158 research outputs found
The High-Velocity Outflow of PG1211+143 May Not be That Fast
We analyze the X-ray spectrum of the quasar PG1211+143 observed with the CCD
and grating spectrometers on board XMM-Newton. Using an ion by ion fitting
model we find an outflow component of about 3000 km/s that includes absorption
lines of K-shell and L-shell ions of the astrophysically abundant elements. We
also identify and include in our model broad (FWHM = 6000 km/s) emission lines
from H-like ions of C, N, O, and Ne, and He-like ions of O, Ne, and Mg. The
outflow velocity we find is an alternative interpretation of the data and is in
contrast with the ultra high velocity of ~24000 km/s reported previously for
this object. Nevertheless, we can not completely rule out the presence of a
high velocity component due to the poor signal-to-noise ratio of the data.Comment: 7 pages, 2 figures, emulateapj, accepted for publication in The
Astrophysical Journa
Is The Fe M-shell Absorber Part of The Outflow in Active Galactic Nuclei?
The X-ray emission of many active galactic nuclei (AGNs) is absorbed between
15 and 17 Angstrom by means of unresolved (inner-shell) transition arrays
(UTAs) of Fe M-shell ions. The outflow velocities implied by the Doppler shifts
of the individual UTAs in the spectrum have never before been measured. Thus,
the Fe-M absorber has been commonly assumed to be part of the ionized AGN
outflow, whose velocities are readily obtained from more easily measured
spectral lines. The best spectrum of Fe-M absorption is available from the
integrated 900 ks Chandra HETGS observations of NGC 3783, in which some Fe-M
ions are clearly resolved. We measure the velocities of the individual Fe-M
ions in NGC 3783 for the first time. Surprisingly, we find that the Fe-M
absorber, most noticeably Fe, Fe, and Fe, is not
outflowing at the same velocity as the previously known wind. In fact, it
appears to be stationary and therefore not part of the outflow at all. It
could, alternatively, be ascribed to the skin of the dusty torus. This reduces
appreciably the mass loss rate estimated for the NGC 3783 outflow and perhaps
for other similar sources as well, in which the various Fe-M ions are not
resolved.Comment: To be published in Ap
Reverberation Mapping of High-z, High-luminosity Quasars
We present Reverberation Mapping results after monitoring a sample of 17
high-z, high-luminosity quasars for more than 10 years using photometric and
spectroscopic capabilities. Continuum and line emission flux variability is
observed in all quasars. Using cross-correlation analysis we successfully
determine lags between the variations in the continuum and broad emission lines
for several sources. Here we present a highlight of our results and the
determined radius--luminosity relations for Ly_alpha and CIV.Comment: Contributed talk at conference "Quasars at all cosmic epochs", held
in Padova 2-7 April 2017, published in Frontiers in Astronomy and Space
Science
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