Abstract We report on follow-up observations of the Seyfert 1.9 galaxy IC 3599 with the NASA Neil Gehrels Swift mission. The detection of a second X-ray outburst in 2010 by Swift after the first ...discovery of a bright X-ray outburst in 1990 by ROSAT led to the suggestion of two very different explanations. The first one assumed that IC 3599 exhibits outbursts due to repeated partial tidal stripping of a star, predicting another outburst of IC 3599 in 2019/2020. The second, alternative scenario assumed that the event observed in X-rays is due to an accretion-disk instability, which would suggest a much longer period between the large outbursts. Our continued monitoring campaign by Swift allowed us to test the first scenario that predicted a repetition of high-amplitude flaring activity in 2019/2020. We do not find any evidence of dramatic flaring activity with factors of 100 since the last X-ray outburst seen in 2010. These observations support the accretion-disk scenario. Further, while IC 3599 remains in low-emission states, the long-term X-ray light curve of IC 3599 reveals ongoing strong variability of a factor of a few. The most remarkable event is a miniflare of a factor of 10 in X-rays in 2022 December. After that flare, the otherwise supersoft X-ray spectrum shows an exceptional hardening, reminiscent of a temporary corona formation.
We present Hubble Space Telescope Advanced Camera for Surveys (ACS) observations of 10 galaxies that host narrow-line Seyfert 1 (NLS1) nuclei, believed to contain relatively smaller mass black holes ...accreting at high Eddington ratios. We deconvolve each ACS image into a nuclear point source (AGN), a bulge, and a disk, and fitted the bulge with a Sersic profile and the disk with an exponential profile. We find that at least five galaxies can be classified as having pseudobulges. All 10 galaxies lie below the M sub(BH)-L sub(bulge) relation, confirming earlier results. Their locus is similar to that occupied by pseudobulges. This leads us to conclude that the growth of BHs in NLS1s is governed by secular processes rather than merger driven. Active galaxies in pseudobulges point to an alternative track of black hole-galaxy co-evolution. Because of the intrinsic scatter in black hole mass-bulge properties scaling relations caused by a combination of factors such as the galaxy morphology, orientation, and redshift evolution, application of scaling relations to determine BH masses may not be as straightforward as has been hoped.
The Seyfert galaxy Mrk 335 is known for its frequent changes of flux and spectral shape in the X-ray band that occurred during recent years. These variations may be explained by the onset of a wind ...that previous, noncontemporaneous high-resolution spectroscopy in X-ray and UV bands located at accretion disk scale. A simultaneous new campaign by XMM-Newton and the Hubble Space Telescope (HST) caught the source at a historically low flux in the X-ray band. The soft X-ray spectrum is dominated by prominent emission features and by the effect of a strong ionized absorber with an outflow velocity of (5-6) × 103 km s−1. The broadband spectrum obtained by the EPIC-pn camera reveals the presence of an additional layer of absorption by gas at moderate ionization covering ∼80% of the central source, as well as tantalizing evidence for absorption in the Fe K band outflowing at the same velocity of the soft X-ray absorber. The HST Cosmic Origins Spectrograph spectra confirm the simultaneous presence of broad absorption troughs in C iv, Ly , Lyβ, and O vi, with velocities of the order of 5000 km s−1 and covering factors in the range of 20%-30%. Comparison of the ionic column densities and of other outflow parameters in the two bands shows that the X-ray and UV absorbers are likely originated by the same gas. The resulting picture from this latest multiwavelength campaign confirms that Mrk 335 undergoes the effect of a patchy, medium-velocity outflowing gas in a wide range of ionization states that seem to be persistently obscuring the nuclear continuum.
Abstract
Broad absorption line quasars are actively accreting supermassive black holes that have strong outflows characterized by broad absorption lines in their rest-UV spectra. Variability in these ...absorption lines occurs over months to years depending on the source. WPVS 007, a low-redshift, low-luminosity narrow-line Seyfert 1 (NLS1) shows strong variability over shorter timescales, providing a unique opportunity to study the driving mechanism behind this variability that may mimic longer-scale variability in much more massive quasars. We present the first variability study using the spectral synthesis code
SimBAL
, which provides velocity-resolved changes in physical conditions of the gas using constraints from multiple absorption lines. Overall, we find WPVS 007 to have a highly ionized outflow with a large mass-loss rate and kinetic luminosity. We determine the primary cause of the absorption-line variability in WPVS 007 to be a change in covering fraction of the continuum by the outflow. This study is the first
SimBAL
analysis where multiple epochs of observation were fit simultaneously, demonstrating the ability of
SimBAL
to use the time domain as an additional constraint in spectral models.
ABSTRACT BL Lac, the eponymous blazar, flared to historically high levels at millimeter, infrared, X-ray, and gamma-ray wavelengths in 2012. We present observations made with Herschel, Swift, NuSTAR, ...Fermi, the Submillimeter Array, CARMA, and the VLBA in 2012-2013, including three months with nearly daily sampling at several wavebands. We have also conducted an intensive campaign of 30 hr with every-orbit observations by Swift and NuSTAR, accompanied by Herschel, and Fermi observations. The source was highly variable at all bands. Time lags, correlations between bands, and the changing shapes of the spectral energy distributions can be explained by synchrotron radiation and inverse Compton emission from nonthermal seed photons originating from within the jet. The passage of four new superluminal very long baseline interferometry knots through the core and two stationary knots about 4 pc downstream accompanied the high flaring in 2012-2013. The seed photons for inverse Compton scattering may arise from the stationary knots and from a Mach disk near the core where relatively slow-moving plasma generates intense nonthermal radiation. The 95 spectral energy distributions obtained on consecutive days form the most densely sampled, broad wavelength coverage for any blazar. The observed spectral energy distributions and multi-waveband light curves are similar to simulated spectral energy distributions and light curves generated with a model in which turbulent plasma crosses a conical shock with a Mach disk.
Abstract
To understand the formation and growth of supermassive black holes (SMBHs) and their coevolution with host galaxies, it is essential to know the impact of environment on the activity of ...active galactic nuclei (AGNs). We present new Chandra X-ray observations of nuclear emission from member galaxies in the Antlia cluster, the nearest non-cool core and the nearest merging galaxy cluster, residing at
D
= 35.2 Mpc. Its inner region, centered on two dominant galaxies NGC 3268 and NGC 3258, has been mapped with three deep Chandra ACIS-I pointings. Nuclear X-ray sources are detected in 7/84 (8.3%) early-type galaxies (ETG) and 2/8 (25%) late-type galaxies with a median detection limit of 8 × 10
38
erg s
−1
. All nuclear X-ray sources but one have a corresponding radio continuum source detected by MeerKAT at the
L
band. Nuclear X-ray sources detected in early-type galaxies are considered the genuine X-ray counterpart of low-luminosity AGN. When restricted to a detection limit of
log
(
L
X
/
erg
s
−
1
)
≥
38.9
and a stellar mass of
10
≤
log
(
M
⋆
/
M
⊙
)
<
11.6
, six of 11 ETGs are found to contain an X-ray AGN in Antlia, exceeding the AGN occupation fraction of 7/39 (18.0%) and 2/12 (16.7%) in the more relaxed, cool core clusters, Virgo and Fornax, respectively, and rivaling that of the AMUSE-Field ETG of 27/49 (55.1%). Furthermore, more than half of the X-ray AGN in Antlia is hosted by its younger subcluster, centered on NGC 3258. We believe that this is because SMBH activity is enhanced in a dynamically young cluster compared to relatively relaxed clusters.
We present near-infrared spectra of 10 luminous, intermediate-redshift quasars (z 2; L bol 1047 erg s-1), observed with SofI at the NTT of ESO/La Silla. With these rest-frame optical spectra we probe ...the Hb-O III emission line region. Using the standard scaling relation involving the width of the Hb line and the continuum luminosity, we measure black hole (BH) masses in the range of ~2 X 109 M bh 1010 M for these sources. We also used Sloan Digital Sky Survey spectra to probe Mg II l2798 and C IV l1549 emission lines and used these for BH mass measurements as well. The BH mass estimates using C IV l1549 are on average smaller by about 60% than those based on Hb. The massive BHs we observe could not have grown by simple radiatively efficient accretion at the observed accretion rate starting from seeds of up to a thousand solar masses. About 10% of the observed BH mass must have been accumulated by earlier merger events and radiatively inefficient accretion. Radiatively efficient accretion would further grow these BHs to masses of several 109 M in 2-3 e-folding times, i.e., in several 108 yr. This scenario is consistent with recent models of BH growth. The Hb-based Eddington luminosity ratios are in the range of ~0.2-0.7, with an average of L bol/L edd = 0.39 ± 0.05. The L bol/L edd ratio distribution follows a lognormal distribution which is consistent with prior studies of quasars with comparable luminosity. We also find that the gas metallicity of the broad-line region is super-solar with ~3 Z/Z , based on N IIIl1750/O IIIl1663 and N V l1240/C IV l1549 emission line ratios. We find no correlation of the gas metallicity with the optical Fe II emission line strength in our small sample, contrary to a recent suggestion.
This is the first of two papers reporting observations and analysis of the unusually bright (m sub(b) = 14.4), luminous (M sub(B) = -25.5), nearby (z = 0.192) narrow-line quasar PHL 1811, focusing on ...the X-ray properties and the spectral energy distribution. Two Chandra observations reveal a weak X-ray source with a steep spectrum. Variability by a factor of 4 between the two observations separated by 12 days suggests that the X-rays are not scattered emission. The XMM-Newton spectra are modeled in the 0.3-5 keV band by a steep power law with Gamma = 2.3 plus or minus 0.1, and the upper limit on intrinsic absorption is 8.7 x 10 super(20) cm super(-2). The spectral slopes are consistent with power-law indices commonly observed in NLS1s, and it appears that we observe the central engine X-rays directly. Including two recent Swift ToO snapshots, a factor of similar to 5 variability was observed among the five X-ray observations reported here. In contrast, the UV photometry obtained by the XMM-Newton OM and Swift UVOT, and the HST spectrum reveal no significant UV variability. The alpha sub(ox) inferred from the Chandra and contemporaneous HST spectrum is -2.3 plus or minus 0.1, significantly steeper than observed from other quasars of the same optical luminosity. The steep, canonical X-ray spectra, lack of absorption, and significant X-ray variability lead us to conclude that PHL 1811 is intrinsically X-ray weak. We also discuss an accretion disk model and the host galaxy of PHL 1811.
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