Publication Search Results

ID: 159343
Type: article
Authors: Horne, Keith; De Rosa, G.; Peterson, B. M.; Barth, A. J.; Ely, J.; Fausnaugh, M. M.; Kriss, G. A.; Pei, L.; Bentz, M. C.; Cackett, E. M.; Edelson, R.; Eracleous, M.; Goad, M. R.; Grier, C. J.; Kaastra, J.; Kochanek, C. S.; Krongold, Y.; Mathur, S.; Netzer, H.; Proga, D.; Tejos, N.; Vestergaard, M.; Villforth, C.; Adams, S. M.; Anderson, M. D.; Arévalo, P.; Beatty, T. G.; Bennert, V. N.; Bigley, A.; Bisogni, S.; Borman, G. A.; Boroson, T. A.; Bottorff, M. C.; Brandt, W. N.; Breeveld, A. A.; Brotherton, M.; Brown, J. E.; Brown, J. S.; Canalizo, G.; Carini, M. T.; Clubb, K. I.; Comerford, J. M.; Corsini, E. M.; Crenshaw, D. M.; Croft, S.; Croxall, K. V.; Dalla Bontà, E.; Deason, A. J.; Dehghanian, M.; De Lorenzo-Cáceres, A.; Denney, K. D.; Dietrich, M.; Done, C.; Efimova, N. V.; Evans, P. A.; Ferland, G. J.; Filippenko, A. V.; Flatland, K.; Fox, O. D.; Gardner, E.; Gates, E. L.; Gehrels, N.; Geier, S.; Gelbord, J. M.; Gonzalez, L.; Gorjian, V.; Greene, J. E.; Grupe, D.; Gupta, A.; Hall, P. B.; Henderson, C. B.; Hicks, S.; Holmbeck, E.; Holoien, T. W. -S; Hutchison, T.; Im, M.; Jensen, J. J.; Johnson, C. A.; Joner, M. D.; Jones, J.; Kaspi, S.; Kelly, P. L.; Kennea, J. A.; Kim, M.; Kim, S.; Kim, S. C.; King, A.; Klimanov, S. A.; Korista, K. T.; Lau, M. W.; Lee, J. C.; Leonard, D. C.; Li, Miao; Lira, P.; Lochhaas, C.; Ma, Zhiyuan; MacInnis, F.; Malkan, M. A.; Manne-Nicholas, E. R.; Mauerhan, J. C.; McGurk, R.; McHardy, I. M.; Montuori, C.; Morelli, L.; Mosquera, A.; Mudd, D.; Müller-Sánchez, F.; Nazarov, S. V.; Norris, R. P.; Nousek, J. A.; Nguyen, M. L.; Ochner, P.; Okhmat, D. N.; Pancoast, A.; Papadakis, I.; Parks, J. R.; Penny, M. T.; Pizzella, A.; Pogge, R. W.; Poleski, R.; Pott, J. -U; Rafter, S. E.; Rix, H. -W; Runnoe, J.; Saylor, D. A.; Schimoia, J. S.; Schnülle, K.; Scott, B.; Sergeev, S. G.; Shappee, B. J.; Shivvers, I.; Siegel, M.; Simonian, G. V.; Siviero, A.; Skielboe, A.; Somers, G.; Spencer, M.; Starkey, D.; Stevens, D. J.; Sung, H. -I; Tayar, J.; Treu, T.; Turner, C. S.; Uttley, P.; Van Saders, J.; Vican, L.; Villanueva, S., Jr.; Weiss, Y.; Woo, J. -H; Yan, H.; Young, S.; Yuk, H.; Zheng, W.; Zhu, W.; Zu, Y.
Abstract: 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 $\tau =(R/c)(1-\sin i)\approx 5$ days gives the inclination i ≍ 45°. The inferred black hole mass is M_BH ≍ 7 × 10⁷ M_⊙. 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.

ID: 158791
Type: article
Authors: Lusso, E.; Risaliti, G.; Nardini, E.; Bargiacchi, G.; Benetti, M.; Bisogni, S.; Capozziello, S.; Civano, Francesca; Eggleston, L.; Elvis, Martin; Fabbiano, Giuseppina; Gilli, R.; Marconi, A.; Paolillo, M.; Piedipalumbo, E.; Salvestrini, F.; Signorini, M.; Vignali, C.
Abstract: We present a new catalogue of ˜2400 optically selected quasars with spectroscopic redshifts and X-ray observations from either Chandra or XMM-Newton. The sample can be used to investigate the non-linear relation between the ultraviolet (UV) and X-ray luminosity of quasars as well as to build a Hubble diagram up to a redshift of z ˜ 7.5. We selected sources that are neither reddened by dust in the optical and UV nor obscured by gas in the X-rays, and whose X-ray fluxes are free from flux-limit-related biases. After checking for any possible systematics, we confirm, in agreement with our previous works, that the X-ray to UV relation provides distance estimates matching those from supernovae up to z ˜ 1.5, and its slope shows no redshift evolution up to z ˜ 5. We provide a full description of the methodology for testing cosmological models, further supporting a trend whereby the Hubble diagram of quasars is well reproduced by the standard flat cold dark matter model up to z ˜ 1.5-2, but strong deviations emerge at higher redshifts. Since we have minimised all non-negligible systematic effects and proven the stability of the L_X - L_UV relation at high redshifts, we conclude that an evolution of the expansion rate of the Universe should be considered as a possible explanation for the observed deviation, rather than some systematic (redshift-dependent) effect associated with high-redshift quasars.
Full Table 3 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/642/A150

ID: 158810
Type: article
Authors: Williams, P. R.; Pancoast, Anna; Treu, T.; Brewer, B. J.; Peterson, B. M.; Barth, A. J.; Malkan, M. A.; De Rosa, G.; Horne, Keith; Kriss, G. A.; Arav, N.; Bentz, M. C.; Cackett, E. M.; Dalla Bontà, E.; Dehghanian, M.; Done, C.; Ferland, G. J.; Grier, C. J.; Kaastra, J.; Kara, E.; Kochanek, C. S.; Mathur, S.; Mehdipour, M.; Pogge, R. W.; Proga, D.; Vestergaard, M.; Waters, T.; Adams, S. M.; Anderson, M. D.; Arévalo, P.; Beatty, T. G.; Bennert, V. N.; Bigley, A.; Bisogni, S.; Borman, G. A.; Boroson, T. A.; Bottorff, M. C.; Brandt, W. N.; Breeveld, A. A.; Brotherton, M.; Brown, J. E.; Brown, J. S.; Canalizo, G.; Carini, M. T.; Clubb, K. I.; Comerford, J. M.; Corsini, E. M.; Crenshaw, D. M.; Croft, S.; Croxall, K. V.; Deason, A. J.; De Lorenzo-Cáceres, A.; Denney, K. D.; Dietrich, M.; Edelson, R.; Efimova, N. V.; Ely, J.; Evans, P. A.; Fausnaugh, M. M.; Filippenko, A. V.; Flatland, K.; Fox, O. D.; Gardner, E.; Gates, E. L.; Gehrels, N.; Geier, S.; Gelbord, J. M.; Gonzalez, L.; Gorjian, V.; Greene, J. E.; Grupe, D.; Gupta, A.; Hall, P. B.; Henderson, C. B.; Hicks, S.; Holmbeck, E.; Holoien, T. W. -S; Hutchison, T.; Im, M.; Jensen, J. J.; Johnson, C. A.; Joner, M. D.; Jones, J.; Kaspi, S.; Kelly, P. L.; Kennea, J. A.; Kim, M.; Kim, S.; Kim, S. C.; King, A.; Klimanov, S. A.; Knigge, C.; Krongold, Y.; Lau, M. W.; Lee, J. C.; Leonard, D. C.; Li, Miao; Lira, P.; Lochhaas, C.; Ma, Zhiyuan; MacInnis, F.; Manne-Nicholas, E. R.; Mauerhan, J. C.; McGurk, R.; McHardy, I. M.; Montuori, C.; Morelli, L.; Mosquera, A.; Mudd, D.; Müller-Sánchez, F.; Nazarov, S. V.; Norris, R. P.; Nousek, J. A.; Nguyen, M. L.; Ochner, P.; Okhmat, D. N.; Papadakis, I.; Parks, J. R.; Pei, L.; Penny, M. T.; Pizzella, A.; Poleski, R.; Pott, J. -U; Rafter, S. E.; Rix, H. -W; Runnoe, J.; Saylor, D. A.; Schimoia, J. S.; Scott, B.; Sergeev, S. G.; Shappee, B. J.; Shivvers, I.; Siegel, M.; Simonian, G. V.; Siviero, A.; Skielboe, A.; Somers, G.; Spencer, M.; Starkey, D.; Stevens, D. J.; Sung, H. -I; Tayar, J.; Tejos, N.; Turner, C. S.; Uttley, P.; Van Saders, J.; Vaughan, S. A.; Vican, L.; Villanueva, S., Jr.; Villforth, C.; Weiss, Y.; Woo, J. -H; Yan, H.; Young, S.; Yuk, H.; Zheng, W.; Zhu, W.; Zu, Y.
Abstract: 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 Hß, C IV, and Lya broad emission lines. We find an extended disk-like Hß BLR with a mixture of near-circular and outflowing gas trajectories, while the C IV and Lya BLRs are much less extended and resemble shell-like structures. There is clear radial structure in the BLR, with C IV the three lines, we make three independent black hole mass measurements, all of which are consistent. Combining these results gives a joint inference of ${\mathrm{log}}_{10}({M}_{\mathrm{BH}}/{M}_{\odot })={7.64}_{-0.18}^{+0.21}$ . 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 Hß 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.

ID: 154279
Type: article
Authors: Kriss, G. A.; De Rosa, G.; Ely, J.; Peterson, B. M.; Kaastra, J.; Mehdipour, M.; Ferland, G. J.; Dehghanian, M.; Mathur, S.; Edelson, R.; Korista, K. T.; Arav, N.; Barth, A. J.; Bentz, M. C.; Brandt, W. N.; Crenshaw, D. M.; Dalla Bontà, E.; Denney, K. D.; Done, C.; Eracleous, M.; Fausnaugh, M. M.; Gardner, E.; Goad, M. R.; Grier, C. J.; Horne, Keith; Kochanek, C. S.; McHardy, I. M.; Netzer, H.; Pancoast, Anna; Pei, L.; Pogge, R. W.; Proga, D.; Silva, C.; Tejos, N.; Vestergaard, M.; Adams, S. M.; Anderson, M. D.; Arévalo, P.; Beatty, T. G.; Behar, E.; Bennert, V. N.; Bianchi, S.; Bigley, A.; Bisogni, S.; Boissay-Malaquin, R.; Borman, G. A.; Bottorff, M. C.; Breeveld, A. A.; Brotherton, M.; Brown, J. E.; Brown, J. S.; Cackett, E. M.; Canalizo, G.; Cappi, M.; Carini, M. T.; Clubb, K. I.; Comerford, J. M.; Coker, C. T.; Corsini, E. M.; Costantini, E.; Croft, S.; Croxall, K. V.; Deason, A. J.; De Lorenzo-Cáceres, A.; De Marco, B.; Dietrich, M.; Di Gesu, L.; Ebrero, J.; Evans, P. A.; Filippenko, A. V.; Flatland, K.; Gates, E. L.; Gehrels, N.; Geier, S.; Gelbord, J. M.; Gonzalez, L.; Gorjian, V.; Grupe, D.; Gupta, A.; Hall, P. B.; Henderson, C. B.; Hicks, S.; Holmbeck, E.; Holoien, T. W. -S; Hutchison, T. A.; Im, M.; Jensen, J. J.; Johnson, C. A.; Joner, M. D.; Kaspi, S.; Kelly, B. C.; Kelly, P. L.; Kennea, J. A.; Kim, M.; Kim, S. C.; Kim, S. Y.; King, A.; Klimanov, S. A.; Krongold, Y.; Lau, M. W.; Lee, J. C.; Leonard, D. C.; Li, Miao; Lira, P.; Lochhaas, C.; Ma, Zhiyuan; MacInnis, F.; Malkan, M. A.; Manne-Nicholas, E. R.; Matt, G.; Mauerhan, J. C.; McGurk, R.; Montuori, C.; Morelli, L.; Mosquera, A.; Mudd, D.; Müller-Sánchez, F.; Nazarov, S. V.; Norris, R. P.; Nousek, J. A.; Nguyen, M. L.; Ochner, P.; Okhmat, D. N.; Paltani, S.; Parks, J. R.; Pinto, C.; Pizzella, A.; Poleski, R.; Ponti, G.; Pott, J. -U; Rafter, S. E.; Rix, H. -W; Runnoe, J.; Saylor, D. A.; Schimoia, J. S.; Schnülle, K.; Scott, B.; Sergeev, S. G.; Shappee, B. J.; Shivvers, I.; Siegel, M.; Simonian, G. V.; Siviero, A.; Skielboe, A.; Somers, G.; Spencer, M.; Starkey, D.; Stevens, D. J.; Sung, H. -I; Tayar, J.; Teems, K. G.; Treu, T.; Turner, C. S.; Uttley, P.; Van Saders, J.; Vican, L.; Villforth, C.; Villanueva, S., Jr.; Walton, D. J.; Waters, T.; Weiss, Y.; Woo, J. -H; Yan, H.; Yuk, H.; Zheng, W.; Zhu, W.; Zu, Y.
Abstract: 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 Lyα 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 Lyα 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.

ID: 154538
Type: article
Authors: Nardini, E.; Lusso, E.; Risaliti, G.; Bisogni, S.; Civano, Francesca; Elvis, Martin; Fabbiano, Giuseppina; Gilli, R.; Marconi, A.; Salvestrini, F.; Vignali, C.
Abstract: We present the X-ray analysis of 30 luminous quasars at z ≃ 3.0 - 3.3 with pointed XMM-Newton observations (28-48 ks) originally obtained by our group to test the suitability of active galactic nuclei as standard candles for cosmological studies. The sample was selected in the optical from the Sloan Digital Sky Survey Data Release 7 to be representative of the most luminous, intrinsically blue quasar population, and by construction boasts a high degree of homogeneity in terms of optical and UV properties. In the X-rays, only four sources are too faint for a detailed spectral analysis, one of which is formally undetected. Neglecting one more object later found to be radio-loud, the other 25 quasars are, as a whole, the most X-ray luminous ever observed, with rest-frame 2-10 keV luminosities of 0.5 - 7 × 10⁴⁵ erg s^-1. The continuum photon index distribution, centred at Γ ̃ 1.85, is in excellent agreement with those in place at lower redshift, luminosity, and black-hole mass, confirming the universal nature of the X-ray emission mechanism in quasars. Even so, when compared against the well-known L_X-L_UV correlation, our quasars show an unexpectedly varied behaviour, splitting into two distinct subsets. About two-thirds of the sources are clustered around the relation with a minimal scatter of 0.1 dex, while the remaining one-third appear to be X-ray underluminous by factors of > 3-10. Such a large incidence (≈25%) of X-ray weakness has never been reported in radio-quiet, non- broad absorption line (BAL) quasar samples. Several factors could contribute to enhancing the X-ray weakness fraction among our z ≃ 3 blue quasars, including variability, mild X-ray obscuration, contamination from weak-line quasars, and missed BALs. However, the X-ray weak objects also have, on average, flatter spectra, with no clear evidence of absorption. Indeed, column densities in excess of a few ×10²² cm^-2 can be ruled out for most of the sample. We suggest that, at least in some of our X-ray weak quasars, the corona might experience a radiatively inefficient phase due to the presence of a powerful accretion-disc wind, which substantially reduces the accretion rate through the inner disc and therefore also the availability of seed photons for Compton up-scattering. The origin of the deviations from the L_X-L_UV relation will be further investigated in a series of future studies.

ID: 144722
Type: article
Authors: Mathur, S.; Gupta, A.; Page, K.; Pogge, R. W.; Krongold, Y.; Goad, M. R.; Adams, S. M.; Anderson, M. D.; Arévalo, P.; Barth, A. J.; Bazhaw, C.; Beatty, T. G.; Bentz, M. C.; Bigley, A.; Bisogni, S.; Borman, G. A.; Boroson, T. A.; Bottorff, M. C.; Brandt, W. N.; Breeveld, A. A.; Brown, J. E.; Brown, J. S.; Cackett, E. M.; Canalizo, G.; Carini, M. T.; Clubb, K. I.; Comerford, J. M.; Coker, C. T.; Corsini, E. M.; Crenshaw, D. M.; Croft, S.; Croxall, K. V.; Dalla Bontà, E.; Deason, A. J.; Denney, K. D.; De Lorenzo-Cáceres, A.; De Rosa, G.; Dietrich, M.; Edelson, R.; Ely, J.; Eracleous, M.; Evans, P. A.; Fausnaugh, M. M.; Ferland, G. J.; Filippenko, A. V.; Flatland, K.; Fox, O. D.; Gates, E. L.; Gehrels, N.; Geier, S.; Gelbord, J. M.; Gorjian, V.; Greene, J. E.; Grier, C. J.; Grupe, D.; Hall, P. B.; Henderson, C. B.; Hicks, S.; Holmbeck, E.; Holoien, T. W. -S; Horenstein, D.; Horne, Keith; Hutchison, T.; Im, M.; Jensen, J. J.; Johnson, C. A.; Joner, M. D.; Jones, J.; Kaastra, J.; Kaspi, S.; Kelly, B. C.; Kelly, P. L.; Kennea, J. A.; Kim, M.; Kim, S.; Kim, S. C.; King, A.; Klimanov, S. A.; Kochanek, C. S.; Korista, K. T.; Kriss, G. A.; Lau, M. W.; Lee, J. C.; Leonard, D. C.; Li, M.; Lira, P.; Ma, Z.; MacInnis, F.; Manne-Nicholas, E. R.; Malkan, M. A.; Mauerhan, J. C.; McGurk, R.; McHardy, I. M.; Montouri, C.; Morelli, L.; Mosquera, A.; Mudd, D.; Muller-Sanchez, F.; Musso, R.; Nazarov, S. V.; Netzer, H.; Nguyen, M. L.; Norris, R. P.; Nousek, J. A.; Ochner, P.; Okhmat, D. N.; Ou-Yang, B.; Pancoast, Anna; Papadakis, I.; Parks, J. R.; Pei, L.; Peterson, B. M.; Pizzella, A.; Poleski, R.; Pott, J. -U; Rafter, S. E.; Rix, H. -W; Runnoe, J.; Saylor, D. A.; Schimoia, J. S.; Schnülle, K.; Sergeev, S. G.; Shappee, B. J.; Shivvers, I.; Siegel, M.; Simonian, G. V.; Siviero, A.; Skielboe, A.; Somers, G.; Spencer, M.; Starkey, D.; Stevens, D. J.; Sung, H. -I; Tayar, J.; Tejos, N.; Turner, C. S.; Uttley, P.; Van Saders, J.; Vestergaard, M.; Vican, L.; Villanueva, S., Jr.; Villforth, C.; Weiss, Y.; Woo, J. -H; Yan, H.; Young, S.; Yuk, H.; Zheng, W.; Zhu, W.; Zu, Y.
Abstract: 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.