faint radio pulsar (PSR J1124−5916) that is more effectively timed with the LAT. We describe the analysis techniques including a maximum likelihood method for determining pulse times of arrival from unbinned photon data. A major result of this work is improved position determinations, which are crucial for multiwavelength follow-up. For most of the pulsars, we overlay the timing localizations on X-ray images from Swift and describe the status of X-ray counterpart associations. We report glitches measured in PSRs J0007+7303, J1124−5916, and J1813−1246. We analyze a new 20 ks Chandra ACIS observation of PSR J0633+0632 that reveals an arcminute-scale X-ray nebula extending to the south of the pulsar. We were also able to precisely localize the X-ray point source counterpart to the pulsar and find a spectrum that can be described by an absorbed blackbody or neutron star atmosphere with a hard power-law component. Another Chandra ACIS image of PSR J1732−3131 reveals a faint X-ray point source at a location consistent with the timing position of the pulsar. Finally, we present a compilation of new and archival searches for radio pulsations from each of the γ -ray-selected pulsars as well as a new Parkes radio observation of PSR J1124−5916 to establish the γ -ray to radio phase offset.

ISM gas studies towards the TeV PWN HESS J1825−137 and northern region

“…However, the adjacent position of the molecular gas at v lsr = 60 − 80 km/s (with near/far distance d = 4.6/11.4 kpc) appears spatially consistent with the PWN scenario. The molecular cloud north of P2 indeed support the offset position of the pulsar (coincident with AX J1826.1−1257, see Ray et al 2011) with respect to the X-ray (Roberts et al 2007) and TeV emission. At these distances, ηγ would then rise to 1.5 × 10 −3 (d = 4.6 kpc) and 1.0×10 −2 (d = 11.4 kpc), more consistent with the canonical ηγ values.…”

“…1. Ray et al (2011) also discovered the radio quiet pulsar PSR J1826-1256 (P2 in Fig. 1) with a spin down luminosityĖSD = 3.6 × 10 36 erg s −1 , a period P = 100 ms and a characteristic age τc = 13 kyr and powering the PWN G018.5-0.4 observed in X-rays by Roberts et al (2007) .…”

Pulsar timing irregularities and the imprint of magnetic field evolution

“…If future observations (or a deeper analysis of archival data) increase the number of reliable measures of braking indices, and we can firmly establish at which age the transition from the purely diffusive to the oscillatory regime happens, there is coded information about the cooling history of neutron stars of potential interest to place constraints on the interior physics. In this respect, it is also important to mention that precise phase-connected timing solutions can also be performed in other bands, as has been recently done for 17 γ-ray-selected pulsars (Ray et al 2011), using the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope. This and other future high-energy missions can enlarge our data sample and improve the precision of our measurements.…”

X-ray follow-up observations of the twoγ-ray pulsars PSR J1459–6053 and PSR J1614–2230

“…This X-ray phasogram can be seen in Fig. 3 along with the γ-ray phasogram taken directly from Ray et al (2011). For comparison, the Notes.…”

“…The Fermi Large Area Telescope (LAT) has already identified more than ten times the number of pulsars detected with EGRET (e.g. Abdo et al 2010a;Ray et al 2011;Keith et al 2011) and has even detected many new γ-ray selected pulsars (e.g. Abdo et al 2009a).…”