16,244 research outputs found
The Global Implications of the Hard X-ray Excess in Type 1 AGN
Recent evidence for a strong 'hard excess' of flux at energies > 20 keV in
some Suzaku observations of type 1 Active Galactic Nuclei (AGN) has motivated
an exploratory study of the phenomenon in the local type 1 AGN population. We
have selected all type 1 AGN in the Swift Burst Alert Telescope (BAT) 58-month
catalog and cross-correlated them with the holdings of the Suzaku public
archive. We find the hard excess phenomenon to be a ubiquitous property of type
1 AGN. Taken together, the spectral hardness and equivalent width of Fe K alpha
emission are consistent with reprocessing by an ensemble of Compton-thick
clouds that partially cover the continuum source. In the context of such a
model, ~ 80 % of the sample has a hardness ratio consistent with > 50% covering
of the continuum by low-ionization, Compton-thick gas. More detailed study of
the three hardest X-ray spectra in our sample reveal a sharp Fe K absorption
edge at ~ 7 keV in each of them, indicating that blurred reflection is not
responsible for the very hard spectral forms. Simple considerations place the
distribution of Compton-thick clouds at or within the optical broad line
region.Comment: Accepted for publication in Ap
Chandra detection of a parsec scale wind in the Broad Line Radio Galaxy 3C 382
We present unambiguous evidence for a parsec scale wind in the Broad-Line
Radio Galaxy (BLRG) 3C 382, the first radio-loud AGN, with , whereby an outflow has been measured with
X-ray grating spectroscopy. A 118 ks Chandra grating (HETG) observation of 3C
382 has revealed the presence of several high ionization absorption lines in
the soft X-ray band, from Fe, Ne, Mg and Si. The absorption lines are
blue-shifted with respect to the systemic velocity of 3C 382 by -840\pm60 km/s
and are resolved by Chandra with a velocity width of 340\pm70 km/s. The outflow
appears to originate from a single zone of gas of column density cm and ionization parameter . From
the above measurements we calculate that the outflow is observed on parsec
scales, within the likely range from 10-1000 pc, i.e., consistent with an
origin in the Narrow Line Region.Comment: 11 pages, accepted for publication in Astrophysical Journal Letter
Evaluation of the infrared test method for the olympus thermal balance tests
The performance of the infrared (IR) rig used for the thermal balance testing of the Olympus S/C thermal model is discussed. Included in this evaluation are the rig effects themselves, the IRFLUX computer code used to predict the radiation inputs, the Monitored Background Radiometers (MBR's) developed to measure the absorbed radiation flux intensity, the Uniform Temperature Reference (UTR) based temperature measurement system and the data acquisition system. A preliminary set of verification tests were performed on a 1 m x 1 m zone to assess the performance of the IR lamps, calrods, MBR's and aluminized baffles. The results were used, in part, to obtain some empirical data required for the IRFLUX code. This data included lamp and calrod characteristics, the absorptance function for various surface types, and the baffle reflectivities
Evidence for a circum-nuclear and ionised absorber in the X-ray obscured BroadLine Radio Galaxy 3C 445
Here we present the results of a Suzaku observation of the Broad Line Radio
Galaxy 3C 445. We confirm the results obtained with the previous X-ray
observations which unveiled the presence of several soft X-ray emission lines
and an overall X-ray emission which strongly resembles a typical Seyfert 2
despite of the optical classification as an unobscured AGN. The broad band
spectrum allowed us to measure for the first time the amount of reflection
(R~0.9) which together with the relatively strong neutral Fe Kalpha emission
line (EW ~ 100 eV) strongly supports a scenario where a Compton-thick mirror is
present. The primary X-ray continuum is strongly obscured by an absorber with a
column density of NH =2-3 x10^{23} cm^{-2}. Two possible scenarios are proposed
for the absorber: a neutral partial covering or a mildly ionised absorber with
an ionisation parameter log\xi ~ 1.0 erg cm s^{-1}. A comparison with the past
and more recent X-ray observations of 3C 445 performed with XMM-Newton and
Chandra is presented, which provided tentative evidence that the ionised and
outflowing absorber varied. We argue that the absorber is probably associated
with an equatorial disk-wind located within the parsec scale molecular torus.Comment: Accepted by MNRAS; 13 pages, 6 figures, 4 table
FINANCIAL CHARACTERISTICS OF REFRIGERATED FOOD PRODUCTS TRUCKING FIRMS IN THE U.S.
This study provides an overview of the financial characteristics of U. S. refrigerated food products trucking firms as a group and by regions. The analytical tools used for evaluating the financial assessment of the industry were several commonly used liquidity, profitability, and solvency ratios. One of the results reveals that the pre-tax income-to-gross revenue ratio, a measure of profitability, for the firms as a group averaged 0.01. This value means that one-cent of every dollar earned in services ("sales") was available to pay taxes and distribute profits.Agribusiness,
Geochemistry and mineralogy of British carboniferous seatearths from Northern coalfields
The palaeogeographic, tectonic, and biologic conditions of seatearth deposition are briefly reviewed. Detailed mineralogical examination reveals that seatearths are essentially quartz-illite-kaolinite assemblages with minor chlorite, siderite, and organic matter. The illites show wide variation from well ordered sedimentary muscovites to disordered and/or interlayered 'illitic' minerals. The kaolinites are found to be relatively well crystalline and the chlorites are Mg rich. Siderite is commonly associated with minor kaolinite and pyrite in nodules. The organic matter consists of terrestial plant debris. The distribution functions of elements and minerals in seatearths are discussed, A normal model is reasonably satisfactory for SiO(_2), Al(_2)O(_3), CaO, P(_2)O(_5), Ni, Y, and Zr; a lognormal model for TiO(_2), Fe(_2)O(_3), MgO, Na(_2)O, K(_2)O, S, C, H(_2)O(^+), H(_2)O(^-), CO(_2), Ba, Or, Ou, La, Mn, Nb, Rb, Se, Sr, and Zn. Stepwise multiple linear regression is used to assess the relationships between chemistry and mineralogy. It is found that the major components are controlled by the mineralogy to a large extent and that the trace elements and similarly controlled but to a lesser degree. The present data, when compared with previous data, is shown to be comparable .R-mode factor analysis is used to derive factors which control the distributions of trace elements and minerals in seatearths. Eight factors are extracted and they relate to the depositional environment and stratigraphic controls. Roof rocks are examined and the pattern they produce after R-mode factor analysis is shown to be similar to that for a set of clastic cyclothemic sediments. The significance of differences between seatearths and roof rocks are discussed. It is concluded that seatearths are leached relative to their corresponding roof measures. The data is summarised and a detailed theory for the origin and genesis of seatearths, based on that of MOORE (1968), is developed
- …