A5058273503- Galaxies: Formation, Evolution, Phenomena
- Astrophysical Phenomena and Observations
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Astrophysics and Cosmic Phenomena
- Stellar, planetary, and galactic studies
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Radio Astronomy Observations and Technology
- Cosmology and Gravitation Theories
- Phase Equilibria and Thermodynamics
- Astro and Planetary Science
- Particle Accelerators and Free-Electron Lasers
- Scientific Research and Discoveries
- Statistical and numerical algorithms
- Geophysics and Gravity Measurements
- Solar and Space Plasma Dynamics
- Pulsars and Gravitational Waves Research
- X-ray Spectroscopy and Fluorescence Analysis
- Spectroscopy and Laser Applications
- Atomic and Molecular Physics
- Calibration and Measurement Techniques
- Scientific Measurement and Uncertainty Evaluation
- Ionosphere and magnetosphere dynamics
- Adaptive optics and wavefront sensing
University of Alabama in Huntsville
2021-2024
University of Cambridge
1998-2016
Institute of Astronomy
2001-2012
Scuola Internazionale Superiore di Studi Avanzati
2007
Fermi National Accelerator Laboratory
1995
Royal Observatory in Greenwich
1995
California Institute of Technology
1995
Lawrence Berkeley National Laboratory
1995
UNSW Sydney
1995
University of California, Berkeley
1995
We present a 90 per cent flux-complete sample of the 201 X-ray-brightest clusters galaxies in northern hemisphere (δ ≥ 0°), at high Galactic latitudes (ǀbǀ 20°), with measured redshifts z ≤ 0.3 and fluxes higher than 4.4 × 10−12 erg cm−2 s−1 0.1–2.4 keV band. The sample, called ROSAT Brightest Cluster Sample (BCS), is selected from All-Sky Survey data largest X-ray-selected cluster compiled to date. In addition Abell clusters, which form bulk BCS also contains Zwicky other their X-ray...
We present the first results from a very deep Chandra X-ray observation of core Perseus cluster galaxies. A pressure map reveals clear thick band high around inner radio bubbles. The gas in must be expanding outward and sharp front to it is identified as shock front, yet we see no temperature jump across it; indeed there more soft emission behind than it. conclude that this region either thermal conduction operates efficiently or co-existing relativistic plasma seen mini-halo mediating...
We report subarcsec-resolution X-ray imaging of the core Perseus cluster around galaxy NGC 1275 with Chandra Observatory. The ROSAT-discovered holes associated radio lobes have bright rims which are cooler than surrounding gas and not due to shocks. themselves may contain some hotter gas. map strong photoelectric absorption across Northern lobe rim a small infalling irregular galaxy, known as high velocity system. Two outer holes, one was previously known, identified recently found spurs...
We present preliminary results from a deep observation lasting almost 200 ks of the centre Perseus cluster galaxies around NGC 1275. The X-ray surface brightness intracluster gas beyond inner 20 kpc, which contains radio bubbles, is very smooth apart some low-amplitude quasi-periodic ripples. A clear density jump at radius 24 kpc to north-east, about 10 out bubble rim, appears be due weak shock driven by northern bubble. similar front may exist both bubbles but masked elsewhere rim emission...
We present a low-flux extension of the X-ray selected ROSAT Brightest Cluster Sample (BCS) published in Paper I this series. Like original BCS and employing an identical selection procedure, is compiled from All-Sky Survey (RASS) data northern hemisphere (dec > 0 deg) at high Galactic latitudes (|b| 20 deg). It comprises 100 clusters galaxies with measured redshifts z < 0.3 (as well as seven more 0.3) total fluxes between 2.8 x 10-12 erg cm-2 s-1 4.4 0.1-2.4 keV band (the latter value...
We present new spectra of dominant galaxies in X-ray selected clusters, which combine with our previously published to form a sample 256 215 clusters; 177 these are members the ROSAT Brightest Cluster Sample. 27% central have emission-line spectra, all but 5 line intensity ratios typical cooling flow nebulae. A further 6% show only [NII] H-alpha absorption. find no evidence for an increase frequency emission luminosity. Purely clusters at low redshift higher probability containing emission....
NGC 1275 in the centre of Perseus cluster galaxies, Abell 426, is surrounded by a spectacular filamentary Hα nebula. Deep Chandra X-ray imaging has revealed that brighter outer filaments are also detected soft X-rays. This can be due to conduction and mixing cold gas with hot, dense intracluster medium. We show correspondence both wavebands draw attention relationship two prominent curved north-west an outer, buoyant radio bubble seen as hole image. There strong resemblance shape disposition...
Cold molecular gas has recently been detected in several cooling flow clusters of galaxies containing huge optical nebula. These filaments are tightly linked to flows and related phenomena, such as rising bubbles relativistic plasma fed by radio jets. We present here a map, the CO(2–1) rotational line, cold associated with some Hα surrounding central galaxy Perseus cluster: NGC 1275. The extending about 50 kpc (135 arcsec) from center galaxy, made 18-receiver array HERA at focus IRAM 30 m...
We present and discuss the X-ray luminosity function (XLF) of ROSAT Brightest Cluster sample (BCS), an flux limited clusters galaxies in northern hemisphere compiled from All-Sky Survey data. The BCS allows local cluster XLF to be determined with unprecedented accuracy over almost three decades provides important reference for searches evolution at higher redshifts.
We present new Chandra images of the X-ray emission from core Perseus cluster galaxies. The total observation time is now 1.4 Ms. New depressions in surface brightness are discovered to north NGC1275, which we interpret as old rising bubbles. They imply that bubbles long-lived and do not readily breakup when hot atmosphere. existence a 300 kpc long NNW-SSW bubble axis means there cannot be significant transverse large scale flows exceeding 100 km/s. Interesting spatial correlations seen...
We present an Integral Field Unit survey of 73 galaxy clusters and groups with the VIsible Multi Object Spectrograph on Very Large Telescope. exploit data to determine H α gas dynamics kpc scales study feedback processes occurring within dense cluster cores. kinematic state ionized show that majority systems (∼2/3) have relatively ordered velocity fields are similar kinematics rotating discs decoupled from stellar brightest galaxy. The flux (>50 per cent) is typically associated these most...
The luminosity–temperature relation for clusters has a wide dispersion which been explained as being due to range of gas density or mass. We show here that the offset cluster from mean is proportional strength its cooling flow. also confirm similar effect on metallicity–temperature relation. Since flow itself cannot produce such large effects, we propose they are more widespread difference between intracluster media and non-cooling clusters. suggest effects may be inhomogeneity medium...
We present a large sample of H- and K-band spectra 32 optically line-luminous central cluster galaxies. find significant rovibrational H2 emission in 23 these galaxies as well H recombination and/or [Fe ii] another five. This represents fourfold increase the number molecular line detections known. A are extended (5–20 kpc). In several objects we [Si vi] that appears to correlate with strength high ionization lines optical (e.g. [O iii]). comprehensive builds on previous work confirms warm...
We use line-of-sight velocity information on the filamentary emission-line nebula of NGC 1275 to infer a dynamical model nebula's flow through surrounding intracluster gas. detect outflowing gas and patterns that match simulations buoyantly rising bubbles from which we deduce some filaments have been drawn out 1275. find radial gradient ratio [NII]6584/H-alpha may be due variation in metallicity, interactions with medium or hardening excitation mechanism. no preferred spatial correlation...
We report the discovery of a 40 arcsec long X-ray filament in core cluster galaxies Abell 1795. The feature coincides with an Hα+N ii found by Cowie et al. early 1980s and resolved into at least two U-band filaments McNamara mid-1990s. (emission-weighted) temperature emitting gas along is 2.5–3 keV, as revealed colour ratios. deprojected will be less. A detailed map presented. cD galaxy head probably moving through or oscillating core. radiative cooling time about 3 × 108 which similar to...
view Abstract Citations (125) References (21) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Supernova at Z = 0.458 and Implications for Measuring the Cosmological Deceleration Perlmutter, S. ; Pennypacker, C. R. Goldhaber, G. Goobar, A. Muller, Newberg, H. J. M. Desai, Kim, Y. Small, I. Boyle, B. Crawford, McMahon, Bunclark, P. Carter, D. Irwin, Terlevich, Ellis, Glazebrook, K. Couch, W. Mould, T. Abraham, We have begun a program to discover high-redshift...
The powerful combination of the Chandra X-ray telescope, SCUBA submillimetre-wave camera and gravitational lensing effect massive galaxy clusters A2390 A1835 has been used to place stringent flux limits on six faint submillimetre sources deep three which lie in fields common both instruments. One further source is marginally detected bands. For all our results are consistent with starburst-dominated emission. two objects, including SMMJ 14011+0252 at z=2.55, constraints strong enough that...
We present Spitzer high-resolution spectra of off-nuclear regions in the central cluster galaxies NGC 1275 and 4696 Perseus Centaurus clusters, respectively. Both objects are surrounded by extensive optical emission-line filamentary nebulae, bright outer parts which targets our observations. The 10-37um show strong pure rotational lines from molecular hydrogen revealing a component to filaments has an excitation temperature ~300-400K. flux 0-0S(1) line correlates well with strength lines,...
We present images of NGC4696, the central galaxy in Centaurus cluster, showing large extent cool filaments which are bright H-alpha line emission. These share detailed structure both dust lane and inner regions arc-like plumes seen soft X-ray The gas is at its coolest, most absorbed this same region. smoothness features implies that local environment not strongly turbulent. suggest these either shaped by confinement due to a strong magnetic field, or bulk flows within intracluster medium....
We present clear spectroscopic detections of molecular hydrogen in the outer filaments Hα nebula surrounding central galaxy Perseus cluster, NGC 1275. This implies presence warm gas clouds at projected distances up to 24 kpc from nucleus host galaxy, embedded hot intracluster medium. The emission-line intensity ratios reveal that H2 is predominately thermally excited with excitation temperatures 1600–2200 K, suggesting a lack pressure balance between component and its Excitation by stellar...
We present a Chandra observation of the only low redshift, z=0.299, galaxy cluster to contain highly luminous radio-quiet quasar, H1821+643. By simulating quasar PSF, we subtract contribution from core and determine physical properties gas down 3 arcsec (15 kpc) point source. The temperature decreases 9.0\pm0.5 keV 1.3\pm0.2 in centre, with short central radiative cooling time 1.0\pm0.1 Gyr, typical strong cool-core cluster. X-ray morphology 100 kpc shows extended spurs emission core, small...