C. S. Stalin

The Peculiar Radio-Loud Narrow Line Seyfert 1 Galaxy 1H 0323+342

We present a multiwavelength study of the radio-loud narrow-line Seyfert 1 galaxy (NLSy1) 1H 0323+342, detected by the Fermi Gamma-Ray Space Telescope. Multiband light curves show many orphan X-ray and optical flares having no corresponding γ-ray counterparts. Such anomalous variability behavior can be due to different locations of the emission region from the central source. During a large flare, a γ-ray flux doubling timescale as small as ~3 hr is noticed. We built spectral energy distributions (SEDs) during different activity states and modeled them using a one-zone leptonic model. The shape of the optical/UV component of the SEDs is dominated by accretion disk emission in all the activity states. In the X-ray band, significant thermal emission from the hot corona is inferred during quiescent and first flaring states; however, during subsequent flares, the nonthermal jet component dominates. The γ-ray emission in all the states can be well explained by inverse-Compton scattering of accretion disk photons reprocessed by the broad-line region. The source showed violent intra-night optical variability, coinciding with one of the high γ-ray activity states. An analysis of the overall X-ray spectrum fitted with an absorbed power-law plus relativistic reflection component hints at the presence of an Fe Kα line and returns a high black hole spin value of a = 0.96 ± 0.14. We argue that 1H 0323+342 possesses dual characteristics, akin to both flat-spectrum radio quasars (FSRQs) and radio-quiet NLSy1 galaxies, though at a low jet power regime compared to powerful FSRQs.

Optical identification of XMM sources in the Canada–France–Hawaii Telescope Legacy Survey

We present optical spectroscopic identifications of X-ray sources in ∼3 square degrees of the XMM-Large Scale Structure survey (XMM-LSS), also covered by the Canada France Hawaii Telescope Legacy Survey (CFHTLS), obtained with the AAOmega instrument at the Anglo Australian Telescope. In a flux limited sample of 829 point like sources in the optical band with g 6 22 mag and the 0.5 − 2 keV flux (f0.5−2keV) > 1 × 10 erg cm s, we observed 695 objects and obtained reliable spectroscopic identification for 489 sources, ∼ 59% of the overall sample. We therefore increase the number of identifications in this field by a factor close to five. Galactic stellar sources represent about 15% of the total (74/489). About 55% (267/489) are broadline Active Galactic Nuclei (AGNs) spanning redshifts between 0.15 and 3.87 with a median value of 1.68. The optical-to-X-ray spectral index (αox) of the broad-line AGNs is 1.47 ± 0.03, typical of optically-selected Type I quasars and is found to correlate with the rest frame X-ray and optical monochromatic luminosities at 2 keV and 2500 Å respectively. Consistent with previous studies, we find αox not to be correlated with z. In addition, 32 and 116 X-ray sources are, respectively absorption and emission-line galaxies at z < 0.76. From a line ratio diagnostic diagram it is found that in about 50% of these emission line galaxies, the emission lines are powered significantly by the AGN. Thirty of the XMM sources are detected at one or more radio frequencies. In addition, 24 sources have ambiguous identification: in 8 cases, two XMM sources have a single optical source within 6 of each of them, whereas, 2 and 14 XMM sources have, respectively, 3 and 2 possible optical sources within 6 of each of them. Spectra of multiple possible counterparts were obtained in such ambiguous cases.

THE NATURE OF γ-RAY LOUD NARROW-LINE SEYFERT I GALAXIES PKS 1502+036 AND PKS 2004–447

Variable ?-ray emission has been discovered in five radio-loud narrow-line Seyfert 1 (NLSy1) galaxies by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. This has clearly demonstrated that these NLSy1 galaxies do have relativistic jets similar to two other cases of ?-ray-emitting active galactic nuclei (AGNs), namely, blazars and radio galaxies. We present here our results on the multi-band analysis of two ?-ray-emitting NLSy1 galaxies, namely, PKS 1502+036 (z = 0.409) and PKS 2004?447 (z = 0.240), using archival data. We generate multi-band long-term light curves of these sources, build their spectral energy distribution (SED), and model them using a one-zone leptonic model. They resemble more the SEDs of the flat spectrum radio quasar (FSRQ) class of AGNs. We then compare the SEDs of these two sources with two other Fermi-detected AGNs along the traditional blazar sequence, namely, the BL Lac Mrk?421 (z = 0.03) and the FSRQ 3C 454.3 (z = 0.86). The SEDs of both PKS 1502+036 and PKS 2004?447 are found to be intermediate to the SEDs of Mrk?421 and 3C 454.3. In the ?-ray spectral index versus ?-ray luminosity plane, both these NLSy1 galaxies occupy a distinct position, wherein they have luminosity between Mrk?421 and 3C 454.3; however, their steep ?-ray spectra are similar to 3C 454.3. Their Compton dominance as well as their X-ray spectral slope also lie between Mrk?421 and 3C 454.3. We argue that the physical properties of both PKS 1502+036 and PKS 2004?447 are generally similar to blazars and intermediate between FSRQs and BL Lac objects and these sources thus could fit into the traditional blazar sequence.

MULTI-WAVELENGTH OBSERVATIONS OF 3C 279 DURING THE EXTREMELY BRIGHT GAMMA-RAY FLARE IN 2014 MARCH–APRIL

The well studied blazar 3C 279 underwent a giant

The violent hard X-ray variability of Mrk 421 observed by NuSTAR in 2013 April

\gamma

Improved characterization of intranight optical variability of prominent AGN classes

-ray outburst in 2014 March-April. The measured

Intranight optical variability of \gamma-ray loud Narrow Line Seyfert 1 galaxies

\gamma

BROADBAND OBSERVATIONS OF THE GAMMA-RAY EMITTING NARROW LINE SEYFERT 1 GALAXY SBS 0846+513

-ray flux (1.21

X-ray and optical properties of broad absorption line quasars in the Canada―France―Hawaii Telescope Legacy Survey

\pm

Mass of the black hole in the Seyfert 1.5 galaxy H 0507+164 from reverberation mapping

0.10