Pulsar Results with the Fermi Large Area Telescope
Paul S. Ray, Pablo M. Saz Parkinson
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21 pages, 9 figures, to appear in Proceedings of ICREA Workshop on The High-Energy Emission from Pulsars and their Systems, Sant Cugat, Spain, 2010 April 12-16 (Springer)
The launch of the Fermi Gamma-ray Space Telescope has heralded a new era in the study of gamma-ray pulsars. The population of confirmed gamma-ray pulsars has gone from 6-7 to more than 60, and the superb sensitivity of the Large Area Telescope (LAT) on Fermi has allowed the detailed study of their spectra and light curves. Twenty-four of these pulsars were discovered in blind searches of the gamma-ray data, and twenty-one of these are, at present, radio quiet, despite deep radio follow-up observations. In addition, millisecond pulsars have been confirmed as a class of gamma-ray emitters, both individually and collectively in globular clusters. Recently, radio searches in the direction of LAT sources with no likely counterparts have been highly productive, leading to the discovery of a large number of new millisecond pulsars. Taken together, these discoveries promise a great improvement in the understanding of the gamma-ray emission properties and Galactic population of pulsars. We summarize some of the results stemming from these newly-detected pulsars and their timing and multi-wavelength follow-up observations.
Over the past 13 years, the Parkes radio telescope has observed a large number of pulsars using digital filterbank backends with high time and frequency resolution and the capability for Stokes recording. Here we use archival data to present polarimetry data at an observing frequency of 1.4 GHz for 600 pulsars with spin-periods ranging from 0.036 to 8.5 s. We comment briefly on some of the statistical implications from the data and highlight the differences between pulsars with high and low spin-down energy. The dataset, images and table of properties for all 600 pulsars are made available in …
In the last few years, the Fermi-LAT telescope has discovered over a 100 pulsars at energies above 100 MeV, increasing the number of known gamma-ray pulsars by an order of magnitude. In parallel, imaging Cherenkov telescopes, such as MAGIC and VERITAS, have detected for the first time VHE pulsed gamma-rays from the Crab pulsar. Such detections have revealed that the Crab VHE spectrum follows a power-law up to at least 400 GeV, challenging most theoretical models, and opening wide possibilities of detecting more pulsars from the ground with the future Cherenkov Telescope Array (CTA). In this co…
Around 160 gamma-ray pulsars were discovered by the Fermi Large Area Telescope (LAT) since 2008. The most energetic of them, 12 objects with emission above 25 GeV, are suitable candidates for the detection with the current and future Imaging Atmospheric Cherenkov Telescopes above few tens of GeV. We perform an analysis of the Fermi-LAT data of these high-energy pulsars in order to determine if such objects can be detected with the Cherenkov Telescope Array (CTA). Our goal is to forecast the significance of their point source detection with CTA. We analyze 5 years of the Fermi-LAT data fitting …
This catalog summarizes 117 high-confidence > 0.1 GeV gamma-ray pulsar detections using three years of data acquired by the Large Area Telescope (LAT) on the Fermi satellite. Half are neutron stars discovered using LAT data, through periodicity searches in gamma-ray and radio data around LAT unassociated source positions. The 117 pulsars are evenly divided into three groups: millisecond pulsars, young radio-loud pulsars, and young radio-quiet pulsars. We characterize the pulse profiles and energy spectra and derive luminosities when distance information exists. Spectral analysis of the off-pea…
We have used the unique low frequency sensitivity of the Large Phased Array radio telescope of Pushchino Radio Astronomy Observatory to collect dataset of the single pulse observations of second period pulsars of the Northern hemisphere. During observational sessions of 2011 - 2017 yrs. We have collected data on 71 pulsars at 111 MHz frequency using digital pulsar receiver. We have discovered Giant Radio Pulses (GRP) from pulsars B0301+09 and B1237+25, and confirmed early reported generation of anomalously strong (probable giant) pulses from B1133+16 on statistically significant dataset. Data …
Our paper presents the results of the second census of pulsars in decametre wave range at UTR-2 radio telescope. Over the past ten years, the number of discovered nearby pulsars in the world has doubled, which has made it urgent to search for a low-frequency radio emission from newly discovered sources. To increase this census sensitivity, the integration time was doubled compared with the first census of 2010-2013. As a result, the decametre radio emission of 20 pulsars was detected, their flux densities and the shape of pulses were obtained. The dispersion measure for 10 pulsars and the rota…
We report on observations of the Crab pulsar with the MAGIC telescopes. Our data were taken in both monoscopic (> 25GeV) and stereoscopic (> 50GeV) observation modes. Two peaks were detected with both modes and phase-resolved energy spectra were calculated. By comparing with Fermi- LAT measurements, we find that the energy spectrum of the Crab pulsar does not follow a power law with an exponential cutoff, but has an additional hard component, extending up to at least 400 GeV. This suggests that the emission above 25 GeV is not dominated by curvature radiation, as suggested in the standard scen…
Globular clusters are known to host an unusually large population of millisecond pulsar when compared to the Galactic disk. This is thanks to the high rate of dynamical encounters occurring in the clusters that can create the conditions to efficiently recycle neutron stars into millisecond pulsars. The result is a rich population of pulsars with properties and companions difficult or impossible to replicate in the Galactic disk. For these reasons, globular clusters have been and still are a prime target of searches for new and exciting pulsars. Because of their large distances, the limiting fa…
The Fermi Large Area Telescope (LAT) data have confirmed the pulsed emission from all six high-confidence gamma-ray pulsars previously known from the EGRET observations. We report results obtained from the analysis of 13 months of LAT data for three of these pulsars (PSR J1057-5226, PSR J1709-4429, and PSR J1952+3252) each of which had some unique feature among the EGRET pulsars. The excellent sensitivity of LAT allows more detailed analysis of the evolution of the pulse profile with energy and also of the variation of the spectral shape with phase. We measure the cutoff energy of the pulsed e…
The Vela supernova remnant is the closest supernova remnant to Earth containing an active pulsar, the Vela pulsar (PSR B0833-45). This pulsar is the archetype of the middle-aged pulsar class and powers a bright pulsar wind nebula (PWN), Vela-X, spanning a region of 2° x 3° south of the pulsar and observed in the radio, X-ray and very high energy gamma-ray domains. The detection of the Vela-X PWN by the Fermi Large Area Telescope (LAT) was reported in the first year of the mission. Subsequently, we have re-investigated this complex region and performed a detailed morphological and spectral anal…
The Green Bank Telescope (GBT) is the largest fully steerable radio telescope in the world and is one of our greatest tools for discovering and studying radio pulsars. Over the last decade, the GBT has successfully found over 100 new pulsars through large-area surveys. Here I discuss the two most recent---the GBT 350 MHz Drift-scan survey and the Green Bank North Celestial Cap survey. The primary science goal of both surveys is to find interesting individual pulsars, including young pulsars, rotating radio transients, exotic binary systems, and especially bright millisecond pulsars (MSPs) suit…
We have completed a 350 MHz drift scan survey using the Robert C. Byrd Green Bank Telescope with the goal of finding new radio pulsars, especially millisecond pulsars that can be timed to high precision. This survey covered ~10300 square degrees and all of the data have now been fully processed. We have discovered a total of 31 new pulsars, seven of which are recycled pulsars. A companion paper by Boyles et al. (2012) describes the survey strategy, sky coverage, and instrumental set-up, and presents timing solutions for the first 13 pulsars. Here we describe the data analysis pipeline, survey …
Context: GeV gamma-ray pulsations from over 140 pulsars have been characterized using the Fermi Large Area Telescope, enabling improved understanding of the emission regions within the neutron star magnetospheres, and the contributions of pulsars to high energy electrons and diffuse gamma rays in the Milky Way. The first gamma-ray pulsars to be detected were the most intense and/or those with narrow pulses. Aims: As the Fermi mission progresses, progressively fainter objects can be studied. In addition to more distant pulsars (thus probing a larger volume of the Galaxy), or ones in high backgr…
We report the detection of high energy gamma-ray emission from the young and energetic pulsar PSR B1509$-$58 and its pulsar wind nebula (PWN) in the composite supernova remnant SNR G320.4-1.2 (aka MSH 15-52). Using 1 year of survey data with the Fermi-Large Area Telescope (LAT), we detected pulsations from PSR B1509-58 up to 1 GeV and extended gamma-ray emission above 1 GeV spatially coincident with the PWN. The pulsar light curve presents two peaks offset from the radio peak by phases 0.96 $\pm$ 0.01 and 0.33 $\pm$ 0.02. New constraining upper limits on the pulsar emission are derived below 1…
We present simulations of the very high energy (VHE) gamma-ray light curve of the Crab pulsar as observed by the Cherenkov Telescope Array (CTA). The CTA pulse profile of the Crab pulsar is simulated with the specific goal of determining the accuracy of the position of the interpulse. We fit the pulse shape obtained by the MAGIC telescope with a three-Gaussian template and rescale it to account for the different CTA instrumental and observational configurations. Simulations are performed for different configurations of CTA and for the ASTRI mini-array. The northern CTA configuration will provi…
We present a summary of the Fermi Pulsar Search Consortium (PSC), an international collaboration of radio astronomers and members of the Large Area Telescope (LAT) collaboration, whose goal is to organize radio follow-up observations of Fermi pulsars and pulsar candidates among the LAT gamma-ray source population. The PSC includes pulsar observers with expertise using the world's largest radio telescopes that together cover the full sky. We have performed very deep observations of all 35 pulsars discovered in blind frequency searches of the LAT data, resulting in the discovery of radio pulsati…
We present results of optical-UV observations of the 200 Myr old rotation-powered radio pulsar J0108$-$1431 with the Hubble Space Telescope. We found a putative candidate for the far-UV (FUV) pulsar counterpart, with the flux density $f_ν= 9.0\pm 3.2$ nJy at $λ= 1528$ Å. The pulsar was not detected, however, at longer wavelengths, with $3σ$ upper limits of 52, 37, and 87 nJy at $λ=$ 4326, 3355, and 2366 Å, respectively. Assuming that the pulsar counterpart was indeed detected in FUV, and the previously reported marginal $U$ and $B$ detections with the Very Large Telescope were real, the optica…
We report on the observations of the Crab pulsar with the MAGIC telesopes. Data were taken both in the mono-mode ($>25$ GeV) and in the stereo-mode ($>50$ GeV). Clear signals from the two peaks were detected with both modes and the phase resolved energy spectra were calculated. By comparing with the measurements done by Fermi-LAT, we found that the energy spectra of the Crab pulsar does not follow a power law with an exponential cutoff, but that it extends as a power law after the break at around 5 GeV. This suggests that the emission above 25 GeV is not dominated by the curvatura radiation, w…
The Fermi Large Area Telescope (LAT) has been scanning the gamma-ray sky since 2008. The number of pulsars detected by the LAT now exceeds 200, making them by far the largest class of Galactic gamma-ray emitters. I discuss some of the latest pulsar discoveries made by the LAT, in particular those made since the release of the Pass 8 data.
Many energetic gamma-ray pulsars discovered by Fermi are promising candidates for optical follow-ups. We present the results of the first deep optical observations of the two Vela-like Fermi pulsars PSR J1357-6429 and PSR J1048-5832 performed with the VLT. However, they have not been detected down to V~27 and V~27.6, respectively (3 sigma). These upper limits suggest an efficiency in converting spin-down power into optical luminosity < 7x10d-7 and <6x10d-6, respectively, lower than the Crab pulsar and, possibly, more compatible with the spin-down age of these two pulsars.
The recently identified source class of pulsar haloes may be numerous and bright enough in the TeV range to constitute a large fraction of the sources that will be observed with the Cherenkov Telescope Array (CTA). In this work, we quantify the prospects for detecting and characterizing pulsar haloes in observations of the projected Galactic Plane Survey (GPS), using a simple phenomenological diffusion model for individual pulsar haloes and their population in the Milky Way. Our ability to uncover pulsar haloes and constrain their main physical parameters in the CTA GPS is assessed in the fram…
Nuclei, if lifted into the radiation zone of a weak axisymmetric pulsar, are accelerated to quasi-monoenergetic spectrum, with more than half of the nuclear luminosity emitted nearly monoenergetically, at the energy E approximately = 4Ze(L/c)^(1/2), where L is the spin-down power. With a number of (not obviously wrong) assumptions, this turns Fermi (-like) weak pulsars into prominent accelerators at energies near the cosmic ray knee. The main uncertainty is purely theoretical: one needs to understand if nuclei are major positive charge carries in some weak pulsar magnetospheres.
The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) project has the primary goal of detecting and characterizing low-frequency gravitational waves through high-precision pulsar timing. The mitigation of interstellar effects is crucial to achieve the necessary precision for gravitational wave detection. Effects like dispersion and scattering are more influential at lower observing frequencies, with the variation of these quantities over week-month timescales requiring high-cadence multi-frequency observations for pulsar timing projects. In this work, we utilize the dual-…
Pulsar Wind Nebulae (PWNe) represent the most numerous population of TeV sources in our Galaxy. These sources, some of which emit very-high-energy (VHE) gamma-rays, are believed to be related to the young and energetic pulsars that power highly magnetized nebulae (a few $μ$G to a few hundred $μ$G). In this scenario, particles are accelerated to VHE along their expansion into the pulsar surroundings, or at the shocks produced in collisions of the winds with the surrounding medium. Those energetic pulsars can be traced using observations with the Fermi-LAT detector. The MAGIC Collaboration has c…
The large number of ongoing surveys for pulsars and transients at various radio observatories is motivated by the science obtained from these sources. Timing and polarisation analysis of relativistic binaries can place strong constraints on theories of gravity. The observation of a growing number of millisecond pulsars (MSPs) spread over the celestial sphere may allow the detection of a stochastic gravitational wave background arising from supermassive black hole binaries. A more complete sample of young pulsars improves our knowledge of neutron star birth and evolution. Transients such as fas…
Due to the low gamma-ray fluxes from pulsars above 50 GeV and the small collecting area of space-based telescopes, the gamma-ray emission discovered by the Fermi-LAT in $\sim$150 pulsars is largely unexplored at these energies. In this regime, the uncertainties on the spectral data points and/or the constraints from upper-limits are not sufficient to provide robust tests of competing emission models in individual pulsars. The discovery of power-law-type emission from the Crab pulsar at energies exceeding 100 GeV provides a compelling justification for exploration of other pulsars at these ener…
The dramatic increase in the number of known gamma-ray pulsars since the launch of the Fermi Gamma-ray Space Telescope (formerly GLAST) offers the first opportunity to study a population of these high-energy objects. This catalog summarizes 46 high-confidence pulsed detections using the first six months of data taken by the Large Area Telescope (LAT), Fermi's main instrument. Sixteen previously unknown pulsars were discovered by searching for pulsed signals at the positions of bright gamma-ray sources seen with the LAT, or at the positions of objects suspected to be neutron stars based on obse…
2009 has been an extraordinary year for gamma-ray pulsar astronomy and 2010 promises to be equally good. Not only have we registered an extraordinary increase in the number of pulsars detected in gamma rays, but we have also witnessed the birth of new sub-families: first of all, the radio-quiet gamma pulsars and later an ever growing number of millisecond pulsars, a real surprise. We started with a sample of 7 gamma-ray emitting neutron stars (6 radio pulsars and Geminga) and now the Fermi-LAT harvest encompasses 24 "Geminga-like" new gamma-ray pulsars, a dozen millisecond pulsars and about th…
The Large Area Telescope (LAT), Fermi's main instrument, is providing a new view of the local energetic pulsar population. In addition to identifying a pulsar origin of a large fraction of the bright unidentified Galactic EGRET sources, the LAT results provide a great opportunity to study a sizable population of high-energy pulsars. Correlations of their physical properties, such as the trend of the luminosity versus the rotational energy loss rate, help identify global features of the gamma-ray pulsar population. Several lines of evidence, including the light curve and spectral features, sugg…
We present an overview of precise pulsar timing using data from the Large Area Telescope (LAT) on Fermi. We describe the analysis techniques including a maximum likelihood method for determining pulse times of arrival from unbinned photon data. In addition to determining the spindown behavior of the pulsars and detecting glitches and timing noise, such timing analyses allow the precise determination of the pulsar position, thus enabling detailed multiwavelength follow up.
An excess of $γ$-ray emission from the Galactic Center (GC) region with respect to predictions based on a variety of interstellar emission models and $γ$-ray source catalogs has been found by many groups using data from the {\it Fermi} Large Area Telescope (LAT). Several interpretations of this excess have been invoked. In this paper we search for members of an unresolved population of $γ$-ray pulsars located in the inner Galaxy that are predicted by the interpretation of the GC excess as being due to a population of such sources. We use cataloged LAT sources to derive criteria that efficientl…
We report on detection of the double pulsar system J0737-3039 in the far-UV with the ACS/SBC detector aboard HST. We measured the energy flux F = 4.5+/-1.0e-17 erg cm-2s-1 in the 1250-1550 AA band, which corresponds to the extinction-corrected luminosity L~1.5e28 erg s-1 for the distance d=1.1 kpc and a plausible reddening E(B-V)=0.1. If the detected emission comes from the entire surface of one of the neutron stars with a 13 km radius, the surface blackbody temperature is in the range T~2-5e5 K for a reasonable range of interstellar extinction. Such a temperature requires an internal heating …
Enabled by the Fermi Large Area Telescope, we now know young and recycled pulsars fill the gamma-ray sky, and we are beginning to understand their emission mechanism and their distribution throughout the Galaxy. However, key questions remain: Is there a large population of pulsars near the Galactic center? Why do the most energetic pulsars shine so brightly in MeV gamma rays but not always at GeV energies? What is the source and nature of the pair plasma in pulsar magnetospheres, and what role does the polar cap accelerator play? Addressing these questions calls for a sensitive, wide-field MeV…
The Large Area Telescope (LAT) on board the Fermi satellite has detected ~120 pulsars above 100 MeV. While most gamma-ray pulsars have spectra that are well modeled by a power law with an exponential cut-off at around a few GeV, some show significant pulsed high-energy (HE, >10 GeV) emission. I present a study of HE emission from LAT gamma-ray pulsars and discuss prospects for the detection of pulsations at very high energies (VHE, >100 GeV) with ground-based instruments.
Over thirteen times more gamma-ray pulsars have now been studied with the Large Area Telescope on NASA's Fermi satellite than the ten seen with the Compton Gamma-Ray Observatory in the nineteen-nineties. The large sample is diverse, allowing better understanding both of the pulsars themselves and of their roles in various cosmic processes. Here we explore the prospects for even more gamma-ray pulsars as Fermi enters the 2nd half of its nominal ten-year mission. New pulsars will naturally tend to be fainter than the first ones discovered. Some of them will have unusual characteristics compared …
We have constructed timing solutions for 81 gamma-ray pulsars covering more than five years of Fermi data. The sample includes 37 radio-quiet or radio-faint pulsars which cannot be timed with other telescopes. These timing solutions and the corresponding pulse times of arrival are prerequisites for further study, e.g. phase-resolved spectroscopy or searches for mode switches. Many gamma-ray pulsars are strongly affected by timing noise, and we present a new method for characterizing the noise process and mitigating its effects on other facets of the timing model. We present an analysis of timi…
My thesis deals with a fundamental question of high energy gamma-ray astronomy. Namely, I studied the cut-off shape of the Crab pulsar spectrum to distinguish between the leading scenarios for the pulsar models. Pulsars are celestial objects, which emit periodic pulsed electromagnetic radiation (pulsation) from radio to high energy gamma-rays. Two major scenarios evolved in past 40 years to explain the pulsation mechanism: the inner magnetosphere scenario and the outer magnetosphere scenario. Both scenarios predict a high energy cut-off in the gamma-ray energy spectrum, but with different cut-…
In 8 years of operation, the Large Area Telescope (LAT) on the Fermi satellite has impacted our understanding of gamma-ray pulsars dramatically. The LAT now sees over two hundred pulsars: the largest class of GeV sources in the Milky Way. They are diverse -- radio loud versus quiet, young versus millisecond, in evolving binary systems versus isolated, and so on. Relatively few of the GeV pulsars have also been seen in soft gamma rays. After an overview, we present 10 new radio pulsars, six young and four recycled, for which we detect gamma-ray pulsations.
The 2nd Fermi-LAT pulsar catalog includes 117 gamma-ray pulsars, of which roughly one third are millisecond pulsars (MSPs) while the remaining two thirds split evenly into young radio-loud and radio-quiet pulsars. Although this large population will enable future, detailed studies of emission mechanisms and the evolution of the underlying neutron star population, some nearly-universal properties are already clear and unequivocal. We discuss some of these aspects below, including the altitude of the gamma-ray emission site and the shape of the gamma-ray spectrum and its implications for the rad…
The Crab pulsar is the only astronomical pulsed source detected above 100 GeV. The emission mechanism of very high energy gamma-ray pulsation is not yet fully understood, although several theoretical models have been proposed. In order to test the new models, we measured the light curve and the spectra of the Crab pulsar with high precision by means of deep observations. We analyzed 135 hours of selected MAGIC data taken between 2009 and 2013 in stereoscopic mode. In order to discuss the spectral shape in connection with lower energies, 4.6 years of Fermi-LAT data were also analyzed. The known…
We present observations of HESS J1640-465 with the Fermi-LAT. The source is detected with high confidence as an emitter of high-energy gamma-rays. The spectrum lacks any evidence for the characteristic cutoff associated with emission from pulsars, indicating that the emission arises primarily from the pulsar wind nebula. Broadband modeling implies an evolved nebula with a low magnetic field resulting in a high gamma-ray to X-ray flux ratio. The Fermi emission exceeds predictions of the broadband model, and has a steeper spectrum, possibly resulting from a distinct excess of low energy electron…
We present results of our pulsar population synthesis of normal pulsars from the Galactic disk using our previously developed Monte-Carlo code. From our studies of observed radio pulsars that have clearly identifiable core and cone components, in which we fit the polarization sweep as well as the pulse profiles in order to constrain the viewing geometry, we develop a model describing the luminosity and ratio of radio core-to-cone peak fluxes. In this model, short period pulsars are more cone-dominated. We explore models of neutron star evolution with and without magnetic field decay, and with …
We report the results from our analysis of the \textit{Fermi} Large Area Telescope data of the \textit{Fermi} unassociated source 2FGL J1906.5$+$0720, which is a high-ranked candidate pulsar. In order to better study our target, we first update the ephemeris for PSR J1907$+$0602, which is used to help remove any possible contamination due to strong emission from this nearby pulsar. From our analysis, 2FGL J1906.5$+$0720 is confirmed to have a significant low energy cutoff at $\sim$ 1~GeV in its emission (14$σ$--18$σ$ significance), consistent with those seen in young pulsars. We search for pul…
The Large Area Telescope (LAT) on Fermi has detected ~150 gamma-ray pulsars, about a third of which were discovered in blind searches of the $γ$-ray data. Because the angular resolution of the LAT is relatively poor and blind searches for pulsars (especially millisecond pulsars, MSPs) are very sensitive to an error in the position, one must typically scan large numbers of locations. Identifying plausible X-ray counterparts of a putative pulsar drastically reduces the number of trials, thus improving the sensitivity of pulsar blind searches with the LAT. I discuss our ongoing program of Swift, …
We observed a nearby millisecond pulsar J2124-3358 with the Hubble Space Telescope in broad far-UV (FUV) and optical filters. The pulsar is detected in both bands with fluxes F(1250-2000 A)= (2.5+/-0.3)x10^-16 erg/s/cm^2 and F(3800-6000 A)=(6.4+/-0.4)x10^-17 erg/s/cm^2, which correspond to luminosities of ~5.8x10^27 and 1.4x10^27 erg/s, for d=410 pc and E(B-V)=0.03. The optical-FUV spectrum can be described by a power-law model, f_nu~nu^alpha, with slope alpha=0.18-0.48 for a conservative range of color excess, E(B-V)=0.01-0.08. Since a spectral flux rising with frequency is unusual for pulsar…
We have used LOFAR to perform targeted millisecond pulsar surveys of Fermi gamma-ray sources. Operating at a center frequency of 135 MHz, the surveys use a novel semi-coherent dedispersion approach where coherently dedispersed trials at coarsely separated dispersion measures are incoherently dedispersed at finer steps. Three millisecond pulsars have been discovered as part of these surveys. We describe the LOFAR surveys and the properties of the newly discovered pulsars.
The Cherenkov Telescope Array (CTA) will be the next generation instrument for the very high energy gamma-ray astrophysics domain. With its enhanced sensitivity in comparison with the current facilities, CTA is expected to shed light on a varied population of sources. In particular, we will achieve a deeper knowledge of the Crab nebula and pulsar, which are the best characterized pulsar wind nebula and rotation powered pulsar, respectively. We aim at studying the capabilities of CTA regarding these objects through simulations, using the main tools currently in development for the CTA future da…
The high sensitivity of the Fermi-LAT (Large Area Telescope) offers the first opportunity to study faint and extended GeV sources such as pulsar wind nebulae (PWNe). After one year of observation the LAT detected and identified three pulsar wind nebulae: the Crab Nebula, Vela-X and the PWN inside MSH 15-52. In the meantime, the list of LAT detected pulsars increased steadily. These pulsars are characterized by high energy loss rates from ~3 \times 10^{33} erg s$^{-1}$ to 5 \times 10$^{38}$ erg s$^{-1}$ and are therefore likely to power a PWN. This paper summarizes the search for PWNe in the of…
The Fermi Large Area Telescope (LAT) has recently reported the detection of pulsed gamma-rays from 6 young pulsars (J0631+1036, J0659+1414, J0742-2822, J1420-6048, J1509-5850, and J1718-3825), all exhibiting single-peaked pulse profiles (Weltevrede et al., 2010). High-quality radio polarization data are also available for 5 of these pulsars, allowing derivation of constraints on their viewing geometries. We obtain independent constraints on the viewing geometries of these pulsars by using a geometric pulsar emission code to model the Fermi LAT and radio light curves. We find fits for the magne…
The Cherenkov Telescope Array (CTA) is planned to serve as a ground-based observatory for (very-)high-energy gamma-ray astronomy, open to a wide astrophysics community, providing a deep insight into the non-thermal high-energy universe. It foresees a factor of ~10 improvement in sensitivity above 100 GeV, with substantially better angular and spectral resolutions and wider field-of-view in comparison with currently operational experiments. The CTA consortium is investigating the different physics cases for different proposed array configurations and subsets. Pulsar Wind Nebulae (PWNe), the mos…
The pulsar search was started at the radio telescope LPA LPI at the frequency 111~MHz. The first results deals of a search for right ascension $0^h - 24^h$ and declinations $+21^{\circ} - +42^{\circ}$ are presented in paper. The data with sampling 100 ms and with 6 frequency channals was used. It were found 34 pulsars. Seventeen of them previously been observed at radio telescope LPA LPI, and ten known pulsars has not previously been observed. It were found 7 new pulsars.
Using archival as well as freshly acquired data, we assess the X-ray behaviour of the Fermi/LAT gamma-ray pulsars listed in the First Fermi source catalog. After revisiting the relationships between the pulsars' rotational energy losses and their X and gamma-ray luminosities, we focus on the distance-indipendent gamma to X-ray flux ratios. When plotting our Fgamma/Fx values as a function of the pulsars' rotational energy losses, one immediately sees that pulsars with similar energetics have Fgamma/Fx spanning 3 decades. Such spread, most probably stemming from vastly different geometrical conf…
Since its launch in June 2008, the Large Area Telescope (LAT), onboard the \emph{Fermi} Gamma-ray Space Telescope, has greatly added to our understanding of gamma-ray pulsars. Its fine point spread function and large effective area, combined with the time-differencing method, make it the first gamma-ray instrument capable of discovering a new population of gamma-ray pulsars. We will present the recent discovery of the youngest (~4600 yr) radio-quiet gamma-ray pulsar discovered in a blind frequency search so far: PSR J1022-5746, a pulsar associated with an extended TeV source. We also present m…
Measurement of distances and moments of inertia of pulsars must be useful, for instance, for three-dimensional mapping of the dispersion and rotation measures, constraining the nuclear equation of state, etc. The distances and moments of inertia can be measured by fitting the gamma-ray lightcurves of pulsars, because the gamma-ray emission seems to be governed by easily calculable physics. The (first-principle) theoretical lightcurves have been computed only for weak pulsars (pair production near the light cylinder much smaller than Goldreich-Julian [1] per rotation), and at insufficient accur…
We report our analysis of the Fermi Large Area Telescope data for 39 millisecond pulsars (MSPs) listed in the second $γ$-ray pulsar catalog. Spectra of the pulsars are obtained. We fit the spectra with a function of a power law with exponential cutoff, and find the best-fit parameters of photon index $Γ= 1.54^{+0.10}_{-0.11}$ and cutoff energy $E_{c} = 3.70^{+0.95}_{-0.70}$ GeV. This spectral shape, which includes the intrinsic differences in the spectra of the MSPs, can be used for finding candidate MSPs and unidentified types of sources detected by Fermi at high Galactic latitudes. In one of…
Using the Gamma ray Burst Monitor (GBM) on Fermi we are monitoring accreting pulsar systems. We use the rates from GBM's 12 NaI detectors in the 8-50 keV range to detect and monitor pulsations with periods between 0.5 and 1000 seconds. After discussing our analysis approach we present results for individual sources from the first year of monitoring. Updated figures for these and other sources are available at http://gammaray.nsstc.nasa.gov/gbm/science/pulsars/ .
We describe an image-based method that uses two radio criteria, compactness and spectral index, to identify promising pulsar candidates among Fermi Large Area Telescope (LAT) unassociated sources. These criteria are applied to those radio sources from the Giant Metrewave Radio Telescope all-sky survey at 150 MHz (TGSS ADR1) found within the error ellipses of unassociated sources from the 3FGL catalog and a preliminary source list based on 7 years of LAT data. After follow-up interferometric observations to identify extended or variable sources, a list of 16 compact, steep-spectrum candidates i…
