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

Bachev, R.; Grupe, D.; Boeva, S.; Ovcharov, E.; Valcheva, A.; Semkov, E.; Georgiev, Ts. B.; Gallo, Luigi

doi:10.1111/j.1365-2966.2009.15301.x

Cited by 27 publications

(30 citation statements)

References 72 publications

(108 reference statements)

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“…This is observed for the first time among γ-ray detected NLS1s. Similar correlated UV/optical-X-ray variations on similar timescales have been previously reported in a limited number of AGNs, mostly radio-quiet, with intensive simultaneous monitoring observations, e.g., NGC 4051 (Breedt et al 2010;Alston et al 2013), MR2251−178 (Arévalo et al 2008), Mrk79 (Breedt et al 2009), PG 1211 +143 (Bachev et al 2009). The most promising explanation invokes reprocessing of the primary X-ray emission by an irradiated "cold" accretion disk, whose local temperature may, in turn, be altered by the reprocessed energy dissipated into the disk.…”

Section: On the Short-term Correlated X-ray/uv Variationssupporting

confidence: 51%

THEγ-RAY DETECTED NARROW-LINE SEYFERT 1 GALAXY 1H 0323+342:SWIFTMONITORING ANDSUZAKUSPECTROSCOPY

Yao

Yuan

Komossa

et al. 2015

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As a radio-loud narrow-line Seyfert 1 galaxy (NLS1) detected by Fermi/LAT in GeV γ-rays, 1H 0323+342 is a remarkable active galactic nucleus showing properties characteristic of both NLS1s and blazars. Here we present results of simultaneous X-ray and UV/optical monitoring observations on 1H 0323+342 taken with the UV/Optical Telescope and X-ray Telescope onboard the Swift satellite over six years from 2006. Overall, the object showed statistically correlated variations in both the UV and X-ray bands on timescales of years as well as on timescales of days. A deep Suzaku observation reveals X-ray variability on timescales as short as a few tens of thousand seconds, and an X-ray spectrum typical of Seyfert galaxies. The broadband spectral energy distribution, for which the data of UV and X-ray observations taken on 2009 July 26-27 were used, can be well modeled with a simple one-zone leptonic jet model plus accretion disk/corona emission. The latter is predominantly responsible for the UV/optical and X-ray (0.3-10 keV) emission and their observed variations. The correlated UV-X-ray variability on the timescale of days is consistent with reprocessing of the X-ray radiation by the accretion disk. The shortest timescale and large normalized excess variance of the X-ray variability detected with Suzaku suggest a relatively small black hole mass of the order of M 10 7  , consistent with the estimation based on the broad Hβ line in the optical.

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Section: On the Short-term Correlated X-ray/uv Variationssupporting

confidence: 51%

THEγ-RAY DETECTED NARROW-LINE SEYFERT 1 GALAXY 1H 0323+342:SWIFTMONITORING ANDSUZAKUSPECTROSCOPY

Yao

Yuan

Komossa

et al. 2015

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“…This is because the pointing length of 91 ks (∼1.05 days) is shorter than the expected delay between the two bands. Thermal reprocessing of X-ray emission in the disk has also recently been found to drive the short-term UV variability in NGC 4051 (Alston et al 2013) and PG 1211+143 (Bachev et al 2009). …”

Section: Discussionmentioning

confidence: 91%

The Fast Uv Variability of the Active Galactic Nucleus in Fairall 9

Lohfink

Reynolds

Vasudevan

et al. 2014

ApJ

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We present the results from a new optical/UV/X-ray monitoring campaign of the luminous Seyfert galaxy Fairall 9 using the Swift satellite. Using the UV-Optical Telescope on Swift, we find correlated optical/UV variability on all timescales ranging from the sampling time (4 days) to the length of the campaign (2.5 months). In one noteworthy event, the UW2-band flux dips by 20% in four days, and then recovers equally quickly; this event is not seen in either the optical or the X-ray bands. We argue that this event provides further evidence that a significant fraction of the UV-emission must be driven by irradiation/reprocessing of emission from the central disk. We also use an archival XMM-Newton observation to examine shorter timescale UV/X-ray variability. We find very rapid (<10 ks) UV flares of small amplitude. We show that, unless this emission is non-thermal, we must be seeing the Wien tail from a compact (<3 light hours), hot (T > 8 × 10 4 K) region. The possible association with X-ray microflares suggests that we may be seeing the UV signatures of direct X-ray flare heating of the innermost disk.

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“…We find peaks in the DCF at 0 ± 5 days, consistent with previous findings, but these are not significant at the 99% level. Bachev et al (2009) studied the first section of Swift observations, along with ground-based photometry down to I -band. They found lags compatible with a λ 4/3 relation at approximately twice the expected lag.…”

Section: Pg 1211+143mentioning

confidence: 99%

Ultraviolet and X-ray variability of active galactic nuclei withSwift

Buisson

Lohfink

Alston

et al. 2016

Mon. Not. R. Astron. Soc.

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We analyse a sample of 21 active galactic nuclei (AGN) using data from the Swift satellite to study the variability properties of the population in the X-ray, UV and optical band. We find that the variable part of the UV-optical emission has a spectrum consistent with a powerlaw, with an average index of −2.21±0.13, as would be expected from central illumination of a thin disc (index of −7/3). We also calculate the slope of a powerlaw from UV to X-ray variable emission, α OX,Var ; the average for this sample is α OX,Var = −1.06 ± 0.04. The anticorrelation of α OX with the UV luminosity, L UV , previously found in the average emission is also present in the variable part: α OX,Var = (−0.177 ± 0.083) log(L ν,Var (2500Å))+ (3.88 ± 2.33). Correlated variability between the emission in X-rays and UV is detected significantly for 9 of the 21 sources. All these cases are consistent with the UV lagging the X-rays, as would be seen if the correlated UV variations were produced by the reprocessing of X-ray emission. The observed UV lags are tentatively longer than expected for a standard thin disc.

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

Cited by 27 publications

References 72 publications

THEγ-RAY DETECTED NARROW-LINE SEYFERT 1 GALAXY 1H 0323+342:SWIFTMONITORING ANDSUZAKUSPECTROSCOPY

THEγ-RAY DETECTED NARROW-LINE SEYFERT 1 GALAXY 1H 0323+342:SWIFTMONITORING ANDSUZAKUSPECTROSCOPY

The Fast Uv Variability of the Active Galactic Nucleus in Fairall 9

Ultraviolet and X-ray variability of active galactic nuclei withSwift

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