We present very deep HST/ACS images of five QSO host galaxies, classified as undisturbed ellipticals in earlier studies. For four of the five objects, our images reveal strong signs of interaction such as tidal tails, shells, and other fine structure, suggesting that a large fraction of QSO host galaxies may have experienced a relatively recent merger event. Our preliminary results for a control sample of inactive elliptical galaxies do not reveal comparable fine structure.

For a sample of 52 double-peaked broad-lines AGNs from the Sloan Digital Sky Survey (SDSS), we do the spectral decomposition to obtain the host spectrum and the nuclei spectrum from their SDSS spectra, as well as the bulge luminosity (Lbulge), stellar velocity dispersion (σ*). A strong correlation is found between the σ* and the gaseous velocity dispersion in narrow line regions. With the Mbh − σ* relation, we estimate the black hole masses, range from 1.0 × 107 to 6 × 108 M⊙, and the Eddington ratio from about 0.01 to about 1. It is consistent with the result from Mbh − Lbulge relation. However, it is not consistent with the mass from the Hβ FWHM. It seems that the empirical size-luminosity relation for broad line regions dose not hold for double-peaked AGNs, otherwise the calibration factor is as small as 0.185, suggesting the non-virial dynamics of broad line regions.

Recently a new approach was presented where astronomical objects as galaxies and clusters are idealized as self-gravitating systems living in a universe endowed with more than 3+1 dimensions. A such paradigm, named GEDi (Gravitation with Extra Dimensions), may solve exactly the missing mass problem for rotation curves of galaxies or gravitational lensing of clusters with no dark matter particles. Here we present an introductory discussion about the construction of a real galaxy using a Miyamoto-Nagai solution for isotropical coordinates to mimic spiral galaxies with bulges.

We study the pairing of massive black holes embedded in a massive circum–nuclear, rotationally supported disc, until they form a close binary. Using high resolution SPH simulations, we follow the black hole dynamics, and in particular the eccentricity evolution, as a function of the composition in stars and gas of the disc. Binary–disc interaction always leads to orbital decay and, in case of co–rotating black holes, to orbit circularization. We present also a higher resolution simulation performed using the particle–splitting technique showing that the binary orbital decay is efficient down to a separation of ~ 0.1 pc, comparable to our new resolution limit. We detail the gaseous mass profile bound to each black hole. Double nuclear activity is expected to occur on an estimated timescale of ≲ 10 Myrs.

In this paper, we used the method to determine the central black mass (M), and the boosting factor (δ), the propagation angle (Φ), and the distance along the axis to the site of the γ-ray production (d) as well for 32 γ-ray loud blazars with available variability timescales. If we take the intrinsic γ-ray luminosity to be λ times the Eddington luminosity, i.e. , then we have following results: the masses of the black hole are in the range of (0.9 ~ 101)×107M⊙(λ = 1.0) or (1.30 ~ 153)×107M⊙(λ=0.1).

In this work, using the database of the university of Michigan Radio Astronomy Observatory (UMRAO), we determined the brightness temperatures, TB for a sample of 167 radio sources. The value of TB is in a range of log TB(K) = 10.46 to 20.08, which suggested that the boosting factors are in a range of δ = 0.41 to 41.26.

We analyzed the distribution and kinematics of the atomic gas (HI) in 16 nearby spiral galaxies. Our results indicate that the morphology of the atomic gas and dynamically disturbed outer disks correlate with the AGN type present (Seyfert, LINER). From the combined HI and CO data (from the NUGA project), 2-dimensional maps of the gas flow are computed and gas inflow rates are derived as a function of radius within the disks.

In order to investigate how the growth of galactic bulges is accompanied with the growth of central black holes (BHs), we observed molecular gas (fuel for the coming star formation) in possibly young active galaxies, narrow-line Seyfert 1 galaxies (NLS1s). We present the results of pilot observations of 12CO (1→0) line using the Nobeyama Millimeter Array for two FIR-bright NLS1s, ending in the first detection of their CO emission. Corresponding molecular-gas masses M(H2) of (1−3)×109M⊙ are the 2nd and 4th largest ones among NLS1s. Together with CO data for other NLS1s (including our sub-kpc observations) and for broad-line Seyfert 1 galaxies (BLS1s), we found that NLS1s and BLS1s contain a similar amount of molecular–gas. We do not see a significant difference in M(H2)/MBH ratios and in M(H2)/Mbulge ratios between NLS1s and BLS1s. The lack of a clear difference in M(H2) between them indicates either that bulge and BH growth phases are not overlapped or that the duration of star formation is much longer than that of active galaxies.

Using three radio databases of the university of Michigan Radio Astronomy Observatory (UMRAO), the National Radio Astronomy Observatory (NRAO), and the Metsähovi Observatory, we analyzed the radio light curves by the power spectral analysis and CLEANest method in search for possible periodicity. Multiple periods are found in some sources at multi-frequencies. We adopted the wavelets for period analysis of unevenly sampled time series to search for the evolution of the parameters (period, amplitude) of possible periodicities. Some possible variation of these parameters are found.

Over the past decade we have learned that probably all ellipticals and bulges contain a central supermassive black hole (SMBH). The mass of the SMBH correlates both with the mass of the bulge component (about 0.15% of the bulge mass) and with the velocity dispersion σ of the bulge. We are investigating whether these relations remain valid or how they change when galaxies with pseudobulges, very low-mass bulges or bulgeless galaxies are considered. Studying SMBH relations for both classical bulges and pseudobulges can reveal the importance of different growing mechanisms (mergers vs. secular evolution) for the evolution of SMBHs. Low-mass classical bulges and bulgeless galaxies may harbour seed black holes in their earliest evolutionary stages, and studying them is of paramount importance for understanding the link between bulge evolution and black hole growth.

Stability of spherical and thin disk stellar clusters surrounding massive black holes are studied. Due to the black hole, stars with sufficiently low angular momenta escape from the system through the loss cone. We show that stability of spherical clusters crucially depend on whether the distribution of stars is monotonic or non-monotonic in angular momentum. It turns out that only non-monotonic distributions can be unstable. At the same time the instability in disk clusters is possible for both types of distributions.

We explore the connection between the central supermassive blackholes (SMBH) in galaxies and the dark matter halo through the relation between the masses of the SMBHs and the maximum circular velocities of their host galaxies, as well as the relationship between stellar velocity dispersion of the spheroidal component and the circular velocity. We rely on a heterogeneous sample containing galaxies of all types. The only requirement is that the galaxy has direct measurements of its SMBH mass, MBH, circular velocity, vc, and velocity dispersion, σ. We present a direct observational MBH − vc relation.

Compact star clusters are commonly found in the centers of galaxies and may foster formation of intermediate-mass “seed” black holes that facilitate the growth of supermassive black holes in galaxy nuclei. Such star clusters can be studied with minimal background starlight contamination in bulgeless galaxies. We present new results that point to the presence of an accreting black hole associated with the central star cluster in the Sd galaxy NGC 1042, and discuss implications for the bulge-black hole connection.

Gigahertz Peaked Spectrum (GPS) radio galaxies are generally thought to be the young counterparts of classical extended radio sources and live in massive ellipticals. GPS sources are vital for studying the early evolution of radio-loud AGN, the trigger of their nuclear activity, and the importance of feedback in galaxy evolution. We study the Parkes half-Jansky sample of GPS radio galaxies of which now all host galaxies have been identified and 80% has their redshifts determined (0.122 < z < 1.539). Analysis of the absolute magnitudes of the GPS host galaxies show that at z > 1 they are on average a magnitude fainter than classical 3C radio galaxies. This suggests that the AGN in young radio galaxies have not yet much influenced the overall properties of the host galaxy. However their restframe UV luminosities indicate that there is a low level of excess as compared to passive evolution models.

Absorption in the X-ray spectra of active galactic nuclei from outflowing gas can be modeled to yield critical physical information on the outflows. The outflow rate of mass ejected back into the ISM of the host galaxy and the resulting feedback could potentially have an impact on evolution. We give a brief overview of the current observational constraints on the outflows that should be taken into account by models of evolution and feedback.

We discuss some recent integral field spectroscopy using the SAURON instrument of a sample consisting of 24 early-type spirals, part of the SAURON Survey, and 18 late-type spirals. Using 2-dimensional maps of their stellar radial velocity, velocity dispersion, and absorption line strength, it is now much easier to understand the nature of nearby galactic bulges. We discuss a few highlights of this work, and point out some new ideas about the formation of galactic bulges.

Panoramic spectroscopy of the sample of 80 nearby lenticular galaxies is presented. The SSP-equivalent ages, [Z/H], and [Mg/Fe] are determined through the Lick indices Hβ, Mgb, and 〈Fe〉 separately for the nuclei and for the bulges. About a half of the sample contain chemically distinct nuclei, more metal-rich and younger than the bulges. The statistics of stellar population properties for the nearby S0s is discussed.

Globular Clusters provide a unique method for tracing the formation and evolution of their host galaxies. As single stellar populations they are far easier to interpret than the multi-population complexity of galaxy field stars. The scaling properties of globular clusters provide important constraints on the hierarchical assembly history of galaxies. Here we briefly review recent progress using the Hubble Space Telescope for imaging and the Keck plus Gemini telescopes for spectroscopy. We argue that the red, or metal-rich, subpopulation of GCs is associated with the bulge/spheroid component of galaxies. As one of the oldest stellar systems available for study, we discuss how globular clusters can be used to constrain the formation of galaxy bulges, in particular the role of mergers vs secular evolution. We conclude that metal-rich GCs, and hence bulges, formed very early in the Universe with more recent mergers having a small effect at most.

The stellar populations in the bulges of S0s, together with the galaxies' dynamics, masses and globular clusters, contain very interesting clues about their formation. I present here recent evidence suggesting that S0s are the descendants of fading spirals whose star formation ceased.

We seek to understand whether the stellar populations of galactic bulges show evidence of secular evolution triggered by the presence of the disc. To this end we re-analyse the sample of Proctor & Sansom (2002), deriving stellar population ages and element abundances from absorption line indices as functions of central velocity dispersion and Hubble type. In agreement with other studies in the literature, we find that bulges have relatively low luminosity weighted ages, the lowest age derived being 1.3 Gyr. Hence bulges are not generally old, but actually rejuvenated systems. We discuss evidence that this might be true also for the bulge of the Milky Way. The smallest bulges are the youngest with the lowest α/Fe ratios indicating the presence of significant star formation events involving 10 − 30 per cent of their total mass in the past 1 − 2 Gyr. No significant correlations of the stellar population parameters with Hubble Type are found. We show that the above relationships with σ coincide perfectly with those of early-type galaxies. At a given velocity dispersion, bulges and elliptical galaxies are indistinguishable as far as their stellar populations are concerned. These results favour an inside-out formation scenario and indicate that the discs in spiral galaxies of Hubble types Sbc and earlier cannot have a significant influence on the evolution of the stellar populations in the bulge component. The phenomenon of pseudobulge formation must be restricted to spirals of types later than Sbc.