We searched for radio pulsars in 25 of the non-variable, unassociated sources in the Fermi LAT Bright Source List with the Green Bank Telescope at 820 MHz. We report the discovery of three radio and ...Delta *g-ray millisecond pulsars (MSPs) from a high Galactic latitude subset of these sources. All of the pulsars are in binary systems, which would have made them virtually impossible to detect in blind Delta *g-ray pulsation searches. They seem to be relatively normal, nearby (<=2 kpc) MSPs. These observations, in combination with the Fermi detection of Delta *g-rays from other known radio MSPs, imply that most, if not all, radio MSPs are efficient Delta *g-ray producers. The Delta *g-ray spectra of the pulsars are power law in nature with exponential cutoffs at a few GeV, as has been found with most other pulsars. The MSPs have all been detected as X-ray point sources. Their soft X-ray luminosities of ~1030-1031 erg s--1 are typical of the rare radio MSPs seen in X-rays.
We report the discovery of nine previously unknown gamma-ray pulsars in a blind search of data from the Fermi Large Area Telescope (LAT). The pulsars were found with a novel hierarchical search ...method originally developed for detecting continuous gravitational waves from rapidly rotating neutron stars. Designed to find isolated pulsars spinning at up to kHz frequencies, the new method is computationally efficient and incorporates several advances, including a metric-based gridding of the search parameter space (frequency, frequency derivative, and sky location) and the use of photon probability weights. The nine pulsars have spin frequencies between 3 and 12 Hz, and characteristic ages ranging from 17 kyr to 3 Myr. Two of them, PSRs J1803-2149 and J2111+ 4606, are young and energetic Galactic-plane pulsars (spin-down power above 6 x 10 super(35) erg s super(-1) and ages below 100 kyr). The seven remaining pulsars, PSRs J0106+4855, J0622+3749, J1620-4927, J1746-3239, J2028+3332, J2030+4415, and J2139+4716, are older and less energetic; two of them are located at higher Galactic latitudes (b > 10degrees). PSR J0106+4855 has the largest characteristic age (3 Myr) and the smallest surface magnetic field (2 x 10 super(11) G) of all LAT blind-search pulsars. PSR J2139+4716 has the lowest spin-down power (3 x 10 super(33) erg s super(-1)) among all non-recycled gamma-ray pulsars ever found. Despite extensive multi-frequency observations, only PSR JO 106+4855 has detectable pulsations in the radio band. The other eight pulsars belong to the increasing population of radio-quiet gamma-ray pulsars.
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 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.
The paper ‘Evidence for an intermediate-mass black hole in the globular cluster NGC 6624’ was published in MNRAS, 468, 2114 (2017). When estimating the model-dependent minimum mass of the ...intermediate-mass black hole (IMBH) of 60 000 M⊙ in Section 5, we used the separation of 0.15 pc for PSR J1823−3021C from the globular cluster centre, as given in Peuten et al. (2014, see table 2 therein). Unfortunately, this value is incorrect and the correct separation is 0.34 pc based on the position given in Table 1 (also see Lynch et al. 2012). This correct distance measurement changes the result presented in Fig. 9 in the published version, and the modified figure based on the positions given in Table 1 is appended here. Note that this does not affect any other results presented in the paper, in particular, the IMBH mass estimation obtained through orbital dynamics given in Section 4.
We have discovered five millisecond pulsars (MSPs) in a survey of 14 unidentified Fermi Large Area Telescope sources in the southern sky using the Parkes radio telescope. PSRs J0101-6422, J1514-4946, ...and J1902-5105 reside in binaries, while PSRs J1658-5324 and J1747-4036 are isolated. Using an ephemeris derived from timing observations of PSR J0101-6422 (P = 2.57 ms, DM = 12 pc cm super(-3)), we have detected gamma -ray pulsations and measured its proper motion. Its gamma -ray spectrum (a power law of Gamma = 0.9 with a cutoff at 1.6 GeV) and efficiency are typical of other MSPs, but its radio and gamma -ray light curves challenge simple geometric models of emission. The high success rate of this survey-enabled by selecting gamma -ray sources based on their detailed spectral characteristics-and other similarly successful searches indicate that a substantial fraction of the local population of MSPs may soon be known.
We announce the discovery of 1-100 GeV gamma-ray emission from the archetypal TeV pulsar wind nebula (PWN) HESS J1825--137 using 20 months of survey data from the Fermi-Large Area Telescope (LAT). ...The gamma-ray emission detected by the LAT is significantly spatially extended, with a best-fit rms extension of Delta *s = 056 ? 007 for an assumed Gaussian model. The 1-100 GeV LAT spectrum of this source is well described by a power law with a spectral index of 1.38 ? 0.12 ? 0.16 and an integral flux above 1 GeV of (6.50 ? 0.21 ? 3.90) X 10--9 cm--2 s--1. The first errors represent the statistical errors on the fit parameters, while the second ones are the systematic uncertainties. Detailed morphological and spectral analyses bring new constraints on the energetics and magnetic field of the PWN system. The spatial extent and hard spectrum of the GeV emission are consistent with the picture of an inverse Compton origin of the GeV-TeV emission in a cooling-limited nebula powered by the pulsar PSR J1826--1334.
We report the Fermi Large Area Telescope discovery of gamma-ray pulsations from the 22.7 ms pulsar A in the double pulsar system J0737−3039A/B. This is the first mildly recycled millisecond pulsar ...(MSP) detected in the GeV domain. The 2.7 s companion object PSR J0737−3039B is not detected in gamma rays. PSR J0737−3039A is a faint gamma-ray emitter, so that its spectral properties are only weakly constrained; however, its measured efficiency is typical of other MSPs. The two peaks of the gamma-ray light curve are separated by roughly half a rotation and are well offset from the radio and X-ray emission, suggesting that the GeV radiation originates in a distinct part of the magnetosphere from the other types of emission. From the modeling of the radio and the gamma-ray emission profiles and the analysis of radio polarization data, we constrain the magnetic inclination alpha and the viewing angle zeta to be close to 90 deg., which is consistent with independent studies of the radio emission from PSR J0737−3039A. A small misalignment angle between the pulsar's spin axis and the system's orbital axis is therefore favored, supporting the hypothesis that pulsar B was formed in a nearly symmetric supernova explosion as has been discussed in the literature already.
Aims. We have observed two newly detected γ-ray pulsars, PSR J1459−6053 and PSR J1614−2230, in the X-ray domain with XMM-Newton to try to enlarge the sample of pulsars for which multi-wavelength data ...exist. We use these data with the aim of understanding the pulsar emission mechanisms of these pulsars. Methods. We analysed the X-ray spectra to determine whether the emission emanates from the neutron star surface (thermal emission) or from the magnetosphere (non-thermal emission) and compared this to the region in the magnetosphere in which the γ-ray emission is generated. Furthermore, we compared the phase-folded X-ray lightcurves with those in the γ-ray and, where possible, radio domains, to elicit additional information on the emission sites. Results. J1459−6053 shows X-ray spectra that are best fitted with a power law model with a photon index \hbox{$\Gamma=2.10^{+1.24}_{-0.85}$}Γ=2.10-0.85+1.24. The γ-ray data suggest that either the slot gap or the outer gap model may be best to describe the emission from this pulsar. Analysis of the X-ray lightcurve folded on the γ-ray ephemeris shows modulation at the 3.7σ level in the 1.0−4.5 keV domain. Possible alignment of the main γ-ray and X-ray peaks also supports the interpretation that the emission in the two energy domains emanates from similar regions. The millisecond pulsar J1614−2230 exhibits an X-ray spectrum with a substantial thermal component, where the best-fitting spectral model is either two blackbodies, with \hbox{$kT=0.15^{+0.04}_{-0.04}$}kT=0.15-0.04+0.04 and 0.88\hbox{$^{+2.54}_{-0.54}$}+2.54-0.54 keV or a blackbody with similar temperature to the previous cooler component, \hbox{$kT=0.13^{+0.04}_{-0.02}$}kT=0.13-0.02+0.04 keV and a power law component with a photon index \hbox{$\Gamma=1.25^{+2.30}_{-1.75}$}Γ=1.25-1.75+2.30. The cooler blackbody component is likely to originate from the hot surface at the polar cap. Analysis of the X-ray lightcurve folded on the radio ephemeris shows modulation at the 4.0σ level in the 0.4−3.0 keV domain.
We report the discovery of the millisecond pulsar PSR J2043+1711 in a search of a Fermi Large Area Telescope (LAT) source with no known associations, with the Nancay Radio Telescope. The new pulsar, ...confirmed with the Green Bank Telescope, has a spin period of 2.38 ms, is relatively nearby (d approx. < 2 kpc) and is in a 1.48-d orbit around a low-mass companion, probably an He-type white dwarf. Using an ephemeris based on Arecibo, Nancay and Westerbork timing measurements, pulsed gamma-ray emission was detected in the data recorded by the Fermi LAT. The gamma-ray light curve and spectral properties are typical of other gamma-ray millisecond pulsars seen with Fermi. X-ray observations of the pulsar with Suzaku and the Swift X-ray Telescope yielded no detection. At 1.4 GHz, we observe strong flux density variations because of interstellar diffractive scintillation; however, a sharp peak can be observed at this frequency during bright scintillation states. At 327 MHz, the pulsar is detected with a much higher signal-to-noise ratio and its flux density is far more steady. However, at that frequency the Arecibo instrumentation cannot yet fully resolve the pulse profile. Despite that, our pulse time-of-arrival measurements have a post-fit residual rms of 2 micro s. This and the expected stability of this system have made PSR J2043+1711 one of the first new Fermi-selected millisecond pulsars to be added to pulsar gravitational wave timing arrays. It has also allowed a significant measurement of relativistic delays in the times of arrival of the pulses due to the curvature of space-time near the companion, but not yet with enough precision to derive useful masses for the pulsar and the companion. Nevertheless, a mass for the pulsar between 1.7 and 2.0 solar Mass can be derived if a standard millisecond pulsar formation model is assumed. In this paper, we also present a comprehensive summary of pulsar searches in Fermi LAT sources with the Nancay Radio Telescope to date.
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