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Register a new userThe rotating wind of the quasar PG 1700+518
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It is now widely accepted that most galaxies undergo an active phase, during which a central super-massive black hole generates vast radiant luminosities through the gravitational accretion of gas. Winds launched from a rotating accretion disk surrounding the black hole are thought to play a critical role, allowing the disk to shed angular momentum that would otherwise inhibit accretion. Such winds are capable of depositing large amounts of mechanical energy in the host galaxy and its environs, profoundly affecting its formation and evolution, and perhaps regulating the formation of large-scale cosmological structures in the early Universe. Although there are good theoretical grounds for believing that outflows from active galactic nuclei originate as disk winds, observational verification has proven elusive. Here we show that structures observed in polarized light across the broad H-alpha emission line in the quasar PG 1700+158 originate close to the accretion disk in an electron scattering wind. The wind has large rotational motions (~4,000 km/s), providing direct observational evidence that outflows from active galactic nuclei are launched from the disks. Moreover, the wind rises nearly vertically from the disk, favouring launch mechanisms that impart an initial acceleration perpendicular to the disk plane.
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It is found that feii emission contributes significantly to the optical and ultraviolet spectra of most active galactic nuclei. The origin of the optical/UV feii emission is still a question open to debate. The variability of feii would give clues to this origin. Using 7.5 yr spectroscopic monitoring data of one Palomer-Green (PG) quasi-stellar object (QSO), PG 1700+518, with strong optical feii emission, we obtain the light curves of the continuum lv, feii, the broad component of hb, and the narrow component of hb by the spectral decomposition. Through the interpolation cross-correlation method, we calculate the time lags for light curves of feii, the total hb, the broad component of hb, and the narrow component of hb with respect to the continuum light curve. We find that the feii time lag in PG1700+518 is $209^{+100}_{-147}$ days, and the hb time lag cannot be determined. Assuming that feii and hb emission regions follow the virial relation between the time lag and the FWHM for the hb and feii emission lines, we can derive that the hb time lag is $148^{+72}_{-104}$ days. The hb time lag calculated from the empirical luminosity--size relation is 222 days, which is consistent with our measured feii time lag. Considering the optical feii contribution, PG 1700+518 shares the same characteristic on the spectral slope variability as other 15 PG QSOs in our previous work, i.e., harder spectrum during brighter phase.
We present the results of a recent reverberation-mapping campaign undertaken to improve measurements of the radius of the broad line region and the central black hole mass of the quasar PG 2130+099. Cross correlation of the 5100 angstrom continuum and H-beta emission-line light curves yields a time lag of 22.9 (+4.4 - 4.3) days, corresponding to a central black hole mass MBH= 3.8 (+/- 1.5) x 10^7 Msun. This value supports the notion that previous measurements yielded an incorrect lag. We re-analyzed previous datasets to investigate the possible sources of the discrepancy and conclude that previous measurement errors were apparently caused by a combination of undersampling of the light curves and long-term secular changes in the H-beta emission-line equivalent width. With our new measurements, PG 2130+099 is no longer an outlier in either the R-L or the MBH-Sigma relationships.
By observing the near-infrared spectrum of the quasar PG 1116+215 at z = 0.176 and combining with the HST/FOS spectrum, we obtained the relative strengths of three permitted OI lines ({lambda}1304, {lambda}8446, and {lambda}11287) in a quasar for the first time. The photon flux ratios of the OI lines of the quasar were compared with those previously measured in a Seyfert 1 and six narrow-line Seyfert 1s. No significant differences were found in the OI line flux ratios between the quasar and the other Seyferts, suggesting that the gas density in the OI and FeII line-emitting regions in the quasar is of the same order as those in low-luminosity AGNs. It was also found that the line width of OI {lambda}11287 is significantly narrower than that of Ly{alpha}, which is consistent with OI and FeII emission occurring in the partly ionized regions at the outermost portion of the broad-line region where velocities are small.
We study the connection between the X-ray and UV properties of the broad absorption line (BAL) wind in the highly X-ray variable quasar PG 2112+059 by comparing Chandra-ACIS data with contemporaneous UV HST/STIS spectra in three different epochs. We observe a correlation whereby an increase in the equivalent-widths (EWs) of the BALs is accompanied by a redder UV spectrum. The growth in the BALs EWs is also accompanied by a significant dimming in soft X-ray emission (<2 keV), consistent with increased absorption. Variations in the hard X-ray emission (>2 keV) are only accompanied by minor spectral variations of the UV-BALs and do not show significant changes in the EW of BALs. These trends suggest a wind-shield scenario where the outflow inclination with respect to the line of sight is decreasing and/or the wind mass is increasing. These changes elevate the covering fraction and/or column densities of the BALs and are likely accompanied by a nearly contemporaneous increase in the column density of the shield.
We present the analysis of four XMM-Newton observations of the narrow-line quasar PG 1543+489 at z=0.400 carried out over a rest-frame time-scale of about three years. The X-ray spectrum is characterized by a broad, relativistic iron K_alpha emission line and a steep photon index, which can be both explained by a ionized reflection model, where the source of X-ray photons is presumably very close to the black hole. If this were the case, strong light-bending effects are expected, and actually they provide the most plausible explanation for the large equivalent width (EW=3.1+/-0.8 keV in the source rest frame) of the iron line. Although the light-bending model provides a good description of the X-ray data of PG 1543+489, it is not possible to rule out an absorption model, where obscuring matter partially covers the X-ray source. However, the apparent lack of variations in the properties of the absorber over the time-scale probed by our observations may indicate that this model is less likely.
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