Robotic Reverberation Mapping of Arp 151

Abstract

We present the first results from the Las Cumbres Observatory Global Telescope (LCOGT) Network's Active Galactic Nuclei Key Project, a large program devoted to using the robotic resources of LCOGT to perform time domain studies of active galaxies. We monitored the Seyfert 1 galaxy Arp~151 (Mrk~40) for $\sim$200 days with robotic imagers and with the FLOYDS robotic spectrograph at Faulkes Telescope North. Arp~151 was highly variable during this campaign, with $V$-band light curve variations of $\sim$0.3 mag and H$\beta$ flux changing by a factor of $\sim$3. We measure robust time lags between the $V$-band continuum and the H$\alpha$, H$\beta$ and H$\gamma$ emission lines, with ${\tau }_{\mathrm{cen}}=13.89_{-1.41}^{+1.39}$, 7.52${}_{-1.06}^{+1.43}$ and 7.40${}_{-1.32}^{+1.50}$ days, respectively. The lag for the \ion{He}{2} $\lambda 4686$ emission line is unresolved. We measure a velocity-resolved lag for the H$\beta$ line, which is clearly asymmetric with higher lags on the blue wing of the line which decline to the red, possibly indicative of radial inflow, and is similar in morphology to past observations of the H$\beta$ transfer function shape. Assuming a virialization factor of $f$=5.5, we estimate a black hole mass of $M_{\mathrm{BH}}=6.2_{-1.2}^{+1.4}\times$10${}^6$~$M_{\odot }$, also consistent with past measurements for this object. These results represent the first step to demonstrate the powerful robotic capabilities of LCOGT for long-term, AGN time domain campaigns that human intensive programs cannot easily accomplish. Arp 151 is now one of just a few AGN where the virial product is known to remain constant against substantial changes in H$\beta$ lag and luminosity.

Accepted for publication in ApJL

References in corpus (3)

• The Lick AGN Monitoring Project 2011: Spectroscopic Campaign and Emission-Line Light Curves
• Modeling reverberation mapping data I: improved geometric and dynamical models and comparison with cross-correlation results
• First Results from the Lick AGN Monitoring Project: The Mass of the Black Hole in Arp 151

Cited by in corpus (9)

• Reverberation Mapping of Optical Emission Lines in Five Active Galaxies
• Continuum Reverberation Mapping of the Accretion Disks in Two Seyfert 1 Galaxies
• Calibration of the virial factor $f$ in supermassive black hole masses of reverberation-mapped AGNs
• The mass of the black hole in RE J1034+396
• Stability of the Broad Line Region Geometry and Dynamics in Arp 151 Over Seven Years
• Monitoring AGNs with Hβ Asymmetry. II. Reverberation Mapping of Three Seyfert Galaxies Historically Displaying Hβ Profiles with Changing Asymmetry: Mrk 79, NGC 3227, and Mrk 841
• Black hole mass estimation using X-ray variability measurements in Seyfert galaxies
• Reverberation Mapping of PG 0934+013 with the Southern African Large Telescope
• Robotic reverberation mapping of the broad-line radio galaxy 3C 120