We use a large sample of upper limits and accurate estimates of supermassive black hole (SMBH) masses coupled with libraries of host galaxy velocity dispersions, rotational velocities and photometric ...parameters extracted from Sloan Digital Sky Survey i-band images to establish correlations between the SMBH and host galaxy parameters. We test whether the mass of the black hole, M
*, is fundamentally driven by either local or global galaxy properties. We explore correlations between M
* and stellar velocity dispersion σe, i-band bulge luminosity L
i, bulge, bulge mass M
bulge, bulge Sérsic index n, bulge mean effective surface brightness 〈μe, bulge〉, i-band luminosity of the galaxy L
i, gal, galaxy stellar mass
, maximum circular velocity V
c, and galaxy dynamical and effective masses M
dyn, gal and M
e, gal. We verify the tightness of the M
*-σe relation and find that correlations with other galaxy parameters do not yield tighter trends. We do not find differences in the M
*-σe relation of barred and unbarred galaxies. The M
*-σe relation of pseudo-bulges is also coarser and has a different slope than that involving classical bulges. The M
*-M
bulge is not as tight as the M
*-σe relation, despite the bulge mass proving to be a better proxy of M
* than bulge luminosity, and despite adding the bulge effective radius as an additional fitting parameter. Contrary to various published reports, we find a rather poor correlation between M
* and n (or 〈μe, bulge〉), suggesting that M
* is not related to the bulge light concentration. The correlations between M
* and galaxy luminosity or mass are not a marked improvement over the M
*-σe relation. These scaling relations depend sensitively on the host galaxy morphology: early-type galaxies follow a tighter relation than late-type galaxies. If V
c is a proxy for the dark matter halo mass, the large scatter of the M
*-V
c relation then suggests that M
* is more coupled to the baryonic rather than the dark matter. We have tested the need for a third parameter in the M
* scaling relations, through various linear correlations with bulge and galaxy parameters, only to confirm that the Fundamental Plane of the SMBH is mainly driven by σe with a small tilt due to the effective radius. We provide a compendium of galaxy structural properties for most of the SMBH hosts known to date.
The Fornax cluster provides a uniquely compact laboratory in which to study the detailed history of early-type galaxies and the role played by the environment in driving their evolution and their ...transformation from late-type galaxies. Using the superb capabilities of the Multi Unit Spectroscopic Explorer on the Very Large Telescope, high-quality integral-field spectroscopic data were obtained for the inner regions of all the bright (mB ≤ 15) galaxies within the virial radius of Fornax. The stellar haloes of early-type galaxies are also covered out to about four effective radii. State-of-the-art stellar dynamical and population modelling allows characterising the disc components of fast-rotating early-type galaxies, constraining radial variations in the stellar initial-mass functions and measuring the stellar age, metallicity, and α-element abundance of stellar haloes in cluster galaxies. This paper describes the sample selection, observations, and overall goals of the survey, and provides initial results based on the spectroscopic data, including the detailed characterisation of stellar kinematics and populations to large radii; decomposition of galaxy components directly via their orbital structure; the ability to identify globular clusters and planetary nebulae, and derivation of high-quality emission-line diagnostics in the presence of complex ionised gas.
This work aims to study the distribution of the luminous and dark matter in Coma early-type galaxies. Dynamical masses obtained under the assumption that mass follows light do not match with the ...masses of strong gravitational lens systems of similar velocity dispersions. Instead, dynamical fits with dark matter haloes are in good agreement with lensing results. We derive mass-to-light ratios of the stellar populations from Lick absorption line indices, reproducing well the observed galaxy colours. Even in dynamical models with dark matter haloes the amount of mass that follows the light increases more rapidly with the galaxy velocity dispersion than expected for a constant stellar initial mass function (IMF). While galaxies around σeff≈ 200 km s−1 are consistent with a Kroupa IMF, the same IMF underpredicts luminous dynamical masses of galaxies with σeff≈ 300 km s−1 by a factor of 2 and more. A systematic variation in the stellar IMF with the galaxy velocity dispersion could explain this trend with a Salpeter IMF for the most massive galaxies. If the IMF is instead constant, then some of the dark matter in high-velocity-dispersion galaxies must follow a spatial distribution very similar to that of the light. A combination of both, a varying IMF and a component of dark matter that follows the light is possible as well. For a subsample of galaxies with old stellar populations, we show that the tilt in the Fundamental Plane can be explained by systematic variations of the total (stellar + dark) mass inside the effective radius. We tested commonly used mass estimator formulae, finding them accurate at the 20-30 per cent level.
We investigate the relations between the properties of bars and their host galaxies in a sample of 77 nearby barred galaxies, spanning a wide range of morphological types and luminosities, with 34 ...SB0-SBa and 43 SBab-SBc galaxies. The sample includes all the galaxies with reliable direct measurement of their bar pattern speed based on long-slit or integral-field stellar spectroscopy using the Tremaine-Weinberg method. We limited our analysis to the galaxies with a relatively small relative error on the bar pattern speed (≤50%) and that do not host an ultrafast bar. For each galaxy, we collected the radius, strength, pattern speed, corotation radius, and rotation rate for the bar and we also collected the Hubble type and absolute SDSS
r
-band magnitude. We also used literature bulge-to-total luminosity ratios for a subsample of 53 galaxies with an available photometric decomposition. We confirmed earlier observational findings that longer bars rotate at lower bar pattern speeds, shorter bars are weaker, and bars with a low rate of bar rotation rotate at faster bar pattern speeds and have smaller corotation radii. In addition, we found that stronger bars rotate at lower bar pattern speeds, as predicted from the interchange of angular momentum during bar evolution, which in turn may depend on different galaxy properties. Moreover, we report that brighter galaxies host longer bars, which rotate at lower bar pattern speeds and have larger corotation radii. This result is in agreement with a scenario of downsizing in bar formation, if more massive galaxies formed earlier and had sufficient time to slow down, grow in length, and push corotation outwards.
Nuclear star clusters (NSCs) are the densest stellar systems in the Universe and are found in the centres of all types of galaxies. They are thought to form via mergers of star clusters such as ...ancient globular clusters (GCs) that spiral to the centre as a result of dynamical friction or through in situ star formation directly at the galaxy centre. There is evidence that both paths occur, but the relative contribution of either channel and their correlation with galaxy properties are not yet constrained observationally. Our aim was to derive the dominant NSC formation channel for a sample of 25 nucleated galaxies, mostly in the Fornax galaxy cluster, with stellar masses between
M
gal
∼ 10
8
and 10
10.5
M
⊙
and NSC masses between
M
NSC
∼ 10
5
and 10
8.5
M
⊙
. Using Multi-Unit Spectroscopic Explorer data from the Fornax 3D survey and the ESO archive, we derived star formation histories, mean ages, and metallicities of NSCs, and compared them to the host galaxies. In many low-mass galaxies, the NSCs are significantly more metal poor than their hosts, with properties similar to GCs. In contrast, in the massive galaxies we find diverse star formation histories and cases of ongoing or recent in situ star formation. Massive NSCs (> 10
7
M
⊙
) occupy a different region in the mass–metallicity diagram than lower-mass NSCs and GCs, indicating a different enrichment history. We find a clear transition of the dominant NSC formation channel with both galaxy and NSC mass. We hypothesise that while GC accretion forms the NSCs of the dwarf galaxies, central star formation is responsible for the efficient mass build up in the most massive NSCs in our sample. At intermediate masses both channels can contribute. The transition between these formation channels seems to occur at galaxy masses
M
gal
∼ 10
9
M
⊙
and NSC masses
M
NSC
∼ 10
7
M
⊙
.
The 31 brightest galaxies (mB ≤ 15 mag) inside the virial radius of the Fornax cluster were observed from the centres to the outskirts with the Multi Unit Spectroscopic Explorer on the Very Large ...Telescope. These observations provide detailed high-resolution maps of the line-of-sight kinematics, line strengths of the stars, ionised gas reaching 2–3 Re for 21 early-type galaxies, and 1–2 Re for 10 late-type galaxies. The majority of the galaxies are regular rotators, with eight hosting a kinematically distinct core. Only two galaxies are slow rotators. The mean age, total metallicity, and Mg/Fe abundance ratio in the bright central region inside 0.5 Re and in the galaxy outskirts are presented. Extended emission-line gas is detected in 13 galaxies, most of them are late-type objects with wide-spread star formation. The measured structural properties are analysed in relation to the galaxies’ position in the projected phase space of the cluster. This shows that the Fornax cluster appears to consist of three main groups of galaxies inside the virial radius: the old core; a clump of galaxies, which is aligned with the local large-scale structure and was accreted soon after the formation of the core; and a group of galaxies that fell in more recently.
Abstract
We study a sample of 28 S0 galaxies extracted from the integral field spectroscopic (IFS) survey Calar Alto Legacy Integral Field Area. We combine an accurate two-dimensional (2D) ...multicomponent photometric decomposition with the IFS kinematic properties of their bulges to understand their formation scenario. Our final sample is representative of S0s with high stellar masses (M⋆/M⊙ > 1010). They lay mainly on the red sequence and live in relatively isolated environments similar to that of the field and loose groups. We use our 2D photometric decomposition to define the size and photometric properties of the bulges, as well as their location within the galaxies. We perform mock spectroscopic simulations mimicking our observed galaxies to quantify the impact of the underlying disc on our bulge kinematic measurements (λ and v/σ). We compare our bulge corrected kinematic measurements with the results from Schwarzschild dynamical modelling. The good agreement confirms the robustness of our results and allows us to use bulge deprojected values of λ and v/σ. We find that the photometric (n and B/T) and kinematic (v/σ and λ) properties of our field S0 bulges are not correlated. We demonstrate that this morpho-kinematic decoupling is intrinsic to the bulges and it is not due to projection effects. We conclude that photometric diagnostics to separate different types of bulges (disc-like versus classical) might not be useful for S0 galaxies. The morpho-kinematics properties of S0 bulges derived in this paper suggest that they are mainly formed by dissipational processes happening at high redshift, but dedicated high-resolution simulations are necessary to better identify their origin.
New photometric and long-slit spectroscopic observations are presented for NGC 7113, PGC 1852, and PGC 67207 which are three bright galaxies residing in low-density environments. The ...surface-brightness distribution is analysed from the KS-band images taken with adaptive optics at the Gemini North Telescope and the ugriz-band images from the Sloan Digital Sky Survey while the line-of-sight stellar velocity distribution and line-strength Lick indices inside the effective radius are measured along several position angles. The age, metallicity, and a-element abundance of the galaxies are estimated from single stellar-population models. In spite of the available morphological classification, images show that PGC 1852 is a barred spiral which we do not further consider for mass modelling. The structural parameters of the two early-type galaxies NGC 7113 and PGC 67207 are obtained from a two-dimensional photometric decomposition and the mass-to-light ratio of all the (luminous and dark) mass that follows the light is derived from orbit-based axisymmetric dynamical modelling together with the mass density of the dark matter halo. The dynamically derived mass that follows the light is about a factor of 2 larger than the stellar mass derived using stellar-population models with Kroupa initial mass function. Both galaxies have a lower content of halo dark matter with respect to early-type galaxies in high-density environments and in agreement with the predictions of semi-analytical models of galaxy formation.
Context. Historically, galaxy bulges were thought to be single-component objects at the center of galaxies. However, this picture is now questioned since different bulge types with different ...formation paths, namely classical and pseudobulges, have been found coexisting within the same galaxy. Aims. We study the incidence and nature of composite bulges in a sample of 10 face-on barred galaxies to constrain the formation and evolutionary processes of the central regions of disk galaxies. Methods. We analyze the morphological, photometric, and kinematic properties of each bulge. Then, by using a case-by-case analysis we identify composite bulges and classify every component into a classical or pseudobulge. In addition, bar-related boxy/peanut (B/P) structures were also identified and characterized. Results. We find only three galaxies hosting a single-component bulge (two pseudobulges and one classical bulge). Thus, we demonstrate the high incidence of composite bulges (70%) in barred galaxies. We find evidence of composite bulges coming in two main types based on their formation: secular-built and merger- and secular-built. We denote as secular-built those composite bulges that are made up of structures associated with secular processes, such as pseudobulges, central disks, or B/P bulges. We find four composite bulges of this kind in our sample. On the other hand, merger- and secular-built bulges are those where structures with different formation paths coexist within the same galaxy, i.e., a classical bulge coexisting with a secular-built structure (pseudobulge, central disk, or B/P). Three bulges of this kind were found in the sample. We notice the importance of detecting kinematic structures such as σ-drops to identify composite bulges. A high percentage (~80%) of galaxies were found to host σ-drops or σ-plateaus in our sample, revealing their high incidence in barred galaxies. Conclusions. The high frequency of composite bulges in barred galaxies points toward a complex formation and evolutionary scenario. Moreover, the evidence of coexisting merger- and secular-built bulges reinforce this idea. We discuss how the presence of different bulge types with different formation histories and timescales can constrain current models of bulge formation.
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