TY - JOUR

T1 - Multiwavelength variability of the broad line radio galaxy 3C 120

AU - Marshall, Kevin

AU - Ryle, Wesley T.

AU - Miller, H. Richard

AU - Marscher, Alan P.

AU - Jorstad, Svetlana G.

AU - Chicka, Benjamin

AU - McHardy, Ian M.

PY - 2009/5/1

Y1 - 2009/5/1

N2 - We present results from a multiyear monitoring campaign of the broad-line radio galaxy 3C 120, using the Rossi X-ray Timing Explorer for nearly five years of observations. Additionally, we present coincident optical monitoring using data from several ground-based observatories. Both the X-ray and optical emission are highly variable and appear to be strongly correlated, with the X-ray emission leading the optical by 28 days. The X-ray power density spectrum is best fit by a broken power law, with a low-frequency slope of -1.2, breaking to a high-frequency slope of -2.1, and a break frequency of log?b = -5.75 Hz, or 6.5 days. This value agrees well with the value expected based on 3C 120's mass and accretion rate. We find no evidence for a second break in the power spectrum. Combined with a moderately soft X-ray spectrum (T = 1.8) and a moderately high accretion rate (m/mEdd ∼ 0.3), this indicates that 3C 120 fits in well with the high/soft variability state found in most other active galactic nuclei. Previous studies have shown that the spectrum has a strong Fe Kα line, which may be relativistically broadened. The presence of this line, combined with a power spectrum similar to that seen in Seyfert galaxies, suggests that the majority of the X-ray emission in this object arises in or near the disk, and not in the jet.

AB - We present results from a multiyear monitoring campaign of the broad-line radio galaxy 3C 120, using the Rossi X-ray Timing Explorer for nearly five years of observations. Additionally, we present coincident optical monitoring using data from several ground-based observatories. Both the X-ray and optical emission are highly variable and appear to be strongly correlated, with the X-ray emission leading the optical by 28 days. The X-ray power density spectrum is best fit by a broken power law, with a low-frequency slope of -1.2, breaking to a high-frequency slope of -2.1, and a break frequency of log?b = -5.75 Hz, or 6.5 days. This value agrees well with the value expected based on 3C 120's mass and accretion rate. We find no evidence for a second break in the power spectrum. Combined with a moderately soft X-ray spectrum (T = 1.8) and a moderately high accretion rate (m/mEdd ∼ 0.3), this indicates that 3C 120 fits in well with the high/soft variability state found in most other active galactic nuclei. Previous studies have shown that the spectrum has a strong Fe Kα line, which may be relativistically broadened. The presence of this line, combined with a power spectrum similar to that seen in Seyfert galaxies, suggests that the majority of the X-ray emission in this object arises in or near the disk, and not in the jet.

KW - Galaxies: active

KW - Galaxies: individual (3C 120)

KW - Galaxies: seyfert

UR - http://www.scopus.com/inward/record.url?scp=70349881277&partnerID=8YFLogxK

U2 - 10.1088/0004-637X/696/1/601

DO - 10.1088/0004-637X/696/1/601

M3 - Article

AN - SCOPUS:70349881277

VL - 696

SP - 601

EP - 607

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1

ER -