Globular clusters (GCs) are an important test bed for Newtonian gravity in the weak-acceleration regime, which is vital to our understanding of the nature of the gravitational interaction. Recent claims have been made that the velocity dispersion profiles of GCs flatten out at large radii, despite an apparent paucity of dark matter (DM) in such objects, indicating the need for ...

New kinematic data based on the calcium IR triplet lines are presented that define rotation and velocity disersion profiles for the nuclei of M31 and M32 with high accuracy. New dynamical models are used to determine the mass distribution of the centers of these galaxies with much greater reliability than in the past. The results demonstrate that the nuclei rotate very rapidly ...

We present measurements of the excess mass-to-light ratio measured around MaxBCG galaxy clusters observed in the SDSS. This red sequence cluster sample includes objects from small groups with M{sub 200} {approx} 5 x 10{sup 12}h{sup -1}M{sub {circle_dot}} to clusters with M{sub 200} {approx} 5 x 10{sup 15}h{sup -1}M{sub {circle_dot}}. Using cross-correlation weak lensing, we ...

We measure the average mass properties of a sample of 41 strong gravitational lenses at moderate redshift (z ~ 0.4-0.9) and present the lens redshift for six of these galaxies for the first time. Using the techniques of strong and weak gravitational lensing on archival data obtained from the Hubble Space Telescope, we determine that the average mass overdensity profile of the ...

We present measurements of the excess mass-to-light ratio (M/L) measured around MaxBCG galaxy clusters observed in the Sloan Digital Sky Survey. This red-sequence cluster sample includes objects from small groups with M 200 ~ 5 � 1012 h -1 M sun to clusters with M 200 ~ 1015 h -1 M sun. Using cross-correlation weak lensing, we measure the excess mass density ...

We compare the properties of local spiral galaxies with the predictions of the Cole et al. semi-analytic model of hierarchical galaxy formation, in order to gain insight into the baryonic processes, such as gas cooling and star formation, that were responsible for shaping these galaxies. On the whole, the models reproduce the properties of present-day spirals rather well, including the trend in ...

We present a new method to remove the impact of random and small-scale noncircular motions from H I velocity fields in (dwarf) galaxies in order to better constrain the dark matter properties for these objects. This method extracts the circularly rotating velocity components from the H I data cube and condenses them into a so-called bulk velocity field. We derive high-resolution (~0.2 kpc) ...

We investigate the dynamical status of the low-mass globular cluster Palomar 13 by means of N-body computations to test whether its unusually high mass-to-light ratio of about 40 and its peculiarly shallow surface density profile can be caused by tidal shocking. Alternatively, we test - by varying the assumed proper motion - if the orbital phase of Palomar ...

We present a performance analysis of the DiskMass Survey. The survey uses collisionless tracers in the form of disk stars to measure the surface density of spiral disks, to provide an absolute calibration of the stellar mass-to-light ratio ({Upsilon}{sub *}), and to yield robust estimates of the dark-matter halo density profile in the inner regions of ...

We present mass models for a sample of Freeman Type I spiral galaxies taken from the southern sky Fabry-Perot Tully-Fisher survey(Schommer \\etal 1993, Bothun \\etal 1992). We fit two component, bulge and disk, photometric models directly to I- and R-band images. The bulge model is a series expansion of Gaussians (a Gabor expansion): each Gaussian in the series has a common center, ellipticity and ...

We present detailed luminosity profiles of the young massive clusters M82-F, NGC 1569-A and NGC 1705-1 which show significant departures from equilibrium (King and Elson, Fall & Freeman) profiles. We compare these profiles with those from N-body simulations of clusters that have undergone the rapid removal of a significant fraction ...

We present measurements of the excess mass-to-light ratio (M/L) measured around MaxBCG galaxy clusters observed in the Sloan Digital Sky Survey. This red-sequence cluster sample includes objects from small groups with M {sub 200} approx 5 x 10{sup 12} h {sup -1} M {sub sun} to clusters with M {sub 200} approx 10{sup 15} h {sup -1} M {sub sun}. Using cross-correlation weak ...

Using the caustic method, we identify the member stars of five dwarf spheroidal (dSph) galaxies of the Milky Way, the smallest dark matter (DM) dominated systems in the Universe. After our interloper rejection, we compute line-of-sight velocity dispersion profiles that are substantially smoother than previous results. Moreover, two dSphs have line-of-sight velocity dispersions ...

The dynamics of Abell 2256 is investigated by combining X-ray observations of the intracluster gas with optical observations of the galaxy distribution and kinematics. Magnitudes and positions are presented for 172 galaxies and new redshifts for 75. Abell 2256 is similar to the Coma Cluster in its X-ray luminosity, mass, and galaxy density. Both the X-ray surface brightness and the galaxy surface ...

We present a weak-lensing analysis of 22 early-type (strong) lens galaxies, based on deep HST images obtained as part of the Sloan Lens ACS Survey. Using advanced techniques to control systematic uncertainties, we show that weak-lensing signal is detected out to ~300 h-1 kpc (at the mean lens redshift z=0.2). We analyze blank control fields from COSMOS in the same manner, inferring that the ...

We model the dynamical structure of M87 (NGC4486) using high spatial resolution long-slit observations of stellar light in the central regions, two-dimensional stellar light kinematics out to half of the effective radius, and globular cluster velocities out to eight effective radii. We simultaneously fit for four parameters: black hole mass, dark halo core radius, dark halo circular velocity, and ...

We present nonparametric radial mass profiles for 10 QSO strong-lensing galaxies. Five of the galaxies have profiles close to ?(r)~r-2, while the rest are closer to r-1, consistent with an NFW profile. The former are all relatively isolated early types and dominated by their stellar light. The latter-although the modeling code did not ...

This is the first in a series of papers on the weak lensing effect caused by clusters of galaxies in Sloan Digital Sky Survey. The photometrically selected cluster sample, known as MaxBCG, includes ~130,000 objects between redshift 0.1 and 0.3, ranging in size from small groups to massive clusters. We split the clusters into bins of richness and luminosity and stack the surface density contrast to ...

This is the first in a series of papers on the weak lensing effect caused by clusters of galaxies in Sloan Digital Sky Survey. The photometrically selected cluster sample, known as MaxBCG, includes {approx}130,000 objects between redshift 0.1 and 0.3, ranging in size from small groups to massive clusters. We split the clusters into bins of richness and luminosity and stack the surface density ...

This is the first in a series of papers on the weak lensing effect caused by clusters of galaxies in Sloan Digital Sky Survey. The photometrically selected cluster sample, known as MaxBCG, includes approx130,000 objects between redshift 0.1 and 0.3, ranging in size from small groups to massive clusters. We split the clusters into bins of richness and luminosity and stack the surface density ...

Velocity dispersion profiles and rotation curves have been determined for a sample of 13 brightest cluster galaxies (BCGs) in order to study their internal stellar kinematics and investigate their relationship to ellipticals. We find that BCGs generally display velocity dispersion profiles with gradients similar to those found in normal bright ellipticals. ...

We create dynamical models of the massive elliptical galaxy, NGC 4649, using the N-body made-to-measure code, NMAGIC, and kinematic constraints from long-slit and planetary nebula (PN) data. We explore a range of potentials based on previous determinations from X-ray observations and a dynamical model fitting globular cluster (GC) velocities and a stellar density profile. The ...

We report the results of an ongoing project to conduct both axis-symmetric and triaxial dynamical modeling on a number of giant elliptical galaxies. This work is based primarily on stellar kinematic IFU data obtained with the VIRUS-P instrument on the 2.7m telescope at McDonald Observatory. This instrument allows for measurement of the stellar kinematics, including higher order Gauss-Hermite ...

Aims: Using a counter-dispersed slitless spectroscopy technique, we detect and measure the line-of-sight velocities of 187 planetary nebulae (PNe) around one of the nearest cD galaxies, NGC 1399, with FORS1 on the VLT. Methods: We describe the method for identifying and classifying the emission-line sources and the procedure for computing their J2000 coordinates and velocities. The number of PN ...

We present new Planetary Nebula Spectrograph observations of the ordinary elliptical galaxy NGC 4494, resulting in positions and velocities of 255 planetary nebulae out to seven effective radii (25 kpc). We also present new wide-field surface photometry from MMT/Megacam, and long-slit stellar kinematics from VLT/FORS2. The spatial and kinematical distributions of the planetary nebulae agree with ...

We examine the nuclear morphology, kinematics, and stellar populations in nearby S0 galaxy NGC 404 using a combination of adaptive optics assisted near-IR integral-field spectroscopy, optical spectroscopy, and Hubble Space Telescope imaging. These observations enable study of the NGC 404 nucleus at a level of detail possible only in the nearest galaxies. The surface brightness ...

We use a particle tagging technique to dynamically populate the N-body Via Lactea II high-resolution simulation with stars. The method is calibrated using the observed luminosity function of Milky Way satellites and the concentration of their stellar populations, and self-consistently follows the accretion and disruption of progenitor dwarfs and the build-up of the stellar halo in a cosmological ...

We have conducted axisymmetric, orbit-based dynamical modeling on M87, the second rank galaxy in the Virgo cluster, and find clear evidence for a large dark matter halo. The total enclosed mass within 47 kpc is 6e12 solar masses making M87 one of the most massive dark halos ever measured in the local universe. To construct these dynamical models we fit for the stellar ...

We examine two extreme models for the build-up of the stellar component of luminous elliptical galaxies. In one case, we assume the build-up of stars is dissipational, with centrally accreted gas radiating away its orbital and thermal energy; the dark matter (DM) halo will undergo adiabatic contraction and the central DM density profile will steepen. For the second model, we ...

We present new, two-dimensional stellar kinematic data on several of the most massive galaxies in the local universe. These data were taken with the integral field spectrograph, VIRUS-P, and extend to unprecedented radial distances. Once robust stellar kinematics are in hand, we run orbit-based axisymmetric dynamical models in order to constrain the stellar mass-to-light ratio ...

We examine two extreme models for the build-up of the stellar component of luminous elliptical galaxies. In one case, we assume the build-up of stars is dissipational, with centrally accreted gas radiating away its orbital and thermal energy; the dark matter (DM) halo will undergo adiabatic contraction and the central DM density profile will steepen. For the second model, we ...

We continue to see a range of values for the Hubble constant obtained from gravitationally lensed multiple image time-delays when assuming an isothermal lens despite a robust value from the Hubble Space Telescope (HST) key project (72 +/- 8 kms-1 Mpc-1). One explanation is that there is a variation in Hubble constant values due to a fundamental heterogeneity in lens galaxies present in groups, ...

We have analysed the mass and velocity distributions of two samples of relaxed elliptical-like objects (ELOs) identified, at z = 0, in a set of self-consistent hydrodynamical simulations operating in the context of a concordance cosmological model. ELOs have been identified as those virtual galaxies having a prominent, dynamically relaxed stellar spheroidal component, with no extended discs and ...

We perform a detailed analysis of the optical gravitational lens ER 0047-2808 imaged with the Wide Field Planetary Camera 2 on the Hubble Space Telescope. Using software specifically designed for the analysis of resolved gravitational lens systems, we focus on how the image alone can constrain the mass distribution in the lens galaxy. We find that the data are of sufficient quality to strongly ...

Using high-resolution N-body simulations, we study the stellar properties of dwarf spheroidal (dSph) galaxies resulting from the tidally induced morphological transformation of disky dwarfs on a cosmologically motivated eccentric orbit around the Milky Way. The dwarf galaxy models initially consist of an exponential stellar disk embedded in an extended spherical dark matter halo. Depending on the ...

Using high-resolution N-body simulations, we study the stellar properties of dwarf spheroidal (dSph) galaxies resulting from the tidally induced morphological transformation of disky dwarfs on a cosmologically motivated eccentric orbit around the Milky Way. The dwarf galaxy models initially consist of an exponential stellar disk embedded in an extended spherical dark matter halo. Depending on the ...

The compact group of galaxies HCG 62(z = 0.0145) was observed for 120ks with Suzaku XIS and HXD-PIN. The XIS spectra for four annular regions were fitted with a two-temperature vapec model with variable abundance, combined with the foreground Galactic component. The Galactic component was described by a two-temperature apec model, and constrained to have a common surface brightness among the four ...

For some time, the Draco dwarf spheroidal galaxy has garnered interest as a possible source for the indirect detection of dark matter. Its large mass-to-light ratio and relative proximity to the Earth provide favorable conditions for the production of a detectable flux of gamma rays from dark matter self-annihilation in its core. The Solar Tower Atmospheric Cherenkov Effect ...

For some time, the Draco dwarf spheroidal galaxy has garnered interest as a possible source for the indirect detection of dark matter. Its large mass-to-light ratio and relative proximity to the Earth provide favorable conditions for the production of a detectable flux of gamma rays from dark matter self-annihilation in its core. The Solar Tower Atmospheric Cherenkov Effect ...

Look at a spiral; what do you see? Stars zooming `round in the galaxy! Their motions indicate total mass, but how much is DM, stars, and gas? Study motions in and out; first find monochromatic stars- that's my kind. Find us, get our velocities, then: determine disk mass! I'm a PN! Rotation curves indicate the total mass of spirals, but halo mass profiles cannot be decoupled ...

We present axisymmetric, orbit-based models to study the central black hole (BH), stellar mass-to-light ratio (M/L), and dark matter (DM) halo of NGC 4594 (M104, the Sombrero Galaxy). For stellar kinematics, we use published high-resolution kinematics of the central region taken with the Hubble Space Telescope, newly obtained Gemini long-slit spectra of the major axis, and ...

The Arecibo 305-m telescope was used to make neutral hydrogen observations of the poor clusters MKW 7, MKW 9, AWM 1, and AWM 3. The observations are almost complete for MKW 7 and AWM 1 galaxies brighter than 15.7 mag within one-half of a degree of the D or cD galaxy, and for MKW 9 galaxies brighter than 15.7 mag within one degree of the D galaxy. Both the integrated H I ...

By manipulating the spherical Jeans equation, Wolf et al. (2010) show that the mass enclosed within the 3D deprojected half-light radius r1/2 can be determined with only mild assumptions about the spatial variation of the stellar velocity dispersion anisotropy as long as the projected velocity dispersion profile is fairly flat near the half-light radius, as is typically ...

We report 10 lens candidates in the Extended Chandra Deep Field South from the GEMS survey. Nine of the systems are new detections and only one of the candidates is a known lens system. For the most promising five systems including the known lens system, we present results from preliminary lens mass modeling, which tests if the candidates are plausible lens systems. Photometric redshifts of the ...

We first review the results of the tidal stirring model for the transformation of gas-rich dwarf irregulars into dwarf spheroidals, which turns rotationally supported stellar systems into pressure supported ones. We emphasize the importance of the combined effect of ram pressure stripping and heating from the cosmic ultraviolet background in removing the gas and converting the object into a gas ...

A new large-area Washington M, T2+DDO51 filter survey of more than 10 deg2 around the Carina dSph galaxy reveals a spectroscopically confirmed power-law radial density ``break'' population of Carina giant stars extending several degrees beyond the central King profile. Magellan telescope MIKE spectroscopy establishes the existence of Carina stars to at least 4.5 times its ...

We study the dynamics of galaxies in the Coma cluster and find that the cluster is probably dominated by a central binary of galaxies NGC 4874--NGC4889. We estimate their total mass to be about 3 x 10/sup 14/ M/sub sun/ by two independent methods (assuming in Hubble constant of 100 km s/sup -1/ Mpc/sup -1/). This binary is efficient in dynamically ejecting smaller galaxies, some of of which are ...

We use a combination of new AAOmega multi-object wide-field spectroscopic observations and literature data to define 111 spectroscopically confirmed members of the massive NGC5044 group with MB <= -13.5mag, providing a three-fold increase in group members over previous analyses of this group. We find the group to have a dynamical mass of 9.2 � 1013Msolar, placing it on ...

From high signal-to-noise ratio GMOS-N and AAOmega spectra, we have measured line-strength indices in the Lick/IDS system for several luminous and spatially dispersed compact stellar systems (CSSs) located in the Virgo and Fornax galaxy clusters. We estimate their [?/Fe] ratios, ages and metallicities using a simple (single-burst) stellar population model. We confirm that the ...

This paper addresses the challenge of understanding the typical star formation histories of red-sequence galaxies, using linestrength indices and mass-to-light ratios as complementary constraints on their stellar age distribution. We first construct simple parametric models of the star formation history that bracket a range of scenarios, and fit these models to the linestrength indices of ...

SDSSJ120602.09+514229.5 is a gravitational lens system formed by a group of galaxies at redshift zFG = 0.422 lensing a bright background galaxy at redshift zBG = 2.001. The main peculiarity of this system is the presence of a luminous satellite near the Einstein radius, which slightly deforms the giant arc. This makes SDSSJ120602.09+514229.5 the ideal system to test our grid-based Bayesian lens ...

We use Very Large Telescope (VLT)/Fibre Large Array Multi Element Spectrograph (FLAMES) intermediate-resolution (R� 6500) spectra of individual red giant branch stars in the near-infrared Ca II triplet (CaT) region to investigate the wide-area metallicity properties and internal kinematics of the Sextans dwarf spheroidal galaxy (dSph). Our final sample consists of 174 probable members of Sextans ...

We present a detailed analysis of the dynamical and photometric properties of a disk galaxy simulated in the ? cold dark matter (?CDM) cosmogony. The galaxy is assembled through a number of high-redshift mergers followed by a period of quiescent accretion after z~1 that lead to the formation of two distinct dynamical components: a spheroid of mostly old stars and a rotationally supported disk of ...

Context. That the rotation curves of spiral galaxies are generally flat in the outer regions is commonly considered an indication that galaxy disks are embedded in quasi-isothermal halos. In practice, disk-halo decompositions of galaxy rotation curves are performed in a parametric way by modeling the halo force contribution by means of expressions that approximately describe the properties of the ...

NGC 1407 is the central elliptical in a nearby evolved group of galaxies apparently destined to become a galaxy cluster core. We use the kinematics of globular clusters (GCs) to probe the dynamics and mass profile of the group's center, out to a radius of 60 kpc ({approx}10 galaxy effective radii)-the most extended data set to date around an early-type galaxy. This ...

Dwarf elliptical (dE) galaxies are the most common galaxy type in nearby galaxy clusters. How these objects formed remains an open question, and many basic properties of dEs have yet to be quantified. The first part of this thesis is a Keck/ESI study of the internal dynamics of six Virgo Cluster dEs. We model their observed velocity dispersion profiles using HST /WFPC2 surface ...

Chapter 7 Conclusions and future work ABSTRACT Measuring the CDM substructure mass function threshold of mass substructure. #12;116 Conclusions and future work 7.2 Future work In this section I present the physical properties of dark matter. Because of the predicted large total mass-to-light ratio of the missing

. Utilizing spatially resolved VLT/FORS spectroscopy and HST/� ACS imaging, we constructed a sample of over and total mass re� mains roughly constant over the observed epochs, in compliance with the frame� work of hierarchical structure growth. However, the stellar mass--to--light ratios evolve more strongly in low--mass

We present 2-D stellar kinematics of M87 out to R = 238" taken with the integral field spectrograph VIRUS-P. We run a large set of axisymmetric, orbit-based dynamical models and find clear evidence for a massive dark matter halo. While a logarithmic parameterization for the dark matter halo is preferred, we do not constrain the dark matter scale radius for an NFW profile and ...

We present two-dimensional stellar kinematics of M87 out to R = 238'' taken with the integral field spectrograph VIRUS-P. We run a large set of axisymmetric, orbit-based dynamical models and find clear evidence for a massive dark matter halo. While a logarithmic parameterization for the dark matter halo is preferred, we do not constrain the dark matter scale radius for a Navarro-Frenk-White (NFW) ...

We present a detailed dynamical analysis of the projected density and kinematical data available for the globular cluster ? Centauri. We solve the spherical anisotropic Jeans equation for a given density profile to predict the projected profiles of the rms velocity {\\bar{?}}(R), in each of the three orthogonal coordinate directions (line of sight, proper ...

We present a detailed dynamical analysis of the projected density and kinematical data available for the globular cluster omega Centauri. We solve the spherical anisotropic Jeans equation for a given density profile to predict the projected profiles of the rms velocity sigma-bar(R), in each of the three orthogonal coordinate directions (line of sight, ...

We present kinematic and metallicity profiles for the M 31 dwarf elliptical (dE) satellite galaxies NGC 147 and NGC 185. The profiles represent the most extensive spectroscopic radial coverage for any dE galaxy, extending to a projected distance of 8 half-light radii (8r{sub eff} {approx} 14'). We achieve this coverage via Keck/DEIMOS multislit ...

There appears to be a cluster of galaxies within ~2-arcmin of S1189 in the optical and infrared images. We obtained AAOmega observations for sources within a degree of S1189 in a service mode during the night of 2008 October 18. (2 data files).

The Galaxy and Mass Assembly (GAMA) survey has been operating since 2008 February on the 3.9-m Anglo-Australian Telescope using the AAOmega fibre-fed spectrograph facility to acquire spectra with a resolution of R? 1300 for 120 862 Sloan Digital Sky Survey selected galaxies. The target catalogue constitutes three contiguous equatorial regions centred at 9h (G09), 12h (G12) and ...

We have performed numerical simulations to investigate whether galactic tides can elevate the apparent mass-to-light ratio (M/L) in a dwarf spheroidal galaxy (dSph). In our simulations the dSph is composed only of luminous matter and falls towards the Milky Way on various orbits and in various galactic potentials starting from apogalacticon. We assume a single perigalacticon ...

We have obtained velocity dispersions from Keck high-resolution integrated spectroscopy of 10 M31 globular clusters (GCs), including three candidate intermediate-age GCs. We show that these candidates have the same V-band mass-to-light (M/L{sub V} ) ratios as the other GCs, implying that they are likely to be old. We also find a trend of derived velocity dispersion with ...

We present new optical long-slit data along six position angles of the bulge region of M 31. We derive accurate stellar and gas kinematics reaching 5 arcmin from the center, where the disk light contribution is always less than 30%, and out to 8 arcmin along the major axis, where the disk provides 55% of the total light. We show that the velocity dispersions of McElroy (1983) are severely ...

We present new results from the integral-field spectrograph SAURON. Based upon the TIGER concept, SAURON has a panoramic field of view (33"x41") and a high throughput, and has been optimized for studies of the stellar and gaseous components of early type galaxies. The SAURON survey of the kinematics and stellar populations of a representative sample of ~80 nearby E, S0 and Sa galaxies will ...

Utilizing spatially resolved VLT/FORS spectroscopy and HST/ACS imaging, we constructed a sample of over 200 field spiral galaxies at redshifts 0.1 < z < 1.0. We find that the ratio between stellar and total mass remains roughly constant over the observed epochs, in compliance with the framework of hierarchical structure growth. However, the stellar mass-to-light ratios ...

Baryonic acoustic oscillations (BAOs) modulate the density ratio of baryons to dark matter across large regions of the Universe. We show that the associated variation in the mass-to-light ratio of galaxies should generate an oscillatory, scale-dependent bias of galaxies relative to the underlying distribution of dark matter. A measurement of this effect would calibrate the dependence of the ...

Baryonic acoustic oscillations (BAOs) modulate the density ratio of baryons to dark matter across large regions of the Universe. We show that the associated variation in the mass-to-light ratio of galaxies should generate an oscillatory, scale-dependent bias of galaxies relative to the underlying distribution of dark matter. A measurement of this effect would calibrate the dependence of the ...

The differential bending of radio waves by a suitably placed ''gravitational screen'' such as an intervening galaxy can lead to large magnification of the separation velocity of the components in the nuclear region of a quasar. It is suggested tha the apparent superluminal separation of such components observed in some quasars by the VLBI techniques could be due ...

We present preliminary measurements of the central black hole mass MBH, and stellar mass-to-light ratio M*/LR, in the Brightest Cluster Galaxy of Abell 2162 (A2162-BCG), using integral-field unit (IFU) data from OSIRIS on Keck 2 with laser guide star adaptive optics (LGS-AO). Our results demonstrate early success in an ongoing effort to obtain stellar dynamical measurements of ...

We present a multiwavelength study (BVRI-band photometry and H I line interferometry) of nine late-type galaxies selected from the HIPASS Bright Galaxy Catalog on the basis of apparently high H I mass-to-light ratios (3 Msolar/Lsolar,B

Velocity dispersion measurements of recently discovered Milky Way satellites with M{sub V} {approx_gt} -7 imply that they posses high mass-to-light ratios. The expected velocity dispersions due to their baryonic mass are {approx}0.2 km s{sup -1}, but values {approx_gt}3 km s{sup -1} are measured. We perform Monte Carlo simulations of mock radial velocity measurements of these ...

Context: Regarding the significant interest in both dark matter and the application of MOND to early-type galaxies, we investigate the MOND theory by comparing its predictions, for models of constant mass-to-light ratio, with observational data of the early-type galaxy NGC 4649. Aims: We study whether measurements for NGC 3379 and NGC 1399 are typical of early-type systems ...

We revisit the notion that galaxy motions can efficiently heat intergalactic gas in the central regions of clusters through dynamical friction. For plausible values of the galaxy mass-to-light ratio, the heating rate is comparable with the cooling rate due to X-ray emission. Heating occurs only for supersonic galaxy motions, so the mechanism is self-regulating: it becomes ...

Thermal X-ray emission from cooling flows in elliptical galaxies indicates that ~1 Msolar of hot (T~107 K) interstellar gas cools each year, accumulating ~1010 Msolar over a Hubble time. Paradoxically, optical and radio frequency emission from the cooled gas is lacking, indicating that less than ~10-3 of the cooled gas remains. Many have speculated that the cooled gas has formed into relatively ...

Observations have shown that massive galaxies at high redshift have much smaller effective radii than galaxies of similar mass today; however, recent work has shown that they have similar central densities. The primary growth of size, therefore, relates to the apparent relative abundance of low-density material at low redshifts. But various models have been proposed to accomplish this, and the ...

To better understand the prevalence of bulgeless galaxies in the nearby field, we dissect giant Sc-Scd galaxies with Hubble Space Telescope (HST) photometry and Hobby-Eberly Telescope (HET) spectroscopy. We use the HET High Resolution Spectrograph (resolution R ? ?/FWHM ~= 15, 000) to measure stellar velocity dispersions in the nuclear star clusters and (pseudo)bulges of the pure-disk galaxies M ...

To better understand the prevalence of bulgeless galaxies in the nearby field, we dissect giant Sc-Scd galaxies with Hubble Space Telescope (HST) photometry and Hobby-Eberly Telescope (HET) spectroscopy. We use the HET High Resolution Spectrograph (resolution R {identical_to} {lambda}/FWHM {approx_equal} 15, 000) to measure stellar velocity dispersions in the nuclear star clusters and ...

Mapping out stellar families to trace the evolutionary star formation history of the Milky Way requires a spectroscopic facility able to deliver high spectral resolution (R>=30k) with both good wavelength coverage (~400 Ang) and target multiplex advantage (~400 per 2 degree field). Such a facility can survey 1,200,000 bright stars over 10,000 square degrees in about 400 nights with a 4-meter ...

The galaxies for GAMA spectroscopy will initially be selected from SDSS and UKIDSS data and the final GAMA merger rates The buildup of both dark matter halos and the baryonic mass of galaxies is one recent merger remnants through their asymmetric light distribution. These methods require spectroscopy

The Australia Telescope Large Area Survey (ATLAS), which is the widest deep field radio survey so far attempted, aims to probe the evolution of radio galaxies out to the edge of the Universe. Using AAOmega on the Anglo-Australian Telescope we have successfully obtained spectroscopic redshifts for 395 of the ATLAS radio galaxies. Coupled with 169 redshifts from the existing ...

Using K-band imaging for 15 of the Canadian Network for Observational Cosmology (CNOC1) clusters we examine the near-infrared properties of moderate-redshift (0.19 < z < 0.55) galaxy clusters. We find that the number of K-band selected cluster galaxies within R{sub 500} (the Halo Occupation Number, HON) is well-correlated with the cluster dynamical mass (M{sub 500}) and X-ray ...

Galaxy clustering and galaxy-galaxy lensing probe the connection between galaxies and their dark matter haloes in complementary ways. Since the clustering of dark matter haloes depends on cosmology, the halo occupation statistics inferred from the observed clustering properties of galaxies are degenerate with the adopted cosmology. Consequently, different cosmologies imply different ...

Recent measurements of the anisotropy of the microwave background radiation of the local Hubble flow suggest that the local group of galaxies has a motion of 300--500 km s/sup -1/ directed toward Virgo. If this velocity is generated by the Virgo supercluster, it provides a powerful test of the cosmological parameter ..cap omega... Using a catalog of redshift data complete to m/sub b/=14.0, we have ...

We report the discovery of a new gravitationally lensed radio source. Radio maps of MG0751+2716 show four lensed images, which, at higher resolution, are resolved into long arcs of emission. A group of galaxies is present in optical images, including the principal lensing galaxy, with a much brighter galaxy just a few arcseconds away. We have measured the redshift of this brighter galaxy. No ...

The observed stellar population in the solar neighborhood is used to derive a relationship between the local stellar mass density and the visual and near-IR brightness, which is then extended to a wide range of galaxies. This technique is applied to near-IR (J, H, and K) images of the central 2.3 kpc (50 arcsec) of the Whirlpool Galaxy (M51, NGC 5194). It is estimated that the current high rate of ...

A detailed test of the quality of a simple family of anisotropic self-consistent global models for quasi-spherical galaxies is made by considering a set of bright ellipticals with available photometric and kinematical data. The photometric fit, under the assumption of constant mass-to-light ratio, not only proves to be very good but also better than fits based upon the ...

The authors have repeated calculations by Fuchs & Materne (1982) of the variation of the velocity dispersion with radius in the Coma cluster using the new data of Godwin, Metcalfe & Peach on the galaxy surfacedensity. The authors find that the data are best represented by a model of constant velocity anisotropy (possibly by isotropy). This is contrary to Fuchs & Materne's result but ...

Our understanding of galaxy formation and evolution is severely limited by poorly known galaxy mass profiles. Flat rotation curves indicate the presence of dark matter in the outer regions of spirals and determine total galactic mass, but rotation curves alone cannot decouple the mass contribution of the dark halo from that of the disk. Thus astronomers typically assume a ...

We have measured the weak-lensing signal as a function of rest-frame B-, V-, and R-band luminosity for a sample of ``isolated'' galaxies. These results are based on four-band photometry from the Red-Sequence Cluster Survey, enabling us to determine photometric redshifts for a large number of galaxies. We select a secure sample of lenses with photometric redshifts 0.2

I review a technique for interpreting faint galaxy data which traces the evolution with cosmic time of the galaxy luminosity density, as determined from several deep spectroscopic samples and the HDF. The method relies on the rest frame UV and near-IR continua of galaxies as indicators, for a given IMF and dust content, of their instantaneous SFR and total stellar mass, and offers the prospect of ...

Stellar masses play a crucial role in the exploration of galaxy properties and the evolution of the galaxy population. In this paper, we explore the minimum possible uncertainties in stellar mass-to-light ratios (M */L) from the assumed star formation history (SFH) and metallicity distribution, with the goals of providing a minimum set of requirements for observational ...

We present internal velocity dispersions and precise radial velocities for 200 globular clusters (GCs) in M31 that are derived using new high-resolution spectra from MMT/Hectochelle. Of these, 163 also have King model structural parameters that allow us to estimate their mass-to-light ratios. This is, by far, the largest such dataset available for any galaxy, including the Milky Way. These data ...

We present internal velocity dispersions and precise radial velocities for 200 globular clusters (GCs) in M31 that are derived using new high-resolution spectra from MMT/Hectochelle. Of these, 163 also have King model structural parameters that allow us to estimate their mass-to-light ratios. This is, by far, the largest such data set available for any galaxy, including the Milky Way. These data ...

We have measured the velocity dispersion of the Galactic globular cluster NGC 2419 to determine if a substantial amount of dark matter is present in this cluster. NGC 2419 is one of the best globular clusters to look for dark matter due to its large mass, long relaxation time and large Galactocentric distance, which makes tidal stripping of dark matter unlikely. Our results can be summarized as ...

We studied, for the first time, the near-infrared, stellar and baryonic Tully-Fisher relations for a sample of field galaxies taken from a homogeneous Fabry-Perot sample of galaxies [the Gassendi HAlpha survey of SPirals (GHASP) survey]. The main advantage of GHASP over other samples is that the maximum rotational velocities were estimated from 2D velocity fields, avoiding assumptions about the ...

We studied, for the first time, the near-infrared, stellar and baryonic Tully-Fisher relations for a sample of field galaxies taken from a homogeneous Fabry-Perot sample of galaxies [the Gassendi HAlpha survey of SPirals (GHASP) survey]. The main advantage of GHASP over other samples is that the maximum rotational velocities were estimated from 2D velocity fields, avoiding assumptions about the ...

We present a compilation of galaxies in the NGC 1023 Group, an accumulation of late-type galaxies at a distance of 10 Mpc. Members at high and intermediate luminosities were identified from their spectroscopic velocities. Members at low luminosities were identified from their morphologies on wide-field CCD images. The faint-end slope is in the range -1.27 < ? < -1.12. There is evidence for ...

We examine a sample of 30 edge-on spiral and S0 galaxies that have boxy and peanut-shaped bulges. We compute model stellar kinematics by solving the Jeans equations for axisymmetric mass distributions derived from K-band images. These simple models have only one free parameter: the dynamical mass-to-light ratio, which we assume is independent of radius. Given the simplicity of ...

The final data release of the Sloan Digital Sky Survey (SDSS) provides reliable photometry and spectroscopy for about half a million galaxies with median redshift 0.09. Here, we use these data to estimate projected autocorrelation functions wp(rp) for the light of galaxies in the five SDSS photometric bands. Comparison with the analogous stellar mass autocorrelation, estimated in a previous paper, ...

Photometric results are presented for twenty-nine elliptical galaxies, with the objective of finding a general relation---if one exists---between the mass and the potential energies of elliptical galsxies. The potential energies of these galaxies are found to be proportional to the threehalves power of the masses, for galaxies from 3 x 10 to 3 x 10/sup 12/ solar masses. The form of the ...

We report the spectroscopic confirmation of 29 new, 12 plausible, and three previously known quasars behind the central ~1.5deg2^ region of the Small Magellanic Cloud (SMC). These were identified in a single 2df/AAOmega observation on the Anglo-Australian Telescope of 268 candidates selected primarily based on their mid-IR colors, along with a smaller number of optically ...

We present two-dimensional line-of-sight stellar kinematics of the lens galaxy in the Einstein Cross, obtained with the GEMINI 8 m telescope, using the GMOS integral-field spectrograph. The stellar kinematics extend to a radius of 4'' (with 0.''2 spaxels), covering about two-thirds of the effective (or half-light) radius R{sub e} {approx_equal} ...

Context: The observed dynamical mass-to-light (M/L) ratios of globular clusters (GCs) are systematically lower than the value expected from �canonical� simple stellar population models, which do not account for dynamical effects such as the preferential loss of low-mass stars due to energy equipartition. It has recently been shown that low-mass star depletion can ...

Ultra compact dwarf galaxies (UCDs) are dense stellar systems at the border between massive star-clusters and small galaxies. Their on average high optical mass-to-light (M/L) ratio cannot be explained by stellar populations with the canonical stellar initial mass function (IMF), while it is doubtful that non-baryonic dark matter can accumulate enough on the scales of UCDs for ...

At present, dwarf spheroidal galaxies satellites of the Milky Way may represent the best astrophysical objects for dark matter (DM) searches with gamma-ray telescopes. They present the highest mass-to-light ratios known in the Universe. Furthermore, many of them are near enough from the Earth to be able to yield high predicted DM annihilation fluxes that might be observed by ...

Modified Newtonian dynamics (MOND) has been shown to be able to fit spiral galaxy rotation curves as well as giving a theoretical foundation for empirically determined scaling relations, such as the Tully-Fisher law, without the need for a dark matter halo. As a complementary analysis, one should investigate whether MOND can also reproduce the dynamics of early-type galaxies (ETGs) without dark ...

We present the first detection of weak gravitational shear at infrared wavelengths, using observations of the lensing cluster Abell 1689, taken with the SofI camera on the ESO-NTT telescope. The imprint of cluster lenses on the shapes of the background galaxy population has previously been harnessed at optical wavelengths, and this gravitational shear signal enables cluster mass distributions to ...

Some extensions of standard particle physics postulate that dark matter may be partially composed of weakly interacting sterile neutrino particles that have so far eluded detection. We use a short (~5 ks) archival X-ray observation of Segue 1 obtained with the X-ray Telescope (XRT) onboard the Swift satellite to exclude the presence of sterile neutrinos in the 1.6-14 keV mass range down to a flux ...

We present the first results from a new and unique integral-field spectrograph, SAURON, for the 4.2-m William Herschel Telescope on La Palma. Based upon the TIGER concept, SAURON uses a lens array to obtain two-dimensional spectroscopy with complete spatial coverage over a field of 33''�41'' in low-resolution mode (0.94'' lenslets) and of 9''�11'' in high-resolution mode (0.26'' lenslets). The ...

We report on the method developed by Zibetti, Charlot & Rix (2009) to construct resolved stellar mass maps of galaxies from optical and NIR imaging. Accurate pixel-by-pixel colour information (specifically g - i and i - H) is converted into stellar mass-to-light ratios with typical accuracy of 30%, based on median likelihoods derived from a Monte Carlo library of 50,000 ...

We have reexamined the relation between the mass of the central black holes in nearby galaxies, Mbh, and the stellar mass of the surrounding spheroid or bulge, Mbulge. For a total of 30 galaxies bulge masses were derived through Jeans equation modeling or adopted from dynamical models in the literature. In stellar mass-to-light ratios, the spheroids and bulges span a range of ...

We present a simple and efficient anisotropic generalization of the semi-isotropic (two-integral) axisymmetric Jeans formalism, which is used to model the stellar kinematics of galaxies. The following is assumed: (i) a constant mass-to-light ratio (M/L) and (ii) a velocity ellipsoid that is aligned with cylindrical coordinates (R, z) and characterized by the classic anisotropy ...

We rederive the made-to-measure (M2M) method of Syer & Tremaine for modelling stellar systems and individual galaxies, and demonstrate how extensions to the M2M method may be implemented and used. We illustrate the enhanced M2M method by determining the mass-to-light ratio of a galaxy modelled as a Plummer sphere. From the standard galactic observables of surface brightness and line-of-sight ...

We present the star formation histories, luminosities, colors, mass-to-light ratios, and halo masses of ``galaxies'' formed in a simulation of cosmological reionization. We compare these galaxies with Lyman break galaxies observed at high redshift. While the simulation is severely limited by the small box size, the simulated galaxies do appear as fainter cousins of the ...

Numerical simulations of the effect of a long-range scalar interaction (LRSI) acting only on nonbaryonic dark matter, with strength comparable to gravity, show patterns of disruption of satellites that can agree with what is seen in the Milky Way. This includes the symmetric Sagittarius (Sgr) stellar stream. The exception presented here to the Kesden and Kamionkowski demonstration that an LRSI ...

. We describe two fiber-optical arrays under construction for the 9m Hobby-Eberly Telescope's (HET) Medium Resolution Spectrograph (MRS). These arrays optimize integral-field spectroscopy for kinematic studies of individual nearby and moderately distant galaxies. The arrays are formatted to deliver simultaneous rotation curve and disk velocity dispersion measurements for galaxies over a range ...

The modification of Newtonian attraction suggested by Sanders (1984) contains a repulsive Yukawa component which is characterised by two physical parameters: a coupling constant, ?, and a length scale, r0. Although this form of the gravitational potential can result in flat rotation curves for a galaxy (or a point mass) it is not obvious that any modification of gravity associated with a definite ...

We study gaseous outflows from disk galaxies driven by radiation pressure on dust grains. We include the effect of bulge and dark matter halo and show that the existence of such an outflow implies a maximum value of disk mass-to-light ratio. We show that the terminal wind speed is proportional to the disk rotation speed in the limit of a cold gaseous outflow, and that in ...

Two algorithms for the identification of galaxy groups from redshift surveys are tested by application to simulated data derived from N-body simulation. The accuracy of the membership assignments by these algorithms is studied in a companion to this paper (Frederic 1995). Here we evaluate the accuracy of group mass estimates and the group-group correlation function. We find a strong bias to low ...

We present the first direct measurement of the central black hole mass, M �, in NGC 6086, the Brightest Cluster Galaxy (BCG) in A2162. Our investigation demonstrates for the first time that stellar-dynamical measurements of M � in BCGs are possible beyond the nearest few galaxy clusters. We observed NGC 6086 with laser guide star adaptive optics and the integral-field spectrograph (IFS) OSIRIS ...

Using a resimulation technique, we perform high-resolution cosmological simulations of dry mergers in a massive (10{sup 15} M {sub sun}) galaxy cluster identified in the Millennium Run. Our initial conditions include well resolved compound galaxy models consisting of dark matter halos and stellar bulges that are used to replace the most massive cluster progenitor halos at redshift z = 3, allowing ...

We present Gemini integral-field unit spectroscopy and Hubble Space Telescope (HST) F435W- and F814W-band images of a newly discovered four-image gravitational lens, SDSS J140228.22+632133.3 (hereafter SDSSJ1402). The system is the first of 49 spectroscopically selected gravitational lens candidates to be imaged with the Advanced Camera for Surveys Wide-Field Channel on board HST as part of a ...

We have observed two blank fields of approximately 30 � 23 arcmin2 using the William Herschel Telescope. The fields have been studied as part of the Canadian Network for Observational Cosmology Field Galaxy Redshift Survey (CNOC2), and spectroscopic redshifts are available for 1125 galaxies in the two fields. We measured the lensing signal caused by large-scale structure, and found that the ...

We study Tully-Fisher (TF) relations for a sample that combines extremely faint (MB < -14) galaxies along with bright (i.e. ~L*) galaxies. Accurate (~10 per cent) distances, I-band photometry and B - V colours are known for the majority of the galaxies in our sample. The faint galaxies are drawn from the Faint Irregular Galaxy GMRT survey (FIGGS), and we have HI rotation velocities derived from ...

We present the results of a comprehensive Keck/DEIMOS spectroscopic survey of the ultra-faint Milky Way satellite galaxy Segue 1. We have obtained velocity measurements for 98.2% of the stars within 67 pc (10', or 2.3 half-light radii) of the center of Segue 1 that have colors and magnitudes consistent with membership, down to a magnitude limit of r = 21.7. Based on photometric, kinematic, and ...

Various stellar parameters were extracted, using two different reduction pipelines, from individual stellar spectra obtained with AAOmega on the Anglo-Australia Telescope. These spectra were obtained from ten fields centered on Galactic globular clusters, namely M4, M12, M22, M30, M53, M55, M68, NGC 288, NGC 6752 and 47 Tuc. Stellar parameters provided include the radial ...

Up to now, planet search programs have concentrated on main sequence stars later than spectral type F5. However, identifying planets of early type stars would be interesting. For example, the mass loss of planets orbiting early and late type stars is different because of the differences of the EUV and X-ray radiation of the host stars. As an initial step, we carried out a program to identify ...

In this dissertation, I investigate the transverse proximity effect in Lyalpha transmitted flux, the baryon fraction and stellar mass-to-light ratio in early-type galaxies, and the relation between dark matter halos and optical observables of galaxy clusters. The proximity effect is the observed reduction in absorption by HI in the Lyalpha forest in the proximity of QSOs. This ...

We report on the limitations of sky-subtraction accuracy for long-duration fibre-optic multiobject spectroscopy of faint astronomical sources during long-duration exposures. We show that while standard sky subtraction techniques yield accuracies consistent with the Poisson noise limit for exposures of 1h duration, there are large-scale systematic defects that inhibit the sensitivity gains expected ...

We present radial velocity and metallicity measurements for the far southern Galactic globular cluster IC 4499. We selected several hundred target red giant stars in and around the cluster from the 2MASS point source catalogue, and obtained spectra at the near-infrared calcium triplet using the AAOmega spectrograph. Observations of giants in globular clusters M4, M22 and M68 ...

AAOmega is the new spectrograph for the 2dF fibre-positioning system on the Anglo-Australian Telescope. It is a bench-mounted, double-beamed design, using volume phase holographic (VPH) gratings and articulating cameras. It is fed by 392 fibres from either of the two 2dF field plates, or by the 512 fibre SPIRAL integral field unit (IFU) at Cassegrain focus. Wavelength coverage ...

The number of luminous quasars that have thus far eluded optical surveys is a subject of ongoing debate. Dust reddening and significant host galaxy light tend to exclude candidates from traditional UV-excess selection. UKIDSS, the near-infrared counterpart to SDSS, has started to provide the large area NIR data required to quantify the number of quasars missing from optical surveys. The ...

The AAOmega project replaces the two 2dF spectrographs, which are mounted on the top end of the Anglo Australian Telescope, with a bench mounted double beam spectrograph covering 370 to 950nm. The 2dF positioner, field plate tumbler mechanism, and fiber retractors will be retained. The new spectrograph will be fed by 392 fibers from either of the two 2dF field plates, or by ...

We present new Keck/DEIMOS spectroscopic observations of hundreds of individual stars along the sightline to the first three of the Andromeda (M31) dwarf spheroidal (dSph) galaxies to be discovered, And I, II, and III, and combine them with recent spectroscopic studies by our team of three additional M31 dSphs, And VII, X, and XIV, as a part of the SPLASH Survey (Spectroscopic and Photometric ...

We present new Keck/DEIMOS spectroscopic observations of hundreds of individual stars along the sightline to the first three of the Andromeda (M31) dwarf spheroidal (dSph) galaxies to be discovered, And I, II, and III, and combine them with recent spectroscopic studies by our team of three additional M31 dSphs, And VII, X, and XIV, as a part of the SPLASH Survey (Spectroscopic and Photometric ...

The fundamental plane (FP) of early-type galaxies is observed to have finite thickness and to be tilted from the virial relation. Both of these represent departures from the simple assumption that dynamical mass-to-light ratios (M dyn/L) are constant for all early-type galaxies. We use a sample of 16,000 quiescent galaxies from the Sloan Digital Sky Survey to map out the ...

The fundamental plane (FP) of early-type galaxies is observed to have finite thickness and to be tilted from the virial relation. Both of these represent departures from the simple assumption that dynamical mass-to-light ratios (M{sub dyn}/L) are constant for all early-type galaxies. We use a sample of 16,000 quiescent galaxies from the Sloan Digital Sky Survey to map out the ...

We compare optical and high-quality X-ray data for three bright elliptical galaxies in the Virgo Cluster, NGC 4472, 4649, and 4636. The distribution of total mass in NGC 4472 and 4649 determined from X-ray data is sensitive to the stellar mass over a considerable range in galactic radius extending to r ~ re, the effective radius. The agreement of X-ray and optically determined stellar masses ...

We present optical (UBVJ), ultraviolet (FUV, NUV), and high-resolution atomic hydrogen (H I) observations of the nearby blue compact dwarf (BCD), VII Zw 403. We find that VII Zw 403 has a relatively high H I mass-to-light ratio for a BCD. The rotation velocity is nominally 10-15 km s�1, but rises to ~20 km s�1 after correction for the ~8-10 km s�1 random motions present ...

We use the results of large-scale simulations of reionization to explore methods for characterizing the topology and sizes of H II regions during reionization. We use four independent methods for characterizing the sizes of ionized regions. Three of them give us a full size distribution: the friends-of-friends (FoF) method, the spherical average (SPA) method and the power spectrum (PS) of the ...

We report the discovery of broad MgII emission from the high-redshift radio galaxy 3C 265 ({ital z}=0.81). We detect the broad line in the nuclear spectrum {ital and} {ital in} {ital the} {ital spatially} {ital extended} {ital galaxian} {ital component}, both near the nucleus and in the spectrum of an off-nuclear knot located 31 kpc southeast of the nucleus of the galaxy. These data provide strong ...

The masses of the most massive supermassive black holes (SMBHs) predicted by the MBH-? and MBH-L relations appear to be in conflict. Which of the two relations is the more fundamental one remains an open question. NGC 1332 is an excellent example that represents the regime of conflict. It is a massive lenticular galaxy which has a bulge with a high velocity dispersion ? of �320 km s-1; ...

I will present some results from my thesis research on the scatter in the Tully-Fisher relations and the Dark Matter content of spiral galaxies as a function of morphology, luminosity etc., making use of detailed photometric and kinematic information of galactic disks. A volume limited sample of 79 galaxies was selected from the spiral rich currently forming Ursa Major cluster which has a low ...

We describe a technique for constructing accurate 2D maps of the stellar mass distribution in nearby galaxies from S4G 3.6 micron images, for extension to the full S4G sample. To isolate the old stellar light from contaminant emission (e.g. hot dust and the 3.3 PAH feature) in the IRAC 3.6 and 4.5 micron bands we use an ICA technique (fastICA; Hyvarinen 1999 and Hyvarinen & Oja 2000) designed ...

We investigate the role of secular and hierarchical processes in galaxy evolution and the relationships between spirals and S0s. We present results from a project that examines a sample of 30 edge-on spiral and S0 (lenticular) galaxies that have boxy and peanut-shaped bulges. We compute model kinematics for the sample by solving the Jeans equations for mass distributions which we derive from ...

We investigate the formation and evolution of satellite galaxies using smoothed particle hydrodynamics (SPH) simulations of a Milky Way(MW)-like system, focussing on the best resolved examples, analogous to the classical MW satellites. Comparing with a pure dark matter simulation, we find that the condensation of baryons has had a relatively minor effect on the structure of the satellites' dark ...

The evolution of galaxies is influenced by the environment in which they reside. This effect should be strongest for the lowest-mass and -luminosity galaxies. To study dwarf galaxies in extremely low density environments, we have compiled a deep catalogue of dwarf galaxies in the nearby Lynx-Cancer void. This void hosts some of the most metal-poor dwarfs known to date. It borders the Local Volume ...

The stellar content of the nuclear regions of seven nearby Sc galaxies has been determined by means of population syntheses utilizing narrow-band spectrophotometry covering the wavelength range 3300--10400 A. A linear-programming fitting technique is used in conjunction with simple models of star formation to provide physically consistent population models incorporating multiple generations of ...

We explore whether global observed properties, specifically half-light radii, mean surface brightness, and integrated stellar kinematics, suffice to unambiguously differentiate galaxies from star clusters, which presumably formed differently and lack dark matter halos. We find that star clusters lie on the galaxy scaling relationship referred to as the fundamental manifold (FM), on the extension ...

We construct self-consistent models of non-spherical isothermal halos embedding a zero-thickness disk, by assuming that the halo distribution function is a Maxwellian, as motivated by the discovery of halos of dark matter from the study of flat rotation curves of spiral galaxies. The approach followed here is fully self-consistent. The halo is taken to be collisionless and stationary and described ...

Halo-model interpretations of the luminosity dependence of galaxy clustering assume that there is a central galaxy in every sufficiently massive halo, and that this central galaxy is very different from all the others in the halo. The halo-model decomposition makes the remarkable prediction that the mean luminosity of the non-central galaxies in a halo should be almost independent of halo mass - ...

As the first step to determine disk mass-to-light ratios for normal spiral galaxies, we present the results of an imaging survey for planetary nebulae (PNe) in six nearby, face-on systems: IC 342, M74 (NGC 628), M83 (NGC 5236), M94 (NGC 4736), NGC 5068, and NGC 6946. Using Blanco/Mosaic II and WIYN/OPTIC, we identify 165, 153, 241, 150, 19, and 71 PN candidates, respectively, ...

Observations in the Chandra Deep Field South (CDFS) have provided us with a useful set of data in the optical (COMBO-17), near-infrared (GOODS JHK), and mid-infrared (GOODS IRAC bands 1,2) wavelength regimes to test and improve a new spectral galaxy template library, designed to operate in the rest-frame wavelength range between 0.1 and 5 microns. In this range the stellar continuum and ...

We have modelled 38 barred galaxies by using near-infrared and optical data from the Ohio State University Bright Spiral Galaxy Survey. We constructed the gravitational potentials of the galaxies from H-band photometry, assuming a constant mass-to-light ratio. The halo component we choose corresponds to the so-called universal rotation curve. In each case, we used the response ...

The Lynx arc, with a redshift of 3.357, was discovered during spectroscopic follow-up of the z = 0.570 cluster RX J0848+4456 from the ROSAT Deep Cluster Survey. The arc is characterized by a very red R - K color and strong, narrow emission lines. Analysis of HST WFPC 2 imaging and Keck optical and infrared spectroscopy shows that the arc is an H II galaxy magnified by a factor of {approx} 10 by a ...

We study the origin and properties of the population of unbound stars in the kinematic samples of dwarf spheroidal galaxies. For this purpose we have run a high resolution N- body simulation of a two-component dwarf galaxy orbiting in a Milky Way potential. In agreement with the tidal stirring scenario of Mayer et al., the dwarf is placed on a highly eccentric orbit, its initial stellar component ...

We have conducted a study of optical and H I properties of spiral galaxies (size, luminosity, H? flux distribution, circular velocity, H I gas mass) to investigate causes (e.g., nature vs. nurture) for variation within the cluster environment. We find H I-deficient cluster galaxies to be offset in fundamental plane space, with disk scale lengths decreased by a factor of 25%. This may be a relic of ...

We present luminosity and surface-brightness distributions of 40111 galaxies with K-band photometry from the United Kingdom Infrared Telescope (UKIRT) Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS), Data Release 3 and optical photometry from Data Release 5 of the Sloan Digital Sky Survey (SDSS). Various features and limitations of the new UKIDSS data are examined, such as a problem ...

We investigate the possibility that the observed flatness of the rotation curves of spiral galaxies is not evidence for the existence of dark matter haloes, but rather a signal of the breakdown of General Relativity. To this aim, we consider power-law fourth-order theories of gravity obtained by replacing the scalar curvature R with f(R) = f0 Rn in the gravity Lagrangian. We show that, in the low ...

Context. Intermediate-mass black holes (IMBHs) are of interest in a wide range of astrophysical fields. In particular, the possibility of finding them at the centers of globular clusters has recently drawn attention. IMBHs became detectable since the quality of observational data sets, particularly those obtained with HST and with high resolution ground based spectrographs, advanced to the point ...

Observations of spiral galaxies strongly support a one-to-one analytical relation between the inferred gravity of dark matter at any radius and the enclosed baryonic mass. It is baffling that baryons manage to settle the dark matter gravitational potential in such a precise way, leaving no 'messy' fingerprints of the merging events and 'gastrophysical' feedbacks ...

From data on distance ratios of eight clusters and groups of galaxies in the velocity interval 800--2000 km s/sup -1/, the infall of the Local Group toward the Virgo Cluster center due to the overdensity of the Virgo complex is determined to be v/sub vc/ = 200 +- 50 km s/sup -1/, in agreement with many previous high-weight determinations. If all mass in the universe is clustered like galaxies, ...

The abundance of galaxy clusters as a function of mass is determined from the 2dF Galaxy Redshift Survey (2dFGRS) Percolation-Inferred Galaxy Group (2PIGG) catalogue. This is used to estimate the amplitude of the matter fluctuation spectrum, parametrized by the linear theory rms density fluctuations in spheres of radius 8h-1Mpc,?8. The best-fitting value for this parameter is highly correlated ...

We measure the contribution of galaxy disks to the overall gravitational potential of 30 nearly face-on intermediate-to-late-type spirals from the DiskMass Survey. The central vertical velocity dispersion of the disk stars (?disk z, R = 0) is related to the maximum rotation speed (V max) as ?disk z, R = 0 ~ 0.26V max, consistent with previous measurements for edge-on disk galaxies and a mean ...

Modified Newtonian dynamics (MOND) can fit a broad range of galaxy kinematic data, but struggles with clusters of galaxies. MONDian clusters need dark matter (DM), and here we test the 11 eVc-2 sterile neutrino (SN) - used to fit the first three acoustic peaks of the cosmic microwave background (CMB) - by investigating their equilibrium distributions in 30 groups and clusters over a wide range of ...

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 ...

Using new data from the UVES spectrograph on the ESO Very Large Telescope and archive images from the Hubble Space Telescope, we have measured projected velocity dispersions and structural parameters for two bright young star clusters in the nearby spiral galaxy NGC 5236. One cluster is located near the nuclear starburst of NGC 5236, at a projected distance of 440 pc from the centre, while the ...

We measured stellar velocity dispersions ? and derived dynamical masses of nine massive (M ? 1011 M sun) early-type galaxies (ETGs) from the Galaxy Mass Assembly ultra-deep Spectroscopic Survey (GMASS) sample at redshift 1.4 lsim z lsim 2.0. The ? are based on individual spectra for two galaxies at z ? 1.4 and on a stacked spectrum for seven galaxies with 1.6 < z < 2.0, with 202 hr of ...

Combining resolved optical spectroscopy with panoramic HST imaging, we study the dynamical properties of spiral galaxies as a function of position across two intermediate-redshift clusters, and we compare the cluster population to field galaxies in the same redshift range. By modeling the observed rotation curves, we derive maximal rotation velocities for 40 cluster spirals and 37 field spirals, ...

Using data from the Near-Infrared S0 Survey of nearby, early-type galaxies, we examine the distribution of bar strengths in S0 galaxies as compared to S0/a and Sa galaxies, and as compared to previously published bar strength data for Ohio State University Bright Spiral Galaxy Survey spiral galaxies. Bar strengths based on the gravitational torque method are derived from 2.2 ?m Ks -band images for ...

We investigate structural properties of dark matter halos of disk galaxies, using a well-defined sample of 81 disk-dominated galaxies from the SDSS redshift survey. We model the mass-velocity (TF) and fundamental plane (FP) relations of these galaxies, using the observed stellar mass M*, disk scale length Rd, and optical H? rotation velocity at 2.2 Rd. We calculate model galaxy populations, ...

Using data from the Near-Infrared S0 Survey of nearby, early-type galaxies, we examine the distribution of bar strengths in S0 galaxies as compared to S0/a and Sa galaxies, and as compared to previously published bar strength data for Ohio State University Bright Spiral Galaxy Survey spiral galaxies. Bar strengths based on the gravitational torque method are derived from 2.2 {mu}m K{sub s} -band ...

We recently found that massive cluster elliptical galaxies have strong Na I ?8183, 8195 and FeH ?9916 Wing-Ford band absorption, indicating the presence of a very large population of stars with masses <~ 0.3 M sun. Here we test this result by comparing the elliptical galaxy spectra to those of luminous globular clusters associated with M31. These globular clusters have similar metallicities, ...

We present the first automated spectroscopic search for disk-galaxy lenses, using the Sloan Digital Sky Survey (SDSS) database. We follow up eight gravitational lens candidates, selected among a sample of {approx}40,000 candidate massive disk galaxies, using a combination of ground-based imaging and long-slit spectroscopy. We confirm two gravitational lens systems: one probable disk galaxy and one ...

Our analysis of the two magnitude-limited samples of LINERs suggests a correlation between LFIR/LB, or f(25 ?m)/f(60 ?m), and Hubble-type index at greater than 99.99% significance level. As LFIR/LB and f(25 ?m)/f(60 ?m) are considered to be indicators of star formation activity and active galactic nuclei (AGN) activity, respectively, our results suggest that LINERs with higher AGN activity may ...

Elliptical galaxies are renowned for the correlation among their stellar properties known as the Fundamental Plane. All normal ellipticals are found on or near this two-dimensional locus in the three-dimensional space of optical half-light radius, mean surface brightness, and central stellar velocity dispersion. The Fundamental Plane is understood to be mostly a consequence of the Virial Theorem, ...

Many 3D N-body barred models of the Galaxy extending beyond the Solar circle are realised by self-consistent evolution of various bar unstable axisymmetric models. The COBE/DIRBE K-band map, corrected for extinction, is used to constrain the location of the observer in these models, assuming a constant mass-to-light ratio. The resulting view points in the best matching models ...