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Accretion disk winds launched close to supermassive black holes (SMBHs) are a viable mechanism to provide feedback between the SMBH and the host galaxy. We aim to characterize the X-ray properties of the inner accretion disk wind of the nearby active galactic nucleus (AGN) PG 1126-041, and to study its connection with the ultraviolet (UV)-absorbing wind. We perform spectroscopic analysis of eight XMM-Newton observations of PG 1126-041 taken between 2004 and 2015, using both phenomenological models and the most advanced accretion disk wind models available. For half of the dataset, we can compare the X-ray analysis results with the results of quasi-simultaneous, high-resolution spectroscopic UV observations taken with the Cosmic Origins Spectrograph (COS) on board the Hubble Space Telescope. The X-ray spectra of PG 1126-041 are complex and absorbed by ionized material which is highly variable on multiple time scales, sometimes as short as 11 days. Accretion disk wind models can account for most of the X-ray spectral complexity of PG 1126-041, with the addition of massive clumps, represented by a partially covering absorber. Variations in column density ($N_H \sim 5-20 \times 10^{22}$ cm$^{-2}$) of the partially covering absorber drive the observed X-ray spectral variability of PG 1126-041. The absorption from the X-ray partially covering gas and from the blueshifted C IV troughs appear to vary in a coordinated way. The line of sight toward PG 1126-041 offers a privileged view through a highly dynamic nuclear wind originating on inner accretion disk scales, making the source a very promising candidate for future detailed studies of the physics of accretion disk winds around SMBHs., 24 pages, 13 figures, accepted for publication in Astronomy & Astrophysics

Powerful winds driven by supermassive black holes (SMBHs) are likely the main mechanism through which SMBHs regulate their own growth and influence the host galaxy evolution. However, their origin and their capability to impact the large-scale environment are still highly debated. Fundamental results will come from high-energy and spatial resolution X-ray observatories., Science White Paper Submitted for the Astro2020 Decadal Survey on Astronomy and Astrophysics

We review results from our monitoring observations of several lensed quasars performed in the optical, UV, and X-ray bands. Modeling of the multi-wavelength light curves provides constraints on the extent of the optical, UV, and X-ray emission regions. One of the important results of our analysis is that the optical sizes as inferred from the microlensing analysis are significantly larger than those predicted by the theoretical-thin-disk estimate. In a few cases we also constrain the slope of the size-wavelength relation. Our size constraints of the soft and hard X-ray emission regions of quasars indicate that in some objects of our sample the hard X-ray emission region is more compact than the soft and in others the soft emission region is smaller. This difference may be the result of the relative strengths of the disk-reflected (harder and extended) versus corona-direct (softer and compact) components in the quasars of our sample. Finally, we present the analysis of several strong microlensing events where we detect an evolution of the relativistic Fe line profile as the magnification caustic traverses the accretion disk. These caustic crossings are used to provide constraints on the innermost stable circular orbit (ISCO) radius and the accretion disk inclination angle of the black hole in quasar RX J1131-1231., 6 pages, 6 figures, To appear in Astronomische Nachrichten (Astronomical Notes)

We present the results of X-ray spectral analysis of two mini-BAL QSOs, PG 1126-041 and PG 1351+640, aimed at getting insights into the physics of quasar outflows. We find strong X-ray spectral variability on timescales of years. These variations can be well reproduced by variations of physical properties as the covering factor and column density of ionized gas along the line of sight, compatible with radiatively-driven accretion disk wind models., 2 pages, 2 figures. Proceedings of "Accretion and Ejection in AGN: a global view", Como (Italy) 06/22-26/2009, ASP Conference Series, Eds: L. Maraschi, G. Ghisellini, R. Della Ceca and F. Tavecchio

We present results from an observation of the gravitationally lensed z=1.51 narrow absorption line AGN HS 0810+2554 performed with the Chandra X-ray Observatory. The factor of ~100 lensing magnification of HS 0810+2554 makes this source exceptionally bright. Absorption lines are detected at rest-frame energies of ~ 7.7 keV and ~11.0 keV at >97% significance. By interpreting these lines to arise from highly ionized iron the implied outflow velocities of the X-ray absorbing gas corresponding to these lines are 0.13c and 0.41c, respectively. The presence of these relativistic outflows and the absence of any significant low-energy X-ray absorption suggest that a shielding gas is not required for the generation of the relativistic X-ray absorbing winds in HS 0810+2554. UV spectroscopic observations with VLT/UVES indicate that the UV absorbing material is outflowing at v_UV ~0.065c. Our analysis indicates that the fraction of the total bolometric energy released by HS 0810+2554 into the IGM in the form of kinetic energy is epsilon_k = 1.0(-0.6,+0.8). An efficiency of greater than unity implies that magnetic driving is likely a significant contributor to the acceleration of this X-ray absorbing wind. We also estimate the mass-outflow rate of the strongest absorption component to be Mdot_abs=1.1(-0.7,+0.9) M_solar yr^-1. Assuming that the energetic outflow detected in the NAL AGN HS 0810+2554 is a common property of most AGN it would suggest that the X-ray absorbing wind may have a larger opening angle than previously thought. This has important consequences for estimating the feedback contribution of X-ray absorbing winds to the surrounding IGM., 25 pages, includes 11 figures, Accepted for publication in ApJ

A significant fraction of the sub-damped Lyman-alpha (sub-DLA) absorption systems in quasar spectra appear to be metal-rich, many with even super-solar element abundances. This raises the question whether some sub-DLAs may harbor active galactic nuclei (AGN) since supersolar metallicities are observed in AGN. Here we investigate this question based on a mini-survey of 21 quasars known to contain sub-DLAs in their spectra. The X-ray observations were performed with the Chandra X-ray Observatory. In cases of no detection we estimated upper limits of the X-ray luminosities of possible AGNs at the redshifts of the sub-DLAs. In six cases we find possible X-ray emission within ~ 1 arcsec of the background quasar consistent with the presence of a nearby X-ray source. If these nearby X-ray sources are at the redshifts of the sub-DLAs, their estimated 0.2-10 keV luminosities range between 0.8 x 10^{44}h^{-2} and 4.2 x 10^{44}h^{-2} erg s^{-1}, thus ruling out a normal late-type galaxy origin, and suggesting that the emission originates in a galactic nucleus near the center of a protogalaxy. The projected distances of these possible nearby X-ray sources from the background quasars lie in the range of 3-7 h^{-1} kpc, consistent with our hypothesis that they represent AGNs centered on the sub-DLAs. Deeper follow-up X-ray and optical observations are required to confirm the marginal detections of X-rays from these sub-DLA galaxies., Comment: 12 pages, includes 4 figures, Accepted for publication in ApJ

We present a detailed analysis of the X-ray emission of HS 1700+6416, a high redshift (z=2.7348), luminous quasar, classified as a Narrow Absorption Line (NAL) quasar on the basis of its SDSS spectrum. The source has been observed 9 times by Chandra and once by XMM from 2000 to 2007. Long term variability is clearly detected, between the observations, in the 2-10 keV flux varying by a factor of three (~3-9x10^-14 erg s^-1 cm^-2) and in the amount of neutral absorption (Nh < 10^22 cm^-2 in 2000 and 2002 and Nh=4.4+-1.2x10^22 cm^-2 in 2007). Most interestingly, one broad absorption feature is clearly detected at 10.3+-0.7 keV (rest frame) in the 2000 Chandra observation, while two similar features, at 8.9+-0.4 and at 12.5+-0.7 keV, are visible when the 8 contiguous Chandra observations of 2007 are stacked together. In the XMM observation of 2002, strongly affected by background flares, there is a hint for a similar feature at 8.0+-0.3 keV. We interpreted these features as absorption lines from a high velocity, highly ionized (i.e. Fe XXV, FeXXVI) outflowing gas. In this scenario, the outflow velocities inferred are in the range v=0.12-0.59c. To reproduce the observed features, the gas must have high column density (Nh>3x10^23 cm^-2), high ionization parameter (log(xi)>3.3 erg cm s^-1) and a large range of velocities (Delta V~10^4 km s^-1). This Absorption Line QSO is the fourth high-z quasar displaying X-ray signatures of variable, high velocity outflows, and among these, is the only one non-lensed. A rough estimate of the minimum kinetic energy carried by the wind of up to 18% L(bol), based on a biconical geometry of the wind, implies that the amount of energy injected in the outflow environment is large enough to produce effective mechanical feedback., 10 pages, 6 figures. Accepted for publication in Astronomy and Astrophysics

One of the main themes in extragalactic astronomy for the next decade will be the evolution of galaxies over cosmic time. Many future observatories, including JWST, ALMA, GMT, TMT and E-ELT will intensively observe starlight over a broad redshift range, out to the dawn of the modern Universe when the first galaxies formed. It has, however, become clear that the properties and evolution of galaxies are intimately linked to the growth of their central black holes. Understanding the formation of galaxies, and their subsequent evolution, will therefore be incomplete without similarly intensive observations of the accretion light from supermassive black holes (SMBH) in galactic nuclei. To make further progress, we need to chart the formation of typical SMBH at z>6, and their subsequent growth over cosmic time, which is most effectively achieved with X-ray observations. Recent technological developments in X-ray optics and instrumentation now bring this within our grasp, enabling capabilities fully matched to those expected from flagship observatories at longer wavelengths., 8 pages, Science White paper submitted to Astro2010 Decadal survey. Supplementary information available at http://astro.imperial.ac.uk/research/ixo/smbh_growth.shtml

We present results from a statistical analysis of 173 bright radio-quiet AGNs selected from the Chandra Deep Field-North and Chandra Deep Field-South surveys (hereafter, CDFs) in the redshift range of 0.1 < z < 4. We find that the X-ray power-law photon index (Gamma) of radio-quiet AGNs is correlated with their 2-10 keV rest-frame X-ray luminosity (L_X) at the > 99.5 percent confidence level in two redshift bins, 0.3 < z < 0.96, and 1.5 < z < 3.3 and is slightly less significant in the redshift bin 0.96 < z < 1.5. We investigate the redshift evolution of the correlation between the power-law photon index and the hard X-ray luminosity and find that the slope and offset of a linear fit to the correlation change significantly (at the > 99.9 percent confidence level) between redshift bins of 0.3 < z < 0.96 and 1.5 < z < 3.3. We explore physical scenarios explaining the origin of this correlation and its possible evolution with redshift in the context of steady corona models focusing on its dependency on variations of the properties of the hot corona with redshift., Comments: 20 pages, includes 17 figures, Accepted for publication in AJ

Microlensing of gravitationally lensed quasars by the stars in the foreground lens galaxy can be used to probe the nature of dark matter, to determine the mean stellar mass in the lens galaxy, and to measure the internal structure of quasar accretion disks. Until recently, little progress has been made toward using microlensing for these purposes because of the difficulty in obtaining the necessary data and the lack of good analysis methods. In the last few years, both problems have been solved. In particular, Bayesian analysis methods provide a general approach to measuring quantities of physical interest and their uncertainties from microlensing light curves. We discuss the data and the analysis methods and show preliminary results for all three astrophysical applications., Comment: To appear in Statistical Challenges in Modern Astronomy IV, 2007, G. J. Babu and E. D. Feigelson (eds.), San Francisco:Astron. Soc. Pacific, minor corrections for final version

The observed enhancement of the Fe K$��$ line in three gravitationally lensed QSOs (MG J0414+0534, QSO 2237+0305, H1413+117) is interpreted in terms of microlensing, even when equivalent X-ray continuum amplification is not observed. In order to interpret these observations, first we studied the effects of microlensing on quasars spectra, produced by straight fold caustic crossing over standard relativistic accretion disk. The disk emission was analyzed using the ray tracing method, considering Schwarzschild and Kerr metrics. When the emission is separated in two regions (an inner disk corresponding to the Fe K$��$ line and an outer annulus corresponding to the continuum, or vice-versa) we find microlensing events which enhance the Fe K$��$ line without noticeable amplification of the X-ray continuum, but only during a limited time interval. Continuum amplification is expected if a complete microlensing event is monitored. Second, we studied a more realistic case of amplification by caustic magnification pattern. In this case we could satisfactorily explain the observations if the Fe K$��$ line is emitted from the innermost part of the accretion disk, while the continuum is emitted from a larger region. Also, we studied the chromatic effects of microlensing, finding that the radial distribution of temperature in the accretion disk, combined with microlensing itself, can induce wavelength dependent variability of $\sim$ 30% for microlenses with very small masses. All these results show that X-ray monitoring of gravitational lenses is a well suited method for studying of the innermost structure of AGN accretion disks., 27 pages, 12 figures, 1 table. Accepted for publishing in Astrophysical Journal

We consider the influence of (milli/micro)lensing on the spectra of lensed QSOs. We propose a method for the observational detection of microlensing in the spectra of lensed QSOs and apply it to the spectra of the three lensed QSOs (PG 1115+080, QSO 1413+117 and QSO 0957+561) observed with Hubble Space Telescope (HST). We find that the flux ratio between images A1 and A2 of PG 1115+080 is wavelength-dependent and shows differential magnification between the emission lines and the continuum. We interpret this magnification as arising from millilensing. We also find that the temporal variations in the continuum of image C of QSO 1413+117 may be caused by microlensing, while the temporal variation observed in QSO 0957+561 was probably an intrinsic one., 11 pages, accepted for publication in MNRAS

With its excellent spatial resolution, low background, and hard-band response, the Chandra X-ray Observatory is ideal for performing exploratory surveys. These efficient, sensitive observations can place constraints on fundamental properties of a quasar continuum including the X-ray luminosity, the ratio of X-ray to UV power, and the X-ray spectral shape. To demonstrate the power of such surveys to provide significant insight, we consider two examples, a Large Bright Quasar Survey sample of broad absorption line quasars and a sample of Sloan Digital Sky Survey (SDSS) quasars with extreme CIV blueshifts. In both cases, exploratory Chandra observations provide important information for a physical understanding of UV spectroscopic differences in quasars., 4 pages, 2 figures, requires newpasp.sty. To appear in "AGN Physics with the Sloan Digital Sky Survey", ASP Conference Series, G.T. Richards and P.B. Hall, eds

We present the results from an X-ray and optical survey of a sample of 17 radio jets in AGN performed with Chandra and HST. The sample was selected from the radio and is unbiased toward detection at shorter wavelengths, but preferentially it includes beamed sources. We find that X-ray emission is common on kpc-scales, with over half radio jets exhibiting at least one X-ray knot on the Chandra images. The distributions of the radio-to-X-ray and radio-to-optical spectral indices for the detected jets are similar to the limits for the non-detections,suggesting all bright radio jets have X-ray counterparts which will be visible in longer observations. Comparing the radio and X-ray morphologies shows that the majority of the X-ray jets have structures that closely map the radio. Analysis of the SED of the jet knots suggest the knots in which the X-ray and radio morphologies track each other produce X-rays by IC scattering of the Cosmic Microwave Background. The remaining knots produce X-rays by the synchrotron process. Spectral changes are detected along the jets, with the ratio of the X-ray-to-radio and optical-to-radio flux densities decreasing from the inner to the outer regions. This suggests the presence of an additional contribution to the X-ray flux in the jet's inner part, either from synchrotron or IC of the stellar light. Alternatively, in a pure IC/CMB scenario, the plasma decelerates as it flows from the inner to the outer regions. Finally, the X-ray spectral indices for the brightest knots are flat, indicating that the bulk of the luminosity of the jets is emitted at GeV energies, and raising the interesting possibility of future detections with GLAST., Comment: 26 pages, 6 ps figures, 6 jpeg figures (1 replaced); accepted for publication in ApJ

We present the results of Chandra observations of six radio-loud quasars (RLQs) and one optically bright radio-quiet quasar (RQQ) at z = 4.1-4.4. These observations cover a representative sample of RLQs with moderate radio-loudness (R ~ 40-400), filling the X-ray observational gap between optically selected RQQs and the five known blazars at z > 4 (R ~ 800-27000). We study the relationship between X-ray luminosity and radio-loudness for quasars at high redshift and constrain RLQ X-ray continuum emission and absorption. From a joint spectral fit of nine moderate-R RLQs observed by Chandra, we find tentative evidence for absorption above the Galactic N_H, with a best-fit neutral intrinsic column density of N_H = 2.4^{+2.0}_{-1.8} x 10^{22} cm^{-2}, consistent with earlier claims of increased absorption toward high-redshift RLQs. We also search for evidence of an enhanced jet-linked component in the X-ray emission due to the increased energy density of the cosmic microwave background (CMB) at high redshift, but we find neither spatial detections of X-ray jets nor a significant enhancement in the X-ray emission relative to comparable RLQs at low-to-moderate redshifts. Overall, the z ~ 4-5 RLQs have basic X-ray properties consistent with comparable RLQs in the local universe, suggesting that the accretion/jet mechanisms of these objects are similar as well., 12 pages, The Astronomical Journal, in press

We provide X-ray constraints and perform the first X-ray spectral analyses for bright (f_850>=5mJy; S/N>=4) SCUBA sources in an 8.4'x8.4' area of the 2 Ms Chandra Deep Field-North survey containing the Hubble Deep Field-North. X-ray emission is detected from 7 of the 10 bright submm sources in this region, corresponding to an X-ray detected submm source density of ~360 deg^-2 (>~36% of the bright submm source population). Two of the X-ray detected sources have nearby (within 3") X-ray companions, suggesting merging/interacting sources or gravitational lensing effects, and 3 lie within the approximate extent of a proto-cluster candidate. Five of the X-ray detected sources have flat X-ray spectral slopes, suggesting obscured AGN activity. X-ray spectral analyses suggest that one of these AGNs may be a Compton-thick source; of the other 4 AGNs, 3 appear to be Compton-thin sources and one has poor constraints. The rest-frame unabsorbed X-ray luminosities of these AGNs are more consistent with those of Seyfert galaxies than QSOs. Thus, the low X-ray detection rate of bright submm sources by moderately deep X-ray surveys appears to be due to the relatively low luminosities of the AGNs rather than Compton-thick absorption. A comparison of these sources to the well-studied heavily obscured AGN NGC6240 shows that the average AGN contribution is negligible at submm wavelengths. The X-ray properties of the other 2 X-ray detected sources are consistent with those expected from luminous star formation; however, we cannot rule out the possibility that low-luminosity AGNs are present. The 3 X-ray undetected sources appear to lie at high redshift (z>4) and could be either AGNs or starbust galaxies., AJ in press (February 2003), 16 pages, includes emulateapj5.sty

We present the first results from an X-ray and optical survey of a sample of AGN radio jets with Chandra and HST. We focus here on the first six sources observed at X-rays, in four of which a bright X-ray jet was detected for the first time. In three out of four cases optical emission from the jet is also detected in our HST images. We compare the X-ray morphology with the radio as derived from improved processing of archival VLA data and we construct spectral energy distributions (SED) for the most conspicuous emission knots. In most cases the SEDs, together with the similarity of the X-ray and radio morphologies, favor an inverse Compton origin of the X-rays. The most likely origin of the seed photons is the Cosmic Microwave Background, implying the jets are still relativistic on kiloparsec scales. However, in the first knot of the PKS 1136-135 jet, X-rays are likely produced via the synchrotron process. In all four cases bulk Lorentz factors of a few are required. The radio maps of the two jets not detected by either Chandra or HST suggest that they are less beamed at large scales than the other four detected sources. Our results demonstrate that, at the sensitivity and resolution of Chandra, X-ray emission from extragalactic jets is common, yielding essential information on their physical properties., 32 pages; Fig 1-5 are in color. Accepted for publication in The Astrophysical Journal

We are in the process of obtaining a complete sample of exploratory X-ray observations of broad absorption line (BAL) QSOs from the Large Bright Quasar Survey (LBQS). This survey is composed of short (5-7 ks) Chandra ACIS-S3 observations designed to significantly constrain X-ray fluxes and hardness ratios. Our sample avoids the selection biases of some previous surveys while providing X-ray data of similar quality. Of 17 BAL QSOs observed to date, 13 are detected. In general, our results are consistent with absorption as the primary cause of X-ray weakness in BAL QSOs. As found by Green et al. (2001), those BAL QSOs with low-ionization absorption lines are found to be notably X-ray weaker than BAL QSOs with only high ionization lines., Comment: 4 pages, 3 figures. To appear in the proceedings of the workshop "X-ray spectroscopy of AGN with Chandra and XMM-Newton", eds., Th. Boller, S. Komossa, S. Kahn, and H. Kunieda

For the population of QSOs with broad ultraviolet absorption lines, we are just beginning to accumulate X-ray observations with enough counts for spectral analysis at CCD resolution. From a sample of eight QSOs [including four Broad Absorption Line (BAL) QSOs and three mini-BAL QSOs] with ASCA or Chandra spectra with more than 200 counts, general patterns are emerging. Their power-law X-ray continua are typical of normal QSOs with Gamma~2.0, and the signatures of a significant column density [N_H~(0.1-4)x10^{23} cm^{-2}] of intrinsic, absorbing gas are clear. Correcting the X-ray spectra for intrinsic absorption recovers a normal ultraviolet-to-X-ray flux ratio, indicating that the spectral energy distributions of this population are not inherently anomalous. In addition, a large fraction of our sample shows significant evidence for complexity in the absorption. The subset of BAL QSOs with broad MgII absorption apparently suffers from Compton-thick absorption completely obscuring the direct continuum in the 2-10 keV X-ray band, complicating any measurement of their intrinsic X-ray spectral shapes., 9 pages, 6 figures, uses AASTeX. Accepted to the Astrophysical Journal

An extremely deep X-ray survey (about 1 Ms) of the Hubble Deep Field North and its environs (about 450 arcmin^2) has been performed with the Advanced CCD Imaging Spectrometer on board the Chandra X-ray Observatory. This is one of the two deepest X-ray surveys ever performed; for point sources near the aim point it reaches 0.5-2.0 keV and 2-8 keV flux limits of 3 x 10^{-17} erg/cm^2/s and 2 x 10^{-16} erg/cm^2/s, respectively. Here we provide source catalogs along with details of the observations, data reduction, and technical analysis. Observing conditions, such as background, were excellent for almost all of the exposure. We have detected 370 distinct point sources: 360 in the 0.5-8.0 keV band, 325 in the 0.5-2.0 keV band, 265 in the 2-8 keV band, and 145 in the 4-8 keV band. Two new Chandra sources in the HDF-N itself are reported and discussed. Source positions are accurate to within 0.6-1.7 arcsec (at 90% confidence) depending mainly on the off-axis angle. We also detect two highly significant extended X-ray sources and several other likely extended X-ray sources. We present basic number count results for sources located near the center of the field. Source densities of 7100^{+1100}_{-940} deg^{-2} (at 4.2 x 10^{-17} erg/cm^2/s) and 4200^{+670}_{-580} deg^{-2} (at 3.8 x 10^{-16} erg/cm^2/s) are observed in the soft and hard bands, respectively., 41 pages, AJ, in press; tables 3 and 6, images, and version with full-resolution figures at http://www.astro.psu.edu/users/niel/hdf/hdf-chandra.html

We report results from Chandra observations of the X-ray jet of 3C~273 during the calibration phase in 2000 January. The zeroeth-order images and spectra from two 40-ks exposures with the HETG and LETG+ACIS-S show a complex X-ray structure. The brightest optical knots are detected and resolved in the 0.2-8 keV energy band. The X-ray morphology tracks well the optical. However, while the X-ray brightness decreases along the jet, the outer parts of the jet tend to be increasingly bright with increasing wavelength. The spectral energy distributions of four selected regions can best be explained by inverse Compton scattering of (beamed) cosmic microwave background photons. The model parameters are compatible with equipartition and a moderate Doppler factor, which is consistent with the one-sidedness of the jet. Alternative models either imply implausible physical conditions and energetics (the synchrotron self-Compton model) or are sufficiently ad hoc to be unconstrained by the present data (synchrotron radiation from a spatially or temporally distinct particle population)., 3 figures; Figure 1 in color. Accepted for publication by ApJ Letters

An observation of the gravitationally lensed system 2016+112 with the Chandra X-ray Observatory has resolved a mystery regarding the proposed presence of a dark matter object in the lens plane of this system. The Chandra ACIS observation has clearly detected the lensed images of 2016+112 with positions in good agreement with those reported in the optical and also detects 13 additional X-ray sources within a radius of 3.5 arcmin. Previous X-ray observations in the direction of 2016+112 with the ROSAT HRI and ASCA SIS have interpreted the X-ray data as arising from extended emission from a dark cluster. However, the present Chandra observation can account for all the X-ray emission as originating from the lensed images and additional point X-ray sources in the field. Thus cluster parameters based on previous X-ray observations are unreliable. We estimate an upper limit on the mass-to-light ratio within a radius of 800 h_(50)^(-1) kpc of M/L_(V) < 190 h_(50) (M/L_(V))_Sun. The lensed object is quite unusual, with reported narrow emission lines in the optical that suggest it may be a type-2 quasar (Yamada et. al. 1999). Our modeling of the X-ray spectrum of the lensed object implies that the column density of an intrinsic absorber must lie between 3 and 85 x 10^22 cm^-2 (3 sigma confidence level). The 2-10 keV luminosity of the lensed object, corrected for the lens magnification effect and using the above range of intrinsic absorption, is 3 x 10^43 - 1.4 x 10^44 erg/s., 9 pages, includes 2 figures, Accepted for publication in ApJL

The mini Broad Absorption Line (BAL) quasar RX J0911.4+0551 was observed with the Advanced CCD Imaging Spectrometer (ACIS) of the Chandra X-ray Observatory for ~ 29 ks as part of a gravitational lens (GL) survey aimed at measuring time-delays. Timing analysis of the light-curve of the lensed image A2 shows a rapid flux variation with a duration of about 2000s. A Kolmogorov-Smirnov test shows that the probability that a constant-intensity source would produce the observed variability is less than ~ 0.2 percent. We discuss possible origins for the observed short-term X-ray variability. Our gravitational lens models for the RX J0911.4+0551 GL system predict a time-delay of less than a day between images A1 and A2. The rapid variability combined with the predicted short-time delay make RX J0911.4+0551 an ideal system to apply the GL method for estimating the Hubble constant. We describe the prospects of measuring H_0 within single X-ray observations of GL systems with relatively short time delays. Modeling of the spectrum of the mini-BAL quasar RX J0911.4+0551 suggests the presence of an intrinsic absorber. Partial covering models are slightly preferred over models that contain absorption due to intrinsic ionized or neutral gas., Comment: 17 pages, includes 5 figures, Accepted for publication in ApJ

We have used the Chandra X-ray Observatory to resolve spatially and spectrally the X-ray emission from the Circinus Galaxy. We report here on the nature of the X-ray emission from the off-nuclear point sources associated with the disk of Circinus. We find that many of the serendipitous X-ray sources are concentrated along the optical disk of the galaxy, but few have optical counterparts within 1" of their X-ray positions down to V=23-25. At 3.8 Mpc, their intrinsic 0.5-10 keV luminosities range from approx. 2E37 erg/s to 4E39 erg/s. One quarter of the sources are variable over the duration of the 67 ks observation, and spectral fitting of these off-nuclear sources shows a diverse range of spectral properties. The properties of the two strongest off-nuclear sources are remarkable, with average X-ray luminosities of 3.7E39 erg/s and 3.4E39 erg/s. The former displays large and periodic flux variations every 7.5 hr and is well fit by a multicolor blackbody accretion-disk model with T_in=1.35 keV, properties consistent with an eclipsing >50 M_sun black-hole binary. The latter appears to be a young supernova remnant, as it coincides with a non-thermal radio counterpart and an H\alpha-detected HII region. This source exhibits both long-term (approx. 4 yr) X-ray variability and a 6.67-6.97 keV iron emission-line blend with a 1.6 keV equivalent width. These two objects further support the notion that super-Eddington X-ray sources in nearby galaxies can be explained by a mixture of intermediate-mass black holes in X-ray binaries and young supernova remnants. (abridged), Comment: LaTex using emulateApJ5, 12 pages with 11 embedded figures, AJ in press. Also available at http://www.astro.psu.edu/~fbauer/RESEARCH/Circinus.ps.gz

We present the results of a 17 ks Chandra observation of the nearby dwarf spiral galaxy NGC 4395, focusing on the X-ray properties of the moderate-mass black hole that resides in its nucleus. Chandra affords the first high-quality, broadband X-ray detection of this object that is free of contamination from nearby sources in the field. We find that the nuclear X-ray emission is unresolved in the Chandra image and confirm the rapid, large-amplitude X-ray variability reported in previous studies. The spectrum of the nuclear source shows evidence for absorption by an ionized medium. There is also evidence for spectral variability over the course of the Chandra observation, although contrary to prior reports, it appears to be uncorrelated with fluctuations in the hard X-ray count rate. It is possible that the short-term spectral variability results from column density changes in the ionized absorber. By far the most unusual high-energy property of NGC 4395 is the shape of its spectrum above 1 keV. The Chandra data indicate a power-law photon index of Gamma \approx 0.6, which is much flatter than the Gamma \approx 1.8 X-ray spectra typical of active galactic nuclei and the slope of the nuclear X-ray spectrum measured from an earlier ASCA observation of NGC 4395. This extreme flatness and dramatic long-term variability of the X-ray spectrum are unprecedented among active galactic nuclei. A variety of possibilities for the origin of the flat continuum slope are considered; none provides a fully satisfactory explanation., Comment: 22 pages, including 9 figures. Submitted to the Astronomical Journal

BAL QSOs are notoriously faint X-ray sources, presumably due to extreme intrinsic absorption. However, several objects have begun to appear through the obscuration with recent X-ray observations by Chandra and ASCA. Where enough counts are present for X-ray spectroscopy, the signatures of absorption are clear. The evidence is also mounting that the absorbers are more complicated than previous simple models assumed; current absorber models need to be extended to the high-luminosity, high-velocity, and high-ionization regime appropriate for BAL QSOs., Comment: 6 pages, 4 postscript figures, LaTeX, requires newpasp.sty. To appear in the conference proceedings for Mass Outflow in AGN: New Perspectives, ASP Conference Series, eds. D. M. Crenshaw, S. B. Kraemer, and I. M. George

We present results from the zeroth-order imaging of a Chandra HETGS observation of the nearby Seyfert 2 galaxy Circinus. Twelve X-ray sources were detected in the ACIS-S image of the galaxy, embedded in diffuse X-ray emission. The latter shows a prominent (~18arcsec) soft ``plume'' in the N-W direction, coincident with the [OIII] ionization cone. The radial profiles of the brightest X-ray source at various energies are consistent with an unresolved (FWHM ~0.8arcsec) component, which we identify as the active nucleus, plus two extended components with FWHMs ~ 2.3arcsec and 18arcsec, respectively. In a radius of 3arcsec, the nucleus contributes roughly the same flux as the extended components at the softest energies (< 2 keV). However, at harder energies (> 2 keV), the contribution of the nucleus is dominant. The zeroth-order ACIS spectrum of the nucleus exhibits emission lines at both soft and hard X-rays, including a prominent Fe Kalpha line at 6.4 keV, showing that most of the X-ray lines previously detected with ASCA originate in a compact region (, Figure 1 in color. ApJ Letters, in press

Results from a 60 ks Chandra HETGS observation of the nearby Seyfert 2 Circinus are presented. The spectrum shows a wealth of emission lines at both soft and hard X-rays, including lines of Ne, Mg, Si, S, Ar, Ca, and Fe, and a prominent Fe Kalpha line at 6.4 keV. We identify several of the He-like components and measure several of the Lyman lines of the H-like ions. The lines' profiles are unresolved at the limited signal-to-noise ratio of the data. Our analysis of the zeroth-order image in a companion paper constrains the size of the emission region to be 20-60 pc, suggesting that emission within this volume is almost entirely due to the reprocessing of the obscured central source. Here we show that a model containing two distinct components can reproduce almost all the observed properties of this gas. The ionized component can explain the observed intensities of the ionized species, assuming twice-solar composition and an N \propto r^{-1.5} density distribution. The neutral component is highly concentrated, well within the 0.8arcsec point source, and is responsible for almost all of the observed Kalpha (6.4 keV) emission. Circinus seems to be different than Mkn~3 in terms of its gas distribution., Figure 1 in color. ApJ Letters, in press

We report the detection with Chandra of a Low-Luminosity AGN (LLAGN) in the Low Ionization Emission Line Region (LINER) hosted by Hydra A, a nearby (z=0.0537) powerful FRI radio galaxy with complex radio and optical morphology. In a 20 ks ACIS-S exposure during the calibration phase of the instrument, a point source is detected at energies $\grtsim$ 2 keV at the position of the compact radio core, embedded in diffuse thermal X-ray emission ($kT \sim 1$ keV) at softer energies. The spectrum of the point source is well fitted by a heavily absorbed power law with intrinsic column density N$_H^{int} \sim 3 \times 10^{22}$ \nh and photon index $\Gamma \sim 1.7$. The intrinsic (absorption-corrected) luminosity is $L_{2-10 keV} \sim 1.3 \times 10^{42}$ \lum. These results provide strong evidence that an obscured AGN is present in the nuclear region of Hydra~A. We infer that the optical/UV emission of the AGN is mostly hidden by the heavy intrinsic reddening. In order to balance the photon budget of the nebula, we must either postulate that the ionizing spectrum includes a UV bump or invoke and additional power source (shocks in the cooling flow or interaction with the radio jets). Using an indirect estimate of the black hole mass and the X-ray luminosity, we infer that the accretion rate is low, suggesting that the accretion flow is advection dominated. Finally, our results support current unification schemes for radio-loud sources, in particular the presence of the putative molecular torus in FR~Is. These observations underscore the power of the X-rays and of \chandra in the quest for black holes., Comment: figure 1 in color. accepted for publication in ApJ Letters

We present results from a study of 2-8 keV X-ray sources detected by the Advanced CCD Imaging Spectrometer (ACIS) instrument on the Chandra X-ray Observatory in the field of the z=0.516 cluster CRSS J0030.5+2618. In our 63.5 arcmin^2 search area, we detect 10 sources with 2-8 keV fluxes down to approximately 4x10^{-15} erg cm^{-2} s$^{-1}; our lowest flux sources are approximately 10 times fainter than those previously available for study in this band. Our derived source density is about an order of magnitude larger than previous source counts above 2 keV, although this density may be enhanced somewhat due to the presence of the cluster. We detail our methods for source detection and characterization, and we show that the resulting source list and parameters are robust. We have used the Marcario Low Resolution Spectrograph on the Hobby-Eberly Telescope to obtain optical spectra for several of our sources; combining these spectra with archival data we find that the sources appear to be active galaxies, often with narrow permitted lines, red optical continua or hard X-ray spectra. Four of the X-ray sources are undetected to R=21.7; if they reside in L* galaxies they must have z > 0.55-0.75 and hard X-ray luminosities of L_{2-8} > 4x10^{42} erg s^{-1}. We detect all but one of our 2-8 keV sources in the 0.2-2 keV band as well. This result extends to significantly lower fluxes the constraints on any large, completely new population of X-ray sources that appears above 2-3 keV., 22 pages, AJ, in press

The quasar PKS 0637-753, the first celestial X-ray target of the Chandra X-ray Observatory, has revealed asymmetric X-ray structure extending from 3 to 12 arcsec west of the quasar, coincident with the inner portion of the jet previously detected in a 4.8 GHz radio image (Tingay et al. 1998). At a redshift of z=0.651, the jet is the largest (~100 kpc) and most luminous (~10^{44.6} ergs/s) of the few so far detected in X-rays. This letter presents a high resolution X-ray image of the jet, from 42 ks of data when PKS 0637-753 was on-axis and ACIS-S was near the optimum focus. For the inner portion of the radio jet, the X-ray morphology closely matches that of new ATCA radio images at 4.8 and 8.6 GHz. Observations of the parsec scale core using the VSOP space VLBI mission show structure aligned with the X-ray jet, placing important constraints on the X-ray source models. HST images show that there are three small knots coincident with the peak radio and X-ray emission. Two of these are resolved, which we use to estimate the sizes of the X-ray and radio knots. The outer portion of the radio jet, and a radio component to the east, show no X-ray emission to a limit of about 100 times lower flux. The X-ray emission is difficult to explain with models that successfully account for extra-nuclear X-ray/radio structures in other active galaxies. We think the most plausible is a synchrotron self-Compton (SSC) model, but this would imply extreme departures from the conventional minimum-energy and/or homogeneity assumptions. We also rule out synchrotron or thermal bremsstrahlung models for the jet X-rays, unless multicomponent or ad hoc geometries are invoked., Comment: 5 Pages, 2 Figures. Submitted to Ap. J. Letters

We present the results of a multi-epoch observational campaign on the mini-broad absorption line quasar (mini-BAL QSO) PG 1126-041 performed with XMM-Newton from 2004 to 2009. Time-resolved X-ray spectroscopy and simultaneous UV and X-ray photometry were performed on the most complete set of observations and on the deepest X-ray exposure of a mini-BAL QSO to date. Complex X-ray spectral variability, found on time scales of both months and hours, is best reproduced by means of variable and massive ionized absorbers along the line of sight. In the highest signal-to-noise observation, highly-ionized X-ray absorbing material outflowing much faster than the UV absorbing one is detected. This highly-ionized absorber is found to be variable on very short time scales of a few hours., 5 pages, 2 figures. Proceedings for a talk given at the "AGN winds in Charleston" conference, Charleston (SC), October 2011. To be published by the Astronomical Society of the Pacific Conference Series

The large scale structure of the present Universe is determined by the growth of dark matter density fluctuations and by the dynamical action of dark energy and dark matter. While much progress has been made in recent years in constraining the cosmological parameters, and in reconstructing the evolution in the large--scale structure of the dark matter distribution, we still lack an understanding of the evolution of the baryonic component of the Universe. Located at nodes of the cosmic web, clusters of galaxies are the largest collapsed structures in the Universe with total masses up to 10$^{15}$ M$_{\sun}$. Over 80% of their mass resides in the form of dark matter. The remaining mass is composed of baryons, most of which (about 85%) is a diffuse, hot plasma that radiates primarily in X-rays. X-ray observations of the evolving cluster population provide a unique opportunity to address such open and fundamental questions as: How do hot diffuse baryons dynamically evolve in dark matter potentials? How and when was the excess energy which we observe in the intergalactic medium generated? What is the cosmic history of heavy-element production and circulation? Our current knowledge comes primarily from detailed studies of clusters in the relatively nearby Universe (z$, Comment: Science white paper submitted to the Astro2010 Decadal Survey

X-ray emission from AGN is believed to be produced via Comptonization of optical/UV seed photons emitted by the accretion disk, up-scattered by hot electrons in a corona surrounding the black hole. A critical compactness vs. temperature threshold is predicted above which any increase in the source luminosity, for a fixed size, would then generate positron-electron pairs rather than continue heating the coronal plasma. Current observations seem to confirm that all AGN populate the region below this critical line. These models, however, have never been probed by observations in the high-luminosity regime, where the critical line is expected to reach low temperatures. To fill this observational gap, we selected two luminous ($log(L_{bol})>47.5$ erg/s) quasars, 2MASSJ1614346+470420 ($z=1.86$) and B1422+231 ($z=3.62$), and obtained XMM-Newton and NuSTAR deep observations for them. We performed detailed spectral analysis of their quasi-simultaneous soft and hard X-ray data, in order to constrain the parameters of their coronae. Using a phenomenological cut-off power-law model, with the inclusion of a reflection component, we derived rest-frame values of the high energy cut-off of $E_{cut}=106^{+102}_{-37}$ keV and $E_{cut}=66^{+17}_{-12}$ keV, respectively. Comptonization models consistently give as best-fit parameters electron temperatures of $\sim45$ keV and $\sim28$ keV, respectively, and optically thick coronae ($��>1$). These low coronal temperatures fall in the limited region allowed at these luminosities to avoid runaway pair production., 8 pages, 2 figures, accepted for publication in ApJ Letter

We present a new X-ray spectroscopic study of $22$ luminous ($2\times10^{45}\lesssim L_{\rm bol}\rm /erg\,s^{-1} \lesssim 2\times10^{46}$) active galactic nuclei (AGNs) at intermediate-redshift ($0.1 \lesssim z \lesssim 0.4$), as part of the SUpermassive Black hole Winds in the x-rAYS (SUBWAYS) sample, mostly composed of quasars (QSOs) and type\,1 AGN. Here, 17 targets were observed with \textit{XMM-Newton} between 2019--2020 and the remaining 5 are from previous observations. The aim of this large campaign ($1.45\,\rm Ms$ duration) is to characterise the various manifestations of winds in the X-rays driven from supermassive black holes in AGN. In this paper we focus on the search and characterization of ultra-fast outflows (UFOs), which are typically detected through blueshifted absorption troughs in the Fe\,K band ($E>7\,\rm keV$). By following Monte Carlo procedures, we confirm the detection of absorption lines corresponding to highly ionised iron (e.g., Fe\,\textsc{xxv}\,H$\alpha$, Fe\,\textsc{xxvi}\,Ly$\alpha$) in 7/22 sources at the $\gtrsim95\%$ confidence level (for each individual line). The global combined probability of such absorption features in the sample is $>99.9\%$. The SUBWAYS campaign extends at higher luminosity and redshifts than previous local studies on Seyferts, obtained using \xmm and \suzaku observations. We find a UFO detection fraction of $\sim30\%$ on the total sample that is in agreement with the previous findings. This work independently provides further support for the existence of highly-ionised matter propagating at mildly relativistic speed ($\gtrsim0.1c$) in a considerable fraction of AGN over a broad range of luminosities, which is expected to play a key role in the self-regulated AGN feeding-feedback cycle, as also supported by hydrodynamical multiphase simulations., Comment: 30 pages, 10 figures, accepted for publication in A&A

We present a UV spectroscopic study of ionized outflows in 21 active galactic nuclei (AGN), observed with the HST. The targets of the SUBWAYS sample were selected with the aim to probe the parameter space of the underexplored AGN between the local Seyfert galaxies and the luminous quasars at high redshifts. Our targets, spanning redshifts of 0.1-0.4 and bolometric luminosities (L_bol) of 10^45-10^46 erg/s, have been observed with a large multi-wavelength campaign. Here, we model the UV spectra and look for different types of AGN outflows. We find that 60% of our targets show a presence of outflowing H I absorption, while 40% exhibit ionized outflows seen as absorption by either C IV, N V, or O VI. This is comparable to the occurrence of ionized outflows seen in the local Seyfert galaxies. All UV absorption lines in the sample are relatively narrow, with outflow velocities reaching up to -3300 km/s. We did not detect any UV counterparts to the X-ray ultra-fast outflows (UFOs), most likely due to their being too highly ionized. However, all SUBWAYS targets with an X-ray UFO demonstrate the presence of UV outflows at lower velocities. We find significant correlations between the column density (N) of the UV ions and L_bol of the AGN, with N of H I decreasing with L_bol, while N of O VI is increasing with L_bol. This is likely to be a photoionization effect, where toward higher AGN luminosities, the wind becomes more ionized, resulting in less absorption by neutral or low-ionization ions and more absorption by high-ionization ions. In addition, we find that N of the UV ions decreases as their outflow velocity increases. This may be explained by a mechanical power that is evacuating the UV-absorbing medium. Our observed relations are consistent with multiphase AGN feeding and feedback simulations indicating that a combination of both radiative and mechanical processes are in play., Comment: Accepted for publication in Astronomy & Astrophysics (A&A), 22 pages, 12 figures

Theoretical models of wind-driven feedback from Active Galactic Nuclei (AGN) often identify Ultra-fast outflows (UFOs) as being the main cause for generating galaxy-size outflows, possibly the main actors in establishing the so-called AGN-galaxy co-evolution. UFOs are well characterized in local AGN but much less is known in quasars at the cosmic time when SF and AGN activity peaked ($z\simeq1-3$). It is therefore mandatory to search for evidences of UFOs in high-$z$ sources to test the wind-driven AGN feedback models. Here we present a study of Q2237+030, the Einstein Cross, a quadruply-imaged radio-quiet lensed quasar located at $z=1.695$. We performed a systematic and comprehensive temporally and spatially resolved X-ray spectral analysis of all the available Chandra and XMM-Newton data (as of September 2019). We find clear evidence for spectral variability, possibly due to absorption column density (or covering fraction) variability intrinsic to the source. We detect, for the first time in this quasar, a fast X-ray wind outflowing at $v_{\rm out}\simeq0.1c$ that would be powerful enough ($\dot{E}_{\rm kin}\simeq0.1 L_{\rm bol}$) to significantly affect the host galaxy evolution. We report also on the possible presence of an even faster component of the wind ($v_{\rm out}\sim0.5c$). Given the large sample and long time interval spanned by the analyzed X-ray data, we are able to roughly estimate, for the first time in a high-$z$ quasar, the wind duty cycle as $\approx0.46\,(0.31)$ at $90\%\,(95\%)$ confidence level. Finally, we also confirm the presence of a Fe K$\alpha$ emission line with variable energy, which we discuss in the light of microlensing effects as well as considering our findings on the source., Comment: 18 pages, 11 figures, 7 tables, Accepted for publication in A&A

We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of the quadruply lensed z=1.51 quasar HS 0810+2554 which provide useful insight on the kinematics and morphology of the CO molecular gas and the ~2 mm continuum emission in the quasar host galaxy. Lens modeling of the mm-continuum and the spectrally integrated CO(3-2) images indicates that the source of the mm-continuum has an eccentricity of e~0.9 with a size of ~1.6 kpc and the source of line emission has an eccentricity of e~0.7 with a size of ~1 kpc. The spatially integrated emission of the CO(2-1) and CO(3-2) lines shows a triple peak structure with the outer peaks separated by Dv_21 = 220 +\- 19 km s^-1 and Dv_32 = 245 +/- 28 km s^-1, respectively, suggesting the presence of rotating molecular CO line emitting gas. Lensing inversion of the high spatial resolution images confirms the presence of rotation of the line emitting gas. Assuming a conversion factor of alpha_CO = 0.8 M_solar (K km s^-1 pc^2)^-1 we find the molecular gas mass of HS 0810+2554 to be M _ Mol = [(5.2 +/- 1.5)/mu_32] x10^10 M_solar, where mu_32 is the magnification of the CO(3-2) emission. We report the possible detection, at the 3.0 - 4.7 sigma confidence level, of shifted CO(3-2) emission lines of high-velocity clumps of CO emission with velocities up to 1702 km s^-1. We find that the momentum boost of the large scale molecular wind is below the value predicted for an energy-conserving outflow given the momentum flux observed in the small scale ultrafast outflow., Comment: 17 pages, includes 15 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society

We present results from a comprehensive study of ultrafast outflows (UFOs) detected in a sample of fourteen quasars, twelve of which are gravitationally lensed, in a redshift range of 1.41-3.91, near the peak of the AGN and star formation activity. New XMM-Newton observations are presented for six of them which were selected to be lensed and contain a narrow absorption line (NAL) in their UV spectra. Another lensed quasar was added to the sample, albeit already studied, because it was not searched for UFOs. The remaining seven quasars of our sample are known to contain UFOs. The main goals of our study are to infer the outflow properties of high-z quasars, constrain their outflow induced feedback, study the relationship between the outflow properties and the properties of the ionizing source, and compare these results to those of nearby AGN. Our study adds six new detections ( > 99% confidence) of UFOs at z > 1.4, almost doubling the current number of cases. Based on our survey of six quasars selected to contain a NAL and observed with XMM-Newton, the coexistence of intrinsic UV NALs and UFOs is found to be significant in > 83% of these quasars suggesting a link between multiphase AGN feedback properties of the meso- and micro-scale. The kinematic luminosities of the UFOs of our high-z sample are large compared to their bolometric luminosities (median of L_K/L_Bol ~ 50%). This suggests they provide efficient feedback to influence the evolution of their host galaxies and that magnetic driving may be a significant contributor to their acceleration., 29 pages, includes 11 figures, accepted for publication in The Astrophysical Journal

Outflows driven by active galactic nuclei (AGN) are expected to have a significant impact on the host galaxy evolution, but it is still debated how they are accelerated and propagate on galaxy-wide scales. This work addresses these questions by studying the link between X-ray, nuclear ultra-fast outflows (UFOs) and extended ionised outflows, for the first time in two quasars close to the peak of AGN activity ($z\sim2$), where AGN feedback is expected to be more effective. As targets, we selected two multiple-lensed quasars at $z\sim1.5$, HS 0810+2554 and SDSS J1353+1138, known to host UFOs and observed with the near-IR integral field spectrometer SINFONI at the VLT. We performed a kinematical analysis of the [O III]$\lambda$5007 optical emission line, in order to trace the presence of ionised outflows. We detected spatially resolved ionised outflows in both galaxies, extended more than 8 kpc and moving up to $v>2000$ km/s. We derived mass outflow rates of $\sim$12 M$_{sun}$/yr and $\sim$2 M$_{sun}$/yr for HS 0810+2554 and SDSS J1353+1138. Comparing with the co-hosted UFO energetics, the ionised outflow energetics in HS 0810+2554 is broadly consistent with a momentum-driven regime of wind propagation, while in SDSS J1353+1138 it differs by a factor of $\sim$100 from theoretical predictions, requiring either a massive molecular outflow or a high variability of the AGN activity to account for such a discrepancy. By additionally considering our results with those from the small sample of well-studied objects (all local but one), with both UFO and extended (ionised/atomic/molecular) outflow detections, we found that in 10 out of 12 galaxies the large-scale outflow energetics is consistent with the theoretical predictions of either a momentum- or an energy-driven scenario. This suggests that such models explain relatively well the acceleration mechanism of AGN-driven winds on large scales., Comment: 19 pages, 9 figures. Accepted for publication in A&A

Ultra-fast outflows (UFO) appear to be common in local active galactic nuclei (AGN) and may be powerful enough ($\dot{E}_{kin}$$\geq$1\% of L$_{bol}$) to effectively quench the star formation in their host galaxies. To test feedback models based on AGN outflows, it is mandatory to investigate UFOs near the peak of AGN activity, that is, at high-z where only a few studies are available to date. UFOs produce Fe resonant absorption lines measured above $\approx$7 keV. The most critical problem in detecting such features in distant objects is the difficulty in obtaining X-ray data with sufficient signal-to-noise. We therefore selected a distant QSO that gravitational lensing made bright enough for these purposes, the z=2.64 QSO MG J0414+0534, and observed it with XMM-Newton for $\approx$78 ks.} The X-ray spectrum of MG J0414+0534 is complex and shows signatures of cold absorption (N$_{H}\approx$4$\times$10$^{22}$ cm$^{-2}$) and of the presence of an iron emission line (E$\approx$6.4 keV, EW$=$95$\pm$53 eV) consistent with it originating in the cold absorber. Our main result, however, is the robust detection (more than 5$\sigma$) of an absorption line at E$_{int}\approx$9.2 keV (E$_{obs}\approx$2.5 keV observer frame). If interpreted as due to FeXXVI, it implies gas outflowing at $v_{out}\approx$0.3c. To our knowledge, this is the first detection of an UFO in a radio-loud quasar at z$\geq$1.5. We estimated that the UFO mechanical output is $\dot{E}_{kin}$$\approx$2.5$L_{bol}$ with $\dot{p}_{out}/\dot{p}_{rad}\approx$17 indicating that it is capable of installing significant feedback between the super-massive black hole (SMBH) and the bulge of the host galaxy. We argue that this also suggests a magnetic driving origin of the UFO., Comment: Accepted for publication on A&A Letter

Matter flows in the central regions of quasars during their active phases are probably responsible for the properties of the super-massive black holes and that of the bulges of host galaxies. To understand how this mechanism works, we need to characterize the geometry and the physical state of the accreting matter at cosmological redshifts. The few high quality X-ray spectra of distant QSO have been collected by adding sparse pointings of single objects obtained during X-ray monitoring campaigns. This could have introduced spurious spectral features due to source variability. Here we present a single epoch, high-quality X-ray spectrum of the z=3.62 quasar B1422+231 whose flux is enhanced by gravitationally lensing (F$_{2-10 keV}\sim$10$^{-12}$erg s$^{-1}$ cm$^{-2}$). The X-ray spectrum of B1422+231 is found to be very similar to the one of a typical nearby Seyfert galaxy. Neutral absorption is detected (N$_{H}\sim$5$\times$10$^{21}$ cm$^{-2}$ at the redshift of the source) while a strong absorption edge is measured at E$\sim$7.5 keV with an optical depth of $\tau\sim$0.14. We also find hints of the FeK$\alpha$ line in emission at E$\sim$6.4 keV line (EW$\lesssim$70 eV) and a hump is detected in the E$\sim$15-20 keV energy band (rest-frame) suggesting the presence of a reflection component. In this scenario, the primary emission of B1422+231 is most probably dominated by the thermal Comptonization of UV seed photons in a corona with kT$\sim$40 keV and the reflection component has a relative direct-to-reflect normalization r$\sim$1. These findings confirm that gravitational lensing is effective to obtain good quality X-ray spectral information of quasar at high-z, moreover they support the idea that the same general picture characterizing active galactic nuclei in the nearby Universe is valid also at high redshift., Comment: Accepted for publication on Astronomy and Astrophysics

We present results from multi-epoch spectral analysis of XMM-Newton and Chandra observations of the broad absorption line (BAL) quasar APM 08279+5255. Our analysis shows significant X-ray BALs in all epochs with rest-frame energies lying in the range of ~ 6.7-18 keV. The X-ray BALs and 0.2-10 keV continuum show significant variability on timescales as short as 3.3 days (proper time) implying a source size-scale of ~ 10 r_g, where r_g is the gravitational radius. We find a large gradient in the outflow velocity of the X-ray absorbers with projected outflow velocities of up to 0.76 c. The maximum outflow velocity constrains the angle between the wind velocity and our line of sight to be less than ~ 22 degrees. We identify the following components of the outflow: (a) Highly ionized X-ray absorbing material (2.9 < logxi < 3.9) and a column density of log N_H ~ 23 outflowing at velocities of up to 0.76 c. (b) Low-ionization X-ray absorbing gas with log N_H ~ 22.8. We find that flatter spectra appear to result in lower outflow velocities. Based on our spectral analysis of observations of APM 08279+5255 over a period of 1.2 years (proper time) we estimate the mass-outflow rate and efficiency of the outflow to have varied between 16(-8,+12) M_solar yr^-1 and 64(-40,+66) M_solar yr^-1 and 0.18(-0.11,+0.15) to 1.7(-1.2+1.9), respectively. Assuming that the outflow properties of APM 08279+5255 are a common property of most quasars at similar redshifts, our results then imply that quasar winds are massive and energetic enough to influence significantly the formation of the host galaxy, provide significant metal enrichment to the interstellar medium and intergalactic medium, and are a viable mechanism for feedback at redshifts near the peak in the number density of galaxy mergers., 27 pages, includes 12 figures, accepted for publication in ApJ

A long XMM-Newton observation of the mini-BAL QSO PG 1126-041 allowed us to detect a highly ionized phase of X-ray absorbing gas outflowing at v~15000 km/s. Physical implications are briefly discussed., 2 pages, 2 figures. Proceedings of "X.ray Astronomy 2009", Bologna 09/7-11/2009, AIP Conference Series, Eds. A. Comastri, M. Cappi, L. Angelini

We present the results of Chandra ACIS-S snapshot observations of six radio-loud quasars (RLQs) at z=3.5-4.7. These observations sample luminous RLQs with moderate-to-high radio-loudness (R=200-9600) and aim to connect the X-ray properties of radio-quiet quasars (R1000) at high redshift. This work extends a study by Bassett et al. (2004) which used similar methods to examine z > 4 RLQs with moderate radio-loudness (R=40-400). All of our targets are clearly detected. A search for extended X-ray emission associated with kpc-scale radio jets revealed only limited evidence for X-ray extension in our sample: three sources showed no evidence of X-ray extension, and the other three had 3-30% of their total X-ray fluxes extended >1 arcsec away from their X-ray cores. Additionally, we do not observe any systematic flattening of the optical-to-X-ray spectral index (alpha_{ox}) compared to low-redshift quasars. These results suggest that kpc-scale X-ray jet emission is not dominated by inverse-Compton scattering of CMB-seed photons off jet electrons. We measured X-ray continuum shapes and performed individual and joint spectral fits of our data combined with eight archival RLQs. A single power-law model acceptably fit the data. We added an intrinsic absorption component to our model, and neither the moderate-R nor the high-R fits set a lower bound on N_H. Our spectral results suggest that intrinsic absorption does not strongly depend on radio-loudness, and high-R sources have flatter power laws than moderate-R sources. Overall, our high-redshift RLQs have basic X-ray properties consistent with similar RLQs in the local universe., 24 pages, 5 figures, Accepted by AJ

We present the results from XMM-Newton observations of the highly optically polarized broad absorption line quasar (BALQSO) CSO 755. By analyzing its X-ray spectrum with a total of ~3000 photons we find that this source has an X-ray continuum of `typical' radio-quiet quasars, with a photon index of Gamma=1.83^{+0.07}_{-0.06}, and a rather flat (X-ray bright) intrinsic optical-to-X-ray spectral slope of alpha_ox=-1.51. The source shows evidence for intrinsic absorption, and fitting the spectrum with a neutral-absorption model gives a column density of N_H~1.2x10^{22} cm^{-2}; this is among the lowest X-ray columns measured for BALQSOs. We do not detect, with high significance, any other absorption features in the X-ray spectrum. Upper limits we place on the rest-frame equivalent width of a neutral (ionized) Fe Ka line, 7 pages (emulateapj), 3 figures. Accepted by AJ

X-ray studies of active galactic nuclei (AGN) with powerful nuclear winds are important for constraining the physics of the inner accretion/ejection flow around supermassive black holes (SMBHs) and for understanding the impact of such winds on the AGN environment. Our main scientific goal is to constrain the properties of the circum-nuclear matter close to the SMBH in the mini-broad absorption line quasar (mini-BAL QSO) PG 1126-041 using a multi-epoch observational campaign with XMM-Newton. We performed temporally resolved X-ray spectroscopy and simultaneous UV and X-ray photometry on the most complete set of observations and on the deepest X-ray exposure of a mini-BAL QSO ever. We found complex X-ray spectral variability on time scales of both months and hours, which is best reproduced by means of variable massive ionized absorbers along the line of sight. As a consequence, the observed optical-to-X-ray spectral index is found to be variable with time. In the highest signal-to-noise observation we detected highly ionized X-ray absorbing material outflowing much faster (v ~ 16500 km/s) than the UV absorbing one (v ~ 5000 km/s). This highly ionized absorber is found to be variable on very short (a few kiloseconds) time scales. Our findings are qualitatively consistent with line-driven accretion disk winds scenarios. Our observations have opened the time-resolved X-ray spectral analysis field for mini-BAL QSOs. Only with future deep studies will we be able to map the dynamics of the inner flow and understand the physics of AGN winds and their impact on the environment., Replaced to match the published version