NGC 5548 in a Low-Luminosity State: Implications for the Broad-Line Region
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NGC 5548 in a Low-Luminosity State : Implications for the Broad-Line Region . / Bentz, Misty C.; Denney, Kelly D.; Cackett, Edward M.; Dietrich, Matthias; Fogel, Jeffrey K. J.; Ghosh, Himel; Horne, Keith D.; Kuehn, Charles; Minezaki, Takeo; Onken, Christopher A.; Peterson, Bradley M.; Pogge, Richard W.; Pronik, Vladimir I.; Richstone, Douglas O.; Sergeev, Sergey G.; Vestergaard, Marianne; Walker, Matthew G.; Yoshii, Yuzuru.
In: Astrophysical Journal, Vol. 662, No. 1, 205, 23.02.2007.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - NGC 5548 in a Low-Luminosity State
T2 - Implications for the Broad-Line Region
AU - Bentz, Misty C.
AU - Denney, Kelly D.
AU - Cackett, Edward M.
AU - Dietrich, Matthias
AU - Fogel, Jeffrey K. J.
AU - Ghosh, Himel
AU - Horne, Keith D.
AU - Kuehn, Charles
AU - Minezaki, Takeo
AU - Onken, Christopher A.
AU - Peterson, Bradley M.
AU - Pogge, Richard W.
AU - Pronik, Vladimir I.
AU - Richstone, Douglas O.
AU - Sergeev, Sergey G.
AU - Vestergaard, Marianne
AU - Walker, Matthew G.
AU - Yoshii, Yuzuru
PY - 2007/2/23
Y1 - 2007/2/23
N2 - We describe results from a new ground-based monitoring campaign on NGC 5548, the best studied reverberation-mapped AGN. We find that it was in the lowest luminosity state yet recorded during a monitoring program, namely L(5100) = 4.7 x 10^42 ergs s^-1. We determine a rest-frame time lag between flux variations in the continuum and the Hbeta line of 6.3 (+2.6/-2.3) days. Combining our measurements with those of previous campaigns, we determine a weighted black hole mass of M_BH = 6.54 (+0.26/-0.25) x 10^7 M_sun based on all broad emission lines with suitable variability data. We confirm the previously-discovered virial relationship between the time lag of emission lines relative to the continuum and the width of the emission lines in NGC 5548, which is the expected signature of a gravity-dominated broad-line region. Using this lowest luminosity state, we extend the range of the relationship between the luminosity and the time lag in NGC 5548 and measure a slope that is consistent with alpha = 0.5, the naive expectation for the broad line region for an assumed form of r ~ L^alpha. This value is also consistent with the slope recently determined by Bentz et al. for the population of reverberation-mapped AGNs as a whole.
AB - We describe results from a new ground-based monitoring campaign on NGC 5548, the best studied reverberation-mapped AGN. We find that it was in the lowest luminosity state yet recorded during a monitoring program, namely L(5100) = 4.7 x 10^42 ergs s^-1. We determine a rest-frame time lag between flux variations in the continuum and the Hbeta line of 6.3 (+2.6/-2.3) days. Combining our measurements with those of previous campaigns, we determine a weighted black hole mass of M_BH = 6.54 (+0.26/-0.25) x 10^7 M_sun based on all broad emission lines with suitable variability data. We confirm the previously-discovered virial relationship between the time lag of emission lines relative to the continuum and the width of the emission lines in NGC 5548, which is the expected signature of a gravity-dominated broad-line region. Using this lowest luminosity state, we extend the range of the relationship between the luminosity and the time lag in NGC 5548 and measure a slope that is consistent with alpha = 0.5, the naive expectation for the broad line region for an assumed form of r ~ L^alpha. This value is also consistent with the slope recently determined by Bentz et al. for the population of reverberation-mapped AGNs as a whole.
KW - astro-ph
U2 - 10.1086/516724
DO - 10.1086/516724
M3 - Journal article
VL - 662
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 1
M1 - 205
ER -
ID: 123372217