PSR J1856+0245: Arecibo Discovery of a Young, Energetic Pulsar Coincident with the TeV Gamma-ray Source HESS J1857+026
J. W. T. Hessels, D. J. Nice, B. M. Gaensler, V. M. Kaspi, D. R. Lorimer, D. J. Champion, A. G. Lyne, M. Kramer, J. M. Cordes, P. C. C. Freire, F. Camilo, S. M.… 展开作者
J. W. T. Hessels, D. J. Nice, B. M. Gaensler, V. M. Kaspi, D. R. Lorimer, D. J. Champion, A. G. Lyne, M. Kramer, J. M. Cordes, P. C. C. Freire, F. Camilo, S. M. Ransom, J. S. Deneva, N. D. R. Bhat, I. Cognard, F. Crawford, F. A. Jenet, L. Kasian, P. Lazarus, J. van Leeuwen, M. A. McLaughlin, I. H. Stairs, B. W. Stappers, A. Venkataraman
备注：
13 pages, 1 figure, accepted for publication in The Astrophysical Journal Letters
We present the discovery of the Vela-like radio pulsar J1856+0245 in the Arecibo PALFA survey. PSR J1856+0245 has a spin period of 81ms, a characteristic age of 21kyr, and a spin-down luminosity Edot = 4.6 x 10^36 ergs/s. It is positionally coincident with the TeV gamma-ray source HESS J1857+026, which has no other known counterparts. Young, energetic pulsars create wind nebulae, and more than a dozen pulsar wind nebulae have been associated with very-high-energy (100GeV-100TeV) gamma-ray sources discovered with the HESS telescope. The gamma-ray emission seen from HESS J1857+026 is potentially produced by a pulsar wind nebula powered by PSR J1856+0245; faint X-ray emission detected by ASCA at the pulsar's position supports this hypothesis. The inferred gamma-ray efficiency is epsilon_gamma = L_gamma/Edot = 3.1% (1-10TeV, for a distance of 9kpc), comparable to that observed in similar associations.
We present the discovery of non-thermal radio and X-ray emission positionally coincident with the TeV $γ$-ray source HESS J1813--178. We demonstrate that the non-thermal radio emission is due to a young shell-type supernova remnant (SNR) G12.8--0.0, and constrain its distance to be greater than 4 kpc. The X-ray emission is primarily non-thermal and is consistent with either an SNR shell or unidentified pulsar/pulsar wind nebula origin; pulsed emission is not detected in archival ASCA data. A simple synchrotron+inverse Compton model for the broadband emission assuming that all of the emission a…
We observed the W28 field (for ~40 h) at Very High Energy (VHE) gamma-ray energies (E>0.1 TeV) with the H.E.S.S. Cherenkov telescopes. A reanalysis of EGRET E>100 MeV data was also undertaken. Results from the NANTEN 4m telescope Galactic plane survey and other CO observations have been used to study molecular clouds. We have discovered VHE gamma-ray emission (HESSJ1801-233) coincident with the northeastern boundary of W28, and a complex of sources (HESSJ1800-240A, B and C) ~0.5 deg south of W28, in the Galactic disc. The VHE differential photon spectra are well fit by pure power laws with ind…
We present the serendipitous discovery of a young stellar cluster in the Galactic disk at l=12deg. Using Keck/NIRSPEC, we obtained high- and low-resolution spectroscopy of several stars in the cluster, and we identified one red supergiant and two blue supergiants. The radial velocity of the red supergiant provides a kinematic cluster distance of 4.7pm0.4 kpc, implying luminosities of the stars consistent with their spectral types. Together with the known Wolf-Rayet star located 2.4' from the cluster center, the presence of the red supergiant and the blue supergiants suggests a cluster age of 6…
We report on a deep search for radio pulsations toward five unidentified ASCA X-ray sources coincident with EGRET gamma-ray sources. This search has led to the discovery of a young and energetic pulsar using data obtained with the new Wideband Arecibo Pulsar Processor. PSR J2021+3651 is likely associated with the X-ray source AX J2021.1+3651, which in turn is likely associated with the COS B high energy gamma-ray source 2CG 075+00, also known as GeV J2020+3658 or 3EG J2021+3716. PSR J2021+3651 has a rotation period P = 104 ms and P_dot = 9.6x10^{-14}, implying a characteristic age ~17 kyr and …
Recently, the HESS collaboration has reported the detection of gamma-ray emission above a few hundred GeV from eight new sources located close to the Galactic Plane. The source HESS J1813-178 has sparked particular interest, as subsequent radio observations imply an association with SNR G12.82-0.02. Triggered by the detection in VHE gamma-rays, a positionally coincident source has also been found in INTEGRAL and ASCA data. In this Letter we present MAGIC observations of HESS J1813-178, resulting in the detection of a differential gamma-ray flux consistent with a hard-slope power law, described…
Recently, the HESS array has reported the detection of gamma-ray emission above a few hundred GeV from eight new sources located close to the Galactic Plane. The source HESS J1834-087 is spatially coincident with SNR G23.3-0.3 (W41). Here we present MAGIC observations of this source, resulting in the detection of a differential gamma-ray flux consistent with a power law, described as dN/(dA dt dE) = (3.7 +/- 0.6)*10^(-12) (E/TeV)^(-2.5 +/- 0.2) \ cm^(-2)s^(-1)TeV^(-1). We confirm the extended character of this flux. We briefly discuss the observational technique used, the procedure implemented…
We discovered independently the shell-type supernova remnant G12.82-0.02, recently reported by Brogan et al. (2005), which is coincident with the unidentified TeV gamma-ray source revealed in the HESS survey of the Galactic plane. Estimating the ambient starlight at the location of this source from the integrated Ly alpha luminosity of the nearby H II region W33, we conclude that inverse Compton emission is a viable explanation for the observed TeV emission. Examining remnants in the survey of Aharonian et al. (2005a) including those detected above 200 Gev and those not detected, we find a str…
The extended TeV gamma-ray source HESS J1023-575 is coincident with the massive, young stellar cluster Westerlund 2 (Wd2) and its surrounding HII region RCW 49. On the basis of an analysis of the CO emission and 21 cm absorption along the line of sight to Wd2, it is argued that this cluster, and by assumption the TeV source as well, must be associated with a giant molecular cloud in the far side of the Carina arm with a mass of 7.5 x 10^5 Mo. Analysis of the spatial and velocity structure of the cloud reveals clear evidence of interaction with Wd2. The cloud's kinematic distance of 6.0 +/- 1.0…
We discover a faint shell-type radio and X-ray source, G353.6-0.7, associated with HESS J1731-347. G353.6-0.7 is likely an old supernova remnant (SNR), based on radio (0.8 GHz, 1.4 GHz and 5 GHz), infrared (8 $μ$m from the GLIMPSE Legacy Project and 21 $μ$m from the Midcourse Space Experiment), and X-ray (0.1 keV - 2.4 keV from the ROSAT survey and 5 - 20 keV from the INTEGRAL survey) data. The SNR, centered at ({\sl l}, {\sl b})=(353.55, -0.65) with a radius of $\sim$ 0.25$^{\circ}$, closely matches the outline of the recently discovered extended TeV source HESS J1731-347, which has no previo…
The High Energy Stereoscopic System (HESS) survey of the Galactic plane has established the existence of a substantial number (~40) of Galactic TeV gamma-ray sources, a large fraction of which remain unidentified. HESS J0632+057 is one of a small fraction of these objects which is point-like in nature(<2' rms), and is one of only two point-like sources that remain unidentified. Follow-up observations of this object with XMM-Newton have revealed an X-ray source coincident with the TeV source and with the massive star MWC 148, of the spectral type B0pe. This source exhibits a hard spectrum, cons…
Suzaku observations of a TeV unidentified (unID) source, HESS J1745-303, are presented. A possible excess of neutral iron line emission is discovered, and is likely associated with the main part of HESS J1745-303, named "region A". It may be an X-ray reflection nebula where the X-rays from previous Galactic Center (GC) activity are reflected by a molecular cloud. This result further strengthens the assumption that the molecular cloud which is spatially coincident with region A of HESS J1745-303 is located in the GC region. The TeV emission from molecular clouds is reminiscent of the diffuse Te…
In recent years, apparent anisotropies in the ~EeV cosmic ray (CR) flux arriving at Earth from the general direction of the galactic center have been reported from the analysis of AGASA and SUGAR data. The more recently commissioned Auger Observatory has not confirmed these results. HESS has now detected an unusually soft TeV source roughly coincident with the location of the previously claimed CR anisotropy. In this paper, we develop a model for the TeV emission from this object, consistent with observations at other wavelengths, and examine the circumstances under which it might have contrib…
The COS B high energy gamma-ray source 2CG 075+00, also known as GeV J2020+3658 or 3EG J2021+3716, has avoided identification with a low energy counterpart for over twenty years. We present a likely identification with the discovery and subsequent timing of a young and energetic pulsar, PSR J2021+3651, with the Wideband Arecibo Pulsar Processor at the Arecibo Observatory. PSR J2021+3651 has a rotation period P = 104ms and Pdot = 9.6 x 10^{-14}, implying a characteristic age T_c = 17kyr and a spin-down luminosity Edot = 3.4 x 10^{36} erg s^{-1}. The pulsar is also coincident with the ASCA sourc…
The High-Energy Stereoscopic System (HESS) has detected intense diffuse TeV emission correlated with the distribution of molecular gas along the galactic ridge at the centre of our Galaxy. Earlier HESS observations of this region had already revealed the presence of several point sources at these energies, one of them (HESS J1745-290) coincident with the supermassive black hole Sagittarius A*. It is still not entirely clear what the origin of the TeV emission is, nor even whether it is due to hadronic or leptonic interactions. It is reasonable to suppose, however, that at least for the diffuse…
We report the discovery of a soft gamma ray source, namely IGR J18135-1751, detected with the IBIS imager on board the INTEGRAL satellite. The source is persistent and has a 20-100 keV luminosity of $\sim$5.7 $\times$ 10$^{34}$ erg s$^{-1}$ (assuming a distance of 4kpc). This source is coincident with one of the eight unidentified objects recently reported by the HESS collaboration as part of the first TeV survey of the inner part of the Galaxy. Two of these new sources found along the Galactic plane, HESS J1813-178 and HESS J1614-518, have no obvious lower energy counterpart, a fact that moti…
Recently, HESS and other air Cerenkov telescopes have detected a source of TeV gamma-rays coincident with the Galactic center. It is not yet clear whether the gamma-rays are produced via leptonic or hadronic processes, so it is important to consider possible acceleration sites for the charged particles which produce the gamma-rays. One exciting possibility for the origin of these particles is the central black hole, Sgr A*, where the turbulent magnetic fields close to the event horizon can accelerate protons to TeV energies. Using a realistic model of the density distribution in a 6 pc x 6 pc …
We present a Chandra X-ray observation of G12.82-0.02, a shell-like radio supernova remnant coincident with the TeV gamma-ray source HESS J1813-178. We resolve the X-ray emission from the co-located ASCA source into a compact object surrounded by structured diffuse emission that fills the interior of the radio shell. The morphology of the diffuse emission strongly resembles that of a pulsar wind nebula. The spectrum of the compact source is well-characterized by a power-law with index approx. 1.3, typical of young and energetic rotation-powered pulsars. For a distance of 4.5 kpc, consistent wi…
We present a Chandra X-ray observation of G12.82-0.02, a shell-like radio supernova remnant coincident with the TeV gamma-ray source HESS J1813-178. We resolve the X-ray emission from the co-located ASCA source into a point source surrounded by structured diffuse emission that fills the interior of the radio shell. The morphology of the diffuse emission strongly resembles that of a pulsar wind nebula. The spectrum of the compact source is well-characterized by a power-law with index Gamma approx 1.3, typical of young and energetic rotation-powered pulsars. For a distance of 4.5 kpc, consistent…
Suzaku deep observations have discovered two highly significant nonthermal X-ray sources, Suzaku J1804$-$2142 (Src 1) and Suzaku J1804$-$2140 (Src 2), positionally coincident with the unidentified TeV $γ$-ray source, HESS J1804$-$216. The X-ray sources are not time variable and show no counterpart in other wavebands, except for the TeV source. Src 1 is unresolved at Suzaku spatial resolution, whereas Src 2 is extended or composed of multiple sources. The X-ray spectra are highly absorbed, hard, and featureless, and are well fitted by absorbed power-law models with best-fit photon indices and a…
We present an X-ray study of the field containing the extended TeV source HESS J1834-087 using data obtained with the XMM-Newton telescope. Previously, the coincidence of this source with both the shell-type supernova remnant (SNR) W41 and a giant molecular cloud (GMC) was interpreted as favoring pi^0-decay gamma-rays from interaction of the old SNR with the GMC. Alternatively, the TeV emission has been attributed to inverse Compton scattering from leptons deposited by PSR J1833-0827, a pulsar assumed to have been born in W41 but now located 24' from the center of the SNR (and the TeV source).…
We present X-ray and 12CO(J=1-0) observations of the very-high-energy (VHE) gamma-ray source HESS J1813-178 with the aim of understanding the origin of the gamma-ray emission. Using this dataset we are able to undertake spectral and morphological studies of the X-ray emission from this object with greater precision than previous studies. NANTEN 12CO(J=1-0) data are used to search for correlations of the gamma-ray emission with molecular clouds which could act as target material for gamma-ray production in a hadronic scenario. The NANTEN 12CO(J=1-0) observations show a giant molecular cloud of …
The supernova remnant (SNR) complex CTB 37 is an interesting candidate for observations with Very High Energy (VHE) gamma-ray telescopes such as H.E.S.S. In this region, three SNRs are seen. One of them is potentially associated with several molecular clouds, a circumstance that can be used to probe the acceleration of hadronic cosmic rays. This region was observed with the H.E.S.S. Cherenkov telescopes and the data were analyzed with standard H.E.S.S. procedures. Recent X-ray observations with Chandra and XMM-Newton were used to search for X-ray counterparts. The discovery of a new VHE gamma-…
The rapidly varying non-thermal X-ray emission observed from Sgr A* points to particle acceleration taking place close to the supermassive black hole. The TeV gamma-ray source HESS J1745-290 is coincident with Sgr A* and may be closely related to the X-ray emission. Simultaneous X-ray and TeV observations are required to elucidate the relationship between these two objects. Here we report on joint H.E.S.S./Chandra observations in July 2005, during which an X-ray flare was detected. Despite a factor >10 increase in the X-ray flux of Sgr A*, no evidence is found for an increase in the TeV gamma-…
Results from gamma-ray observations by the H.E.S.S. telescope array in the direction of the young stellar cluster Westerlund 2 are presented. Stereoscopic imaging of Cherenkov light emission of gamma-ray induced showers in the atmosphere is used to study the celestial region around the massive Wolf-Rayet (WR) binary WR 20a. Spectral and positional analysis is performed using standard event reconstruction techniques and parameter cuts. The detection of a new gamma-ray source is reported from H.E.S.S. observations in 2006. HESS J1023-575 is found to be coincident with the young stellar cluster W…
The rapidly varying (~10 minute timescale) non-thermal X-ray emission observed from Sgr A* implies that particle acceleration is occuring close to the event horizon of the supermassive black hole. The TeV gamma-ray source HESS J1745-290 is coincident with Sgr A* and may be closely related to its X-ray emission. Simultaneous X-ray and TeV observations are required to elucidate the relationship between these objects. We report on joint H.E.S.S./Chandra observations performed in July 2005, during which an X-ray flare was detected. Despite a factor of 9 increase in the X-ray flux of Sgr A*, no evi…
We present results from X-ray and radio observations of the recently discovered young Vela-like pulsar PSR J2021+3651, which is coincident with the EGRET gamma-ray source GeV 2020+3658. A 19.0-ks Chandra ACIS-S observation has revealed a ~20'' x 10'' pulsar wind nebula that is reminiscent of the equatorial tori seen around some young pulsars, along with thermal emission from an embedded point source (kT = 0.15 +/- 0.02 keV). We name the nebula G75.2+0.1. Its spectrum is well fit by an absorbed power-law model with photon index 1.7 +/- 0.3, hydrogen column density nH = 7.8 +/- 1.7 x 10^21 cm^-2…
The HESS collaboration recently reported highly significant detection of TeV gamma-rays coincident with Sgr A*. In the context of other Galactic Center (GC) observations, this points to the following scenario: In the extreme advection-dominated accretion flow (ADAF) regime of the GC black hole (BH), synchrotron radio/sub-mm emission of 100 MeV electrons emanates from an inefficiently radiating turbulent magnetized corona within 20 Schwarzschild radii of the GCBH. These electrons are accelerated through second-order Fermi processes by MHD turbulence. Closer to the innermost stable orbit of the …
In a novel approach in observational high-energy gamma-ray astronomy, observations carried out by imaging atmospheric Cherenkov telescopes provide necessary templates to pinpoint the nature of intriguing, yet unidentified EGRET gamma-ray sources. Using GeV-photons detected by CGRO EGRET and taking advantage of high spatial resolution images from H.E.S.S. observations, we were able to shed new light on the EGRET observed gamma-ray emission in the Kookaburra complex, whose previous coverage in the literature is somewhat contradictory. 3EGJ1420-6038 very likely accounts for two GeV gamma-ray sour…
