Multiwavelength monitoring of the narrow-line Seyfert 1 galaxy Arakelian 564. III. Optical observations and the optical-UV-X-ray connection
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Multiwavelength monitoring of the narrow-line Seyfert 1 galaxy Arakelian 564. III. Optical observations and the optical-UV-X-ray connection. / Shemmer, O.; Romano, P.; Bertram, R.; Brinkmann, W.; Collier, S.; Crowley, K. A.; Detsis, E.; Filippenko, A. V.; Gaskell, C. M.; George, T. A.; Gliozzi, M.; Hiller, M. E.; Jewell, T. L.; Kaspi, S.; Klimek, E. S.; Lannon, M. H.; Li, W.; Martini, P.; Mathur, S.; Negoro, H.; Netzer, H.; Papadakis, I.; Papamastorakis, I.; Peterson, B. M.; Peterson, B. W.; Pogge, R. W.; Pronik, V. I.; Rumstay, K. S.; Sergeev, S. G.; Sergeeva, E. A.; Stirpe, G. M.; Taylor, C. J.; Treffers, R. R.; Turner, T. J.; Uttley, P.; Vestergaard, M.; Von Braun, K.; Wagner, R. M.; Zheng, Z.
In: Astrophysical Journal, Vol. 561, No. 1 PART 1, 01.11.2001, p. 162-170.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Multiwavelength monitoring of the narrow-line Seyfert 1 galaxy Arakelian 564. III. Optical observations and the optical-UV-X-ray connection
AU - Shemmer, O.
AU - Romano, P.
AU - Bertram, R.
AU - Brinkmann, W.
AU - Collier, S.
AU - Crowley, K. A.
AU - Detsis, E.
AU - Filippenko, A. V.
AU - Gaskell, C. M.
AU - George, T. A.
AU - Gliozzi, M.
AU - Hiller, M. E.
AU - Jewell, T. L.
AU - Kaspi, S.
AU - Klimek, E. S.
AU - Lannon, M. H.
AU - Li, W.
AU - Martini, P.
AU - Mathur, S.
AU - Negoro, H.
AU - Netzer, H.
AU - Papadakis, I.
AU - Papamastorakis, I.
AU - Peterson, B. M.
AU - Peterson, B. W.
AU - Pogge, R. W.
AU - Pronik, V. I.
AU - Rumstay, K. S.
AU - Sergeev, S. G.
AU - Sergeeva, E. A.
AU - Stirpe, G. M.
AU - Taylor, C. J.
AU - Treffers, R. R.
AU - Turner, T. J.
AU - Uttley, P.
AU - Vestergaard, M.
AU - Von Braun, K.
AU - Wagner, R. M.
AU - Zheng, Z.
PY - 2001/11/1
Y1 - 2001/11/1
N2 - We present the results of a 2 yr long optical monitoring program of the narrow-line Seyfert 1 galaxy Ark 564. The majority of this monitoring project was also covered by X-ray observations (RXTE), and for a period of ∼50 days, we observed the galaxy in UV (HST) and X-rays (RXTE and ASCA) simultaneously with the ground-based observations. Rapid and large-amplitude variations seen in the X-ray band, on a daily and hourly timescale, were not detected at optical and UV wavelengths, which in turn exhibited much lower variability either on short (1 day) or long (several months) timescales. The only significant optical variations can be described as two 2-4 day events with ∼10% flux variations. We detect no significant optical line variations and thus cannot infer a reverberation size for the broad-line region. Similarly, the large X-ray variations seem to vanish when the light curve is smoothed over a period of 30 days. The UV continuum follows the X-rays with a lag of ∼0.4 days, and the optical band lags the UV band by ∼2 days. No significant correlation was found between the entire X-ray data set and the optical band. Focusing on a 20 day interval around the strongest optical event we detect a significant X-ray-optical correlation with similar events seen in the UV and X-rays. Our data are consistent with reprocessing models on the grounds of the energy emitted in this single event. However, several large X-ray flares produced no corresponding optical emission.
AB - We present the results of a 2 yr long optical monitoring program of the narrow-line Seyfert 1 galaxy Ark 564. The majority of this monitoring project was also covered by X-ray observations (RXTE), and for a period of ∼50 days, we observed the galaxy in UV (HST) and X-rays (RXTE and ASCA) simultaneously with the ground-based observations. Rapid and large-amplitude variations seen in the X-ray band, on a daily and hourly timescale, were not detected at optical and UV wavelengths, which in turn exhibited much lower variability either on short (1 day) or long (several months) timescales. The only significant optical variations can be described as two 2-4 day events with ∼10% flux variations. We detect no significant optical line variations and thus cannot infer a reverberation size for the broad-line region. Similarly, the large X-ray variations seem to vanish when the light curve is smoothed over a period of 30 days. The UV continuum follows the X-rays with a lag of ∼0.4 days, and the optical band lags the UV band by ∼2 days. No significant correlation was found between the entire X-ray data set and the optical band. Focusing on a 20 day interval around the strongest optical event we detect a significant X-ray-optical correlation with similar events seen in the UV and X-rays. Our data are consistent with reprocessing models on the grounds of the energy emitted in this single event. However, several large X-ray flares produced no corresponding optical emission.
KW - Galaxies: active
KW - Galaxies: individual (Arakelian 564)
KW - Galaxies: nuclei
KW - Galaxies: Seyfert
KW - X-rays: galaxies
UR - http://www.scopus.com/inward/record.url?scp=0035510776&partnerID=8YFLogxK
U2 - 10.1086/323236
DO - 10.1086/323236
M3 - Journal article
AN - SCOPUS:0035510776
VL - 561
SP - 162
EP - 170
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 1 PART 1
ER -
ID: 229914609