Jedidah C. Isler

CORRELATED VARIABILITY IN THE BLAZAR 3C 454.3

The blazar 3C 454.3 was revealed by the Fermi Gamma-ray Space Telescope to be in an exceptionally high flux state in 2008 July. Accordingly, we performed a multiwavelength monitoring campaign from 2008 August through December on this blazar using infrared (IR) and optical observations from the Small and Moderate Aperture Research Telescope System telescopes, optical, ultraviolet (UV), and X-ray data from the Swift satellite, and public-release gamma-ray data from Fermi. We find an excellent correlation between the IR, optical, UV, and gamma-ray light curves, with a time lag of less than one day. The amplitude of the IR variability is comparable to that in gamma-rays, and larger than at optical or UV wavelengths. The X-ray flux is not correlated with either the gamma-rays or longer wavelength data. These variability characteristics find a natural explanation in the external Compton model, in which electrons with Lorentz factor ? ~ 103-4 radiate synchrotron emission in the IR-optical and also scatter accretion disk or emission line photons to gamma-ray energies, while much cooler electrons (? ~ 101-2) produce X-rays by scattering synchrotron or other ambient photons.

The time domain spectroscopic survey: variable selection and anticipated results

We present the selection algorithm and anticipated results for the Time Domain Spectroscopic Survey (TDSS). TDSS is an Sloan Digital Sky Survey (SDSS)-IV Extended Baryon Oscillation Spectroscopic Survey (eBOSS) subproject that will provide initial identification spectra of approximately 220,000 luminosity-variable objects (variable stars and active galactic nuclei across 7500 deg2 selected from a combination of SDSS and multi-epoch Pan-STARRS1 photometry. TDSS will be the largest spectroscopic survey to explicitly target variable objects, avoiding pre-selection on the basis of colors or detailed modeling of specific variability characteristics. Kernel Density Estimate analysis of our target population performed on SDSS Stripe 82 data suggests our target sample will be 95% pure (meaning 95% of objects we select have genuine luminosity variability of a few magnitudes or more). Our final spectroscopic sample will contain roughly 135,000 quasars and 85,000 stellar variables, approximately 4000 of which will be RR Lyrae stars which may be used as outer Milky Way probes. The variability-selected quasar population has a smoother redshift distribution than a color-selected sample, and variability measurements similar to those we develop here may be used to make more uniform quasar samples in large surveys. The stellar variable targets are distributed fairly uniformly across color space, indicating that TDSS will obtain spectra for a wide variety of stellar variables including pulsating variables, stars with significant chromospheric activity, cataclysmic variables, and eclipsing binaries. TDSS will serve as a pathfinder mission to identify and characterize the multitude of variable objects that will be detected photometrically in even larger variability surveys such as Large Synoptic Survey Telescope.

An Optical-Near-infrared Outburst with no Accompanying γ-Rays in the Blazar PKS 0208–512

We report the discovery of an anomalous flare in a bright blazar, namely, PKS 0208–512, one of the targets of the Yale/SMARTS optical-near-IR (OIR) monitoring program of Fermi blazars. We identify three intervals during which PKS 0208–512 undergoes outbursts at OIR wavelengths lasting for 3 months. Its brightness increases and then decreases again by at least 1 mag in these intervals. In contrast, the source undergoes bright phases in GeV energies lasting 1 month during intervals 1 and 3 only. The OIR outburst during interval 2 is comparable in brightness and temporal extent to the OIR flares during intervals 1 and 3, which do have γ-ray counterparts. By analyzing the γ-ray, OIR, and supporting multi-wavelength variability data in details, we speculate that the OIR outburst during interval 2 was caused by a change in the magnetic field without any change in the total number of emitting electrons or Doppler factor of the emitting region. Alternatively, it is possible that the location of the outburst in the jet during interval 2 was closer to the black hole where the jet is more compact and the bulk Lorentz factor of the material in the jet is smaller. We also discuss the complex OIR spectral behavior during these three intervals.

The far emission region of the γ-ray blazar PKS B1424–418

We report multi-wavelength (IR-O, UV, X-ray, gamma-ray) data of the flat spectrum radio quasar (FSRQ) PKS B1424-418 (z=1.52) gathered during an active phase in 2013 April . As for a few other cases of FSRQs reported in literature, the detection by the Large Area Telescope onboard Fermi of gamma rays with energy above 10 GeV indicates that the emission likely occurs beyond the highly opaque (tau ~10) broad line region. This conclusion is strengthened by a model fit to the spectral energy distribution, which allows us to locate the emission region even beyond the distance generally assumed for the dusty torus. The consequent large size (~1 pc) inferred for the emission region cannot account for the observed daily-scale variability of the gamma-ray flux. We discuss the possibility that short-term variability results from fast magnetic reconnection events, as proposed in recent works.

Magnetic field amplification and flat spectrum radio quasars

Helmholtz Alliance for Astroparticle Physics. Initiative and Networking Fund of the Helmholtz Association. NASA through Fermi Guest Investigator Grant no. NNX12AP20G, and by the LANL/LDRD programme and by DoE/Office of Fusion Energy Science through CMSO. NASA grant NNX12AE43G. South African Research Chair Initiative of the National Research Foundation and the Department of Science and Technology of South Africa

THE SMARTS MULTI-EPOCH OPTICAL SPECTROSCOPY ATLAS (SaMOSA): AN ANALYSIS OF EMISSION LINE VARIABILITY IN SOUTHERN HEMISPHERE FERMI BLAZARS

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

THE TIME-DOMAIN SPECTROSCOPIC SURVEY: UNDERSTANDING THE OPTICALLY VARIABLE SKY WITH SEQUELS IN SDSS-III

\gamma

Substructure Along M 31’s Southeast Minor Axis: The Forward Continuation of the Giant Southern Stream

-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

SMARTS Optical and Infrared Monitoring of 12 Gamma-Ray Bright Blazars

\gamma

SIMILARITY OF THE OPTICAL-INFRARED AND γ-RAY TIME VARIABILITY OF FERMI BLAZARS

-ray flares. While we do not have sufficient emission line data to quantitatively assess their correlation with the