Active galaxies have been in the forefront of astronomic research since their first discovery, at least 50 years ago . The putative supermassive black hole (SMBH) at their center characterizes their properties and regulates the evolution of these objects. I investigate the evolution of active galactic nuclei (AGN) in the context of a merger-driven evolution scheme. Under this assumption, galaxy mergers trigger activity in galaxies, both in the form of intense star-formation, as well as nuclear activity. This investigation uses the Caltech-Jodrell Bank flat-spectrum (CJF) sample, a statistically complete sample of compact, radio-loud AGN. I find evidence supporting the merger-driven evolution scheme of AGN, exhibiting the relevance of merger events in active galaxies. In particular, almost 30% of the CJF sources in the local Universe (z<0.4) show evidence of recent past, present, or possible future mergers. This is important in light of the unbiased selection effects of the CJF sample. In addition, I find a broken correlation between the near-infrared luminosity of the CJF sources and their total radio luminosity at 5 GHz. Low luminosity sources show an excess of near-infrared emission, compared to their high luminosity counterparts. A correlation between near-infrared colors and multiwavelength variability is also found. Finally, I trace the different stages of AGN evolution by selecting individual sources that fit the respective selection criteria, finding 14 promising candidates for binary black hole (BBH) systems in the CJF. One of the most prominent constituents of radio-loud active galaxies are their radio jets. The morphology, properties, and evolution of the CJF jet ridge lines are studied, in light of a recently revisited kinematic paradigm for BL Lac objects. Different measures for the width, the width evolution, the linear evolution, and the curvature of the jet ridge lines are developed and a statistical analysis of the whole sample on that basis is conducted. BL Lac objects are found to have substantially wider jets than quasars. They are also found to show larger changes in their widths, but significantly weaker linear evolution of their jet ridge lines. We find indications of active evolution of the jet length and linear evolution with time (as a function of redshift). An envelope is found confining a correlation between the total linear evolution of the CJF jet ridge lines and the radio luminosity of the corresponding sources. The above results are explained in terms of the combination of helical structure for AGN jets and projection effects. Coupled to the kinematics of the AGN jets is the emission of gamma-ray radiation. In light of the excellent quality of kinematic data available for the CJF, as well as the wealth of new gamma-ray information provided by the Fermi-LAT program, I investigate the gamma-ray properties of the CJF sample, in terms of their jet kinematics and properties. I find that gamma-ray detected sources show on average higher apparent velocities than their non-detected counterparts. I note however the existence of a low-velocity population of gamma-ray detected CJF sources, that put the argument of beaming as the source of gamma-ray photons under debate. I study a possible correlation between the gamma-ray detection of CJF sources, their luminosity, and their jet morphology. I find a correlation between the gamma-ray luminosity and the maximum apparent jet speed for the gamma-detected CJF sources. The correlation is stronger for variable sources and for those identified as BL Lacs. I find that gamma-detected sources show substantially wider jet ridge lines, with stronger evolution of their widths compared to non-detected sources. I find no significant difference between gamma-detected and non-detected sources concerning the linear evolution of their jet ridge lines. The absence of a strong correlation between gamma-ray properties of the CJF sources and their kinematics is interpreted in the context of a spine-sheath geometry of AGN jet, where, at the low observing frequency used for the CJF, only the slow outer sheath of the jet is uncovered. gamma-ray emission is assumed to originate in the ultra-relativistic spine of AGN jets.

VizieR Online Data Catalog: The 2MASS Extended sources (IPAC/UMass, 2003-2006)

A multi-wavelength study of the evolution and pc-scale jet kinematics of active galaxies

The Andromeda galaxy M31 is the nearest large spiral galaxy to our own Milky Way and therefore gives us the unique opportunity to study this galaxy type in great detail. A longstanding question regarding M31 has been if it harbors a bar. The orientation of the galaxy is too far from face-on to clearly recognize the bar in photometry, but also not sufficiently edge-on to see the boxy/peanut-shape clearly above and below the disk plane. In this thesis, we present results from an observation campaign of the central region of M31 with the Integral Field Unit Spectrograph VIRUS-W. In VIRUS-W, 267 fibers are arranged in a rectangular pattern, each pointing has a field-of-view of 150′′ × 55′′, which, assuming a distance to M31 of D = 780 kpc, corresponds to 397 pc × 208 pc. We observed 198 pointings in total, completely covering the bulge and sampling the disk along six different directions, reaching approximately one disk scalelength along the major axis. The resulting 50,000 spectra are rebinned to 7563 bins in order to increase the signal-to-noise sufficiently to derive stellar line-of-sight velocity distributions and measure absorption line strengths, as well as emission line fluxes and kinematics. The wavelength range of the spectra is 4802 Å – 5500 Å, stellar absorption lines covered are the Hβ line at 4861 Å, the Mg b triplet at 5167 Å, 5173 Å and 5187 Å, as well as several Fe absorption features at 5015 Å, 5270 Å, 5335 Å and 5406 Å. Hβ is also seen in an emission line of ionized gas, other gas lines are the doublets at [OIII]λλ4959, 5007 and [NI]λλ5198, 5200. The stellar and gas kinematics are fitted simultaneously, the stellar kinematics using the absorption lines and the gas kinematics using the emission lines. The line-of-sight velocity distribution of the stellar kinematics is approximated as a Gauss-Hermite series with the moments v, σ, h3 and h4. The stellar kinematics exhibit several features that are regularly seen in bars, like a “double-hump” in the velocity profile and plateaus of the velocity dispersion at the same positions as the “humps”. The Gauss-Hermite moment h3 is correlated with the velocity over much of the bulge region, which can again be explained by the presence of a bar. We compare our measurements to results from a barred N-body model of M31 and find good agreement. The gas kinematics, measured on the [OIII]λ5007 line, is more complicated. For about half the binned spectra, the line has two peaks separated in velocity, pointing to two distinct components. The components corresponding to these peaks show an S-shape in the velocity maps, which has also been found in other barred

VizieR Online Data Catalog: The 2MASS Extended sources (IPAC/UMass, 2003-2006)

Citations

A multi-wavelength study of the evolution and pc-scale jet kinematics of active galaxies

The bar of the Andromeda galaxy revealed by integral field spectroscopy

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