909 research outputs found
SDSS J143030.22-001115.1: A misclassified narrow-line Seyfert 1 galaxy with flat X-ray spectrum
We used multi-component profiles to model H and [O III]4959,5007 lines for SDSS J143030.22-001115.1, a narrow-line Seyfert 1
galaxy (NLS1) in a sample of 150 NLS1s candidates selected from the Sloan
Digital Sky Survey (SDSS) Early Data Release (EDR). After subtracting the
H contribution from narrow line regions (NLRs), we found that its full
width half maximum (FWHM) of broad H line is nearly 2900 \kms,
significantly larger than the customarily adopted criterion of 2000 \kms. With
its weak Fe II multiples, we think that SDSS J143030.22-001115.1 can't be
classified as a genuine NLS1. When we calculate the virial black hole masses of
NLS1s, we should use the H linewidth after subtracting the H
contribution from NLRs.Comment: 7 pages, 1 table, accepted by ChJA
A Complete Sample of Soft X-ray Selected AGN: II. Statistical Analysis
Direct correlations and a Principal Component Analysis (PCA) are presented
for a complete sample of 110 soft X-ray selected AGN of which about half are
Narrow-Line Seyfert 1 galaxies (NLS1s). The direct correlation analyses show
that narrower FWHM(H-beta) correlates with steeper X-ray spectrum, stronger
optical FeII emission, weaker [OIII] emission and stronger short-term X-ray
variability. This direct correlation analysis and the PCA confirm the Boroson &
Green (1992) Eigenvector 1 relationship for AGN: FeII strength anti-correlates
with [OIII] line strength. Eigenvector 1 is well-correlated with the Eddington
luminosity ratio L/L_Edd while Eigenvector 2 shows a very good correlation with
the mass of the central black hole and the mass accretion rate. The Eddington
ratio L/L_Edd correlates with the X-ray spectral index alpha-X and the black
home mass anti-correlates with the X-ray variability chi^2/nu. The Eddington
ration L/L_Edd may be interpreted as the age of an AGN: AGN with steep X-ray
spectra, strong FeII, and weak [OIII] are AGN in an early phase of their
evolution. In this hypothesis NLS1s are young AGN.Comment: Accepted for publication in AJ (April 2004), 21 pages, 13 figure
Eddington Accretion and QSO Emission Lines at z ~ 2
Broad Absorption Line (BAL) QSOs have been suggested to be youthful
super-accretors based on their powerful radiatively driven absorbing outflows
and often reddened continua. To test this hypothesis, we observed near IR
spectra of the H region for 11 bright BAL QSOs at redshift z ~ 2. We
measured these and literature spectra for 6 BAL QSOs, 13 radio-loud and 7
radio-quiet non-BAL QSOs. Using the luminosity and H broad line width to
derive black hole mass and accretion rate, we find that both BAL and non-BAL
QSOs at z ~ 2 tend to have higher than those at low z -- probably a
result of selecting the brightest QSOs. However, we find that the high z QSOs,
in particular the BAL QSOs, have extremely strong Fe II and very weak [O III],
extending the inverse relationship found for low z QSOs. This suggests that,
even while radiating near , the BAL QSOs have a more plentiful fuel
supply than non-BAL QSOs. Comparison with low z QSOs shows for the first time
that the inverse Fe II -- [O III] relationship is indeed related to
, rather than black hole mass.Comment: 18 pages including 5 figures and 1 table. Accepted by the
Astrophysical Journal Letter
Tidal Disruption of a Star By a Black Hole : Observational Signature
We have modeled the time-variable profiles of the Halpha emission line from
the non-axisymmetric disk and debris tail created in the tidal disruption of a
solar-type star by a million solar mass black hole. Two tidal disruption event
simulations were carried out using a three dimensional relativistic
smooth-particle hydrodynamic code, to describe the early evolution of the
debris during the first fifty to ninety days. We have calculated the physical
conditions and radiative processes in the debris using the photoionization code
CLOUDY. We model the emission line profiles in the period immediately after the
accretion rate onto the black hole became significant. We find that the line
profiles at these very early stages of the evolution of the post-disruption
debris do not resemble the double peaked profiles expected from a rotating disk
since the debris has not yet settled into such a stable structure. As a result
of the uneven distribution of the debris and the existence of a ``tidal tail''
(the stream of returning debris), the line profiles depend sensitively on the
orientation of the tail relative to the line of sight. Moreover, the predicted
line profiles vary on fairly short time scales (of order hours to days). Given
the accretion rate onto the black hole we also model the Halpha light curve
from the debris and the evolution of the Halpha line profiles in time.Comment: 20 pages, 9 figures, to appear in ApJ, 1 August 2004 issue; mpeg
simulations of tidal disruption available at
http://www.astro.psu.edu/users/tamarab/tdmovies.htm
Optical Properties of Radio-selected Narrow Line Seyfert 1 Galaxies
We present results from the analysis of the optical spectra of 47
radio-selected narrow-line Seyfert 1 galaxies (NLS1s). These objects are a
subset of the First Bright Quasar Survey (FBQS) and were initially detected at
20 cm (flux density limit ~1 mJy) in the VLA FIRST Survey. We run Spearman rank
correlation tests on several sets of parameters and conclude that, except for
their radio properties, radio-selected NLS1 galaxies do not exhibit significant
differences from traditional NLS1 galaxies. Our results are also in agreement
with previous studies suggesting that NLS1 galaxies have small black hole
masses that are accreting very close to the Eddington rate. We have found 16
new radio-loud NLS1 galaxies, which increases the number of known radio-loud
NLS1 galaxies by a factor of ~5.Comment: 18 pages, 20 figures, Accepted for publication in Ap
Probing the Ionizing Continuum of Narrow-Line Seyfert 1 Galaxies. I.Observational Results
We present optical spectra and emission-line ratios of 12 Narrow-Line Seyfert
1 (NLS1) galaxies that we observed to study the ionizing EUV continuum. A
common feature in the EUV continuum of active galactic nuclei is the big blue
bump (BBB), generally associated with thermal accretion disk emission. While
Galactic absorption prevents direct access to the EUV range, it can be mapped
by measuring the strength of a variety of forbidden optical emission lines that
respond to different EUV continuum regions. We find that narrow emission-line
ratios involving [OII]3727, Hbeta, [OIII]5007, [OI]6300, Halpha,[NII]6583, and
[SII]6716,6731 indicate no significant difference between NLS1s and Broad-Line
Seyfert 1 (BLS1) galaxies, which suggests that the spectral energy
distributions of their ionizing EUV - soft X-ray continua are similar. The
relative strength of important forbidden high ionization lines like [NeV]3426
compared to HeII4686 and the relative strength of [FeX]6374 appear to show the
same range as in BLS1 galaxies. However, a trend of weaker
F([OI]6300)/F(Halpha) emission-line ratios is indicated for NLS1s compared to
BLS1s. To recover the broad emission-line profiles we used Gaussian components.
This approach indicates that the broad Hbeta profile can be well described with
a broad component (FWHM = 3275 +- 800 km/s) and an intermediate broad component
(FWHM = 1200 +- 300 km/s). The width of the broad component is in the typical
range of normal BLS1s. The emission-line flux that is associated with the broad
component in these NLS1s amounts to at least 60% of the total flux. Thus it
dominates the total line flux, similar to BLS1 galaxies.Comment: 34 pages, 9 figures. accepted for publication in the
Astrophys.Journa
The rise of an ionized wind in the Narrow Line Seyfert 1 Galaxy Mrk 335 observed by XMM-Newton and HST
We present the discovery of an outflowing ionized wind in the Seyfert 1
Galaxy Mrk 335. Despite having been extensively observed by most of the largest
X-ray observatories in the last decade, this bright source was not known to
host warm absorber gas until recent XMM-Newton observations in combination with
a long-term Swift monitoring program have shown extreme flux and spectral
variability. High resolution spectra obtained by the XMM-Newton RGS detector
reveal that the wind consists of three distinct ionization components, all
outflowing at a velocity of 5000 km/s. This wind is clearly revealed when the
source is observed at an intermediate flux state (2-5e-12 ergs cm^-2 s^-1). The
analysis of multi-epoch RGS spectra allowed us to compare the absorber
properties at three very different flux states of the source. No correlation
between the warm absorber variability and the X-ray flux has been determined.
The two higher ionization components of the gas may be consistent with
photoionization equilibrium, but we can exclude this for the only ionization
component that is consistently present in all flux states (log(xi)~1.8). We
have included archival, non-simultaneous UV data from HST (FOS, STIS, COS) with
the aim of searching for any signature of absorption in this source that so far
was known for being absorption-free in the UV band. In the COS spectra obtained
a few months after the X-ray observations we found broad absorption in CIV
lines intrinsic to the AGN and blueshifted by a velocity roughly comparable to
the X-ray outflow. The global behavior of the gas in both bands can be
explained by variation of the covering factor and/or column density, possibly
due to transverse motion of absorbing clouds moving out of the line of sight at
Broad Line Region scale.Comment: 24 pages, 12 figures, ApJ accepte
A Complete Sample of Soft X-ray Selected AGN: I. The Data
We present the optical spectra and simple statistical analysis for a complete
sample of 110 soft X-ray selected AGN. About half of the sources are
Narrow-Line Seyfert 1 galaxies (NLS1s), which have the steepest X-ray spectra,
strongest FeII emission and slightly weaker [OIII]5007 emission than broad line
Seyfert 1s (BLS1s).
Kolmogorov Smirnov tests show that NLS1s and BLS1s have clearly different
distributions of the X-ray spectral slope, X-ray short-term variability, and
FeII equivalent widths and luminosity and FeII/H-beta ratios. The differences
in the [OIII]/H-beta and [OIII] equivalent widths are only marginal. We found
no significant differences between NLS1s and BLS1s in their rest frame 0.2-2.0
X-ray luminosities, rest frame 5100A monochromatic luminosities, bolometric
luminosities, redshifts, and their H equivalent widths.Comment: Accepted for publication in AJ (scheduled for January 2004), 21
pages, 10 figures, The paper including the optical spectra and FeII
subtracted spectra can be retrieved from
http://www.astronomy.ohio-state.edu/~dgrupe/research/sample_paper1.htm
HST STIS Ultraviolet Spectral Evidence for Outflow in Extreme Narrow-line Seyfert 1 Galaxies: I. Data and Analysis
We present HST STIS observations of two extreme NLS1s, IRAS 13224-3809 and 1H
0707-495. The spectra are characterized by very blue continua, broad, strongly
blueshifted high-ionization lines (including \ion{C}{4} and \ion{N}{5}), and
narrow, symmetric intermediate- (including \ion{C}{3}], \ion{Si}{3}],
\ion{Al}{3}) and low-ionization (e.g., \ion{Mg}{2}) lines centered at their
rest wavelengths. The emission-line profiles suggest that the high-ionization
lines are produced in a wind, and the intermediate- and low-ionization lines
are produced in low-velocity gas associated with the accretion disk or base of
the wind. In this paper, we present the analysis of the spectra from these two
objects; in a companion paper we present photoionization analysis and a toy
dynamical model for the wind. The highly asymmetric profile of \ion{C}{4}
suggests that it is dominated by emission from the wind, so we develop a
template for the wind from the \ion{C}{4} line. We model the bright emission
lines in the spectra using a combination of this template, and a narrow,
symmetric line centered at the rest wavelength. We also analyzed a comparison
sample of HST spectra from 14 additional NLS1s, and construct a correlation
matrix of emission line and continuum properties. A number of strong
correlations were observed, including several involving the asymmetry of the
\ion{C}{4} line.Comment: 26 pages, 10 figures, accepted for publication in ApJ with no change
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