Studying X-ray reprocessing and continuum variability in quasars: PG 1211+143

Abstract

We present the results from a monitoring campaign of the Narrow-Line Seyfert~1 galaxy PG 1211+143. The object was monitored with ground-based facilities (UBVRI photometry; from February to July, 2007) and with Swift (X-ray photometry/spectroscopy and UV/Optical photometry; between March and May, 2007). We found PG 1211+143 in a historical low X-ray flux state at the beginning of the Swift monitoring campaign in March 2007. It is seen from the light curves that while violently variable in X-rays, the quasar shows little variations in optical/UV bands. The X-ray spectrum in the low state is similar to other Narrow-Line Seyfert 1 galaxies during their low-states and can be explained by a strong partial covering absorber or by X-ray reflection onto the disk. With the current data set, however, it is not possible to distinguish between both scenarios. The interband cross-correlation functions indicate a possible reprocessing of the X-rays into the longer wavelengths, consistent with the idea of a thin accretion disk, powering the quasar. The time lags between the X-ray and the optical/UV light curves, ranging from ~2 to ~18 days for the different wavebands, scale approximately as ~lambda^(4/3), but appear to be somewhat larger than expected for this object, taking into account its accretion disk parameters. Possible implications for the location of the X-ray irradiating source are discussed.

14 pages, 11 figures, to appear in MNRAS

References in corpus (23)

• Determining Central Black Hole Masses in Distant Active Galaxies and Quasars. II. Improved Optical and UV Scaling Relationships
• Photometric Calibration of the Swift Ultraviolet/Optical Telescope
• Testing thermal reprocessing in AGN accretion discs
• X-ray Absorption and Reflection in Active Galactic Nuclei
• The First Swift Ultra-Violet/Optical Telescope GRB Afterglow Catalog
• Investigating the nature of narrow-line Seyfert 1 galaxies with high-energy spectral complexity
• Correlated X-ray/Optical Variability in the Quasar MR2251-178
• Long term optical and X-ray variability of the Seyfert galaxy Markarian 79
• XMM-Newton observations of the Narrow-Line Seyfert 1 galaxy Mrk 335 in an historical low X-ray flux state
• Discovery of the Narrow-Line Seyfert 1 galaxy Mkn 335 in an historical low X-ray flux state
• Confirming the high velocity outflow in PG 1211+143
• Can the soft excess in AGN originate from disc reflection?
• Suzaku observations of Markarian 335: evidence for a distributed reflector
• X-ray and optical variability of Seyfert 1 galaxies as observed with XMM-Newton
• First detection of hard X-ray photons in the soft X-ray transient Narrow-Line Seyfert 1 galaxy WPVS 007: The X-ray photon distribution observed by Swift
• The nature of the intranight variability of radio-quiet quasars
• Is the X-ray spectrum of the narrow emission line QSO PG1211+143 defined by its energetic outflow?
• A longer XMM-Newton look at I Zwicky 1: Variability of the X-ray continuum, absorption, and iron Kalpha line
• Multi-wavelength Variability of the Broad Line Radio Galaxy 3C 120
• An Update on the X-ray transient Narrow-Line Seyfert 1 galaxy WPVS 007: Swift observations of UV variability and persistence of X-ray faintness
• A longer XMM-Newton look at I Zwicky 1: Distinct modes of X-ray spectral variability
• Quasar optical variability: searching for interband time delays
• Modeling the UBVRI time delays in Mrk 335

Cited by in corpus (15)

• The Simultaneous Optical-to-X-ray Spectral Energy Distribution of Soft X-ray Selected AGN observed by Swift
• Magnetically-Driven Accretion-Disk Winds and Ultra-Fast Outflows in PG1211+143
• Ultraviolet and X-ray variability of active galactic nuclei with Swift
• Multi-epoch X-ray observations of the Seyfert 1.2 galaxy Mrk 79: bulk motion of the illuminating X-ray source
• On the Observational Difference Between the Accretion Disk-Corona Connections among Super- and Sub-Eddington Accreting Active Galactic Nuclei
• A High Resolution View of the Warm Absorber in the Quasar MR2251-178
• SDSS J075101.42+291419.1: A Super-Eddington Accreting Quasar with Extreme X-ray Variability
• X-ray timing analysis of the quasar PG 1211+143
• The soft X-ray spectrum of the luminous narrow line Seyfert galaxy PG1211+143 - evidence for a second high velocity outflow component
• Strong UV and X-ray variability of the Narrow Line Seyfert 1 Galaxy WPVS 007 -- on the nature of the X-ray low state
• Discovery of late-time X-ray flare and anomalous emission line enhancement after the nuclear optical outburst in a narrow-line Seyfert 1 Galaxy
• On the UV/optical variation in NGC 5548: new evidence against the reprocessing diagram
• The fast UV variability of the active galactic nucleus in Fairall 9
• The Relation between X-ray and Ultraviolet Variability of Quasars
• Modelling the variable broad-band optical/UV/X-ray spectrum of PG1211+143: Implications for the ionized outflow