557 research outputs found
Broad P V Absorption in the BALQSO, PG 1254+047: Column Densities, Ionizations and Metal Abundances in BAL Winds
This paper discusses the detection of P V 1118,1128 and other broad
absorption lines (BALs) in archival HST spectra of the low-redshift BALQSO, PG
1254+047. The P V identification is secured by excellent redshift and profile
coincidences with the other BALs, such as C IV 1548,1550 and Si IV 1393,1403,
and by photoionization calculations showing that other lines near this
wavelength, e.g. Fe III 1123, should be much weaker than P V. The observed BAL
strengths imply that either 1) there are extreme abundance ratios such as [C/H]
>~ +1.0, [Si/H] >~ +1.8 and [P/C] >~ +2.2, or 2) at least some of the lines are
much more optically thick than they appear. I argue that the significant
presence of P V absorption indicates severe line saturation, which is disguised
in the observed (moderate-strength) BALs because the absorber does not fully
cover the continuum source(s) along our line(s) of sight. Computed optical
depths for all UV resonance lines show that the observed BALs are consistent
with solar abundances if 1) the ionization parameter is at least moderately
high, log U >~ -0.6, 2) the total hydrogen column density is log N_H(cm-2) >~
22.0, and 3) the optical depths in strong lines like C IV and O VI 1032,1038
are >~25 and >~80, respectively. These optical depths and column densities are
at least an order of magnitude larger than expected from the residual
intensities in the BAL troughs, but they are consistent with the large
absorbing columns derived from X-ray observations of BALQSOs. The outflowing
BALR, at velocities from -15,000 to -27,000 km/s in PG 1254+047, is therefore a
strong candidate for the X-ray absorber in BALQSOs.Comment: 16 pages (LaTeX) plus 8 pages of figures in one file
(pg1254_figs.ps.gz), in press with Ap
IRAS observations of active galaxies
The IRAS survey gives an unbiased view of the infrared properties of the active galaxies. Seyfert galaxies occupy much the same area in color-color plots as to normal infrared bright galaxies, but extend the range towards flatter 60 to 25 mm slopes. Statistically the Seyfert 1 galaxies can be distinguished from the Seyfert 2 galaxies, lying predominantly closer to the area with constant slopes between 25 and 200 mm. The infrared measurements of the Seyfert galaxies cannot distinguish between the emission mechanisms in these objects although they agree with the currently popular ideas; they do provide a measure of the total luminosity of the Seyferts. The quasar's position in the color-color diagrams continue the trend of the Seyferts. The quasar 3C48 is shown to be exceptional among the radio loud quasars in that it has a high infrared luminosity which dominates the power output of the quasar and is most likely associated with the underlying host galaxy
The Nature of Associated Absorption and the UV-X-ray Connection in 3C 288.1
We discuss new Hubble Space Telescope spectroscopy of the radio-loud quasar,
3C 288.1. The data cover ~590 A to ~1610 A in the quasar rest frame. They
reveal a wealth of associated absorption lines (AALs) with no accompanying
Lyman-limit absorption. The metallic AALs range in ionization from C III and N
III to Ne VIII and Mg X. We use these data and photoionization models to derive
the following properties of the AAL gas: 1) There are multiple ionization zones
within the AAL region, spanning a factor of at least ~50 in ionization
parameter. 2) The overall ionization is consistent with the ``warm'' X-ray
continuum absorbers measured in Seyfert 1 nuclei and other QSOs. However, 3)
the column densities implied by the AALs in 3C 288.1 are too low to produce
significant bound-free absorption at any UV-X-ray wavelengths. Substantial
X-ray absorption would require yet another zone, having a much higher
ionization or a much lower velocity dispersion than the main AAL region. 4) The
total hydrogen column density in the AAL gas is log N_H (cm-2)= 20.2. 5) The
metallicity is roughly half solar. 6) The AALs have deconvolved widths of ~900
km/s and their centroids are consistent with no shift from the quasar systemic
velocity (conservatively within +/-1000 km/s). 7) There are no direct
indicators of the absorber's location in our data, but the high ionization and
high metallicity both suggest a close physical relationship to the quasar/host
galaxy environment. Finally, the UV continuum shape gives no indication of a
``blue bump'' at higher energies. There is a distinct break of unknown origin
at ~1030 A, and the decline toward higher energies (with spectral index alpha =
-1.73, for f_nu ~ nu^alpha) is even steeper than a single power-law
interpolation from 1030 A to soft X-rays.Comment: 27 pages with figures and tables, in press with Ap
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Tritium retention in tungsten exposed to intense fluxes of 100 eV tritons
Tungsten is a candidate material for ITER as well as other future magnetic fusion energy devices. Tungsten is well suited for certain fusion applications in that it has a high threshold for sputtering as well as a very high melting point. As with all materials to be used on the inside of a tokamak or similar device, there is a need to know the behavior of hydrogen isotopes embedded in the material. With this need in mind, the Tritium Plasma Experiment (TPE) has been used to examine the retention of tritium in tungsten exposed to very high fluxes of 100 eV tritons. Both tungsten and tungsten containing 1% lanthanum oxide were used in these experiments. Measurements were performed over the temperature range of 423 to 973 K. After exposure to the tritium plasma, the samples were transferred to an outgassing system containing an ionization chamber for detection of the released tritium. The samples were outgassed using linear ramps from room temperature up to 1,473 K. Unlike most other materials exposed to energetic tritium, the tritium retention in tungsten reaches a maximum at intermediate temperatures with low retention at both high and low temperatures. For the very high triton fluences used (>10{sup 25} T/m{sup 2}), the fractional retention of the tritium was below 0.02% of the incident particles. This report presents not only the results of the tritium retention, but also includes the modeling of the results and the implication for ITER and other future fusion devices where tungsten is used
AcDc - A new code for the NLTE spectral analysis of accretion discs: application to the helium CV AM CVn
We present a recently developed code for detailed NLTE calculations of
accretion disc spectra of cataclysmic variables and compact X-ray binaries.
Assuming a radial structure of a standard alpha-disc, the disc is divided into
concentric rings. For each disc ring the solution of the radiation transfer
equation and the structure equations, comprising the hydrostatic and radiative
equilibrium, the population of the atomic levels as well as charge and particle
conservation, is done self-consistently. Metal-line blanketing and irradiation
by the central object are taken into account. As a first application, we show
the influence of different disc parameters on the disc spectrum for the helium
cataclysmic variable AM CVn.Comment: 7 pages, 11 figures to be published in A&
The radio core and jet in the broad absorption line quasar PG 1700+518
The blue-shifted broad absorption lines (BAL) or troughs are observed in
Active Galactic Nuclei (AGNs) when our line of sight is intercepted by a high
speed outflow (wind), likely originating in the accretion disc. The outflow or
wind can shed light on the internal structure obscured by the AGN torus.
Recently, it has been shown that this outflow is rotating in the BAL quasar PG
1700+518, further supporting the accretion disc origin of the wind. With the
purpose of giving independent constraints on the wind geometry, we performed
high-resolution European VLBI Network (EVN) observations at 1.6 GHz in 2010.
Combining the VLBI (Very Long Baseline Interferometry) results with the Very
Large Array (VLA) archival data at 8.4 GHz, we present its jet structure on
scales of parsec (pc) to kiloparsec (kpc) for the first time. The source shows
two distinct jet features in East-West direction with a separation of around 4
kpc. The Eastern feature, which has so far been assumed to hide the core, is a
kpc-scale hot spot, which is completely resolved out in the EVN image. In the
western jet feature, we find a compact jet component, which pinpoints the
position of the central black hole in the galaxy. Jet components on both sides
of the core are additionally detected in the Northwest-Southeast direction, and
they show a symmetric morphology on scale of <1 kpc. This two-sided jet feature
is not common in the known BAL quasars and indicates that the jet axis is far
away from the line of sight. Furthermore, it is nearly parallel to the
scattering plane revealed earlier by optical polarimetry. By analogy to
polar-scattered Seyfert 1 galaxies, we conclude that the jet likely has a
viewing angle around 45 degree. The analogy is further supported by the recent
report of significant cold absorption in the soft X-rays, a nearly unique
feature to polar-scattered Seyfert galaxies.Comment: Accepted for publication in MNRAS Letters, 5 pages, 1 figure
The Nucleon-Nucleon Interaction in the Chromo-Dielectric Soliton Model: Dynamics
The present work is an extension of a previous study of the nucleon-nucleon
interaction based on the chromo-dielectric soliton model. The former approach
was static, leading to an adiabatic potential. Here we perform a dynamical
study in the framework of the Generator Coordinate Method. In practice, we
derive an approximate Hill-Wheeler differential equation and obtain a local
nucleon-nucleon potential as a function of a mean generator coordinate. This
coordinate is related to an effective separation distance between the two
nucleons by a Fujiwara transformation. This latter relationship is especially
useful in studying the quark substructure of light nuclei. We investigate the
explicit contribution of the one-gluon exchange part of the six-quark
Hamiltonian to the nucleon-nucleon potential, and we find that the dynamics are
responsible for a significant part of the short-range N-N repulsion.Comment: 16 pages (REVTEX), 6 figures (uuencoded Postscript) optionally
included using epsfig.st
The Ionized Gas and Nuclear Environment in NGC 3783 V. Variability and Modeling of the Intrinsic Ultraviolet Absorption
We present results on the location, physical conditions, and geometry of the
outflow in the Seyfert 1 galaxy NGC 3783 from a study of the variable intrinsic
UV absorption. Based on 18 observations with HST/STIS and 6 observations with
FUSE, we find: 1) The absorption from the lowest-ionization species in each of
the three strong kinematic components varied inversely with the continuum flux,
indicating the ionization structure responded to changes in the photoionizing
flux over the weekly timescales sampled by our observations. 2) A multi-
component model with an unocculted NLR and separate BLR and continuum
line-of-sight covering factors predicts saturation in several lines, consistent
with the lack of observed variability. 3) Column densities for the individual
metastable levels are measured from the resolved C III *1175 absorption complex
observed in one component. Based on our computed metastable level populations,
the electron density of this absorber is ~3x10^4 cm^-3. Photoionization
modeling results place it at ~25 pc from the central source. 4) Using
time-dependent calculations, we are able to reproduce the detailed variability
observed in this absorber, and derive upper limits on the distances for the
other components of 25-50 pc. 5) The ionization parameters derived for the
higher ionization UV absorbers are consistent with the modeling results for the
lowest-ionization X-ray component, but with smaller total column density. They
have similar pressures as the three X-ray ionization components. These results
are consistent with an inhomogeneous wind model for the outflow in NGC 3783. 6)
Based on the predicted emission-line luminosities, global covering factor
constraints, and distances derived for the UV absorbers, they may be identified
with emission- line gas observed in the inner NLR of AGNs. (abridged)Comment: 30 pages, 18 figures (7 color), emulateapj, accepted for publication
in The Astrophysical Journa
Geometrical Effects of Baryon Density Inhomogeneities on Primordial Nucleosynthesis
We discuss effects of fluctuation geometry on primordial nucleosynthesis. For
the first time we consider condensed cylinder and cylindrical-shell fluctuation
geometries in addition to condensed spheres and spherical shells. We find that
a cylindrical shell geometry allows for an appreciably higher baryonic
contribution to be the closure density (\Omega_b h_{50}^2 \la 0.2) than that
allowed in spherical inhomogeneous or standard homogeneous big bang models.
This result, which is contrary to some other recent studies, is due to both
geometry and recently revised estimates of the uncertainties in the
observationally inferred primordial light-element abundances. We also find that
inhomogeneous primordial nucleosynthesis in the cylindrical shell geometry can
lead to significant Be and B production. In particular, a primordial beryllium
abundance as high as [Be] = 12 + log(Be/H) is possible while still
satisfying all of the light-element abundance constraints.Comment: Latex, 20 pages + 11 figures(not included). Entire ps file with
embedded figures available via anonymous ftp at
ftp://genova.mtk.nao.ac.jp/pub/prepri/bbgeomet.ps.g
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