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Register a new userMulti-wavelength observations of the triple-peaked AGN Mrk 622
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A detailed multi-wavelength study of the properties of the triple-peaked AGN Mrk,622 showing different aspects of the nuclear emission region is presented. Radio, near- and mid-infrared, optical and X-ray data has been considered for the analysis. In the optical, the WHAN diagnostic diagrams show that the three nuclear peaks are strong active galactic nuclei since the EW of $H{alpha}$ is $>$,6 AA, and $log$ [NII]$lambda$6584/H$alpha$, ratio is $>$,-0.4. Optical variability of both the continuum flux and intensity of the narrow emission lines is detected in a time-span of 13 years. The size of the narrow line region is found to be 2.7,pc, with a light-crossing time of 8.7,y. Analysis done to an archival Hubble Space Telescope image at 1055.2,nm shows that the host galaxy has a 3.6,kpc inner bar with PA,=,74$^circ$, faint spiral arms and a pseudobulge, evolving through secular processes. High resolution mid-infrared images obtained with the textit{Gran Telescopio Canarias (GTC)} and the instrument textit{CanariCam} show that the nuclear emission at 11.6 $mu$m is not spatially resolved. Very Large Array archival observations at 10,GHz reveal a core source with a total flux density of 1.47,$pm$,0.03,mJy. The spectral index of the core between 8 and 12,GHz is -0.5,$pm$,0.2, characteristic of AGN. The core deconvolves into a source with dimensions of 82,$pm$,13,mas,$,times,$,41,$pm$,20,mas, and a PA,=,70,$pm$,18,deg; which suggests that the core is elongated or that it is constituted by multiple components distributed along a $sim$65$^circ$ axis.
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We present results from a multi-wavelength analysis searching for multiple AGN systems in nearby (z<0.077) triple galaxy mergers. Combining archival Chandra, SDSS, WISE, and VLA observations, we quantify the rate of nearby triple AGN, as well as investigate possible connections between SMBH accretion and merger environments. Analyzing the multi-wavelength observations of 7 triple galaxy mergers, we find that 1 triple merger has a single AGN (NGC 3341); we discover, for the first time, 4 likely dual AGN (SDSS J1027+1749, SDSS J1631+2352, SDSS J1708+2153, and SDSS J2356-1016); we confirm one triple AGN system, SDSS J0849+1114; and 1 triple merger in our sample remains ambiguous (SDSS J0858+1822). Analyzing the WISE data, we find a trend of increasing N_H (associated with the primary AGN) as a function of increasing W1-W2 color, reflecting that the motions of gas and dust are coupled in merging environments, where large amount of both can be funneled into the active central region during mergers. Additionally, we find that the one triple AGN system in our sample has the highest levels of N_H and W1-W2 color, while the dual AGN candidates all have lower levels; these results are consistent with theoretical merger simulations that suggest higher levels of nuclear gas are more likely to activate AGN in mergers.
We report on TeV gamma-ray observations of the blazar Mrk 421 (redshift of 0.031) with the VERITAS observatory and the Whipple 10m Cherenkov telescope. The excellent sensitivity of VERITAS allowed us to sample the TeV gamma-ray fluxes and energy spectra with unprecedented accuracy where Mrk 421 was detected in each of the pointings. A total of 47.3 hrs of VERITAS and 96 hrs of Whipple 10m data were acquired between January 2006 and June 2008. We present the results of a study of the TeV gamma-ray energy spectra as a function of time, and for different flux levels. On May 2nd and 3rd, 2008, bright TeV gamma-ray flares were detected with fluxes reaching the level of 10 Crab. The TeV gamma-ray data were complemented with radio, optical, and X-ray observations, with flux variability found in all bands except for the radio waveband. The combination of the RXTE and Swift X-ray data reveal spectral hardening with increasing flux levels, often correlated with an increase of the source activity in TeV gamma-rays. Contemporaneous spectral energy distributions were generated for 18 nights, each of which are reasonably described by a one-zone SSC model.
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