Multiwavelength Observations of Short-Timescale Variability in NGC 4151. IV. Analysis of Multiwavelength Continuum Variability

Edelson, R.; Alexander, Tal; Crenshaw, D. M.; Kaspi, S.; Malkan, M. A.; Peterson, B. M.; Warwick, R. S.; Clavel, J.; Filippenko, AV; Horne, K.; Korista, KT; Kriss, G. A.; Krolik, Julian H.; Maoz, Dan; Nandra, K.; O’Brien, P.; Penton, SV; Yaqoob, T.; Albrecht, P.; Alloin, D.; Ayres, T.; Balonek, T. J.; Barr, P.; Barth, Aaron J.; Bertram, R.; Bromage, G.; Carini, M. T.; Carone, T.E.; Cheng, F. H.; Chuvaev, K. K.; Dietrich, M.; Dultzin‐Hacyan, D.; Gaskell, C. M.; Glass, I.; Goad, M. R.; Hemar, Shirley; Ho, L. C.; Huchra, J.; Hutchings, J. B.; Johnson, W. N.; Kazanas, D.; Kollatschny, W.; Koratkar, A.P.; Kovo, O.; Laor, Ari; MacAlpine, GM; Magdziarz, P.; Martín, P. G.; Matheson, T.; McCollum, B.; Miller, HR; Morris, Simon L.; Oknyanskij, V. I; Penfold, J. E.; Pérez, E.; Perola, G. C.; Pike, G.; Pogge, R. W.; Ptak, R.; Qian, BC; Recondo, Carmen; Reichert, GA; Rodriguez‐Espinoza, J. M.; Rodríguez-Pascual, P. M.; Rokaki, E.; Roland, J.; Sadun, A. C.; Salamanca, I.; Santos-Lleo, M.; Shields, J. C.; Shull, J. M.; Smith, D. A.; Smith, S.; Snijders, M. A. J.; Stirpe, G. M.; Stoner, RE; Sun, WH; Ulrich, MH; vanGroningen, E; Wagner, R. M.; Wagner, S. J.; Wanders, I.; Welsh, WF; Weymann, R. J.; Wilkes, B. J.; Wu, Huizhen; Wurster, James; Xue, SJ; Zdziarski, A. A.; Zheng, Wei; Zou, ZL

doi:10.1086/177872

Cited by 167 publications

(142 citation statements)

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“…Peterson 1993;Netzer & Peterson 1997 for a review; Marshall et al 1997;Nandra et al 1998;Edelson et al 2000). Thus, over the last decade, several large space-based and ground-based monitoring programs have been undertaken for nearby AGN, such as NGC 5548 (Clavel et al 1991;Peterson et al 1991Peterson et al , 1992Peterson et al , 1994Peterson et al , 1999Maoz et al 1993;Dietrich et al 1993;Korista et al 1995;Chiang et al 2000), NGC 3783 Stirpe et al 1994;Alloin et al 1995), NGC 4151 Kaspi et al 1996;Warwick et al 1996;Edelson et al 1996), Fairall 9 (Rodríguez-Pascual et al 1997Santos-Lleó et al 1997), 3C 390.3 (Leighly et al 1997;Dietrich et al 1998;O'Brien et al 1998), and NGC 7469 (Wanders et al 1997;Collier et al 1998).…”

Section: Introductionmentioning

confidence: 99%

A spectroscopic and photometric study of short-timescale variability in NGC 5548

Dietrich

Bender

Bergmann

et al. 2001

A&A

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Abstract.Results of a ground-based optical monitoring campaign on NGC 5548 in June 1998 are presented. The broad-band fluxes (U , B, V ), and the spectrophotometric optical continuum flux F λ (5100Å) monotonically decreased in flux while the broad-band R and I fluxes and the integrated emission-line fluxes of Hα and Hβ remained constant to within 5%. On June 22, a short continuum flare was detected in the broad band fluxes. It had an amplitude of about ∼18% and it lasted only ≈90 min. The broad band fluxes and the optical continuum F λ (5100Å) appear to vary simultaneously with the EUV variations. No reliable delay was detected for the broad optical emission lines in response to the EUVE variations. Narrow Hβ emission features predicted as a signature of an accretion disk were not detected during this campaign. However, there is marginal evidence for a faint feature at λ 4962Å with F W HM 6Å redshifted by ∆v 1100 km s −1 with respect to Hβnarrow.

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Section: Introductionmentioning

confidence: 99%

A spectroscopic and photometric study of short-timescale variability in NGC 5548

Dietrich

Bender

Bergmann

et al. 2001

A&A

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“…The high-energy continuum variability measured using ROSAT, ASCA and CGRO is complex (Warwick et al, 1996;Edelson et al, 1996). The < 1 keV continuum did not vary significantly.…”

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confidence: 83%

“…The optical continuum lags the UV by < 0.8 days, consistent with the 1.2 day limit derived by Korista et al (1995) using other methods. Similarly, Edelson et al (1996) derived a lag of < 1 day between 1275 and 5125Å for NGC4151, and Reichert et al (1994) find a lag of < 2 days between 1460 and 5000Å for NGC3783. The upper limits on the lags between the various UV continuum bands are somewhat smaller (e.g.…”

mentioning

confidence: 86%

“…The X-ray and UV light-curves indicate strong variability, with normalized variability amplitudes (NVA; Edelson et al 1996) in the period of overlap of 0.32 and 0.31 respectively. The X-ray and UV light curves show a similar functional form and the cross-correlation function obtained using the ZDCF method gives a lag of less than 3 days, and is consistent with zero.…”

Section: X-ray and Uv Continuum Variabilitymentioning

confidence: 99%

“…The derived upper-limits imply signal propagation speeds of > 0.1c, significantly faster than the local sound speed or photon diffusion rate. Edelson et al (1996) propose a disk model for NGC4151 in which all the variable UV/optical emission comes from a small (< 0.1 light-day), hot inner region. This model predicts UV/optical lags and NVAs in agreement with the observations, but does not directly explain the simultaneous large-amplitude soft X-ray variations.…”

Section: Theoretical Implicationsmentioning

confidence: 99%

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AGN Watch continuum monitoring of radio-quiet and radio-loud AGN

O’Brien

Leighly

1998

Advances in Space Research

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The International AGN Watch has monitored a number of radio-quiet and radio-loud Active Galactic Nuclei -the most luminous objects in the universe. We present a review of the main observational results from the continuum monitoring campaigns, concentrating on those which aim to quantify the simultaneous ultraviolet to X-ray variability characteristics. These data provide strong constraints on the proposed continuum emission mechanisms. The AGN Watch campaigns have made extensive use of a wide variety of both ground-and space-based multi-waveband observational facilities, and we stress that long-term simultaneous access to the entire electromagnetic spectrum is essential if further progress is to be made. THE INTERNATIONAL AGN WATCHIn the late 1980's an informal consortium of about 100 astronomers was formed to obtain large, high-quality multi-waveband data for investigation of the continuum and emission-line variability characteristics of Active Galactic Nuclei (AGN). The consortium was formed in response to the realization that small groups were unlikely to obtain large amounts of observing time, and would face great practical difficulty in both coordinating observations over many months and rapidly reducing data from numerous ground-based and orbiting observatories. The AGN Watch exists to obtain such data and rapidly place them in the public domain. Smaller collaborations, drawn from both inside and outside AGN Watch, can then use these data to place firm constraints on the seemingly evergrowing list of proposed AGN models. Here we summarize the continuum monitoring campaigns. The emission-line monitoring is presented elsewhere (e.g. Peterson, these proceedings). CONTINUUM MONITORING OF SEYFERT 1 GALAXIESThe AGN watch has conducted campaigns on 7 AGN to date. The object names, wavebands covered and publications in which the original data can be found are given in Table 1. The initial campaigns concentrated on UV (1150-3200Å) and optical monitoring using IUE and numerous ground-based telescopes. More recently the campaigns have been expanded to the EUV, X-ray and γ-ray wavebands to investigate the photoionizing continuum in detail, and to the IR to investigate the properties of hot dust and the putative dense molecular torus around the nucleus.

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9.5.5 The host galaxy of AGN

Netzer¹

Interstellar Matter, Galaxy, Universe

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Multiwavelength Observations of Short-Timescale Variability in NGC 4151. IV. Analysis of Multiwavelength Continuum Variability

Cited by 167 publications

References 47 publications

A spectroscopic and photometric study of short-timescale variability in NGC 5548

A spectroscopic and photometric study of short-timescale variability in NGC 5548

AGN Watch continuum monitoring of radio-quiet and radio-loud AGN

9.5.5 The host galaxy of AGN

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