-
[show abstract]
[hide abstract]
ABSTRACT: In this paper we study the large scale structures and their galaxy content
around the most X-ray luminous cluster known, RX J1347.5-1145 at z=0.45. We
make use of ugriz CFHT MEGACAM photometry and VIMOS VLT spectroscopy to
identify structures around the RXJ1347 on a scale of 20x20 Mpc2. We construct
maps of the galaxy distribution and the fraction of blue galaxies. We study the
photometric galaxy properties as a function of environment, traced by the
galaxy density. We identify group candidates based on galaxy overdensities and
study their galaxy content. We also use available GALEX NUV imaging to identify
strong unobscured star forming galaxies. We find that the large scale structure
around RXJ1347 extends in the NE-SW direction for at least 20 Mpc, in which
most of the group candidates are located. As other studies, we find that the
fraction of blue galaxies (Fblue) is a function of galaxy number density, but
the bulk of the trend is due to galaxies belonging to massive systems. The
fraction of the UV-bright galaxies is also function of environment, but their
relative numbers compared to the blue population seems to be constant
regardless of the environment. These UV emitters also have similar properties
at all galaxy densities, indicating that the transition between galaxy types
occurs in short time-scales. Candidate galaxy groups show a large variation in
their galaxy content and Fblue in those groups display little dependence with
galaxy density. This may indicate possible differences in their evolutionary
status or the processes that are acting in groups are different than in
clusters. The large scale structure around rich clusters are dynamic places for
galaxy evolution. In the case of RXJ1347 the transformation may start within
infalling groups to finish with the removal of the cold gas once galaxies are
accreted in massive systems. (ABRIDGED)
11/2011;
-
[show abstract]
[hide abstract]
ABSTRACT: The formation of ultra-compact dwarf galaxies (UCDs) is believed to be interaction driven, and UCDs are abundant in the cores of galaxy clusters, environments that mark the end-point of galaxy evolution. Nothing is known about the properties of UCDs in compact groups of galaxies, environments where most of galaxy evolution and interaction is believed to occur and where UCDs in intermediate state of evolution may be expected. The main goal of this study is to detect and characterize, for the first time, the UCD population of compact groups. For that, 2 groups in different evolutionary stages, HCG 22 and HCG 90, were targeted with VLT/FORS2/MXU. We detect 16 and 5 objects belonging to HCG 22 and HCG 90, respectively, covering the magnitude range -10.0 > M_R > -11.5 mag. Their colours are consistent with old ages covering a broad range in metallicities. Photometric mass estimates put 4 objects in HCG 90 and 9 in HCG 22 in the mass range of UCDs (>2x10^6 M_Sun) for an assumed age of 12 Gyr. These UCDs are on average 2-3 times larger than typical Galactic GCs, covering a range of 2 >~ r_h >~ 21 pc. The UCDs in HCG 22 are more concentrated around the central galaxy than in HCG 90, at the 99% confidence level. They cover a broad range in [alpha/Fe] abundances from sub- to super-solar. The spectra of 3 UCDs show tentative evidence for intermediate age stellar populations. We calculate the specific frequency (S_N) of UCDs for both groups, finding that HCG 22 has about three times higher S_N than HCG 90. The ensemble properties of the detected UCDs supports 2 co-existing formation channels: a star cluster origin and an origin as tidally stripped dwarf nuclei. Our results imply that the UCDs detected in both groups do not, in their majority, originate from relatively recent galaxy interactions. Most of the detected UCDs have likely been brought into the group with their host galaxies.[abridged] Comment: Accepted for publication at A&A, 17 pages, 9 figures + 2 additional figures
09/2010;
-
[show abstract]
[hide abstract]
ABSTRACT: We analyse the kinematic and chemical evolution of 203 distant spheroidal (elliptical and S0) galaxies at 0.2 < z < 0.8 which are located in different environments (rich clusters, low-mass clusters and in the field). VLT/FORS and CAHA/MOSCA spectra with intermediate-resolution have been acquired to measure the internal kinematics and stellar populations of the galaxies. From HST/ACS and WFPC2 imaging, surface brightness profiles and structural parameters were derived for half of the galaxy sample. The scaling relations of the Faber-Jackson relation and Kormendy relation as well as the Fundamental Plane indicate a moderate evolution for the whole galaxy population in each density regime. In all environments, S0 galaxies show a faster evolution than elliptical galaxies. For the cluster galaxies a slight radial dependence of the evolution out to one virial radius is found. Dividing the samples with respect to their mass, a mass dependent evolution with a stronger evolution of lower-mass galaxies (M < 2 × 1011 M⊙) is detected. Evidence for recent star formation is provided by blue colours and weak [OII] emission or strong Hδ absorption features in the spectra. The results are consistent with a down-sizing formation scenario which is independent from the environment of the galaxies (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Astronomische Nachrichten 11/2009; 330(9‐10):1010 - 1012. · 1.01 Impact Factor
-
B. L. Ziegler,
A. Böhm,
K. J. Fricke,
K. Jäger,
H. Nicklas,
R. Bender,
N. Drory,
A. Gabasch,
R. P. Saglia,
S. Seitz,
J. Heidt,
D. Mehlert,
C. Möllenhoff,
S. Noll,
and E. Sutorius
[show abstract]
[hide abstract]
ABSTRACT: We present the B-band Tully-Fisher relation (TFR) of 60 late-type galaxies with redshifts 0.1-1. The galaxies were selected from the FORS Deep Field with a limiting magnitude of R = 23. Spatially resolved rotation curves were derived from spectra obtained with FORS2 at the Very Large Telescope. High-mass galaxies with vmax 150 km s-1 show little evolution, whereas the least massive systems in our sample are brighter by ~1-2 mag compared with their local counterparts. For the entire distant sample, the TFR slope is flatter than for local field galaxies (-5.77 ± 0.45 vs. -7.92 ± 0.18). Thus, we find evidence for the evolution of the slope of the TFR with redshift on the 3 σ level. This is still true when we subdivide the sample into three redshift bins. We speculate that the flatter tilt of our sample is caused by the evolution of luminosities and an additional population of blue galaxies at z 0.2. The mass dependence of the TFR evolution also leads to variations for different galaxy types in magnitude-limited samples, suggesting that selection effects can account for the discrepant results of previous TFR studies on the luminosity evolution of late-type galaxies.
The Astrophysical Journal 12/2008; 564(2):L69. · 6.02 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: This continuing study of intragroup light in compact groups of galaxies aims to establish new constraints to models of formation and evolution of galaxy groups, specially of compact groups, which are a key part in the evolution of larger structures, such as clusters. In this paper we present three additional groups (HCG 15, 35 and 51) using deep wide field $B$ and $R$ band images observed with the LAICA camera at the 3.5m telescope at the Calar Alto observatory (CAHA). This instrument provides us with very stable flatfielding, a mandatory condition for reliably measuring intragroup diffuse light. The images were analyzed with the OV\_WAV package, a wavelet technique that allows us to uncover the intragroup component in an unprecedented way. We have detected that 19, 15 and 26% of the total light of HCG 15, 35 and 51, respectively, is in the diffuse component, with colours that are compatible with old stellar populations and with mean surface brightness that can be as low as $28.4 {\rm B mag arcsec^{-2}}$. Dynamical masses, crossing times and mass to light ratios were recalculated using the new group parameters. Also tidal features were analyzed using the wavelet technique. Comment: 12 pages, 5 figures. Accepted for publication in MNRAS. See http://www.eso.org/~cdarocha/publications/DaRochaetal2008_IGL_HCG.pdf for full resolution version. Complementary reference added
05/2008;
-
[show abstract]
[hide abstract]
ABSTRACT: We investigate the influence of ram-pressure stripping on the internal gas kinematics of simulated spiral galaxies. Additional emphasis is put on the question of how the resulting distortions of the gaseous disc are visible in the rotation curve and/or the full 2D velocity field of galaxies at different redshifts. A Milky-Way type disc galaxy is modelled in combined N-body/hydrodynamic simulations with prescriptions for cooling, star formation, stellar feedback, and galactic winds. This model galaxy moves through a constant density and temperature gas, which has parameters similar to the intra-cluster medium (ICM). Rotation curves (RCs) and 2D velocity fields of the gas are extracted from these simulations in a way that follows the procedure applied to observations of distant, small, and faint galaxies as closely as possible. We find that the appearance of distortions of the gaseous disc due to ram-pressure stripping depends on the direction of the acting ram pressure. In the case of face-on ram pressure, the distortions mainly appear in the outer parts of the galaxy in a very symmetric way. In contrast, in the case of edge-on ram pressure we find stronger distortions. The 2D velocity field also shows signatures of the interaction in the inner part of the disc. At angles smaller than 45 degrees between the ICM wind direction and the disc, the velocity field asymmetry increases significantly compared to larger angles. Compared to distortions caused by tidal interactions, the effects of ram-pressure stripping on the velocity field are relatively low in all cases and difficult to observe at intermediate redshift in seeing-limited observations. (abridged) Comment: 9 pages, 11 figures, accepted for publication in A&A
03/2008;
-
[show abstract]
[hide abstract]
ABSTRACT: We conducted a panoramic spectroscopic campaign with MOSCA at the Calar Alto observatory. We acquired spectra of more than 500 objects. Approximately 150 of these spectra were of galaxies that are members of six different clusters, which differ in intrinsic X-ray luminosity. The wavelength range allows us to quantify the star formation activity by using the OII and the Halpha lines. This activity is examined in terms of the large-scale environment expressed by the clustercentric distance of the galaxies as well as on local scales given by the spatial galaxy densities. A global suppression of star-formation is detected in the outskirts of clusters, at about 3Rvir. Galaxies with ongoing star-formation have similar activity, regardless of the environment. Therefore, the decline of the star-formation activity inside the investigated clusters is driven mainly by the significant change in the fraction of active versus passive populations. This suggests that the suppression of the star-formation activity occurs on short timescales. We detect a significant population of red star-forming galaxies whose colors are consistent with the red-sequence of passive galaxies. They appear to be in an intermediate evolutionary stage between active and passive types. Since a suppression of star-formation activity is measured at large clustercentric distances and low projected densities, purely cluster-specific phenomena cannot fully explain the observed trends. Therefore, as suggested by other studies, group preprocessing may play an important role in transforming galaxies before they enter into the cluster environment. Since models predict that a significant fraction of galaxies observed in the outskirts may have already transversed through the cluster center, the effects of ram-pressure stripping cannot be neglected. (ABRIDGED) Comment: Revised version. Astronomy and Astrophysics in press. Important typo corrected
09/2007;
-
[show abstract]
[hide abstract]
ABSTRACT: We investigate distortions in the velocity fields of disc galaxies and their use to reveal the dynamical state of interacting galaxies at different redshift. For that purpose, we model disc galaxies in combined N-body/hydrodynamic simulations. 2D velocity fields of the gas are extracted from these simulations which we place at different redshifts from z=0 to z=1 to investigate resolution effects on the properties of the velocity field. To quantify the structure of the velocity field we also perform a kinemetry analysis. If the galaxy is undisturbed we find that the rotation curve extracted from the 2D field agrees well with long-slit rotation curves. This is not true for interacting systems, as the kinematic axis is not well defined and does in general not coincide with the photometric axis of the system. For large (Milky way type) galaxies we find that distortions are still visible at intermediate redshifts but partly smeared out. Thus a careful analysis of the velocity field is necessary before using it for a Tully-Fisher study. For small galaxies (disc scale length ~2 kpc) even strong distortions are not visible in the velocity field at z~0.5 with currently available angular resolution. Therefore we conclude that current distant Tully-Fisher studies cannot give reliable results for low-mass systems. Additionally to these studies we confirm the power of near-infrared integral field spectrometers in combination with adaptive optics (such as SINFONI) to study velocity fields of galaxies at high redshift (z~2). Comment: 12 pages, 18 figures, accepted for publication in A&A, high resolution version can be found at http://astro.uibk.ac.at/~thomas/kronberger.pdf
07/2007;
-
[show abstract]
[hide abstract]
ABSTRACT: We investigate the near-infrared K-band evolution of early-type galaxies in the cluster of galaxies Abell2390 at z = 0.23. Using the Omega-Prime camera at the 3.5-m Calar Alto telescope deep imaging (texp = 53 min) over a 6' × 6' field has been obtained. The measured K-band magnitudes of 28 galaxies are combined with the spectroscopic and morphological data of Fritz et al. (2005) to construct the Faber-Jackson and Fundamental Plane relations in the NIR. By comparing our distant galaxies to a local sample of cluster ellipticals (Pahre 1999), we find on average a mild luminosity evolution for both scaling relations (ΔMK ~ 0.6 − 0.7 mag) compatible with passive evolution of the stellar populations.
Proceedings of the International Astronomical Union 07/2006; 2:187 - 187.
-
[show abstract]
[hide abstract]
ABSTRACT: We investigate 6 clusters of galaxies at intermediate redshift ( 0.18
< z < 0.3), in particular the star formation activity of galaxies.
Our Calar Alto MOSCA spectra cover large fields of view reaching out to
2-4 virial radii. This outer region is often called the infall region
since here newly arriving galaxies from the surrounding field encounter
the special environment of clusters for the first time. We selected 3
fields containing 2 clusters each from the X-ray Dark Cluster Survey
(XDC, Gilbank et al. 2004 MNRAS, 348, 551, G04) Each 40'×40' field
was observed with 7-8 slit-masks yielding 553 low-resolution galaxy
spectra (R ˜ 500). The results for the first field (R285), were
already published by Gerken et al. (2004, A&A, 421, 59). We select
[OII]λ3717 and Hα equivalent widths as indicators of star
formation activity.
In the analysis, we ``averaged'' 4 clusters: VMF73 (z=0.254) and VMF74
(z=0.18) in XDCS field R285 and VMF131 (z=0.295) and VMF132 (z=0.246) in
field R265 and we found an increase of the star forming activity towards
larger cluster-centric distances as well as towards shallower projected
galaxy densities. Galaxies in the third field R220 exhibit a complex
redshift structure which makes membership determination difficulty and
were excluded of the overall analysis. However, we clearly identified
the cluster VMF194 (z=0.211) and confirm another cluster at z=0.261
detected by G04. In addition, a group of galaxies with similar
coordinates to VMF194 at z=0.243 is significant. We also detected a
population of red star-forming galaxies, belonging to the red-sequence
of the clusters and even redder. Those galaxies show a moderate
star-forming activity and do not show any other spectral peculiarities.
We do not detect any post-starburst galaxy nor AGN in our cluster
sample.
05/2006; 26:201.
-
[show abstract]
[hide abstract]
ABSTRACT: We present an investigation of galaxy-galaxy interactions and their effects on the velocity fields of disc galaxies in combined N-body/hydrodynamic simulations, which include cooling, star formation with feedback, and galactic winds. Rotation curves (RCs) of the gas are extracted from these simulations in a way that follows the procedure applied to observations of distant, small, and faint galaxies as closely as possible. We show that galaxy-galaxy mergers and fly-bys disturb the velocity fields significantly and hence the RCs of the interacting galaxies, leading to asymmetries and distortions in the RCs. Typical features of disturbed kinematics are significantly rising or falling profiles in the direction of the companion galaxy and pronounced bumps in the RCs. In addition, tidal tails can leave strong imprints on the rotation curve. All these features are observable for intermediate redshift galaxies, on which we focus our investigations. We use a quantitative measure for the asymmetry of rotation curves to show that the appearance of these distortions strongly depends on the viewing angle. We also find in this way that the velocity fields settle back into relatively undisturbed equilibrium states after unequal mass mergers and fly-bys. About 1 Gyr after the first encounter, the RCs show no severe distortions anymore. These results are consistent with previous theoretical and observational studies. As an illustration of our results, we compare our simulated velocity fields and direct images with rotation curves from VLT/FORS spectroscopy and ACS images of a cluster at z=0.53 and find remarkable similarities. Comment: 13 pages, 14 figures, accepted for publication in A&A, some improvements and changes, main conclusions are unaffected
03/2006;
-
R. Bender,
I. Appenzeller,
A. Böhm,
N. Drory,
K. J. Fricke,
A. Gabasch,
J. Heidt,
U. Hopp,
K. Jäger,
M. Kümmel, [......],
H. Nicklas,
S. Noll,
R. P. Saglia,
W. Seifert,
S. Seitz,
O. Stahl,
E. Sutorius,
T. Szeifert,
S. J. Wagner, B. L. Ziegler
[show abstract]
[hide abstract]
ABSTRACT: Deep multicolor fields are an important tool to explore the formation and evolution of galaxies out to the highest redshifts
and faintest magnitude limits (Ferguson et al. [11]). This is also the aim of the FORS Deep Field (FDF), which has about 5
times the field-size of the two Hubble Deep Fields together and, in addition, contains a relatively bright quasar of 18.5mag
at z = 3.36 at its center. A full exploration of the FDF multicolor data requires good photometric redshifts. In this paper we
provide an overview of the data, describe our photometric redshift technique and present the redshift distribution in the
FDF.
02/2006: pages 96-101;
-
[show abstract]
[hide abstract]
ABSTRACT: Faber-Jackson and Tully-Fisher scaling relations for elliptical and spiral galaxy samples up to z=1 provide evidence for a differential behaviour of galaxy evolution with mass. In compliance with the downsizing scenario, the stellar populations of less massive galaxies display a stronger evolution than the more massive ones. For spirals, this may be attributed to a suppressed star formation efficiency in small dark matter halos. For ellipticals, star formation must have been negligible at least during the past ~4Gyr in all environments. Comment: 2 pages, 2 figures, to appear in proceedings of the XXIst IAP Colloquium "Mass Profiles and Shapes of Cosmological Structures", Paris 4-9 July 2005, France, (Eds.) G. Mamon, F. Combes, C. Deffayet, B. Fort, EAS Publications Series
09/2005;
-
[show abstract]
[hide abstract]
ABSTRACT: We have analyzed the intra-group light component of 3 Hickson Compact
Groups (HCG 79, HCG 88 and HCG 95) with detections in two of them: HCG
79, with 46±11% of the total B band luminosity and HCG 95 with
11±26%. HCG 88 had no component detected. This component is
presumably due to tidally stripped stellar material trapped in the group
potential and represents an efficient tool to determine the stage of
dynamical evolution and to map its gravitational potential. To detect
this low surface brightness structure we have applied the wavelet
technique OV_WAV, which separates the different components of the image
according to their spatial characteristic sizes.
EAS Publications Series 09/2005; 20:273-274.
-
[show abstract]
[hide abstract]
ABSTRACT: We investigate in detail 13 early-type field galaxies with 0.2<z<0.7 drawn from the FORS Deep Field. Since the majority (9 galaxies) is at z~0.4, we compare the field galaxies to 22 members of three rich clusters with z=0.37 to explore possible variations caused by environmental effects. We exploit VLT/FORS spectra (R~1200) and HST/ACS imaging to determine internal kinematics, structures and stellar population parameters. From the Faber-Jackson and Fundamental Plane scaling relations we deduce a modest luminosity evolution in the B-band of 0.3-0.5mag for both samples. We compare measured Lick absorption line strengths (Hdelta, Hgamma, Hbeta, Mg_b, & Fe5335) with evolutionary stellar population models to derive light-averaged ages, metallicities and the element abundance ratios Mg/Fe. We find that all these three stellar parameters of the distant galaxies obey a scaling with velocity dispersion (mass) which is very well consistent with the one of local nearby galaxies. In particular, the distribution of Mg/Fe ratios of local galaxies is matched by the distant ones, and their derived mean offset in age corresponds to the average lookback time. This indicates that there was little chemical enrichment and no significant star formation within the last ~5Gyr. The calculated luminosity evolution of a simple stellar population model for the derived galaxy ages and lookback times is in most cases very consistent with the mild brightening measured by the scaling relations. Comment: A&A acc., 17p., 7 colour figures, comments/discussion welcome! full resolution version available from http://www.uni-sw.gwdg.de/~bziegler/
12/2004;
-
[show abstract]
[hide abstract]
ABSTRACT: We have conducted an observing campaign with FORS at the ESO-VLT to explore the kinematical properties of spiral galaxies in distant galaxy clusters. Our main goal is to analyse transformation- and interaction processes of disk galaxies within the special environment of clusters as compared to the hierarchical evolution of galaxies in the field. Spatially resolved MOS-spectra have been obtained for seven galaxy clusters at 0.3<z<0.6 to measure rotation velocities of cluster members. For three of the clusters, Cl0303+17, Cl0413-65, and MS1008-12, for which we presented results including a TF-diagram in Ziegler et al. 2003, we describe here in detail the observations and data analysis. Each of them was observed with two setups of the standard FORS MOS-unit.With typical exposure times of >2 hours we reach an S/N>5 in the emission lines appropriate for the deduction of the galaxies' internal rotation velocities from [OII], Hbeta, or [OIII] profiles. Preselection of targets was done on the basis of available redshifts as well as from photometric and morphological information gathered from own observations, archive data, and from the literature. Emphasis was laid on the definition of suitable setups to avoid the typical restrictions of the standard MOS unit for this kind of observations. In total we assembled spectra of 116 objects of which 50 turned out to be cluster members. Position velocity diagrams, finding charts as well as tables with photometric, spectral, and structural parameters of individual galaxies are presented. Comment: 18 pages, 6 figures, accepted for publication in Astronomy and Astrophysics. A version with full resolution figures can be downloaded from http://www.uni-sw.gwdg.de/~vwgroup/publications.html
06/2004;
-
[show abstract]
[hide abstract]
ABSTRACT: We present our project on galaxy evolution in the environment of distant rich clusters aiming at disentangling the importance of specific interaction and galaxy transformation processes from the hierarchical evolution of field galaxies. Spatially resolved MOS spectra were gained with VLT/FORS to analyze the internal kinematics of disk galaxies. First results are shown for the clusters MS 1008.1-1224 (z=0.30), Cl 0303+1706 (z=0.42), and Cl 0413-6559 (z=0.51). Out of 35 late type cluster members, 13 galaxies exhibit a rotation curve of the universal form rising in the inner region and passing over into a flat part. The other members have peculiar kinematics. The 13 cluster galaxies for which a maximum rotation velocity could be derived are distributed in the Tully-Fisher diagram very similar to field galaxies from the FORS Deep Field with corresponding redshifts. The same is true for seven non-cluster galaxies observed in the cluster fields. The TF-cluster spirals do not show any significant luminosity evolution as might be expected from certain clusterspecific phenomena. Contrary to that, the disturbed kinematics of the non--TF cluster spirals indicate ongoing or recent interaction processes. Comment: 5 pages with 2 figures, to appear in Proc. of the IAU Colloquium 195: "Outskirts of Galaxy Clusters: Intense Life in the Suburbs", ed. A. Diaferio et al., Torino, Italy, March 12-16 2004
05/2004;
-
[show abstract]
[hide abstract]
ABSTRACT: We combine the latest observations of disk galaxy photometry and rotation curves at moderate redshift from the FORS Deep Field (FDF) with simple models of chemical enrichment. Our method describes the buildup of the stellar component through infall of gas and allows for gas and metal outflows. In this framework, we keep a minimum number of constraints and we search a large volume of parameter space, looking for the models which best reproduce the photometric observations in the observed redshift range (0.5<z<1). We find the star formation efficiency to correlate well with vMAX so that massive disks are more efficient in the formation of stars and have a smaller spread in stellar ages. This trend presents a break at around vMAX 140km/s. Galaxies on either side of this threshold have significantly different age distributions. This break has been already suggested by several authors in connection with the contribution from either gravitational instabilities or supernova-driven turbulence to star formation. No clear trend is seen between galaxy mass and infall timescale or gas outflows. The model presented in this paper suggests massive disks have formation histories resembling those of early-type galaxies, with highly efficient and short-lived bursts, in contrast with low-mass disks, which have a more extended star formation history. One option to explain the observed shallow slope of the Tully-Fisher relation at intermediate redshift could be small episodes of star formation in low-mass disks. Comment: 9 pages, 7 figures, uses mn2e.cls. Accepted for publication in MNRAS
03/2004;
-
S. Noll,
D. Mehlert,
I. Appenzeller,
R. Bender,
A. Boehm,
A. Gabasch,
J. Heidt,
U. Hopp,
K. Jaeger,
S. Seitz,
O. Stahl,
C. Tapken, B. L. Ziegler
[show abstract]
[hide abstract]
ABSTRACT: We present a catalogue and atlas of low-resolution spectra of a well defined sample of 341 objects in the FORS Deep Field. All spectra were obtained with the FORS instruments at the ESO VLT with essentially the same spectroscopic set-up. The observed extragalactic objects cover the redshift range 0.1 to 5.0. 98 objects are starburst galaxies and QSOs at z > 2. Using this data set we investigated the evolution of the characteristic spectral properties of bright starburst galaxies and their mutual relations as a function of the redshift. Significant evolutionary effects were found for redshifts 2 < z < 4. Most conspicuous are the increase of the average C IV absorption strength, of the dust reddening, and of the intrinsic UV luminosity, and the decrease of the average Ly alpha emission strength with decreasing redshift. In part the observed evolutionary effects can be attributed to an increase of the metallicity of the galaxies with cosmic age. Moreover, the increase of the total star-formation rates and the stronger obscuration of the starburst cores by dusty gas clouds suggest the occurrence of more massive starbursts at later cosmic epochs. Comment: 24 pages, 25 figures (35 PS files), 4 tables, accepted for publication in A&A. v2: minor typos corrected and references updated
01/2004;
-
[show abstract]
[hide abstract]
ABSTRACT: Using the Very Large Telescope in Multi Object Spectroscopy mode, we have observed a sample of 113 field spiral galaxies in the FORS Deep Field (FDF) with redshifts in the range 0.1<z<1.0. The galaxies were selected upon apparent brightness (R<23) and encompass all late spectrophotometric types from Sa to Sdm/Im. Spatially resolved rotation curves have been extracted for 77 galaxies and fitted with synthetic velocity fields taking into account all observational effects from inclination and slit misalignment to seeing and slit width. We also compared different shapes for the intrinsic rotation curve. To gain robust values of V_max, our analysis is focussed on galaxies with rotation curves which extend well into the region of constant rotation velocity at large radii. If the slope of the local Tully-Fisher relation (TFR) is held fixed, we find evidence for a mass-dependent luminosity evolution which is as large as up to 2 mag for the lowest-mass galaxies, but is small or even negligible for the highest-mass systems in our sample. In effect, the TFR slope is shallower at z~0.5 in comparison to the local sample. We argue for a mass-dependent evolution of the mass-to-light ratio. An additional population of blue, low-mass spirals does not seem a very appealing explanation. The flatter tilt we find for the distant TFR is in contradiction to the predictions of recent semi-analytic simulations. Comment: 18 pages, 14 figures, A&A, in press. Section on sample completeness added. Please note that the entire analysis is based on undisturbed, high quality rotation curves! Potential effects of tidal interactions are also discussed
09/2003;
