462 research outputs found
A 10 kpc Scale Seyfert Galaxy Outflow: HST/COS Observations of IRAS F22456-5125
We present analysis of the UV-spectrum of the low-z AGN IRAS-F22456-5125
obtained with the Cosmic Origins Spectrograph on board the Hubble Space
Telescope. The spectrum reveals six main kinematic components, spanning a range
of velocities of up to 800 km s-1, which for the first time are observed in
troughs associated with CII, CIV, NV, SiII, SiIII, SiIV and SIV. We also obtain
data on the OVI troughs, which we compare to those available from an earlier
FUSE epoch. Column densities measured from these ions allow us to derive a
well-constrained photoionization solution for each outflow component. Two of
these kinematic components show troughs associated with transitions from
excited states of SiII\ and CII. The number density inferred from these
troughs, in combination with the deduced ioinization parameter, allows us to
determine the distance to these outflow components from the central source. We
find these components to be at a distance of ~ 10 kpc. The distances and the
number densities derived are consistent with the outflow being part of a
galactic wind.Comment: 52 pages, 15 figures, accepted for publication in ApJ March 25, 201
Distance to Multiple Kinematic Components of Quasar Outflows: VLT Observations of QSO 2359-1241 and SDSS J0318-0600
Using high resolution VLT spectra, we study the multi-component outflow
systems of two quasars exhibiting intrinsic Fe II absorption (QSO 2359-1241 and
SDSS J0318-0600). From the extracted ionic column densities and using
photoionization modeling we determine the gas density, total column density,
and ionization parameter for several of the components. For each object the
largest column density component is also the densest, and all other components
have densities of roughly 1/4 of that of the main component. We demonstrate
that all the absorbers lie roughly at the same distance from the source.
Further, we calculate the total kinetic luminosities and mass outflow rates of
all components and show that these quantities are dominated by the main
absorption component.Comment: 27 pages, 5 figure
Physical Conditions in Quasar Outflows: VLT Observations of QSO 2359-1241
We analyze the physical conditions of the outflow seen in QSO 2359-1241 (NVSS
J235953-124148), based on high resolution spectroscopic VLT observations. This
object was previously studied using Keck/HIRES data. The main improvement over
the HIRES results is our ability to accurately determine the number density of
the outflow. For the major absorption component, level population from five
different Fe II excited level yields n_H=10^4.4 cm^-3 with less than 20%
scatter. We find that the Fe ii absorption arises from a region with roughly
constant conditions and temperature greater than 9000 K, before the ionization
front where temperature and electron density drop. Further, we model the
observed spectra and investigate the effects of varying gas metalicities and
the spectral energy distribution of the incident ionizing radiation field. The
accurately measured column densities allow us to determine the ionization
parameter log(U) = -2.4 and total column density of the outflow (log(N_H) =
20.6 cm^-2). Combined with the number density finding, these are stepping
stones towards determining the mass flux and kinetic luminosity of the outflow,
and therefore its importance to AGN feedback processes.Comment: 21 pages, 3 figures (accepted for publication in the ApJ
Interaction of nucleotides and cations with the (Ca2+, Mg2+)-ATPase of sarcoplasmic reticulum as determined by fluorescence changes of bound 1-anilino-8-naphthalenesulfonate
The changes in fluorescence of 1-anilino-8-naphthalenesulfonate (ANS-) have been used to determine binding of ligands to the (Ca2+, Mg2+)-ATPase of sarcoplasmic reticulum vesicles, isolated from rabbit skeletal muscle. ANS- binds to sarcoplasmic reticulum membranes with an apparent Kd of 3.8 X 10(-5) M. The binding of ANS- had no effect on Ca2+ transport or Ca2+-dependent ATPase activity. EGTA, by binding endogenous Ca2+, increased the fluorescence intensity of bound ANS- by 10-12%. Subsequent addition of ATP, ADP, or Ca2+, in the presence or absence of Mg2+, reversed this change of fluorescence. The binding parameters, as determined by these decreases in fluorescence intensity, were as follows: for ATP, Kd = 1.0 X 10(-5) M, nH = 0.80; for ADP, Kd = 1.2 X 10(-5) M, nH = 0.89; and for Ca2+, Kd = 3.4 X 10(-7) M, nH = 1.8. The binding parameters for ITP and for the nonhydrolyzable analogue, adenyl-5'-yl-beta, gamma-methylene)diphosphate, were similar to those of ATP, but GDP, IDP, CDP, AMP, and cAMP had lower apparent affinities. Millimolar concentrations of pyrophosphate also decreased the fluorescence of bound ANS-, whereas orthophosphate caused a small (2-3%) increase in fluorescence in Ca2+-free media. Vanadate, in the presence of EGTA, decreased the fluorescence of bound ANS-with half-maximal effect at 4 X 10(-5) M. The changes of fluorescence intensity of bound ANS- appear to reflect conformational changes of the (Ca2+, Mg2+)-ATPase, consequent to ligand binding, with the low and high fluorescence intensity species corresponding to the E1 and E2 conformations, respectively. These appear to reflect similar conformational states of the (Ca2+, Mg2+)-ATPase to those reported by changes in intrinsic tryptophan fluorescence (DuPont, Y. (1976) Biochem, Biophys. Res. Commun. 71, 544-550)
Anatomy of the AGN in NGC 5548 II. The spatial, temporal, and physical nature of the outflow from HST/COS Observations
Context. AGN outflows are thought to influence the evolution of their host galaxies and of super massive black holes. Our deep multiwavelength campaign on NGC 5548 has revealed a new, unusually strong X-ray obscuration, accompanied by broad UV absorption troughs observed for the first time in this object. The X-ray obscuration caused a dramatic decrease in the incident ionizing flux on the outflow that produces the long-studied narrow UV absorption lines in this AGN. The resulting data allowed us to construct a comprehensive physical, spatial, and temporal picture for this enduring AGN wind.
Aims. We aim to determine the distance of the narrow UV outflow components from the central source, their total column-density, and the mechanism responsible for their observed absorption variability.
Methods. We study the UV spectra acquired during the campaign, as well as from four previous epochs (1998−2011). Our main analysis tools are ionic column-density extraction techniques, photoionization models based on the code CLOUDY, and collisional excitation simulations.
Results. A simple model based on a fixed total column-density absorber, reacting to changes in ionizing illumination, matches the very different ionization states seen in five spectroscopic epochs spanning 16 years. The main component of the enduring outflow is situated at 3.5 ± 1.1 pc from the central source, and its distance and number density are similar to those of the narrow-emitting-line region in this object. Three other components are situated between 5−70 pc and two are farther than 100 pc. The wealth of observational constraints and the anti-correlation between the observed X-ray and UV flux in the 2002 and 2013 epochs make our physical model a leading contender for interpreting trough variability data of quasar outflows.
Conclusions. This campaign, in combination with prior UV and X-ray data, yields the first simple model that can explain the physical characteristics and the substantial variability observed in an AGN outflow
Keck high-resolution spectroscopy of Mrk 335: constraints on the number of emitting clouds in the broad-line region
We present high-resolution (∼6 km s⁻¹), high signal-to-noise ratio (−400 at Hα line centre) spectroscopy of Mrk 335. Cross-correlation (CC) analysis of the data yields a lower limit of ∼ 3 × 10⁶ for the number of emitting clouds in the broad-line region (BLR) of this object. This limit is applicable for clouds with T=2 × 10⁴ K and an optical depth of ∼ 10⁴ in their Hα line. The result is obtained from the absence of a CC signal in the data and from extensive Monte Carlo simulations that show the minimum number of clouds necessary in order to prevent the creation of a detectable CC signal. The simulations can be used to test any BLR model which is based on a contribution from discrete sources provided that the individual emission profile of the sources and their distribution are given. Current BLR models based on stellar atmospheres of bloated stars can be ruled out, unless the linewidth of an individual star exceeds 100 km s⁻¹. The lower limit on the number of emitting clouds also provides constraints on traditional photoionization models for a system of clouds
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