Fe emission and ionized excess absorption in the luminous quasar 3C 109 with XMM–Newton     

G. Miniutti  D. R. Ballantyne  S. W. Allen  A. C. Fabian  R. R. Ross 《Monthly notices of the Royal Astronomical Society》2006,371(1):283-292

The Parkes High-Latitude pulsar survey covers a region of the sky enclosed by Galactic longitudes 220° < l < 260° and Galactic latitudes | b | < 60°. The observations have been performed using the 20-cm multibeam receiver on the Parkes 64-m radio telescope. A total of 6456 pointings of 265 s each have been collected. The system adopted provided a sensitivity limit, for long-period pulsars with 5 per cent duty cycles, of ∼0.5 mJy. Data analysis resulted in the detection of 42 pulsars of which 18 were new discoveries. Four of these belong to the class of the millisecond – or recycled – pulsars; three of these four are in binary systems. The double pulsar system J0737−3039 is among those and has been presented elsewhere. Here, we discuss the other discoveries and provide timing parameters for the objects for which we have a phase-connected solution.  相似文献   

Magnetic fields in the 3C 129 cluster     

G.B. Taylor  F. Govoni  S.W. Allen  A.C. Fabian 《Monthly notices of the Royal Astronomical Society》2001,326(1):2-10

We present multifrequency VLA observations of the two radio galaxies 3C 129 and 3C 129.1 embedded in a luminous X-ray cluster. These radio observations reveal a substantial difference in the Faraday Rotation Measures (RMs) toward 3C 129.1 at the cluster centre and 3C 129 at the cluster periphery. After deriving the density profile from available X-ray data, we find that the RM structure of both radio galaxies can be fitted by a tangled cluster magnetic field with strength 6 μG extending at least 3 core radii (450 kpc) from the cluster centre. The magnetic field makes up a small contribution to the total pressure (5 per cent) in the central regions of the cluster. The radio morphology of 3C 129.1 appears disturbed on the southern side, perhaps by the higher pressure environment. In contrast with earlier claims for the presence of a moderately strong cooling flow in the 3C 129 cluster, our analysis of the X-ray data places a limit on the mass deposition rate from any such flow of < 1.2 M_⊙ yr⁻¹.  相似文献   

An intense soft excess and evidence for light bending in the luminous narrow-line quasar PHL 1092     

L. C. Gallo  Th. Boller  W. N. Brandt  A. C. Fabian  D. Grupe 《Monthly notices of the Royal Astronomical Society》2004,352(3):744-752

  相似文献   

The X-ray variability of the narrow-line type 1 Seyfert galaxy IRAS 13224–3809 from an XMM–Newton observation     

L. C. Gallo  Th. Boller  Y. Tanaka  A. C. Fabian  W. N. Brandt  W. F. Welsh  N. Anabuki  Y. Haba 《Monthly notices of the Royal Astronomical Society》2004,347(1):269-276

  相似文献   

The missing soft X-ray luminosity in cluster cooling flows     

A. C. Fabian  S. W. Allen  C. S. Crawford  R. M. Johnstone  R. G. Morris  J. S. Sanders  R. W. Schmidt 《Monthly notices of the Royal Astronomical Society》2002,332(3):L50-L54

The gas temperature in the cores of many clusters of galaxies drops inward by about a factor of 3 or more within the central 100-kpc radius. The radiative cooling time drops over the same region from 5 or more Gyr down to below a few 10⁸ yr. Although this indicates that cooling flows are taking place, XMM-Newton spectra show no evidence for strong mass cooling rates of gas below  1–2 keV  . The soft X-ray luminosity expected from steady cooling flows is missing. Here we outline and test the energetics of a cold mixing model in which gas below  1–2 keV  falls from the flow and is rapidly cooled by mixing with cold gas. The missing X-ray luminosity can emerge in the ultraviolet, optical and infrared bands, where strong emission nebulosities are commonly seen. We explore further the requirements for any heat sources that balance the radiative cooling in cluster cores.  相似文献   

Adaptive binning of X-ray galaxy cluster images     

J.S. Sanders  A.C. Fabian 《Monthly notices of the Royal Astronomical Society》2001,325(1):178-186

We present a simple method for adaptively binning the pixels in an image. The algorithm groups pixels into bins of size such that the fractional error on the photon count in a bin is less than or equal to a threshold value, and the size of the bin is as small as possible. The process is particularly useful for generating surface brightness and colour maps, with clearly defined error maps, from images with a large dynamic range of counts, for example X-ray images of galaxy clusters. We demonstrate the method in application to data from Chandra ACIS-S and ACIS-I observations of the Perseus cluster of galaxies. We use the algorithm to create intensity maps, and colour images that show the relative X-ray intensities in different bands. The colour maps can later be converted, through spectral models, into maps of physical parameters, such as temperature, column density, etc. The adaptive binning algorithm is applicable to a wide range of data, from observations or numerical simulations, and is not limited to two-dimensional data.  相似文献   

Magnetic fields in the centre of the Perseus cluster     

G. B. Taylor  N. E. Gugliucci  A. C. Fabian  J. S. Sanders  G. Gentile  S. W. Allen 《Monthly notices of the Royal Astronomical Society》2006,368(4):1500-1506

We present Very Long Baseline Array (VLBA) observations of the nucleus of NGC 1275, the central, dominant galaxy in the Perseus cluster of galaxies. These are the first observations to resolve the linearly polarized emission from 3C 84, and from them we determine a Faraday rotation measure (RM) ranging from 6500 to 7500 rad m⁻² across the tip of the bright southern jet component. At 22 GHz some polarization is also detected from the central pc of 3C 84, indicating the presence of even more extreme RMs that depolarize the core at lower frequencies. The nature of the Faraday screen is most consistent with being produced by magnetic fields associated with the optical filaments of ionized gas in the Perseus cluster.  相似文献   

The relationship between the optical Hα filaments and the X-ray emission in the core of the Perseus cluster     

A. C. Fabian  J. S. Sanders  C. S. Crawford  C. J. Conselice  J. S. Gallagher  III    R. F. G. Wyse 《Monthly notices of the Royal Astronomical Society》2003,344(3):L48-L52

  相似文献   

Marginal abatement cost curves: a call for caution     

Fabian Kesicki  Paul Ekins 《Climate Policy》2013,13(2):219-236

Legal commitments to reduce CO₂ emissions require policy makers to find cost-efficient means to meet these obligations. Marginal abatement cost (MAC) curves, which illustrate the economics associated with climate change mitigation, have recently attracted a great amount of attention. A number of limitations with MAC curves are explained by the implication they should be just one tool in a broader set of decision-making aids used in assessing climate policy. MAC curves, for example, omit ancillary benefits of greenhouse gas emission abatement, treat uncertainty in a limited manner, exclude intertemporal dynamics and lack the necessary transparency concerning their assumptions. MAC curves based on the individual assessment of abatement measures suffer from additional shortcomings such as the non-consideration of interactions and non-financial costs, a possibly inconsistent baseline, double counting and limited treatment of behavioural aspects. Reducing emissions from deforestation and forest degradation exhibit many of the above-mentioned problems, making it particularly difficult to capture in a cost curve. Policy makers should therefore be cautious when interpreting MAC curves, pay attention to the underlying assumptions, consider non-financial costs and be aware of the important uncertainties and underlying path dependencies.  相似文献   

A theoretical investigation of tropospheric ozone and stratospheric-tropospheric exchange processes     

Fabian  P. 《Pure and Applied Geophysics》1973,106(1):1044-1057

Summary Based on the global distribution of various surface types the mean tropospheric residence time of ozone is estimated as a function of latitude. Due to the land-sea distribution varies from 50 days in the northern hemisphere to 190 days in the southern hemisphere. For the stratospheric-tropospheric exchange a sinusoidal variation with season is assumed. The annual variation of tropospheric ozone thus gets a sine function from mean, amplitude and phase of whch the injection function for the particular latitude can be determined.  相似文献