617 research outputs found
Quantifying the fast outflow in the luminous Seyfert galaxy PG1211+143
We report two new XMM-Newton observations of PG1211+143 in December 2007,
again finding evidence of the fast outflow of highly ionised gas first detected
in 2001. Stacking the new spectra with those from two earlier XMM-Newton
observations reveals strong and broad emission lines of FeXXV and OVIII,
indicating the fast outflow to be persistent and to have a large covering
factor. This finding confirms a high mass rate for the ionised ouflow in
PG1211+143 and provides the first direct measurement of a wide angle,
sub-relativistic outflow from an AGN transporting mechanical energy with the
potential to disrupt the growth of the host galaxy. We suggest PG1211+143 may
be typical of an AGN in a rapid super-Eddington growth phase.Comment: Accepted for publication in MNRAS. Extended version with new figures
and table
Resolving the large scale spectral variability of the luminous Seyfert 1 galaxy 1H 0419-577: Evidence for a new emission component and absorption by cold dense matter
An XMM-Newton observation of the luminous Seyfert 1 galaxy 1H 0419-577 in
September 2002, when the source was in an extreme low-flux state, found a very
hard X-ray spectrum at 1-10 keV with a strong soft excess below ~1 keV.
Comparison with an earlier XMM-Newton observation when 1H 0419-577 was `X-ray
bright' indicated the dominant spectral variability was due to a steep power
law or cool Comptonised thermal emission. Four further XMM-Newton observations,
with 1H 0419-577 in intermediate flux states, now support that conclusion,
while we also find the variable emission component in intermediate state
difference spectra to be strongly modified by absorption in low ionisation
matter. The variable `soft excess' then appears to be an artefact of absorption
of the underlying continuum while the `core' soft emission can be attributed to
recombination in an extended region of more highly ionised gas. We note the
wider implications of finding substantial cold dense matter overlying (or
embedded in) the X-ray continuum source in a luminous Seyfert 1 galaxy.Comment: 34 pages, 15 figures, submitted to Ap
1WGA J2223.7-0206: a Narrow-Line Quasi-Stellar Object in the XMM-Newton field of view of 3C445
We report the discovery of a Narrow Line QSO located at about 1.3' from the
Broad Line Radio Galaxy 3C445. The source,1WGA J2223.7-0206, although already
revealed by ROSAT has never been optically identified previously. An XMM-Newton
observation of 3C445 has allowed, for the first time, an accurate X-ray
spectral study of 1WGA J2223.7-0206, revealing an ultra-soft spectrum and fast
flux variations typical of Narrow Line AGN. The 0.2-10 keV spectrum is well
represented by a power law (Gamma=2.5) plus a black body component (kT = 117
eV) absorbed by Galactic NH. About 80% of the X-ray flux is emitted below 2
keV. The 0.2-2 keV flux is observed to decrease by about a factor 1.6 in about
5000 s. The optical observations, triggered by the X-ray study, confirm the
Narrow Line AGN nature of this source. The continuum is blue with typical AGN
emission lines, pointing to a redshift z=0.46. The full width half maximum of
H_beta is 2000 km/secand the flux rat io [OIII}]/H_beta=0.21. The optical
luminosity (M_R=-23.2) and the point-like appearance in the optical images
identify 1WGA J2223.7-0206 as a Narrow Line QSO. From the optical-UV-X-ray
Spectral Energy Distribution we obtain a lower limit of the bolometric
luminosity of 1WGA J2223.7-0206 (L_bol > 3 10^{45} erg/sec) implying, for
accretion rates close to the Eddington limit, a black hole mass M_BH > 2.4 x
10^{7} M_{\odot}Comment: 6 pages, 5 figures, accepted by A&A, removed pag. 7 containing a
duplication of Fig.
Fe K emission and absorption features in XMM-Newton spectra of Mkn 766 - evidence for reprocessing in flare ejecta
We report on the analysis of a long XMM-Newton EPIC observation in 2001 May
of the Narrow Line Seyfert 1 galaxy Mkn 766. The 3-11 keV spectrum exhibits a
moderately steep power law continuum, with a broad emission line at ~6.7 keV,
probably blended with a narrow line at ~6.4 keV, and a broad absorption trough
above ~8.7 keV. We identify both broad spectral features with reprocessing in
He-like Fe. An earlier XMM-Newton observation of Mkn 766 in 2000 May, when the
source was a factor ~2 fainter, shows a similar broad emission line, but with a
slightly flatter power law and absorption at a lower energy. In neither
observation do we find a requirement for the previously reported broad 'red
wing' to the line and hence of reflection from the innermost accretion disc.
More detailed examination of the longer XMM-Newton observation reveals evidence
for rapid spectral variability in the Fe K band, apparently linked with the
occurrence of X-ray 'flares'. A reduction in the emission line strength and
increased high energy absorption during the X-ray flaring suggests that these
transient effects are due to highly ionised ejecta associated with the flares.
Simple scaling from the flare avalanche model proposed for the luminous QSO PDS
456 (Reeves etal. 2002) confirms the feasibility of coherent flaring being the
cause of the strong peaks seen in the X-ray light curve of \mkn.Comment: 9 pages, 11 figures, submitted to MNRA
A simultaneous XMM-Newton and BeppoSAX observation of the archetypal Broad Line Seyfert 1 galaxy NGC 5548
We report the spectral analysis of a long XMM-Newton observation of the
well-studied, moderate luminosity Broad Line Seyfert 1 galaxy NGC 5548. The
source was at an historically average brightness and we find the hard (3-10
keV) spectrum can be well fitted by a power law of photon index gamma ~ 1.75,
together with reflection. The only feature in the hard X-ray spectrum is a
narrow emission line near 6.4 keV, with an equivalent width of ~ 60 eV. The
energy and strength of this line is consistent with fluorescence from `neutral'
iron distant from the central continuum source. We find no evidence for a broad
Fe K line, with an upper limit well below previous reports, suggesting the
inner accretion disc is now absent or highly ionised. The addition of
simultaneous BeppoSAX data allows the analysis to be extended to 200 keV,
yielding important constraints on the total reflection. Extrapolation of the
hard X-ray power law down to 0.3 keV shows a clear `soft excess' below ~ 0.7
keV. After due allowance for the effects of a complex warm absorber, measured
with the XMM-Newton RGS, we find the soft excess is better described as a
smooth upward curvature in the continuum flux below ~ 2 keV. The soft excess
can be modelled either by Comptonised thermal emission or by enhanced
reflection from the surface of a highly ionised disc.Comment: 9 pages, 11 figures, accepted by MNRAS; minor changes to text and
figure
The XMM-Newton Iron Line Profile of NGC 3783
We report on observations of the iron K line in the nearby Seyfert 1 galaxy,
NGC 3783, obtained in a long, 2 orbit (240 ks) XMM-Newton observation. The line
profile obtained exhibits two strong narrow peaks at 6.4 keV and at 7.0 keV,
with measured line equivalent widths of 120 and 35 eV respectively. The 6.4 keV
emission is the K-alpha line from near neutral Fe, whilst the 7.0 keV feature
probably originates from a blend of the neutral Fe K-beta line and the H-like
line of Fe at 6.97 keV. The relatively narrow velocity width of the K-alpha
line (<5000 km/s), its lack of response to the continuum emission on short
timescales and the detection of a neutral Compton reflection component are all
consistent with a distant origin in Compton-thick matter such as the putative
molecular torus. A strong absorption line from highly ionized iron (at 6.67
keV) is detected in the time-averaged iron line profile, whilst the depth of
the feature appears to vary with time, being strongest when the continuum flux
is higher. The iron absorption line probably arises from the highest ionization
component of the known warm absorber in NGC 3783, with an ionization of logxi=3
and column density of 5x10^{22}cm{-2} and may originate from within 0.1pc of
the nucleus. A weak red-wing to the iron K line profile is also detected below
6.4 keV. However when the effect of the highly ionized warm absorber on the
underlying continuum is taken into account, the requirement for a relativistic
iron line component from the inner disk is reduced.Comment: 34 pages, including 11 figures. Accepted for publication in Ap
A high velocity ionised outflow and XUV photosphere in the narrow emission line quasar PG1211+143
We report on the analysis of a ~60 ksec XMM observation of the bright, narrow
emission line quasar PG 1211+143. Absorption lines are seen in both EPIC and
RGS spectra corresponding to H- and He-like ions of Fe, S, Mg, Ne, O, N and C.
The observed line energies indicate an ionised outflow velocity of ~24000 km
s^-1. The highest energy lines require a column density of N_H ~ 5 x 10^23
cm^-2, at an ionisation parameter of log(xi) ~ 3.4. If the origin of this high
velocity outflow lies in matter being driven from the inner disc, then the flow
is likely to be optically thick within a radius ~130 Schwarzschild radii,
providing a natural explanation for the Big Blue Bump (and strong soft X-ray)
emission in PG 1211+143.Comment: Accepted by MNRAS; Table 1 correcte
Super-solar N/C in the NLS1 Galaxy Markarian 1044
Narrow-Line Seyfert 1s (NLS1s) are known to have extreme values of a number
of properties compared to Active Galactic Nuclei (AGN) as a class. In
particular, previous emission-line studies have suggested that NLS1s are
unusually metal rich compared to broad-line AGN of comparable luminosity. We
present low- and medium-resolution spectroscopic observations of the NLS1
Markarian 1044 with the Hubble Space Telescope Imaging Spectrometer (STIS). We
identify two blueshifted intrinsic absorption systems at -1145 and -295 km/s
relative to the systemic velocity of the galaxy. Using a simple photoionization
model of the absorbing gas, we find that the strongest and best-measured of the
absorption systems has N/C approximately 6.96 times the solar value. We also
report on the discovery of three new Ly-alpha forest lines with neutral
Hydrogen column density log greater than 12.77 in the log. This number is
consistent with the 2.6 expected in the path length to the source redshift of
Mrk 1044.Comment: Submitted to ApJ. 21 pages including 4 figures & 5 table
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