728 research outputs found
Consistency between the radio and MIR faint source counts using the radio-MIR correlation
We show from the recent extrapolation of the radio-FIR correlation to the MIR
that the 20 cm and 15 um differential source counts are likely to come from the
same parent population.Comment: 2 pages, 2 figures, to appear in proceedings of 'Multi-wavelength AGN
surveys', Cozumel, 200
A deep Giant Metre-wave Radio Telescope 610-MHz survey of the 1^HXMMâNewton/Chandra survey field
We present the results of a deep 610-MHz survey of the 1^HXMMâNewton/Chandra survey area with the Giant Metre-wave Radio Telescope. The resulting maps have a resolution of ~7 arcsec and an rms noise limit of 60 ÎŒJy. To a 5Ï detection limit of 300 ÎŒJy, we detect 223 sources within a survey area of 64 arcmin in diameter. We compute the 610-MHz source counts and compare them to those measured at other radio wavelengths. The well-known flattening of the Euclidean-normalized 1.4-GHz source counts below ~2 mJy, usually explained by a population of starburst galaxies undergoing luminosity evolution, is seen at 610 MHz. The 610-MHz source counts can be modelled by the same populations that explain the 1.4-GHz source counts, assuming a spectral index of â0.7 for the starburst galaxies and the steep spectrum active galactic nucleus (AGN) population. We find a similar dependence of luminosity evolution on redshift for the starburst galaxies at 610 MHz as is found at 1.4 GHz (i.e. 'Q'= 2.45^(+0.3)_(â0.4))
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Coccidioidomycosis Complement Fixation Titer Trends in the Age of Antifungals.
Coccidioidomycosis is associated with a broad spectrum of illness severity, ranging from asymptomatic or self-limited pulmonary infection to life-threatening manifestations of disseminated disease. Serologic studies before the widespread availability of antifungals established current understanding of serologic kinetics and dynamics. Chart histories and complement fixation (CF) titer trends were analyzed for 434 antifungal-treated coccidioidomycosis patients, who were classified by three infectious disease physicians as having either pulmonary uncomplicated coccidioidomycosis (PUC) (n = 248), pulmonary chronic coccidioidomycosis (PCC) (n = 64), disseminated coccidioidomycosis (DC) not including meningitis (n = 86), or coccidioidal meningitis (CM) (n = 36). The median maximal CF titers were 1:4 for PUC patients, 1:24 for PCC patients, 1:128 for DC patients, and 1:32 for CM patients. Approximately 25.4% of PUC patients, 6.2% of PCC patients, 2.3% of DC patients, and 8.3% of CM patients did not develop detectable titers during the study period. Maximal titers developed a mean of 31 days (95% confidence interval [CI], 13 to 50 days) after initial serologic positivity, with no significant differences between groups. Serologic recurrence occurred in 9% of PUC patients, 36% of PCC patients, 50% of DC patients, and 52% of CM patients. Median titer improvement rates were 91 days/dilution for PUC patients, 112 days/dilution for PCC patients, 136 days/dilution for DC patients, and 146 days/dilution for CM patients. Receiver operating characteristic (ROC) analysis revealed that CF testing retains moderate classification value for disseminated infections (area under the curve [AUC], 0.82 [95% CI, 0.78 to 0.87]) and complicated infections (AUC, 0.82 [95% CI, 0.77 to 0.86]). A suitable cutoff value for complicated infections is â„1:32. Findings update serologic parameters that are relevant for clinical assessment of coccidioidomycosis patients in the triazole era
A 100ks XMM-Newton view of the Seyfert 1.8 ESO113-G010. I. Discovery of large X-ray variability and study of the FeKalpha line complex
(Abridged) We present here a long (100ks) XMM-Newton follow-up of the Seyfert
1.8 galaxy ESO113-G010 performed in November 2005, in order to study over a
longer time-scale its main X-ray properties. The source was found in a
higher/softer time-averaged flux state, and timing analysis of this source
reveals strong, rapid variability. The Power Spectral Density (PSD) analysis
indicates (at 95% c.l.) a break at 3.7 x 10^-4 Hz. This cut-off frequency is
comparable to those measured in some other rapidly-variable Seyferts, such as
MCG-6-30-15 and NGC4051. From the mass-luminosity-time-scale, we infer that
M_BH ranges from 4 x 10^6 - 10^7 M_odot and the source is accreting at or close
to the Eddington rate (or even higher). The existing data cannot distinguish
between spectral pivoting of the continuum and a two-component origin for the
spectral softening, primarily because the data do not span a broad enough flux
range. In the case of the two-component model, the fractional offsets measured
in the flux-flux plots increase significantly toward higher energies (similar
to what is observed in MCG-6-30-15) as expected if there exists a constant
reflection component. Contrary to May 2001, no significant highly redshifted
emission line is observed (which might be related to the source flux level),
while two narrow emission lines at about 6.5keV and 7keV are observed. The S/N
is not high enough to establish if the lines are variable or constant. As
already suggested by the 2001 observation, no significant constant narrow
6.4keV FeK line (EW~32eV) is observed, hence excluding any dominant emission
from distant cold matter such as a torus in this Seyfert type 1.8 galaxy.Comment: Accepted for publication in A&A, 10 pages, 11 figures, 2 table
X-ray reverberation in 1H0707-495 revisited
The narrow-line Seyfert 1 galaxy 1H0707-495 has previously been identified as
showing time lags between flux variations in the soft- (0.3-1 keV) and
medium-energy (1-4 keV) X-ray bands that oscillate between positive and
negative values as a function of the frequency of the mode of variation. Here
we measure and analyse the lags also between a harder X-ray band (4-7.5 keV)
and the soft and medium bands, using existing XMM-Newton data, and demonstrate
that the entire spectrum of lags, considering both the full energy range,
0.3-7.5 keV, and the full frequency range, 10^-5 < nu < 10^-2 Hz, are
inconsistent with previous claims of arising as reverberation associated with
the inner accretion disk. Instead we demonstrate that a simple reverberation
model, in which scattering or reflection is present in all X-ray bands,
explains the full set of lags without requiring any ad hoc explanation for the
time lag sign changes. The range of time delays required to explain the
observed lags extends up to about 1800 s in the hard band. The results are
consistent with reverberation caused by scattering of X-rays passing through an
absorbing medium whose opacity decreases with increasing energy and that
partially-covers the source. A high covering factor of absorbing and scattering
circumnuclear material is inferred.Comment: Accepted for publication in MNRA
Implications of the X-ray Variability for the Mass of MCG-6-30-15
The bright Seyfert 1 galaxy \mcg shows large variability on a variety of time
scales. We study the \aproxlt 3 day time scale variability using a set of
simultaneous archival observations that were obtained from \rxte and the {\it
Advanced Satellite for Cosmology and Astrophysics} (\asca). The \rxte\
observations span nearly sec and indicate that the X-ray Fourier Power
Spectral Density has an rms variability of 16%, is flat from approximately
10^{-6} - 10^{-5} Hz, and then steepens into a power law
with \alpha\aproxgt 1. A further steepening to occurs
between 10^{-4}-10^{-3} Hz. The shape and rms amplitude are comparable to what
has been observed in \ngc and \cyg, albeit with break frequencies that differ
by a factor of 10^{-2} and 10^{4}, respectively. If the break frequencies are
indicative of the central black hole mass, then this mass may be as low as
. An upper limit of ks for the relative lag
between the 0.5-2 keV \asca band compared to the 8-15 keV \rxte band was also
found. Again by analogy with \ngc and \cyg, this limit is consistent with a
relatively low central black hole mass.Comment: 5 pages, 3 figures, LaTeX, uses emulateapj.sty and apjfonts.sty,
revised version, accepted for publication in ApJ Letter
Tumour antigenicity in ovarian cancer.
The blastogenic response to a crude cell extract of ovarian cancer cells has been studied in 48 patients with ovarian cancer (9, autologous, 39 allogeneic), in 26 female controls matched for age and in 18 female patients with other types of cancer in remission from disease. The responses in ovarian cancer patients in remission and relapse were considered separately. The blastogenic responses to cell extracts of foetal ovary, foetal lung, foetal liver and normal adult ovary were also assessed in a proportion of all 3 groups. The blastogenic responses to ovarian cancer and foetal ovary cell extracts were found to be significantly greater in the ovarian cancer patients in remission than in the controls, but the responses to ovarian cancer extract were not greater in the relapse group or in patients with other cancers. As a blastogenic response to normal ovarian extract was also present in some of these patients, the data so far do not support the hypothesis of a tumour specific antigen. This tumour associated response may be occurring to determinants in foetal or adult ovarian tissue to which the patient becomes sensitized in malignant disease. The response is complex and the nature of the antigen requires further analysis
The Star-formation History of the Universe as Revealed from Deep Radio Observations of the 13^H XMM-Newton/Chandra Deep Field
Discerning the exact nature of the faint (sub-mJy) radio population has been historically difficult due to the low luminosity of these sources at most wavelengths. Using deep observations from Chandra/XMM-Newton/Spitzer and ground based follow up we are able to disentangle the AGN and star-
forming populations for the first time in a deep multi-frequency GMRT/VLA/MERLIN Survey. The many diagnostics include radio luminosity, morphology, radio to mid-IR flux density ratios, radio to optical flux density ratios and
radio spectral indices. Further diagnostics, e.g. optical spectra, X-ray spectra/hardness ratios, IR colours indicate the presence of the AGN independent of whether the radio emission is powered by AGN or star-formation. We are able to
examine the star-formation history of the universe up to z = 2.5 in a unique way based on an unbiased star-formation rate indicator, radio luminosity. This work provides an alternative perspective on the distribution of star-formation by mass, âdownsizingâ and allows us to examine the prevalence of AGN in star-bursts
Constraints on the distribution of absorption in the X-ray selected AGN population found in the 13H XMM-Newton/Chandra deep field
We present an analysis of the X-ray properties of sources detected in the 13H
XMM-Newton deep (200ks) field. In order to constrain the absorbed AGN
population, we use extensive Monte Carlo simulations to directly compare the
X-ray colours of observed sources with those predicted by several model
distributions. We have tested the simplest form of the AGN unified scheme,
whereby the intrinsic XLF of absorbed AGN is set to be the same as that of
their unabsorbed brethren, coupled with various model distributions of
absorption. The best fitting of these models sets the fraction of AGN with
absorbing column NH, proportional to (logNH)^8. We have also tested two
extensions to the unified scheme: an evolving absorption scenario, and a
luminosity dependent model distribution. Both of these provide poorer matches
to the observed X-ray colour distributions than the best fitting simple unified
model. We find that a luminosity dependent density evolution XLF reproduces
poorly the 0.5-2 keV source counts seen in the 13H field. Field to field
variations could be the cause of this disparity. Computing the simulated X-ray
colours with a simple absorbed power-law + reflection spectral model is found
to over-predict, by a factor of two, the fraction of hard sources that are
completely absorbed below 0.5 keV, implying that an additional source of
soft-band flux must be present for a number of the absorbed sources. Finally,
we show that around 40% of the 13H sample are expected to be AGN with NH>10^22
cm^-2.Comment: 13 pages, 9 figures, Accepted for publication in MNRA
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