Paper detail

The SMARTS Multi-epoch Optical Spectroscopy Atlas (SAMOSA): Using Emission Line Variability to Probe the Location of the Blazar Gamma-emitting Region

We present multi-epoch optical spectroscopy of seven southern Fermi-monitored blazars from 2008 - 2013 using the Small and Medium Aperture Research Telescope System (SMARTS), with supplemental spectroscopy and polarization data from the Steward Observatory. We find that the emission lines are much less variable than the continuum; 4 of 7 blazars had no detectable emission line variability over the 5 years. This is consistent with photoionization primarily by an accretion disk, allowing us to use the lines as a probe of disk activity. Comparing optical emission line flux with Fermi $γ$-ray flux and optical polarized flux, we investigate whether relativistic jet variability is related to the accretion flow. In general, we see no such dependence, suggesting the jet variability is likely caused by internal processes like turbulence or shock acceleration rather than a variable accretion rate. However, three sources showed statistically significant emission line flares in close temporal proximity to very large Fermi $γ$-ray flares. While we do not have sufficient emission line data to quantitatively assess their correlation with the $γ$-ray flux, it appears that in some cases, the jet might provide additional photoionizing flux to the broad line region, which implies some gamma-rays are produced within the broad line region, at least for these large flares.