Search

In this contribution, we achieve the primary goal of the active galactic nucleus (AGN) STORM campaign by recovering velocity-delay maps for the prominent broad emission lines (Lyα, C iv, He ii, and Hβ) in the spectrum of NGC 5548. These are the most detailed velocity-delay maps ever obtained for an AGN, providing unprecedented information on the geometry, ionization structure, and kinematics of the broad-line region. Virial envelopes enclosing the emission-line responses show that the reverberating gas is bound to the black hole. A stratified ionization structure is evident. The He ii response inside 5-10 lt-day has a broad single-peaked velocity profile. The Lyα, C iv, and Hβ responses extend from inside 2 to outside 20 lt-day, with double peaks at ±2500 km s-1 in the 10-20 lt-day delay range. An incomplete ellipse in the velocity-delay plane is evident in Hβ. We interpret the maps in terms of a Keplerian disk with a well-defined outer rim at R = 20 lt-day. The far-side response is weaker than that from the near side. The line-center delay days gives the inclination i ≈ 45°. The inferred black hole mass is M BH ≈ 7 × 107 M o˙. In addition to reverberations, the fit residuals confirm that emission-line fluxes are depressed during the "BLR Holiday"identified in previous work. Moreover, a helical "Barber-Pole"pattern, with stripes moving from red to blue across the C iv and Lyα line profiles, suggests azimuthal structure rotating with a 2 yr period that may represent precession or orbital motion of inner-disk structures casting shadows on the emission-line region farther out.

We present geometric and dynamical modeling of the broad line region (BLR) for the multi-wavelength reverberation mapping campaign focused on NGC 5548 in 2014. The data set includes photometric and spectroscopic monitoring in the optical and ultraviolet, covering the Hβ, C iv, and Ly broad emission lines. We find an extended disk-like Hβ BLR with a mixture of near-circular and outflowing gas trajectories, while the C iv and Ly BLRs are much less extended and resemble shell-like structures. There is clear radial structure in the BLR, with C iv and Ly emission arising at smaller radii than the Hβ emission. Using the three lines, we make three independent black hole mass measurements, all of which are consistent. Combining these results gives a joint inference of . We examine the effect of using the V band instead of the UV continuum light curve on the results and find a size difference that is consistent with the measured UV-optical time lag, but the other structural and kinematic parameters remain unchanged, suggesting that the V band is a suitable proxy for the ionizing continuum when exploring the BLR structure and kinematics. Finally, we compare the Hβ results to similar models of data obtained in 2008 when the active galactic nucleus was at a lower luminosity state. We find that the size of the emitting region increased during this time period, but the geometry and black hole mass remained unchanged, which confirms that the BLR kinematics suitably gauge the gravitational field of the central black hole.

We model the ultraviolet spectra of the Seyfert 1 galaxy NGC 5548 obtained with the Hubble Space Telescope during the 6 month reverberation mapping campaign in 2014. Our model of the emission from NGC 5548 corrects for overlying absorption and deblends the individual emission lines. Using the modeled spectra, we measure the response to continuum variations for the deblended and absorption-corrected individual broad emission lines, the velocity-dependent profiles of Ly and C iv, and the narrow and broad intrinsic absorption features. We find that the time lags for the corrected emission lines are comparable to those for the original data. The velocity-binned lag profiles of Ly and C iv have a double-peaked structure indicative of a truncated Keplerian disk. The narrow absorption lines show a delayed response to continuum variations corresponding to recombination in gas with a density of ∼105 cm-3. The high-ionization narrow absorption lines decorrelate from continuum variations during the same period as the broad emission lines. Analyzing the response of these absorption lines during this period shows that the ionizing flux is diminished in strength relative to the far-ultraviolet continuum. The broad absorption lines associated with the X-ray obscurer decrease in strength during this same time interval. The appearance of X-ray obscuration in ∼2012 corresponds with an increase in the luminosity of NGC 5548 following an extended low state. We suggest that the obscurer is a disk wind triggered by the brightening of NGC 5548 following the decrease in size of the broad-line region during the preceding low-luminosity state.

During the Space Telescope and Optical Reverberation Mapping Project observations of NGC 5548, the continuum and emission-line variability became decorrelated during the second half of the six-month-long observing campaign. Here we present Swift and Chandra X-ray spectra of NGC 5548 obtained as part of the campaign. The Swift spectra show that excess flux (relative to a power-law continuum) in the soft X-ray band appears before the start of the anomalous emission-line behavior, peaks during the period of the anomaly, and then declines. This is a model-independent result suggesting that the soft excess is related to the anomaly. We divide the Swift data into on- and off-anomaly spectra to characterize the soft excess via spectral fitting. The cause of the spectral differences is likely due to a change in the intrinsic spectrum rather than to variable obscuration or partial covering. The Chandra spectra have lower signal-to-noise ratios, but are consistent with the Swift data. Our preferred model of the soft excess is emission from an optically thick, warm Comptonizing corona, the effective optical depth of which increases during the anomaly. This model simultaneously explains all three observations: the UV emission-line flux decrease, the soft-excess increase, and the emission-line anomaly.

In this work, we present the results of the survey carried out on one of the deepest X-ray fields observed by the XMM-Newton satellite. The 1.75 Ms Ultra Narrow Deep Field (XMM175UNDF) survey is made by 13 observations taken over 2 yr with a total exposure time of 1.75 Ms (1.372 Ms after flare-filtered) in a field of 30′ × 30′ centered around the blazar 1ES 1553+113. We stacked the 13 observations reaching flux limits of 4.03 × 10−16, 1.3 × 10−15, and 9.8 × 10−16 erg s−1 cm−2 in the soft (0.2–2 keV), hard (2–12 keV), and full (0.2–12 keV) bands, respectively. Using a conservative threshold of Maximum Likelihood significance of ML ≥ 6, corresponding to 3σ, we detected 301 point-sources for which we derived positions, fluxes in different bands, and hardness ratios. Thanks to an optical follow-up that was carried out using the 10.4m the Gran Telescopio Canarias on the same field in the u′g′r′i′z′ bands, combined with WISE/2MASS IR data, we identified 244 optical/IR counterpart candidates for our X-ray sources and estimated their X-ray luminosities, redshift distribution, X-ray/optical–X-ray/IR flux ratios, and absolute magnitudes. Finally, we divided this subsample into 40 non-active sources and 204 active galactic nuclei, of which 139 are classified as Seyfert galaxies and 41 as Quasars. [ABSTRACT FROM AUTHOR]

We present a detailed analysis of XMM-Newton X-ray spectra of the Narrow-Line Seyfert 1 galaxy Mrk 1044. We find robust evidence for a multiphase, ultrafast outflow, traced by four separate components in the grating spectrum. One component has high column density and ionization state, and is outflowing at ∼0.15c. The other three wind components have lower temperature, lower column density, and have outflow velocities ∼0.08c. This wind structure is strikingly similar to that found in IRAS 17020+4544, suggesting that stratified winds may be a common feature of ultrafast outflows. Such structure is likely produced by fluid instabilities that form when the nuclear wind shocks the ambient medium. We show that, in an energy-driven wind scenario, the wind in Mrk 1044 might carry enough energy to produce significant feedback on its host galaxy. We further discuss the implications of the presence of a fast wind in yet another NLS1 galaxy with high Eddington ratio. [ABSTRACT FROM AUTHOR]

We present Chandra High Energy Transmission Grating Spectra of the narrow-line Seyfert-1 galaxy Ark 564. The spectrum shows numerous absorption lines which are well modeled with low-velocity outflow components usually observed in Seyfert galaxies. There are, however, some residual absorption lines which are not accounted for by low-velocity outflows. Here, we present identifications of the strongest lines as Kα transitions of OVII (two lines) and OVI at outflow velocities of ~0.1c. These lines are detected at 6.9σ, 6.2σ, and 4.7σ, respectively, and cannot be due to chance statistical fluctuations. Photoionization models with ultra-high velocity components improve the spectral fit significantly, providing further support for the presence of relativistic outflow in this source. Without knowing the location of the absorber, its mass and energy outflow rates cannot be well constrained; we find Ė (outflow)/Lbol lower limit of ⩾0.006% assuming a bi-conical wind geometry. This is the first time that absorption lines with ultra-high velocities are unambiguously detected in the soft X-ray band. The presence of outflows with relativistic velocities in active galactic nuclei (AGNs) with Seyfert-type luminosities is hard to understand and provides valuable constraints to models of AGN outflows. Radiation pressure is unlikely to be the driving mechanism for such outflows and magnetohydrodynamic may be involved. [ABSTRACT FROM AUTHOR]

We present the first results from our pilot 500 ks Chandra Low Energy Transmission Grating Large Program observation of the soft X-ray brightest source in the z ≳ 0.4 sky, the blazar 1ES 1553+113, aimed to secure the first uncontroversial detections of the missing baryons in the X-rays.We identify a total of 11 possible absorption lines, with single-line statistical significances between 2.2σ and 4.1σ. Six of these lines are detected at high single-line statistical significance (3.6⩽ σ ⩽ 4.1), while the remaining five are regarded as marginal detections in association with either other X-ray lines detected at higher significance and/or far-ultraviolet (FUV) signposts. Three of these lines are consistent with metal absorption at z ≃ 0, and we identify them with Galactic Oi and C ii. The remaining eight lines may be imprinted by intervening absorbers and are all consistent with being high-ionization counterparts of FUV Hi and/or Ovi intergalactic medium signposts. In particular, five of these eight possible intervening absorption lines (single-line statistical significances of 4.1σ, 4.1σ, 3.9σ, 3.8σ, and 2.7σ), are identified as Cv and C vi Kα absorbers belonging to three WHIM systems at zX = 0.312, zX = 0.237, and X> = 0.133, which also produce broad Hi (and Ovi for the zX = 0.312 system) absorption in the FUV. For two of these systems (zX = 0.312 and 0.237), the Chandra X-ray data led the a posteriori discovery of physically consistent broad Hi associations in the FUV (for the third system the opposite applies), so confirming the power of the X-ray-FUV synergy forWHIM studies. The true statistical significances of these three X-ray absorption systems, after properly accounting for the number of redshift trials, are 5.8σ (zX = 0.312; 6.3σ if the low-significance Ov and C v Kβ associations are considered), 3.9σ (zX = 0.237), and 3.8σ (X> = 0.133), respectively. [ABSTRACT FROM AUTHOR]

The Seyfert 1 galaXy Ark 564 was observed with Chandra high-energy transmission gratings for 250 ks. We present the high-resolution X-ray spectrum that shows several associated absorption lines. The photoionization model requires two warm absorbers (WAs) with two different ionization states (logU = 0.39 ± 0.03 and logU = -0.99 ± 0.13), both with moderate outflow velocities (~100 km s-1) and relatively low line of sight column densities (logNH = 20.94 and 20.11 cm-2). The high-ionization phase produces absorption lines of OVII, OVIII, NeIX, NeX, MgXI, FeXVII , and Fe XVIII , while the low-ionization phase produces lines at lower energies (O VI and OVII). The pressure-temperature equilibrium curve for the Ark 564 absorber does not have the typical "S" shape, even if the metallicity is super-solar; as a result, the two WA phases do not appear to be in pressure balance. This suggests that the continuum incident on the absorbing gas is perhaps different from the observed continuum. We also estimated the mass outflow rate and the associated kinetic energy and find it to be at most 0.009% of the bolometric luminosity of Ark 564. Thus, it is highly unlikely that these outflows proVIde significant feedback required by the gala Xy formation models. [ABSTRACT FROM AUTHOR]

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 Reflection Grating Spectrometer (RGS) detector reveal that the wind consists of three distinct ionization components, all outflowing at a velocity of ~5000 km s-1>. This wind is clearly revealed when the source is observed at an intermediate flux state (2-5 × 10-12 erg 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 (log ξ ~ 2.3 and 3.3) 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 ξ ~ 1.8). We have included archival, non-simultaneous UV data from Hubble Space Telescope (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 Cosmic Origins Spectrograph (COS) spectra obtained a few months after the X-ray observations, we found broad absorption in Civ lines intrinsic to the active galactic nucleus 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. [ABSTRACT FROM AUTHOR]

We present an analysis of the co-added and individual 0.7-40keV spectra from seven Suzaku observations of the Sy 1.5 galaxy NGC 5548 taken over a period of eight weeks. We conclude that the source has a moderately ionized, three-zone warm absorber, a power-law continuum, and exhibits contributions from cold, distant reflection. Relativistic reflection signatures are not significantly detected in the co-added data, and we place an upper limit on the equivalent width of a relativistically broad Fe Kα line at EW ≤ 26 eV at 90% confidence. Thus NGC 5548 can be labeled as a "weak" type 1 active galactic nucleus (AGN) in terms of its observed inner disk reflection signatures, in contrast to sources with very broad, strong iron lines such as MCG-6-30-15, which are likely much fewer in number. We compare physical properties of NGC 5548 and MCG-6-30-15 that might explain this difference in their reflection properties. Though there is some evidence that NGC 5548 may harbor a truncated inner accretion disk, this evidence is inconclusive, so we also consider light bending of the hard X-ray continuum emission in order to explain the lack of relativistic reflection in our observation. If the absence of a broad Fe Kα line is interpreted in the light-bending context, we conclude that the source of the hard X-ray continuum lies at radii rs ≳ 100rg. We note, however, that light-bending models must be expanded to include a broader range of physical parameter space in order to adequately explain the spectral and timing properties of average AGNs, rather than just those with strong, broad iron lines. [ABSTRACT FROM AUTHOR]

We report on the detection of ultra-fast outflows in the Seyfert 1 galaxy Mrk 590. These outflows are identified through highly blueshifted absorption lines of O VIII and Ne IX in the medium energy grating spectrum and Si XIV and Mg XII in the high energy grating spectrum on board the Chandra X-ray observatory. Our best-fit photoionization model requires two absorber components at outflow velocities of 0.176c and 0.0738c and a third tentative component at 0.0867c. The components at 0.0738c and 0.0867c have high ionization parameters and high column densities, similar to other ultra-fast outflows detected at low resolution by Tombesi et al. We also found suggestive evidence for super-solar silicon in these components. These outflows carry sufficient mass and energy to provide effective feedback proposed by theoretical models. The component at 0.176c, on the other hand, has a low ionization parameter and low column density, similar to those detected by Gupta et al. in Ark 564. These absorbers occupy a different locus on the velocity versus ionization parameter plane and have opened up a new parameter space of active galactic nucleus (AGN) outflows. The presence of ultra-fast outflows in moderate luminosity AGNs poses a challenge to models of AGN outflows. [ABSTRACT FROM AUTHOR]

The 1.5 Seyfert galaxy NGC 3516 presents a strong time variability in X-rays. We re-analyzed the nine observations performed in 2006 October by XMM-Newton and Chandra in the 0.3 to 10 keV energy band. An acceptable model was found for the XMM-Newton data fitting the EPIC-PN and RGS spectra simultaneously; later, this model was successfully applied to the contemporary Chandra high-resolution data. The model consists of a continuum emission component (power law + blackbody) absorbed by four ionized components (warm absorbers), and 10 narrow emission lines. Three absorbing components are warm, producing features only in the soft X-ray band. The fourth ionization component produces Fe XXV and Fe XXVI in the hard-energy band. We study the time response of the absorbing components to the well-detected changes in the X-ray luminosity of this source and find that the two components with the lower ionization state show clear opacity changes consistent with gas close to photoionization equilibrium. These changes are supported by the models and by differences in the spectral features among the nine observations. On the other hand, the two components with higher ionization state do not seem to respond to continuum variations. The response time of the ionized absorbers allows us to constrain their electron density and location. We find that one component (with intermediate ionization) must be located within the obscuring torus at a distance 2.7 × 1017 cm from the central engine. This outflowing component likely originated in the accretion disk. The three remaining components are at distances larger than 1016-1017 cm. Two of the absorbing components in the soft X-rays have similar outflow velocities and locations. These components may be in pressure equilibrium, forming a multi-phase medium, if the gas has metallicity larger than the solar one (≳ 5 Z☼). We also search for variations in the covering factor of the ionized absorbers (although partial covering is not required in our models). We find no correlation between the change in covering factor and the flux of the source. This, in connection with the observed variability of the ionized absorbers, suggests that the changes in flux are not produced by this material. If the variations are indeed produced by obscuring clumps of gas, these must be located much closer in to the central source. [ABSTRACT FROM AUTHOR]

We report a detection of an absorption line at ∼44.8 Å in a >500 ks Chandra HRC-S/LETG X-ray grating spectrum of the blazar H 2356-309. This line can be identified as intervening C V-Kα absorption, at z ≈ 0.112, produced by a warm (log T = 5.1 K) intergalactic absorber. The feature is significant at a 2.9σ level (accounting for the number of independent redshift trials). We estimate an equivalent hydrogen column density of log NH = 19.05(Z/Z☼)–1 cm–2. Unlike other previously reported FUV/X-ray metal detections of warm-hot intergalactic medium (WHIM), this C V absorber lies in a region with locally low galaxy density, at ∼2.2 Mpc from the closest galaxy at that redshift, and therefore is unlikely to be associated with an extended galactic halo. We instead tentatively identify this absorber with an intervening WHIM filament possibly permeating a large-scale, 30 Mpc extended, structure of galaxies whose redshift centroid, within a cylinder of 7.5 Mpc radius centered on the line of sight to H 2356-309, is marginally consistent (at a 1.8σ level) with the redshift of the absorber. [ABSTRACT FROM AUTHOR]