596 research outputs found
X-ray view of four high-luminosity Swift/BAT AGN: Unveiling obscuration and reflection with Suzaku
The Swift/BAT nine-month survey observed 153 AGN, all with ultra-hard X-ray
BAT fluxes in excess of 10^-11 erg cm^-2 s^-1 and an average redshift of 0.03.
Among them, four of the most luminous BAT AGN (44.73 < Log L(BAT) < 45.31) were
selected as targets of Suzaku follow-up observations: J2246.0+3941 (3C 452),
J0407.4+0339 (3C 105), J0318.7+6828, and J0918.5+0425. The column density,
scattered/reflected emission, the properties of the Fe K line, and a possible
variability are fully analyzed. For the latter, the spectral properties from
Chandra, XMM-Newton and Swift/XRT public observations were compared with the
present Suzaku analysis. Of our sample, 3C 452 is the only certain
Compton-thick AGN candidate because of i) the high absorption and strong
Compton reflection; ii) the lack of variability; iii) the "buried" nature, i.e.
the low scattering fraction (<0.5%) and the extremely low relative [OIII]
luminosity. In contrast 3C 105 is not reflection-dominated, despite the
comparable column density, X-ray luminosity and radio morphology, but shows a
strong long-term variability in flux and scattering fraction, consistent with
the soft emission being scattered from a distant region (e.g., the narrow
emission line region). The sample presents high (>100) X-to-[OIII] luminosity
ratios, confirming the [OIII] luminosity to be affected by residual extinction
in presence of mild absorption, especially for "buried" AGN such as 3C 452.
Three of our targets are powerful FRII radio galaxies, making them the most
luminous and absorbed AGN of the BAT Seyfert survey despite the inversely
proportional N_H - L_X relation.Comment: A&A paper in press, 17 page
Relationship between X-ray and ultraviolet emission in 3C 273
In 3C 273, ultraviolet flux and X-ray flux measured by BATSE are not well
correlated, contrarily to predictions of several models, unless the X-ray flux
lags the UV emission by 1.75 yr. The absence of observed correlation at small
lag cannot be due to spectral variability. A Comptonizing corona model is
however compatible with all UV and X-ray observations covering the BATSE
period.Comment: LaTeX, 4 pages, 6 figures. espcrc2.sty style file included. Poster
contribution to the symposium "The Active X-ray Sky: Results from BepppoSAX
and Rossi-XTE", Rome, October 199
Silicon Photo-Multiplier radiation hardness tests with a beam controlled neutron source
We report radiation hardness tests performed at the Frascati Neutron
Generator on silicon Photo-Multipliers, semiconductor photon detectors built
from a square matrix of avalanche photo-diodes on a silicon substrate. Several
samples from different manufacturers have been irradiated integrating up to
7x10^10 1-MeV-equivalent neutrons per cm^2. Detector performances have been
recorded during the neutron irradiation and a gradual deterioration of their
properties was found to happen already after an integrated fluence of the order
of 10^8 1-MeV-equivalent neutrons per cm^2.Comment: 7 pages, 6 figures, Submitted to Nucl. Inst. Meth.
Transient and Highly Polarized Double-Peaked H-alpha Emission in the Seyfert 2 Nucleus of NGC 2110
We have discovered an extremely broad, double-peaked H-alpha emission line in
the polarized flux spectrum of NGC 2110, establishing that this well-studied
Seyfert 2 galaxy contains a disk-like hidden broad-line region (BLR). Several
properties of NGC 2110 suggest that it is an obscured twin of Arp 102B, the
prototypical double-peaked emission-line active galactic nucleus (AGN). A
comparison between our data and previous spectra of NGC 2110 indicates that the
double-peaked H-alpha feature is transient. The presence of a disk-like BLR in
NGC 2110 has important implications for AGNs: it expands the range of
properties exhibited by Seyfert 2 galaxies, and the fact that the BLR is
obscured by a torus-like structure provides the first evidence that
double-peaked emitters and classical Seyfert nuclei may have the same basic
parsec-scale geometry.Comment: 5 pages, including 3 postscript figures. Uses emulateapj. Accepted
for publication in ApJ Letter
XMM-Newton observations of ULIRGs I: A Compton-thick AGN in IRAS19254-7245
We present the XMM-Newton observation of the merging system IRAS 19254-7245,
also known as The Superantennae, whose southern nucleus is classified as a
Seyfert 2 galaxy. The XMM-Newton data have allowed us to perform a detailed
X-ray imaging and spectral analysis of this system. We clearly detect, for the
first time in this system, a strong EW ~ 1.4 keV Fe emission line at 6.49+/-0.1
keV (rest-frame). The X-ray spectrum requires a soft thermal component (kT~0.9
keV; L(0.5-2) ~ 4E41 cgs), likely associated with the starburst, and a hard
power-law continuum above 2 keV (observed L(2-10) ~ 4E42 cgs). We confirm the
flatness of this latter component, already noted in previous ASCA data. This
flatness, together with the detection of the strong Fe-Kalpha line and other
broad band indicators, suggest the presence of a Compton-thick AGN with
intrinsic luminosity > 1E44 cgs. We show that a Compton-thick model can
perfectly reproduce the X-ray spectral properties of this object.Comment: 6 pages, 4 figures, Latex manuscript, Accepted for publication in
Astronomy and Astrophysic
Prospective study on nanoparticle albumin-bound paclitaxel in advanced breast cancer. Clinical results and biological observations in taxane-pretreated patients
Background: There is a deep need to improve the care of metastatic breast cancer (MBC) patients, since even today it remains an incurable disease. Taxanes are considered the most effective cytotoxic drugs for the treatment of MBC, both in monotherapy and in combined schedules, but the need for synthetic solvents contributes to the severe toxicities and may have a negative impact on the efficacy. Nanoparticle albumin-bound paclitaxel (Nab-paclitaxel) is a colloidal suspension of paclitaxel and human serum albumin initially developed to avoid the toxicities associated with conventional taxanes. Patients and methods: The aim of this prospective, single-center open-label, noncomparative study was to evaluate the efficacy and safety of nab-paclitaxel in MBC patients pretreated with taxanes. The patients were treated with nab-paclitaxel as a single agent, 260 mg/m2 on day 1 of each 3-week cycle or 125 mg/m2 weekly. The primary endpoint was the overall response rate (ORR). Secondary objectives were duration of response, clinical benefit rate, progression-free survival (PFS), overall survival, and safety. Results: A total of 42 patients (median age 48 years, median Eastern Cooperative Oncology Group performance status 0, triple-negative MBC 19%, all pretreated with a taxane-based therapy, mainly in advanced disease) were enrolled in the study. The ORR was 23.8%, including one complete response (2.4%) and nine partial responses (21.4%); the disease control rate was 50%. The median duration of response was 7.2 months. After a median follow-up of 9 months, the median PFS was 4.6 months. ORR and PFS were similar irrespective of the previous chemotherapy lines, metastatic sites, and biomolecular expression. Nab-paclitaxel was well tolerated, and the most frequent treatment-related toxicities were mild to moderate (grades 1–2). Conclusion: This real-life study shows that nab-paclitaxel has a significant antitumor activity and a manageable safety profile in patients pretreated with taxanes and experiencing a treatment failure after at least one line of chemotherapy
BeppoSAX view of NGC 526A: a Seyfert 1.9 galaxy with a flat spectrum
In the present work we report the BeppoSAX observation of the Seyfert 1.9
galaxy NGC 526A in the band 0.1-150 keV. The high energy instrument onboard,
PDS, has succeeded in measuring for the first time the spectrum of this source
in the 13-150 keV range. The combined analysis of all Narrow Field Instruments
provides a power law spectral index of ~ 1.6 and confirms the flat spectral
nature of this source. Although NGC 526A varies strongly in the 2-10 keV over
period of months/years, its spectral shape remains constant over these
timescales. An Fe K-alpha line, characterized by a complex structure, has been
detected in the 6-7 keV range. The line, which has an equivalent width of 120
eV, is not compatible with being produced in an absorbing torus with N_H ~
10^22 cm^-2, but most likely originates by reflection in an accretion disk
viewed at an intermediate inclination angle of ~ 42 deg. The reflection
component is however small (R < 0.7) and so it is not sufficient to steepen the
spectrum to photon index values more typical of AGNs. Instead, we find that the
data are more consistent with a flat power law spectrum cut-off at around 100
keV plus a small reflection component which could explain the observed iron
line. Thus NGC 526A is the only bona-fide Seyfert 2 galaxy which maintains a
"flat spectrum" even when broad band data are considered: in this sense its
properties, with respect to the general class of Seyfert 2's, are analogous to
those of NGC 4151 with respect to the vast majority of Seyfert 1's.Comment: 8 pages, 6 PostScript figures, Latex manuscript, new A&A file style
included, accepted for publication on Astronomy and Astrophysic
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