A5014686072- Astrophysics and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Galaxies: Formation, Evolution, Phenomena
- Radio Astronomy Observations and Technology
- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Particle Accelerators and Free-Electron Lasers
- Astronomical Observations and Instrumentation
- Pulsars and Gravitational Waves Research
- Particle Detector Development and Performance
- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Dark Matter and Cosmic Phenomena
- Particle accelerators and beam dynamics
- Cosmology and Gravitation Theories
- Solar and Space Plasma Dynamics
- Scientific Measurement and Uncertainty Evaluation
- Geophysics and Gravity Measurements
- Laser-Plasma Interactions and Diagnostics
- Adaptive optics and wavefront sensing
- History and Developments in Astronomy
- Nuclear Physics and Applications
- Medical Imaging Techniques and Applications
- Calibration and Measurement Techniques
- Superconducting Materials and Applications
University of Bristol
2015-2024
Bristol Robotics Laboratory
2009-2023
Smithsonian Astrophysical Observatory
1980-2019
Max Planck Institute for Astronomy
2019
Max Planck Society
2019
Center for Astrophysics Harvard & Smithsonian
2005-2016
Harvard University
1986-2008
Harvard University Press
1996
Goddard Space Flight Center
1978-1984
University of California, San Diego
1981-1984
The Large Area Telescope (LAT) aboard the Fermi Gamma-ray Space provides an unprecedented opportunity to study gamma-ray blazars. To capitalize on this opportunity, beginning in late 2007, about a year before start of LAT science operations, we began large-scale, fast-cadence 15 GHz radio monitoring program with 40-m telescope at Owens Valley Radio Observatory (OVRO). This 1158 northern (declination>-20 deg) sources from Candidate Blazar Survey (CGRaBS) and now encompasses over 1500 sources,...
Aims. Pointed observations with XMM-Newton provide the basis for creating catalogues of X-ray sources detected serendipitously in each field. This paper describes creation and characteristics 2XMM catalogue.
The quasar PKS 0637-753, the first celestial X-ray target of Chandra Observatory, has revealed asymmetric structure extending from 3 to 12 arcsec west quasar, coincident with inner portion jet previously detected in a 4.8 GHz radio image (Tingay et al. 1998). At redshift z=0.651, is largest (~100 kpc) and most luminous (~10^{44.6} ergs/s) few so far X-rays. This letter presents high resolution jet, 42 ks data when 0637-753 was on-axis ACIS-S near optimum focus. For morphology closely matches...
We report performance verification observations of the giant elliptical galaxy M 87 in Virgo Cluster with MOS, pn, and optical monitor instruments on board XMM-Newton. With energy sensitive imaging MOS pn we obtain first spatially constrained X-ray spectra nucleus jet galaxy. The good photon statistics allow a detailed analysis radial temperature abundance distribution 6 elements. data provide no indication multi-temperature structure for radii 2'. An apparent sharp metal drop deduced...
We use new and archival Chandra data to investigate the X-ray emission from a large sample of compact hot spots FR II radio galaxies quasars 3C catalog. find that only most luminous tend be in good agreement with predictions synchrotron self-Compton model equipartition magnetic fields. At low spot luminosities inverse Compton are routinely exceeded by several orders magnitude, but this is never seen more spots. argue an additional component present low-luminosity luminosity controls ability...
We present spectral results from Chandra and XMM-Newton observations of a sample 22 low-redshift (z < 0.1) radio galaxies consider whether the core emission originates base relativistic jet, or an accretion flow, contains contributions both. find correlations between unabsorbed X-ray, radio, optical fluxes luminosities FR I-type radio-galaxy cores, implying common origin in form jet. On other hand, we that X-ray spectra II-type galaxy cores are dominated by absorbed emission, with NH ≳ 1023...
We present new, high dynamic range VLA images of the inner jet closest radio galaxy, Centaurus A. Over a ten-year baseline we detect apparent sub-luminal motions (v ~ 0.5c) in on scales hundreds pc. The inferred speeds are larger than those previously determined using VLBI smaller scales, and provide new constraints angle made by to line sight if assume jet-counterjet symmetry. also allow us faint counterparts number unidentified X-ray knots part counterjet, showing conclusively that these...
We present results from two Chandra/ACIS-I observations and one XMM-Newton observation of X-ray emission the interstellar medium (ISM) inner radio lobes nearby galaxy Centaurus A. The ISM has an average radial surface brightness profile that is well described by a β-model with index β = 0.40 ± 0.04 temperature kBTISM ~ 0.29 keV beyond 2 kpc nucleus. find diffuse coincident outer half southwest lobe, bright enhancement detected along edge lobe. On basis energetic lifetime arguments, we reject...
The HEAO A2 experiment data was systematically searched for unresolved galactic disc emission. Although there were suggestions of non-uniformities in the emission, consistent with a half-thickness 241 + 22 pc and surface emissivity (2-10 keV) at radius R(kpc) 2.2 10 to minus 7th power exp(-R/3.5) erg/sq cm (-2)power/s (R 7.8 kpc). giving luminosity approximately 4.4 37th erg S (-1) power. If model is extrapolated radii less than kpc, emission 1.4 38th i.e., few percent galaxy resolved...
The core-dominated radio-loud quasar PKS 0637-752 (z = 0.654) was the first celestial object observed with Chandra X-ray Observatory, offering early surprise of detection a remarkable jet. Several observations variety detector configurations contribute to total exposure time Advanced CCD Imaging Spectrometer (ACIS; Garmire et al. 2000, in preparation) about 100ks. A spatial analysis all available data, making use Chandra's resolving power 0.4 arcsec, reveals jet that extends 10 arcsec west...
We present new results on the shock around southwest radio lobe of Centaurus A using data from Chandra Very Large Programme observations. The X-ray spectrum emission outer southwestern edge is well described by a single power-law model with Galactic absorption -- thermal models are strongly disfavoured, except in region closest to nucleus. conclude that significant fraction part synchrotron, not thermal. infer where strongest and ambient gas density lowest, inflation accelerating particles...
We present a detailed study of the environments sample nine low-power [Fanaroff–Riley type I (FR I)] radio galaxies, based on new and archival XMM–Newton observations. report detections group-scale around three galaxies: 3C 296, NGC 1044 76.1. As with previous studies, we find that FR galaxies inhabit group ranging over nearly two orders magnitude in bolometric X-ray luminosity; however, no evidence for tight relationship between large-scale environment radio-source properties such as size,...
We report on deep Chandra observations of the nearby broad-line radio galaxy Pictor A, which we combine with new Australia Telescope Compact Array (ATCA) observations. The X-ray data have a factor 4 more exposure than previously presented and span 15 yr time baseline, allowing detailed study spatial, temporal spectral properties AGN, jet, hotspot lobes. present evidence for further variation though flare that reported in previous work remains most significantly detected time-varying feature....
Our Chandra observation of the FR I radio galaxy 3C 66B has resulted in first detection an X-ray counterpart to previously known radio, infrared and optical jet. The jet is detected up 7 arcsec from core a steep spectrum, α≈1.3±0.1. overall flux density spectrum are consistent with synchrotron origin for emission. However, inner knot higher ratio emission than others. This suggests that either two distinct processes present or differences acceleration mechanism required; there may be...
This paper describes the performance of XMM-Newton for serendipitous surveys and summarises scope potential Serendipitous Survey. The role Survey Science Centre (SSC) in project is outlined. SSC's follow-up identification programme survey described together with presentation some first results.
view Abstract Citations (159) References (59) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS X-Ray Studies of Quasars with the Einstein Observatory. IV. Dependence on Radio Emission Worrall, D. M. ; Giommi, P. Tananbaum, H. Zamorani, G. Using a sample 114 radio-loud quasars observed Observatory, authors study joint dependence X-ray luminosity radio and optical luminosities. By comparing these results those obtained from large radio-quiet quasars, confirm...
We present results for the first three low-power radio galaxies from B2 bright sample to have been observed with Chandra. Two kiloparsec-scale jets, and in both Chandra resolves jet X-ray emission, detects soft core emission an X-ray-emitting galaxy-scale atmosphere of luminosity a few ×1041 erg s−1. These are detections jets more distant than Centaurus A M87. The cooling time gas implies mass infall rates order 1 M⊙ yr−1. pressure near is comparable minimum implying that may play important...
Over half the 3CRR sample of radio galaxies and quasars has been observed in X-rays with ROSAT pointed observations, we present results from these discussing many sources detail. The improved spatial resolution over earlier missions allows a better separation nuclear extended components X-ray emission. We investigate relationship between core luminosity, show that our support model which every galaxy quasar beamed soft component directly related to core. report evidence for rich cluster...
We present new deep Chandra observations of the Centaurus A jet, with a combined on-source exposure time 719 ks. These data allow detailed X-ray spectral measurements to be made along jet out its disappearance at 4.5 kpc from nucleus. distinguish several regimes high-energy particle acceleration; while inner part is dominated by knots and has properties consistent local acceleration shocks, in outer 3.4 likely an unknown distributed mechanism. In addition compact counterjet features, we...
Chandra observations of a complete, flux-limited sample 38 high-redshift (1<z<2), low-frequency selected (and so unbiased in orientation) 3CRR radio sources are reported. The includes 21 quasars (= broad line galaxies) and 17 narrow galaxies (NLRGs) with matched 178 MHz luminosity (log L_R ~ 44-45). have high core-fraction, X-ray luminosities L_X 45-46) soft hardness ratios (HR -0.5) indicating low obscuration. NLRGs lower apparent 43-45) mostly hard (HR>0) obscuration N_H 22-24 cm^-2)....
Abstract We present the first systematic search for UV signatures from radio source-driven active galactic nuclei (AGN) feedback in Compact Steep Spectrum (CSS) galaxies. Owing to their characteristic sub-galactic jets (1–20 kpc projected linear sizes), CSS hosts are excellent laboratories probing galaxy scale via jet-triggered star formation. The sample consists of seven powerful galaxies, and two galaxies host sources >20 as control, at low intermediate redshifts ( z < 0.6). Our new...