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We describe the HST ACS Coma Cluster Treasury survey, a deep two-passband imaging survey of one of the nearest rich clusters of galaxies, the Coma Cluster (Abell 1656). The survey was designed to cover an area of 740 arcmin2 in regions of different density of both galaxies and intergalactic medium within the cluster. The ACS failure of 2007 January 27 leaves the survey 28% complete, with 21 ACS pointings (230 arcmin2) complete, and partial data for a further four pointings (44 arcmin2). The predicted survey depth for 10 σ detections for optimal photometry of point sources is g'=27.6 in the F475W filter and IC=26.8 mag in F814 (AB magnitudes). Initial simulations with artificially injected point sources show 90% recovered at magnitude limits of g'=27.55 and IC=26.65. For extended sources, the predicted 10 σ limits for a 1 arcsec2 region are g'=25.8 mag arcsec-2 and IC=25.0 mag arcsec-2. We highlight several motivating science goals of the survey, including study of the faint end of the cluster galaxy luminosity function, structural parameters of dwarf galaxies, stellar populations and their effect on colors and color gradients, evolution of morphological components in a dense environment, the nature of ultracompact dwarf galaxies, and globular cluster populations of cluster galaxies of a range of luminosities and types. This survey will also provide a local rich cluster benchmark for various well-known global scaling relations and explore new relations pertaining to the nuclear properties of galaxies. Based on observations with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope Science Institute, which is operated by the association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. These observations are associated with program GO10861.

We describe the HST ACS Coma Cluster Treasury survey, a deep two-passband imaging survey of one of the nearest rich clusters of galaxies, the Coma Cluster (Abell 1656). The survey was designed to cover an area of 740 arcmin2 in regions of different density of both galaxies and intergalactic medium within the cluster. The ACS failure of 2007 January 27 leaves the survey 28% complete, with 21 ACS pointings (230 arcmin2) complete, and partial data for a further four pointings (44 arcmin2). The predicted survey depth for 10 σ detections for optimal photometry of point sources is g'=27.6 in the F475W filter and IC=26.8 mag in F814 (AB magnitudes). Initial simulations with artificially injected point sources show 90% recovered at magnitude limits of g'=27.55 and IC=26.65. For extended sources, the predicted 10 σ limits for a 1 arcsec2 region are g'=25.8 mag arcsec-2 and IC=25.0 mag arcsec-2. We highlight several motivating science goals of the survey, including study of the faint end of the cluster galaxy luminosity function, structural parameters of dwarf galaxies, stellar populations and their effect on colors and color gradients, evolution of morphological components in a dense environment, the nature of ultracompact dwarf galaxies, and globular cluster populations of cluster galaxies of a range of luminosities and types. This survey will also provide a local rich cluster benchmark for various well-known global scaling relations and explore new relations pertaining to the nuclear properties of galaxies. Based on observations with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope Science Institute, which is operated by the association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. These observations are associated with program GO10861.

In integrated light, some color-color diagrams that use optical and near-infrared photometry show surprisingly orthogonal grids as age and metallicity are varied, and they are coming into common usage for estimating the average age and metallicity of spiral galaxies. In this paper we reconstruct these composite grids using simple stellar population models from several different groups convolved with some plausible functional forms of star formation histories at fixed metallicity. We find that the youngest populations present (t

In integrated-light, some color-color diagrams that use optical and near-infrared photometry show surprisingly orthogonal grids as age and metallicity are varied, and they are coming into common usage for estimating the average age and metallicity of spiral galaxies. In this paper we reconstruct these composite grids using simple stellar population models from several different groups convolved with some plausible functional forms of star formation histories at fixed metallicity. We find that the youngest populations present (t, 33 pages, 15 figures. Accepted to ApJ (Apr 2007). The major surgery was Fig. 14

AIM:Learn more about the origin of shells and dust in early type galaxies. METHOD: V-I colours of shells and underlying galaxies are derived, using HST Advanced Camera for Surveys (ACS) data. A galaxy model is made locally in wedges and subtracted to determine shell profiles and colours. We applied Voronoi binning to our data to get smoothed colour maps of the galaxies. Comparison with N-body simulations from the literature gives more insight to the origin of the shell features. Shell positions and dust characteristics are inferred from model galaxy subtracted images. RESULT: The ACS images reveal shells well within the effective radius in some galaxies (at 1.7 kpc in the case of NGC 5982). In some cases, strong nuclear dust patches prevent detection of inner shells. Most shells have colours which are similar to the underlying galaxy. Some inner shells are redder than the galaxy. All six shell galaxies show out of dynamical equilibrium dust features, like lanes or patches, in their central regions. Our detection rate for dust in the shell ellipticals is greater than that found from HST archive data for a sample of normal early-type galaxies, at the 95% confidence level. CONCLUSIONS: The merger model describes better the shell distributions and morphologies than the interaction model. Red shell colours are most likely due to the presence of dust and/or older stellar populations. The high prevalence and out of dynamical equilibrium morphologies of the central dust features point towards external influences being responsible for visible dust features in early type shell galaxies. Inner shells are able to manifest themselves in relatively old shell systems., Comment: accepted by A&A; 36 Figures, 25 pages. A version with full resolution Figures can be found here: http://www.astro.rug.nl/~sikkema/shells.ps

A simple algorithm is employed to deproject the two-dimensional images of a pilot sample of 12 high-quality images of edge-on disc galaxies and to study their intrinsic three-dimensional (3D) stellar distribution. We examine the radial profiles of the stars as a function of height above the plane and report a general trend within our sample of an increasing radial scalelength with height outside of the dust lane. This could be explained by the widespread presence of a thick disc component in these galaxies. In addition, the 3D view allows the study of the vertical distribution of the outer disc, beyond the break region, where we detect a significant increase in scalelength with vertical distance from the major axis for the truncated discs. This could be regarded as a weakening of the ‘truncation’ with increasing distance from the plane. Furthermore, we conclude that the recently revised classification of the radial surface brightness profiles found for face-on galaxies is indeed independent of geometry. In particular, we find at least one example of each of the three main profile classes as defined in complete samples of intermediate to face-on galaxies: not-truncated, truncated and antitruncated. The position and surface brightness that mark the break location in the radial light distribution are found to be consistent with those of face-on galaxies.

We present deep B- and R-band surface photometry for a sample of 21 galaxies with morphological types between S0 and Sab. We present radial profiles of surface brightness, colour, ellipticity, position angle and deviations of axisymmetry for all galaxies, as well as isophotal and effective radii and total magnitudes. We have decomposed the images into contributions from a spheroidal bulge and a flat disk, using an interactive, 2D decomposition technique. We study in detail the relations between various bulge and disk parameters. In particular, we find that the bulges of our galaxies have surface brightness profiles ranging from exponential to De Vaucouleurs, with the average value of the Sersic shape parameter n being 2.5. In agreement with previous studies, we find that the shape of the bulge intensity distribution depends on luminosity, with the more luminous bulges having more centrally peaked light profiles. By comparing the ellipticity of the isophotes in the bulges to those in the outer, disk dominated regions, we are able to derive the intrinsic axis ratio q_b of the bulges. The average axis ratio is 0.55, with an rms spread of 0.12. None of the bulges in our sample is spherical, whereas in some cases, the bulges can be as flat as q_b = 0.3 - 0.4. The bulge flattening seems to be weakly coupled to luminosity, more luminous bulges being on average slightly more flattened than their lower-luminosity counterparts. Our finding that most bulges are significantly flattened and have an intensity profile shallower than R^{1/4} suggests that `pseudobulges', formed from disk material by secular processes, do not only occur in late-type spiral galaxies, but are a common feature in early-type disk galaxies as well. (abridged), Comment: 26 pages, 11 figures. Accepted for publication in MNRAS. A pdf-version with full resolution figures and the full atlas can be found at http://www.nottingham.ac.uk/~ppzen/surfphot.accepted.pdf

We present spatially resolved observations of IRAS sources from the Japanese infrared astronomy satellite AKARI All-Sky Survey during the performance verification phase of the mission. We extracted reliable point sources matched with the IRAS point source catalogue. By comparing IRAS and AKARI fluxes, we found that the flux measurements of some IRAS sources could have been over or underestimated, and affected by the local background, rather than the global background. We also found possible candidates for new AKARI sources and confirmed that AKARI observations resolved IRAS sources into multiple sources. All-Sky Survey observations are expected to verify the accuracies of IRAS flux measurements and to find new extragalactic point sources.

We present spatially resolved observations of IRAS sources from the Japanese infrared astronomy satellite AKARI All-Sky Survey during the performance verification phase of the mission. We extracted reliable point sources matched with the IRAS point source catalogue. By comparing IRAS and AKARI fluxes, we found that the flux measurements of some IRAS sources could have been over or underestimated, and affected by the local background, rather than the global background. We also found possible candidates for new AKARI sources and confirmed that AKARI observations resolved IRAS sources into multiple sources. All-Sky Survey observations are expected to verify the accuracies of IRAS flux measurements and to find new extragalactic point sources.

We present the first near-infrared (K'-band) homogeneous observations of a complete sub-sample of the 3CR radio catalogue comprising all High Excitation Galaxies (HEGs) at z, Comment: Accepted for publication in A&A; high resolution version can be downloaded at http://www.astro.yale.edu/danilom/

The dust extinction in spiral disks can be estimated from the counts of background field galaxies, provided the deleterious effects of confusion introduced by structure in the image of the foreground spiral disk can be calibrated. Gonzalez et al. (1998) developed a method for this calibration, the ``Synthetic Field Method'' (SFM), and applied this concept to a HST/WFPC2 image of NGC4536. The SFM estimates the total extinction through the disk without the necessity of assumptions about the distribution of absorbers or the disk light. The poor statistics, however, result in a large error in individual measurements. We report on improvements to and automation of the Synthetic Field Method which render it suitable for application to large archival datasets. To illustrate the strengths and weaknesses of this new method, the results on NGC 1365, a SBb, and NGC 4536, a SABbc, are presented. The extinction estimate for NGC1365 is A_I = 0.6 (+0.6/-0.7) at 0.45 R_25 and for NGC4536 it is A_I = 1.6 (+1.0/-1.3) at 0.75 R_25. The results for NGC4536 are compared with those of Gonzalez et al. (1998). The automation is found to limit the maximum depth to which field galaxies can be found. Taking this into account, our results agree with those of Gonzalez et al. (1998). We conclude that this method can only give an inaccurate measure of extinction for a field covering a small solid angle. An improved measurement of disk extinction can be done by averaging the results over a series of HST fields, thereby improving the statistics. This can be achieved with the automated method, trading some completeness limit for speed. The results from this set of fields are reported in a companion paper Holwerda et al. (2005b)., updated references, abstract, 37 pages, 12 figures, 6 tables

Dust extinction can be determined from the number of distant field galaxies seen through a spiral disk. To calibrate this number for the crowding and confusion introduced by the foreground image, Gonzalez et al.(1998) and Holwerda et al. (2005) developed the ``Synthetic Field Method'' (SFM), which analyses synthetic fields constructed by adding various deep exposures of unobstructed background fields to the candidate foreground galaxy field. The advantage of the SFM is that it gives the average opacity for area of galaxy disk without assumptions about either the distribution of absorbers or of the disk starlight. However it is limited by low statistics of the surviving field galaxies, hence the need to combine a larger sample of fields. This paper presents the first results for a sample of 32 deep HST/WFPC2 archival fields of 29 spirals. The radial profiles of average dust extinction in spiral galaxies based on calibrated counts of distant field galaxies is presented here, both for individual galaxies as well as for composites from our sample. The effects of inclination, spiral arms and Hubble type on the radial extinction profile are discussed. (Abbreviated), 43 pages, 16 figures, 3 tables, accepted for publication in the Astronomical Journal, (typos, table update, updates abstract)

Halpha+[NII] imaging observations of 369 late-type galaxies in the Virgo cluster and in the Coma/A1367 supercluster are analyzed. They constitute an optically selected sample (m_p10^9yrs) stars. Put together, the young and the old stellar indicators give the ratio of currently formed stars over the stars formed in the past, or "birthrate" parameter b. We also determine the "global gas content" combining HI with CO observations. We define the "gas deficiency" parameter as the logarithmic difference between the gas content of isolated galaxies of a given Hubble type and the measured gas content.For the isolated objects we find that b decreases with increasing NIR luminosity. The gas-deficient objects, primarily members to the Virgo cluster, have their birthrate significantly lower than the isolated objects with normal gas content and of similar NIR luminosity. This indicates that the current star formation is regulated by the gaseous content of spirals.Whatever mechanism (most plausibly ram-pressure stripping) is responsible for the pattern of gas deficiency observed in spiral galaxies members to rich clusters, it also produces the observed quenching of the current star formation., 22 pages,14 figures,3 figures available in jpeg format.To be published in A&A

We analyse the global structure of the old stellar discs in 34 edge-on spiral galaxies. The radial and vertical exponential scale parameters of the discs are obtained by applying an improved two-dimensional decomposition technique to our I-band photometry. We find a clear increase in the disc scaleheight with maximum rotational velocity, in accordance with observations of the stellar velocity dispersions in galaxy discs. The range and maximum of the intrinsic flattening of the disc light seem to increase with both maximum rotational velocity and total HI mass. We use the disc flattening to estimate the disc contribution to the maximum rotational velocity, resulting in an average of 57+-22 percent. The disc light distributions are further investigated for the presence of radial truncations. We find that the radial light distributions of at least 20 spirals are truncated, corresponding to 60 percent of the sample. For small scalelength spirals, which are the most numerous in the local Universe, the results suggest that the average ratio of disc truncation radius to disc scalelength is at least four., 25 pages, 7 figures, appendix, Accepted for MNRAS (April 4 2002)

We present far-infrared and millimetric observations of a sample of 3C objects. Millimetre data were taken at 1.25 mm with the IRAM 30m antenna feeding the MPIfR bolometer array. Mid-infrared (MIR) and far-infrared (FIR) photometry were carried out with the ISOCAM and ISOPHOT cameras on the ISO Satellite. Additional FIR IRAS observations are also included. We present the entire Spectral Energy Distributions (SEDs) from the UV to radio and discuss the emitting mechanisms. Two composite spectra, one for the radio galaxies and one for the radio quasars, are built in the object rest frame. While the SEDs of the two classes differ, they are indistinguishable in the MIR and FIR range where they probably arise as thermal emission from a dusty torus and a larger-scale (cooler) dust distribution in the host galaxy., 15 pages, A&A, in press

We present the first results from the Faint Infra-Red Extragalactic Survey of the Hubble Deep Field South (HDF-S). Using a combination of deep near-infrared (NIR) data obtained with the Infrared Spectrograph and Array Camera at the VLT and the WFPC2 Hubble Space Telescope data, we construct a K-band-selected sample which is 50% and 90% complete for and K-s,K-AB less than or equal to 23.5 K-s,K-AB less than or equal to 22.0, respectively, where the magnitudes are measured over a diameter aperture. For z less than or equal to 3, our selection by the K-band flux chooses galaxies based on wavelengths redder than the rest-frame V band, and so selects them in a way that is less dependent on their current star formation rates than selection in the rest-frame UV. We developed a new photometric redshift technique that models the observed spectral energy distribution (SED) with a linear combination of empirical galaxy templates. We tested this technique using 150 spectroscopic redshifts in the Hubble Deep Field North (HDF-N) from the Cohen et al. sample (published in 2000) and found Deltaz/(1 + z) approximate to 0.07 for z 2 we find very luminous galaxies with L-V(rest) h(-2) L. (for Omega (M) = 0.3, Omega (Lambda) = 0.7, H-0 = 100 h km s(-1) Mpc(-1)). Local B-band luminosity functions predict 0.1 galaxies in the redshift range 2 less than or equal to less than or equal to 3.5 and with L-B(rest) greater than or equal to 5 x 10(10) h(-2) L.(,B), but we find nine. The discrepancy can be explained if L-B(*) increases by a factor of 2.4-3.2 with respect to locally determined values. Random errors in the photometric redshift can also play a role, and spectroscopic confirmation of the redshifts of these bright galaxies is required.

In order to study the nature of the far-infrared emission observed in radio-loud active galaxies, we have obtained 1.2 mill observations with the IRAM 30 m telescope for a sample of eight radio-loud active galaxies. In all objects we find that the 1.2 mm emission is dominated by non-thermal emission. An extrapolation of the non-thermal radio spectrum indicates that the contribution of synchrotron emission to the far-infrared is less than 10% in quasars. and negligible ill the radio galaxies. The quasars in the sample show signs of relativistic beaming at millimeter wavelengths, and the quasar 3C 334 shows evidence for strong variability.

We have obtained integrated spectra and multifilter photometry for a representative sample of similar to 200 nearby galaxies. These galaxies span the entire Hubble sequence in morphological type, as well as a wide range of luminosities (M(B) = -14 to -22) and colors (B-R = 0.4-1.8). Here we describe the sample selection criteria and the U, B, R surface photometry for these galaxies. The spectrophotometric results will be presented in a companion paper. Our goals for the project include measuring the current star formation rates and metallicity of these galaxies, and elucidating their star formation histories, as a function of luminosity and morphology. We thereby extend the work of Kennicutt to lower luminosity systems. We anticipate that our study will be useful as a benchmark for studies of galaxies at high red-shift. We discuss the observing, data reduction, and calibration techniques and show that our photometry agrees well with previous work in those cases in which earlier data are available. We present an atlas of images, radial surface brightness profiles, and color profiles as well as tables of derived parameters. The atlas and tables of measurements will be made available electronically. We study the correlations of galaxy properties determined from the galaxy images. Our findings include the following: (1) colors determined within the effective radius correlate better with morphological type than with M(B) and (2) 50% of the low-luminosity galaxies are bluest in their centers.

The spatial distribution of stars in a disk of a galaxy can be described by a radial scale length and a vertical scale height. The ratio of these two scale parameters contains information on the axis ratio of the velocity ellipsoid, i.e. the ratio of the vertical to radial stellar velocity dispersions of the stars, at least at some fiducial distance from the center. The radial velocity dispersion correlates well with the amplitude of the rotation curve and:with the disk integrated magnitude, as was found by Bottema (1993). These relations can be understood as the result of the stellar disk being (marginally) stable against local instabilities at all length scales. This is expressed by Toomre's well-known criterion, which relates the sheer in the rotation to a minimum value that the radial stellar velocity dispersion should have for stability for a given surface density. Via the Tully-Fisher (1977) relation, the velocity dispersion then becomes related to the integrated magnitude and hence to the scale length. The vertical velocity dispersion relates directly to the scale height through hydrostatic equilibrium. It can be shown that the ratio of the two length scales relates to the axis ratio of the velocity ellipsoid only through the Toomre parameter Q and in particular does not require a choice of the mass-to-light ratio or a distance scale. We have applied this to the statistically complete sample of edge-on galaxies, for which de Grijs (1997) has performed surface photometry and has determined the length scales in the stellar light distribution.

We present results of broad band BVRI observations of a sample of galaxies with a low surface brightness (LSB) disk and a bulge. These galaxies are well described as exponential disks and exponential bulges with no preferred value for either scale length or central surface brightness. The median B band disk scale length is 12.6 kpc (H-0 = 75 km s(-1) Mpc(-1)) which is much larger than scale lengths of typical (disk dominated) LSB or high surface brightness (HSB) galaxies. Furthermore, the disk and bulge scale lengths are correlated, suggesting a coupling in the formation. Bulge dominated LSB galaxies are observed to be redder than disk dominated LSB galaxies and their bulge-to-disk ratios are increasing towards redder wavelengths. We find colors that are comparable to or bluer than HSB galaxies of the same morphological types. Bulge dominated LSB galaxies are therefore not faded HSB galaxies with no current star formation. We find that bulge dominated LSB galaxies fit in with the general trends defined by the HSB galaxies. The properties of these bulge dominated LSB galaxies show that LSB galaxies do not just come in two varieties. They cover the entire range in optical and morphological properties between late-type disk dominated LSBs and giant Malin-1-like LSBs. LSB galaxies thus also form a LSB Hubble sequence, parallel to the classical HSB one.

We have determined a dust-free colour-magnitude (CM) relation for spiral galaxies, by using I - K colours in edge-on galaxies above the plane. We find that the scatter in this relation is small and approximately as large as can be explained by observational uncertainties. The slope of the near-IR CM relation is steeper for spirals than for elliptical galaxies. We suggest two possible explanations. First, the difference could be caused by vertical colour gradients in spiral galaxies. In that case these gradients should be similar for all galaxies, on average similar to 0.15 dex in [Fe/H] per scaleheight, and should increase for rater galaxy types. The most likely explanation, however, is that spirals and ellipticals have intrinsically different CM relations. This means that the stars in spirals are younger than those in ellipticals. The age, however, or the fraction of young stars in spiral galaxies would be determined solely by the luminosity of the galaxy, and not by its environment.

We have determined a dust-free colour-magnitude (CM) relation for spiral galaxies, by using I - K colours in edge-on galaxies above the plane. We find that the scatter in this relation is small and approximately as large as can be explained by observational uncertainties. The slope of the near-IR CM relation is steeper for spirals than for elliptical galaxies. We suggest two possible explanations. First, the difference could be caused by vertical colour gradients in spiral galaxies. In that case these gradients should be similar for all galaxies, on average similar to 0.15 dex in [Fe/H] per scaleheight, and should increase for rater galaxy types. The most likely explanation, however, is that spirals and ellipticals have intrinsically different CM relations. This means that the stars in spirals are younger than those in ellipticals. The age, however, or the fraction of young stars in spiral galaxies would be determined solely by the luminosity of the galaxy, and not by its environment.

A statistical study of global galaxy parameters can help to improve our understanding of galaxy formation processes. In this paper we present the analysis of global galaxy parameters based on optical and near-infrared observations of a large sample of edge-on disc galaxies. We found a correlation between the ratio of the radial to vertical scale parameter and galaxy type: galaxies become systematically thinner when going from S0's to Sc's, whereas the distribution seems to level off for later types. The observed scale length ratios (and thus the radial colour gradients) largely represent the galaxies' dust content. On average the colour gradients indicated by the scale length ratios increase from type Sa to at least type Sc. For galaxy types later than Sc, the average colour gradient seems to decrease again. The distribution of K-band (edge-on) disc central surface brightnesses is rather flat, although with a large scatter. However, the latest-type sample galaxies (T > 6) show an indication that their average disc central surface brightnesses may be fainter than those of the earlier types. This effect is probably not the result of dust extinction., 17 pages, LaTex, 11 figures, accepted for publication in MNRAS

In this paper we present the data from our J-, H-, and K-band imaging program of powerful radio sources. The sample consists of radio galaxies classified as either compact (20 kpc) radio sources. Source images, photometry results, radial profiles, and profile fits are presented. Source decomposition of total flux into point-spread function (PSF) and extended contributions indicate all sources are nucleated to roughly the same level at J, H, and K bands, arguing against the notion that the suspected higher nuclear absorption in the most compact class would render those sources relatively more nucleated at the longer wavelengths. No significant differences in near-IR host galaxy properties have been found. In a companion paper we discuss color-color properties, comparisons with predictions made by a stellar synthesis code, and near-IR broadband spectral properties.

By means of KPNO 2.1 m J-, H-, and K-band data on samples of gigahertz peaked spectrum (GPS, radio size 20 kpc), we have constructed mean broadband spectral energy distributions (SEDs) for each of the object classes and compared these with synthetic SEDs. The host galaxies of the compact and extended radio sources appear to have similar near-IR broadband SEDs, implying similar stellar populations and active galactic nuclei (AGNs). These SEDs are best fitted with a mean metallicity similar to solar and fairly old stellar populations implying formation redshifts of greater than or similar to 5. Redshift evolution of the sources is consistent with a passive evolutionary model. In addition, an extra IR component is needed that can be modeled by emission from dust at a temperature of 900-1300 K, perhaps produced by the putative obscuring torus. All of our results are consistent with the hypothesis that the GPS and CSS are the progenitors of the large-scale 3CR radio galaxies.

This study reports on photometric results of a search for LSB galaxies in a 0.76deg^2 field centered on the HDF-S. We present results from photometric analysis of the derived sample galaxies and compare number densities to results of former surveys. We used public data from the NOAO Deep Wide-Field survey and the multi-wavelength Goddard Space Flight Center survey. The former reaches a limiting surface brightness of mu_BW~29 magarcsec^-2 and is therefore one of the most sensitive ground based data sets systematically analyzed for LSB galaxies. To reduce the contamination by High Surface Brightness (HSB) galaxies at higher redshift, mimicking LSBs due to the ''Tolman Dimming'' effect, we placed a lower diameter limit of 10.8 arcsec and compared the colors of our candidate galaxies with the redshift tracks of 5 ''standard'' HSB galaxy types. We report the detection of 37 galaxies with low apparent central surface brightness (mu_BW>=22 magarcsec^-2). Using color-color diagrams we were able to derive a subsample of 9 LSB galaxy candidates with intrinsic central surface brightnesses below mu_(0,BW)=22.5 magarcsec^-2 and diameters larger than the preselected size limit of 10.8 arcsec. We selected three additional LSB candidates due to there extreme low blue central surface brightness (mu_BW>=25 magarcsec^-2). These galaxies were only found in the larger and more sensitive NOAO data. So finally we derived a sample of 12 LSB galaxy candidates and therfore this survey results in a four times higher surface density than other CCD based surveys for field galaxies before., 22 pages, 23 figures, A&A in press

Edge-on spiral galaxies often have stellar disks with relatively sharp truncations and warped HI-layers in the outer parts. Warps appear to start preferentially near the optical boundaries of the disks. Here we make a comparative study of warps and truncations in edge-on galaxies. The Garc\'��a-Ruiz et al. (2002) sample with extensive HI-mapping is complemented with luminosity distributions from the Sloan Digital Sky Survey. The method to identify truncations has been tested using the sample of edge-on galaxies of van der Kruit & Searle. Results are: (i.) The majority (17 out of 23) of the galaxies show evidence for truncations. (ii.) When an HI-warp is present it starts at 1.1 truncation radii. (iii.) This supplements the rules for warps formulated by Briggs (1990), if the Holmberg radius is replaced for edge-on systems with the truncation radius. (iv.) The truncation radius and the onset of the warps coincide radially with features in the rotation curve and the HI surface density. The latter is also true for less inclined systems. (v.) Inner disks are very flat and the onset of the warp just beyond the truncation radius is abrupt and discontinuous. These findings suggest that the inner flat disk and the outer warped disk are distinct components with quite different formation histories, probably involving quite different epochs. The inner disk forms initially and the warped outer disk forms as a result of much later infall of gas with a higher angular momentum in a different orientation. In an appendix the Holmberg radius is discussed. Contrary to what is often assumed Holmberg radii are not corrected for inclination., Accepted for pubication by Astronomy & Astrophysics

WeestimatedblackholemassesandEddingtonratiosforasampleof X-ray-selectedactivegalacticnuclei(AGNs) inthefieldscoveredbytheGreatObservatoryOriginsDeepSurvey(GOODS).Thespannedrangesinredshift(0:4 < z < 1) and hard X-ray luminosity(10 42 PLX P4 ; 10 43 ergss � 1 )allowus tostudy arepresentative subsampleofthe main contributors to the 2Y10 keV X-ray background. Nuclear and bulge magnitudes in four bands have been measured via a two-dimensional decomposition applied toHSTACS images. Using the black hole versus bulge luminosity relation and the intrinsic nuclear emission, we derived the black hole mass and the AGN bolometric luminosity. Wefindinoursamplethat(1)theX-rayYtoYopticalindicesarelargerthaninopticallyselectedQSOs,asexpecteddue to the X-ray selection); (2) the X-ray bolometric corrections are generally small, suggesting a decrease with the nuclear luminosity; (3) the Eddington ratios are about a factor 10 below the values found at higher redshift and luminosity; (4) the central black holes have rather largemasses; and (5) at least for z P0:8, a scarceness of black holes with

Using imaging data from the SDSS survey, we present the g' and r' radial stellar light distribution of a complete sample of ~90 face-on to intermediate inclined, nearby, late-type (Sb-Sdm) spiral galaxies. The surface brightness profiles are reliable (1sigma uncertainty less than 0.2 mag) down to mu=~27magsqarcsec. Only ~10% of all galaxies have a normal/standard purely exponential disk down to our noise limit. The surface brightness distribution of the rest of the galaxies is better described as a broken exponential. About 60% of the galaxies have a break in the exponential profile between ~1.5-4.5 times the scalelength followed by a downbending, steeper outer region. Another ~30% shows also a clear break between ~4.0-6.0 times the scalelength but followed by an upbending, shallower outer region. A few galaxies have even a more complex surface brightness distribution. The shape of the profiles correlates with Hubble type. Downbending breaks are more frequent in later Hubble types while the fraction of upbending breaks rises towards earlier types. No clear relation is found between the environment, as characterised by the number of neighbours, and the shape of the profiles of the galaxies., LaTeX, 69 pages, 213 (very low resolution) figures, A&A accepted. Second version to match the accepted one including all referee's comments. Version with full resolution figures (highly recommended, but with 7.6MB) available at http://www.astro.rug.nl/~pohlen/pohlenSDSS.pdf

We present near ultraviolet imaging with the Hubble Space Telescope Advanced Camera for Surveys, targeting young radio galaxies (Gigahertz Peaked Spectrum and Compact Steep Spectrum sources), in search of star formation regions in their hosts. We find near UV light which could be the product of recent star formation in eight of the nine observed sources. However, observations at other wavelengths and colors are needed to definitively establish the nature of the observed UV light. In the CSS sources 1443+77 and 1814--637 the near UV light is aligned with and is co-spatial with the radio source, and we suggest that in these sources the UV light is produced by star formation triggered and/or enhanced by the radio source., 4 pages, 1 figure. To appear in from "QSO Hosts: Evolution and Environment", P. D. Barthel, D. B. Sanders, eds., August 2005, Leiden University, New. Astr. Rev

This paper presents surface photometry (B,V, I, J, H, K) and H_alpha rotation curves of 27 isolated spiral galaxies. The final goal is to obtain the mass distribution of a sample of isolated spiral galaxies in order to model their gas kinematics. This is then compared to the observed rotation curve, to determine the necessity of a dark halo in the inner parts (Perez et al. 2004). The azimuthally averaged radial surface brightness profiles and the integrated magnitudes obtained from ellipse fitting are given for each of the sample galaxies. The ellipse fitting technique applied to the light distribution also allowed us to obtain the size of the bar, and the inclination and position angle of the outer isophotes that allow the galaxy deprojection. Using these profiles, 1-D disk-bulge decomposition was performed to obtain the disk scale-length and the bulge effective radius for the different bands. Through the fitting of a parametric function to the observed rotation curve, the maximum rotational velocity and the corresponding radius was obtained. The correlation between the bulge and disk parameters is in agreement with previous studies (de Jong 1996a; Marquez & Moles 1999; Baggett et al. 1998). Regarding the Kormendy relation (Kormendy 1977), in agreement with de Jong, no correlation between the bulge effective radius and its surface brightness is found, possibly due to the small range of bulge magnitudes covered. We find a smaller scatter in the structural relations when compared to non-isolated samples in agreement with Marquez & Moles (1999). Finally, a correlation between the disk scale-length and the bar size is observed, possibly reflecting the rapid growth of a bar., A&A accepted. Fig. 11 and Tables 3-8 can be downloaded at: http://www.astro.rug.nl/~isa (they will also be available at http://www.edpsciences.org)

The recently initiated Arecibo Legacy Fast ALFA (ALFALFA) survey aims to map 7000 square degrees of the high galactic latitude sky visible from Arecibo, providing a HI line spectral database covering the redshift range between -1600 km/s and 18,000 km/s with 5 km/s resolution. Exploiting Arecibo's large collecting area and small beam size, ALFALFA is specifically designed to probe the faint end of the HI mass function in the local universe and will provide a census of HI in the surveyed sky area to faint flux limits, making it especially useful in synergy with wide area surveys conducted at other wavelengths. ALFALFA will also provide the basis for studies of the dynamics of galaxies within the Local and nearby superclusters, will allow measurement of the HI diameter function, and enable a first wide-area blind search for local HI tidal features, HI absorbers at z < 0.06 and OH megamasers in the redshift range 0.16 < z < 0.25. Although completion of the survey will require some five years, public access to the ALFALFA data and data products will be provided in a timely manner, thus allowing its application for studies beyond those targeted by the ALFALFA collaboration. ALFALFA adopts a two-pass, minimum intrusion, drift scan observing technique which samples the same region of sky at two separate epochs to aid in the discrimination of cosmic signals from noise and terrestrial interference. Survey simulations, which take into account large scale structure in the mass distribution and incorporate experience with the ALFA system gained from tests conducted during its commissioning phase, suggest that ALFALFA will detect on the order of 20,000 extragalactic HI line sources out to z=0.06, including several hundred with HI masses of less than 10^{7.5} msun., 37 pages, including 11 figures; to appear in Astron. J.; see http://egg.astro.cornell.edu/alfalfa/pubs.php Authors' list contains 40 names: see paper for full detail

We present the results of a photometric and spectroscopic study of seven members of the NGC 5328 group of galaxies, a chain of galaxies spanning over 200 kpc (H_0 = 70 km/s/Mpc). We analyze the galaxy structure and study the emission line properties of the group members looking for signatures of star formation and AGN activity. We finally attempt to infer, from the modeling of line-strength indices, the stellar population ages of the early-type members. We investigate also the presence of a dwarf galaxy population associated with the bright members. The group is composed of a large fraction of early-type galaxies including NGC 5328 and NGC 5330, two bona fide ellipticals at the center of the group. In both galaxies no recent star formation episodes are detected by the H_beta vs. MgFe indices of these galaxies. 2MASX J13524838-2829584 has extremely boxy isophotes which are believed to be connected to a merging event: line strength indices suggest that this object probably had a recent star formation episode. A warped disc component emerges from the model subtracted image of 2MASX J13530016-2827061 which is interpreted as a signature of an ongoing interaction with the rest of the group. Ongoing star formation and nuclear activity is present in the projected outskirts of the group. The two early-type galaxies 2MASX J13523852-2830444 and 2MASX J13525393-2831421 show spectral signatures of star formation, while a Seyfert 2 type nuclear activity is detected in MCG -5-33-29., Comment: 18 pages, 12 figures, accepted for publication in MNRAS

We analyse the structural and dynamical properties of a sample of 324 nearby elliptical and dwarf elliptical galaxies observed during an extensive NIR survey in H-band (1.65 micron). The Fundamental Plane (FP) is determined and a significant tilt is assessed. The origins of such a tilt are investigated by means of a spherically symmetric, isotropic pressure supported dynamical model relying on the observed surface brightness profiles. The systematic variation of the shape coefficient converting the measured central velocity dispersion $ sigma_0$ into the virial rms velocity $ sigma_{rms}$ is found to be the main cause of the tilt, due to aperture effects. Moreover the ratio between the dynamical mass $M_{dyn}$ and the total H-band luminosity $L_H$ turns out to be roughly constant along the luminosity sequence of ellipticals: H-band luminosity is therefore a reliable and cheap estimator of the dynamical mass of the Es., 28 pages, 6 figures, accepted for publication on ApJ

R-band surface photometry is presented for 171 late-type dwarf and irregular galaxies. For a subsample of 46 galaxies B-band photometry is presented as well. We present surface brightness profiles as well as isophotal and photometric parameters including magnitudes, diameters and central surface brightnesses. Absolute photometry is accurate to 0.1 mag or better for 77% of the sample. For over 85% of the galaxies the radial surface brightness profiles are consistent with published data within the measured photometric uncertainty. For most of the galaxies in the sample HI data have been obtained with the Westerbork Synthesis Radio Telescope. The galaxies in our sample are part of the WHISP project (Westerbork HI Survey of Spiral and Irregular Galaxies), which aims at mapping about 500 nearby spiral and irregular galaxies in HI. The availability of HI data makes this data set useful for a wide range of studies of the structure, dark matter content and kinematics of late-type dwarf galaxies., Accepted for publication in A&A. 30 pages. 5.4 MB version with all figures is available at http://www.robswork.net/publications/WHISPII.ps.gz

We present the first results from the Faint Infra-Red Extragalactic Survey of the Hubble Deep Field South (HDF-S). Using a combination of deep near-infrared (NIR) data obtained with the Infrared Spectrograph and Array Camera at the VLT and the WFPC2 Hubble Space Telescope data, we construct a K-band-selected sample which is 50% and 90% complete for and K-s,K-AB less than or equal to 23.5 K-s,K-AB less than or equal to 22.0, respectively, where the magnitudes are measured over a diameter aperture. For z less than or equal to 3, our selection by the K-band flux chooses galaxies based on wavelengths redder than the rest-frame V band, and so selects them in a way that is less dependent on their current star formation rates than selection in the rest-frame UV. We developed a new photometric redshift technique that models the observed spectral energy distribution (SED) with a linear combination of empirical galaxy templates. We tested this technique using 150 spectroscopic redshifts in the Hubble Deep Field North (HDF-N) from the Cohen et al. sample (published in 2000) and found Deltaz/(1 + z) approximate to 0.07 for z 2 we find very luminous galaxies with L-V(rest) h(-2) L. (for Omega (M) = 0.3, Omega (Lambda) = 0.7, H-0 = 100 h km s(-1) Mpc(-1)). Local B-band luminosity functions predict 0.1 galaxies in the redshift range 2 less than or equal to less than or equal to 3.5 and with L-B(rest) greater than or equal to 5 x 10(10) h(-2) L.(,B), but we find nine. The discrepancy can be explained if L-B(*) increases by a factor of 2.4-3.2 with respect to locally determined values. Random errors in the photometric redshift can also play a role, and spectroscopic confirmation of the redshifts of these bright galaxies is required.

In order to study the nature of the far-infrared emission observed in radio-loud active galaxies, we have obtained 1.2 mm observations with the IRAM 30 m telescope for a sample of eight radio-loud active galaxies. In all objects we find that the 1.2 mm emission is dominated by non-thermal emission. An extrapolation of the non-thermal radio spectrum indicates that the contribution of synchrotron emission to the far-infrared is less than 10% in quasars, and negligible in the radio galaxies. The quasars in the sample show signs of relativistic beaming at millimeter wavelengths, and the quasar 3C334 shows evidence for strong variability., 6 pages, 1 figure, accepted by A&A

We present results of broad band {BVRI} observations of a sample of galaxies with a low surface brightness (LSB) disk and a bulge. These galaxies are well described as exponential disks and exponential bulges with no preferred value for either scale length or central surface brightness. The median {B} band disk scale length is 12.6 kpc (H_(0) = 75 km s^{-1} Mpc^{-1}) which is much larger than scale lengths of typical (disk dominated) LSB or high surface brightness (HSB) galaxies. Furthermore, the disk and bulge scale lengths are correlated, suggesting a coupling in the formation. Bulge dominated LSB galaxies are observed to be redder than disk dominated LSB galaxies and their bulge-to-disk ratios are increasing towards redder wavelengths. We find colors that are comparable to or bluer than HSB galaxies of the same morphological types. Bulge dominated LSB galaxies are therefore not faded HSB galaxies with no current star formation. We find that bulge dominated LSB galaxies fit in with the general trends defined by the HSB galaxies. The properties of these bulge dominated LSB galaxies show that LSB galaxies do not just come in two varieties. They cover the entire range in optical and morphological properties between late-type disk dominated LSBs and giant Malin-1-like LSBs. LSB galaxies thus also form a LSB Hubble sequence, parallel to the classical HSB one., Accepted for publication in Astronomy and Astrophysics, Main Journal

We have obtained integrated spectra and multi-filter photometry for a repre- sentative sample of ~200 nearby galaxies. These galaxies span the entire Hubble sequence in morphological type, as well as a wide range of luminosities (M_B = -14 to -22) and colors (B-R=0.4 to 1.8). Here we describe the sample selection criteria and the U, B, R surface photometry for these galaxies. The spectro- photometric results will be presented in a companion paper. Our goals for the project include measuring the current star formation rates and metallicity of these galaxies, and elucidating their star formation histories, as a function of luminosity and morphology. We thereby extend the work of Kennicutt (1992) to lower luminosity systems. We anticipate that our study will be useful as a benchmark for studies of galaxies at high redshift. We discuss the observing, data reduction and calibration techniques, and show that our photometry agrees well with previous work in those cases where earlier data are available. We present an atlas of images, radial surface brightness profiles and color profiles, as well as tables of derived parameters. The atlas and tables of measurements will be made available electronically. We study the correlations of galaxy properties determined from the galaxy images. Our findings include: (1) colors determined within the effective radius correlate better with morphological type than with M_B and (2) 50 per cent of the low luminosity galaxies are bluest in their centers., Comment: Accepted for publication in ApJS (scheduled for Vol.127, 2000 March); 56 pages, LateX, 5 figures and 3 tables included, atlas of images and radial profiles provided as GIF images in single tar-file; a full 600 dpi version is available at http://www.astro.rug.nl/~nfgs/

The spatial distribution of stars in a disk of a galaxy can be described by a radial scale length and a vertical scale height. The ratio of these two scale parameters contains information on the axis ratio of the velocity ellipsoid, i.e. the ratio of the vertical to radial stellar velocity dispersions of the stars, at least at some fiducial distance from the center. The radial velocity dispersion correlates well with the amplitude of the rotation curve and with the disk integrated magnitude, as was found by Bottema (1993). These relations can be understood as the result of the stellar disk being (marginally) stable against local instabilities at all length scales. This is expressed by Toomre's well-known criterion, which relates the sheer in the rotation to a minimum value that the radial stellar velocity dispersion should have for stability for a given surface density. Via the Tully-Fisher (1977) relation, the velocity dispersion then becomes related to the integrated magnitude and hence to the scale length. The vertical velocity dispersion relates directly to the scale height through hydrostatic equilibrium. It can be shown that the ratio of the two length scales relates to the axis ratio of the velocity ellipsoid only through the Toomre parameter Q and in particular does not require a choice of the mass-to-light ratio or a distance scale. We have applied this to the statistically complete sample of edge-on galaxies, for which de Grijs (1997) has performed surface photometry and has determined the length scales in the stellar light distribution., Comment: 10 pages A&A LaTeX, including 3 postscript figures, A&A in press

We have determined a dust-free colour-magnitude (CM) relation for spiral galaxies, by using I-K colours in edge-on galaxies above the plane. We find that the scatter in this relation is small and approximately as large as can be explained by observational uncertainties. The slope of the near-IR CM relation is steeper for spirals than for elliptical galaxies. We suggest two possible explanations. First, the difference could be caused by vertical colour gradients in spiral galaxies. In that case these gradients should be similar for all galaxies, on average 0.15 dex in [Fe/H] per scale height, and increase for later galaxy types. The most likely explanation, however, is that spirals and ellipticals have intrinsically different CM relations. This means that the stars in spirals are younger than those in ellipticals. The age, however, or the fraction of young stars in spiral galaxies, would be determined solely by the galaxy's luminosity, and not by its environment., 4 pages, to be published in Monthly Notices of the RAS (Letters)