309 research outputs found
The Case for Optically-Thick High Velocity Broad Line Region Gas in Active Galactic Nuclei
A combined analysis of the profiles of the main broad quasar emission lines
in both Hubble Space Telescope and optical spectra shows that while the
profiles of the strong UV lines are quite similar, there is frequently a strong
increase in the Ly-alpha/H-alpha ratio in the high-velocity gas. We show that
the suggestion that the high velocity gas is optically-thin presents many
problems. We show that the relative strengths of the high velocity wings arise
naturally in an optically-thick BLR component. An optically-thick model
successfully explains the equivalent widths of the lines, the Ly-alpha/H-alpha
ratios and flatter Balmer decrements in the line wings, the strengths of CIII]
and the lambda 1400 blend, and the strong variability of high-velocity,
high-ionization lines (especially HeII and HeI).Comment: 34 pages in AASTeX, including 10 pages of figures. Submitted to
Astrophysical Journa
The Host Galaxies of Narrow-Line Seyfert 1s: Evidence for Bar-Driven Fueling
We present a study of the host-galaxy morphologies of narrow- and broad-line
Seyfert 1 galaxies (NLS1s and BLS1s) based on broad-band optical images from
the Hubble Space Telescope archives. We find that large-scale stellar bars,
starting at ~1 kpc from the nucleus, are much more common in NLS1s than BLS1s.
Furthermore, the fraction of NLS1 spirals that have bars increases with
decreasing full-width at half-maximum (FWHM) of the broad component of H-beta.
These results suggest a link between the large-scale bars, which can support
high fueling rates to the inner kpc, and the high mass-accretion rates
associated with the supermassive black holes in NLS1s.Comment: 19 pages, 4 figures (1a, 1b, 2, and 3), Accepted for publication in
the Astronomical Journa
Ultraviolet and optical properties of Narrow-Line Seyfert 1 galaxies
Narrow Line Seyfert 1 (NLS1) galaxies are remarkable for their extreme
continuum and emission line properties which are not well understood. New
results bearing on the spectroscopic characteristics of these objects are
presented here, with the aim of establishing their typical ultraviolet and
optical spectral behavior. We employ HST observations of 22 NLS1s, which
represent a substantial improvement over previous work in terms of data quality
and sample size. High signal-to-noise NLS1 composite spectra are constructed,
allowing accurate measurements of the continuum shape and the strengths,
ratios, and widths for lines, including weak features which are barely
identifiable in other Active Galactic Nuclei (AGN) composites. We find that the
NLS1 sources have redder UV-blue continua than those typically measured in
other quasars and Seyferts. Objects with UV line absorption show redder
spectra, suggesting that dust is important in modifying the continuum shapes.
The data also permit a detailed investigation of the previously proposed link
between NLS1s and z >~ 4 quasars. Direct comparison of their composite spectra,
as well as a Principal Component Analysis, suggest that high-z QSOs do not show
a strong preference toward NLS1 behavior.Comment: 23 pages (incl. 9 figures, 4 tables), to appear in The Publications
of the Astronomical Society of the Pacifi
Образ міста у творчості О. Іваненко (на матеріалі казки “Чарівна квітка”)
Авторка статті досліджує образ міста у творчості відомої письменниці ХХ ст.
Оксани Іваненко. Автор робить спробу виокремити особливості творів, що характерні для її
манери письма. Приділяється увага тематиці творів письменниці, портретній характеристиці її
героїв. Дослідниця робить спробу схарактеризувати образ міста на матеріалі казок “Чарівна
квітка”. “Місто боягузів” у казці “Чарівна квітка” О. Іваненко є точкою відліку в казковому часі, не має логіки у взаємозв’язку з дійсністю. Результатом дослідження є висновок про те, що
письменниця досліджує процес становлення і розвитку дитини, вивчає особливості психології
персонажів.
Ключові слова: казка, логіка, образ, місто, тематика, реальність, персонажі.Автор статьи исследует образ города в творчестве известной писательницы ХХ века
Оксаны Иваненко. Автор статьи делает попытку выделить особенности произведений,
характерные ее письму. Уделяется внимание тематике произведений писательницы, портретной
характеристике ее героев. Исследователь делает попытку охарактеризовать образ города на
материале сказки “Волшебный цветок”. “Город боягузов” в сказке “Волшебный цветок”
Оксаны Иваненко является точкой отсчета в сказочном времени, не имеет логики со
взаимосвязью с действительностью. Результатом исследования является вывод о том, что
писательница исследует процесс становления и развития юного читателя, изучает особенности
психологии персонажей.
Ключевые слова: сказка, логика, образ, город, тематика, реальность, персонажи.The author of the article investigates the figure of the city in the O. Ivanenko’s works, the
famous writer of the XX th century. The author tries to define the peculiarities of her works. There are
paid attentions to the portrait characteristics of the main characters in “Magic flower”, to the themes of
her works. The investigator tries to characterise the figure of the city in the “Magic flower”. The “city of
timorous people” in the “Magic flower” by O. Ivanenko is the beginning in the time of the tale, it does not
have logic. This investigation proves that the writer investigates the process of the child’s growing and
growing, studies the psychological peculiarities of the main characters.
Keywords: tale, logic, figure, city, themes, reality, main characters
The Unified Model of Active Galactic Nuclei: II. Evolutionary Connection
(Abbreviated) We assemble a sample composed of 243 nearby Seyfert galaxies
with redshifts to test the unification scheme. The sample contains
94 BLS1s, 44 NLS1s, 36 X-ray absorbed HBLR S2s, 42 X-ray absorbed non-HBLR S2s
and 27 X-ray unabsorbed Seyfert 2s (unabsorbed non-HBLR S2s and HBLR S2s). We
find that: 1) NLS1s have less massive black hole masses than BLS1s; 2) HBLRS2s
have the same mass distribution of the black holes with BLS1s; 3) the absorbed
non-HBLR S2s have less massive black holes than HBLR S2s; 4) unabsorbed
non-HBLR S2s have the most massive black holes. We thus have a queue of black
hole masses from small to large: narrow to broad line Seyfert galaxies,
providing new evidence for the evolutionary sequence of Seyfert galaxies. We
find that the opening angles of the torus in NLS1s and absorbed non-HBLR S2s
are significantly smaller than that in BLS1s and HBLR S2s. The growth of the
black holes and increases of the opening angles of the tori determine the
various appearances of Seyfert galaxies. We also find that the unabsorbed
Seyfert 2 galaxies could be caused by low gas-to-dust ratios in the present
sample. This indicates that the star formation histories could be different in
the unabsorbed from in absorbed Seyfert 2 galaxies, showing evidence for
suppressed star formation by black hole activities. We outline a new
unification scheme based on the orientation hypothesis: Seyfert galaxies can be
unified by including growth of black holes, Eddington ratios, changing opening
angles of tori and gas-to-dust ratios in the tori. Seyfert galaxies are tending
to finally evolve to unabsorbed non-HBLR Seyfert 2 galaxies, in which the black
holes are accreting with low accretion rates and both the broad line region and
dusty torus disappear.Comment: ApJ, vol 661 (2007), in pres
Increased levels of RNA oxidation enhance the reversion frequency in aging pro-apoptotic yeast mutants
Despite recent advances in understanding the complexity of RNA processes, regulation of the metabolism of oxidized cellular RNAs and the mechanisms through which oxidized ribonucleotides affect mRNA translation, and consequently cell viability, are not well characterized. We show here that the level of oxidized RNAs is markedly increased in a yeast decapping Kllsm4Δ1 mutant, which accumulates mRNAs, ages much faster that the wild type strain and undergoes regulated-cell-death. We also found that in Kllsm4Δ1 cells the mutation rate increases during chronological life span indicating that the capacity to han- dle oxidized RNAs in yeast declines with aging. Lowering intracellular ROS levels by antioxidants recovers the wild- type phenotype of mutant cells, including reduced amount of oxidized RNAs and lower mutation rate. Since mRNA oxidation was reported to occur in different neurodegen- erative diseases, decapping-deficient cells may represent a useful tool for deciphering molecular mechanisms of cell response to such conditions, providing new insights into RNA modification-based pathogenesis
Measurement of the Broad Line Region Size in Two Bright Quasars
We present 4 years of spectrophotometric monitoring data for two radio-quiet
quasars, PG 0804+762 and PG 0953+414, with typical sampling intervals of
several months. Both sources show continuum and emission line variations. The
variations of the H line follow those of the continuum with a time lag,
as derived from a cross-correlation analysis, of 9330 days for PG 0804+762
and 11155 days for PG 0953+414. This is the first reliable measurement of
such a lag in active galactic nuclei with luminosity erg s.
The broad line region (BLR) size that is implied is almost an order of
magnitude larger than that measured in several Seyfert 1 galaxies and is
consistent with the hypothesis that the BLR size grows as .Comment: 5 pages, LaTeX (including aas2pp4 and epsf), including 4 EPS figures.
Accepted for publication in Astrophysical Journal Letter
Sex-Specific Association of the Putative Fructose Transporter SLC2A9 Variants With Uric Acid Levels Is Modified by BMI
OBJECTIVE—High serum uric acid levels lead to gout and have been reported to be associated with an increased risk of hypertension, obesity, metabolic syndrome, type 2 diabetes, and cardiovascular disease. Recently, the putative fructose transporter SLC2A9 was reported to influence uric acid levels. The aim of the present study was to examine the association of four single nucleotide polymorphisms within this gene with uric acid levels and to determine whether this association is modified by obesity
Steps Toward Determination of the Size and Structure of the Broad-Line Region in Active Galactic Nuclei. XV. Long-Term Optical Monitoring of NGC 5548
We present the results of three years of ground-based observations of the
Seyfert 1 galaxy NGC 5548, which combined with previously reported data, yield
optical continuum and broad-line H-beta light curves for a total of eight
years. The light curves consist of over 800 points, with a typical spacing of a
few days between observations. During this eight-year period, the nuclear
continuum has varied by more than a factor of seven, and the H-beta emission
line has varied by a factor of nearly six. The H-beta emission line responds to
continuum variations with a time delay or lag of 10-20 days, the precise value
varying somewhat from year to year. We find some indications that the lag
varies with continuum flux in the sense that the lag is larger when the source
is brighter.Comment: 29 pages, 6 figures. Accepted for publication in ApJ (1999 Jan 10
X-Ray/Ultraviolet Observing Campaign of the Markarian 279 Active Galactic Nucleus Outflow: a close look at the absorbing/emitting gas with Chandra-LETGS
We present a Chandra-LETGS observation of the Seyfert 1 galaxy Mrk 279. This
observation was carried out simultaneously with HST-STIS and FUSE, in the
context of a multiwavelength study of this source. The Chandra pointings were
spread over ten days for a total exposure time of ~360 ks. The spectrum of
Mrk279 shows evidence of broad emission features, especially at the wavelength
of the OVII triplet. We quantitatively explore the possibility that this
emission is produced in the broad line region (BLR). We modeled the broad UV
emission lines seen in the FUSE and HST-STIS spectra following the ``locally
optimally emitting cloud" approach. We find that the X-ray lines luminosity
derived from the best fit BLR model can match the X-ray features, suggesting
that the gas producing the UV lines is sufficient to account also for the X-ray
emission. The spectrum is absorbed by ionized gas whose total column density is
~5x10^{20} cm^{-2}. The absorption spectrum can be modeled by two distinct gas
components (log xi ~ 0.47 and 2.49, respectively) both showing a significant
outflow velocity. However, the data allow also the presence of intermediate
ionization components. The distribution of the column densities of such extra
components as a function of the ionization parameter is not consistent with a
continuous, power law-like, absorber, suggesting a complex structure for the
gas outflow for Mrk 279 (abridged).Comment: 16 pages, 12 figures. To appear in A&
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