119100079
Galaxy stellar mass functions of different morphological types in clusters, and their evolution between z= 0.8 and 0
We present the galaxy stellar mass function and its evolution in clusters from z ∼ 0.8 to the current epoch, based on the WIde-field Nearby Galaxy-cluster Survey (WINGS) (0.04 ≤ z ≤ 0.07), and the ESO Distant Cluster Survey (EDisCS) (0.4 ≤ z ≤ 0.8). We investi- gate the total mass function and find that it evolves noticeably with redshift. The shape at M∗ > 10 11 Mdoes not evolve, but below M∗ ∼ 10 10.8 Mthe mass function at high red- shift is flat, while in the local Universe it flattens out at lower masses. The population of M∗ = 10 10.2 -10 10.8 Mgalaxies must have grown significantly between z = 0.8 and 0. We analyse the mass functions of different morphological types (ellipticals, S0s and late types), and also find that each of them evolves with redshift. All types have proportionally more massive galaxies at high than at low-z, and the strongest evolution occurs among S0 galaxies. Examining the morphology-mass relation (the way the proportion of galaxies of different morphological types changes with galaxy mass), we find it strongly depends on redshift. At both redshifts, ∼40 per cent of the stellar mass is in elliptical galaxies. Another ∼43 per cent of the mass is in S0 galaxies in local clusters, while it is in late types in distant clusters. To explain the observed trends, we discuss the importance of those mechanisms that could shape the mass function. We conclude that mass growth due to star formation plays a crucial role in driving the evolution. It has to be accompanied by infall of galaxies on to clusters, and the mass distribution of infalling galaxies might be different from that of cluster galaxies. However, comparing with high-z field samples, we do not find conclusive evidence for such an environmental mass segregation. Our results suggest that star formation and infall change directly the mass function of late-type galaxies in clusters and, indirectly, that of early-type galaxies through subsequent morphological transformations.
1840
Cluster formation in the LMC
In this work we present preliminary results concerning the properties of about 50 clusters and associations located in a densely populated region at the Southern edge of the supershell LMC~4. The ages of the clusters and associations are derived. The cluster formation rate peaks at about 10-20 Myr ago corresponding to the age of the formation of LMC~4. Objects younger than 10 Myr are located close to CO clouds, indicating a possible trigger of the recent star formation by the interaction of the supershell with the interstellar medium. 
Isophotal analysis has been done for 50% of the clusters. A large number of objects present isophotal distortions commonly interpreted as sign of interaction. Cluster multiplets are coeval within 20 Myr, suggesting a common origin. This indicates that clusters possibly form in large groups. Our findings are in agreement with the unified view of multi-scale star formation, where a size-duration correlation is expected.
16975153
The bright galaxy population of five medium redshift clusters II. Quantitative galaxy morphology
Aims. Following the study presented in our previous paper, based on the Nordic Optical Telescope (NOT) sample, which consists of five clusters of galaxies within the redshift range 0.18 ≤ z ≤ 0.25 imaged in the central 0.5–2 Mpc in very good seeing conditions, we have studied the quantitative morphology of their bright galaxy population Methods. We analyzed the surface brightness profiles of the galaxy population in those clusters, after performing simulations in order to check the reliability of the fits. We also derived a quantitative morphological classification. Results. The structural parameters derived from these analyses are presented. We obtained that the structural parameters of E/S0 galaxies are similar to those shown by galaxies in low redshift clusters. However, the disc scales are different. In particular, the scales of the discs of galaxies in medium redshift clusters are statistically different than those located in similar galaxies in the Coma cluster. However, the scales of the discs of galaxies in medium redshift clusters are similar to nearby field galaxies. Conclusions. Our results suggest that the evolution of the disc component of galaxies in clusters is faster than in field ones. Mechanisms like galaxy harassment showing timescales of ∼1 Gyr could be responsible for this disc scale evolution. This indicates that spiral galaxies in clusters have undergone a strong evolution in the last 2.5 Gyr or that Coma is in some way anomalous.
18425047
The peculiar galaxy IC 1182: An ongoing merger?
Broad and narrow band images and long slit spectroscopy of IC1182 are presented. The broad band images reveal a distorted morphology with a large, heavily obscured disk-like structure and several knots in the central region. Galactic material, some of it in the form of two tails, is detected well beyond the main body of the galaxy. The second, fainter tail and several knots are reported here for the first time. The narrow band images show that the galaxy is a powerful emitter. The emission in the main lines extends all over the galaxy, with plumes and arc-like structures seen in H$\alpha$ at large distances from the center. The uncorrected H$\alpha$ flux corresponds to 3.51$\times10^{41}$ erg s$^{-1}$, 3 times that of Arp 220. The internal extinction deduced from the Balmer decrement is high all along the slit, with E$_{B-V}\approx$ 1. There are no clear signs of nuclear activity and the observed line ratios can be explained in terms of stellar photoionization. The metallicity of the gas in the two brightest central knots is low, 0.1 Z$_{\odot}$ and 0.06 Z$_{\odot}$ respectively. In the main body of the galaxy, besides the reported knots, the distribution of the ionized gas resembles that of an inclined disk about 12 kpc in size. The rotation pattern is complex and corresponds to two identifiable disk galaxies with observed rotation amplitudes of 200 \kms and 100 \kms respectively. The data presented here indicate that IC 1182 is a high luminosity starburst system, involving two systems in the process of merging, with two tidal tails emerging from the central region of the galaxy.
14891588
The visible environment of galaxies with counterrotation
In this paper we present a statistical study of the environments of 49 galaxies in which there is gas- or stellar-counterrotation. The number of possible companions in the field (to apparent magnitude 22), their size and concentration were considered. All the statistical parameters were analysed by means of Kolgomorov-Smirnov tests, using a control sample of 43 galaxies without counterrotation. From our data, no significant differences between the counter-rotating and control samples appear. This is different to Seyfert or radio-loud galaxies which lie in environments with a higher density of companions. On the contrary, if a weak tendency exists, for galaxies with gas counterrotation only, it is discovered in regions of space where the large scale density of galaxies is smaller. Our results tend to disprove the hypothesis that counterrotation and polar rings derive from a recent interaction with a small satellite or a galaxy of similar size. To a first approximation, they seem to follow the idea that all galaxies are born through a merger process of smaller objects occurring very early in their life, or that they derive from a continuous, non-traumatic infall of gas that formed stars later. Whatever the special machinery is which produces counterrotation or polar rings instead of a co-planar, co-rotating distribution of gas and stars, it seems not to be connected to the present galaxy density of their environments.
119325667
The scaling relations of early{type galaxies in clusters ? I. Surface photometry in seven nearby clusters
This is the first paper of a series investigating the scaling relations of early–type galaxies in clusters. Here we illustrate the multi–band imagery and the image reduction and calibration procedures relative to the whole sample of 22 clusters at $0.05 \mathrel{\raise0.35ex\hbox{$\scriptstyle <$}\kern-0.6em \lower0.40ex\hbox{{$\scriptstyle \sim$}}}z \mathrel{\raise0.35ex\hbox{$\scriptstyle <$}\kern-0.6em \lower0.40ex\hbox{{$\scriptstyle \sim$}}}0.25$. We also present detailed surface photometry of 312 early–type galaxies in 7 clusters in the first redshift bin, $z \approx0.025$–0.075. We give for each galaxy the complete set of luminosity and geometrical profiles, and a number of global, photometric and morphological parameters. They have been evaluated taking into account the effects of seeing. Internal consistency checks and comparisons with data in the literature confirm the quality of our analysis. These data, together with the spectroscopic ones presented in the second paper of the series, will provide the local calibration of the scaling relations.
119456485
Measurement of the branching ratios psi-prime ---> e+ e-, psi-prime ---> J/psi pi pi and psi-prime ---> J/psi eta
The authors have measured several branching ratios for {psi}' decay using the data collected by FNAL E835 experiment during year 2000, obtaining {beta}({psi}' {yields} e{sup +}e{sup -}) = 0.0068 {+-} 0.0001 {+-} 0.0004, {beta}({psi}' {yields} J/{psi}{pi}{sup +}{pi}{sup -}) = 0.292 {+-} 0.005 {+-} 0.018, {beta}({psi}' {yields} J/{psi}{pi}{sup 0}{pi}{sup 0}) = 0.167 {+-} 0.005 {+-} 0.014 and {beta}({psi}' {yields} J/{psi}{eta}) = 0.028 {+-} 0.002 {+-} 0.002. They also present a measurement of the dipion mass distribution in the decays {psi}' {yields} J/{psi}{pi}{pi}.
116975111
RICH for PANDA
Abstract The powerful particle identification detection system of the P ¯ ANDA (antiProton ANihilations at DArmstadt) experiment contains three Cherenkov detectors. In the forward direction a conventional RICH detector is planned. In the high solenoid field of the target spectrometer thin Cherenkov detectors using the DIRC principle are mandatory and are envisaged in the form of a barrel and a vertical disc. The combination of the time of arrival of the photons with their spatial image determines not only the particle velocity, but also the wavelength of the photons. Therefore dispersion corrections on the lower and upper detection threshold is possible. Investigations concerning the development of a 3D-Barrel-DIRC are discussed as well as two different studies realizing a new Disc-DIRC for the forward angles. One is based on the Time of Propagation (ToP) method the other on the readout with focusing light guides.
123275132
The new scintillating fiber detector of E835 at Fermilab
Abstract The scintillating fiber tracker for the measurement of the polar coordinate θ for experiment E835 at Fermilab has been upgraded, by adding two extra layers (240 fibers each), at R ≈9 cm from the beam axis. Photons from the fibers are detected by Visible Light Photon Counters (VLPCs). The high granularity, flexibility and fast response of the scintillating fibers, combined with the high quantum efficiency of the VLPCs, allow high rate capability, high efficiency, good tracking and time resolution. Signals from the outer two layers are used to provide θ information to the first-level trigger.
119676532
Development of a cylindrical scintillating fiber tracker for experiment E835 at FNAL
Abstract A tracking detector made of scintillating fibers wound on a cylinder is being developed at FNAL, for the experiment E835 (study of the spectroscopy of charmonium formed in p p annihilations, at the Fermilab Antiproton Accumulator). The tracker will be used for the measurement of the polar angle, i.e. of the longitudinal coordinate. The small amount of light from the fibers will be detected by solid state devices (Visible Light Photon Counters) with very high QE, currently being developed and tested by the D0 Fiber Tracking Group at FNAL. This paper reports the performance of a prototype fiber tracker, as measured at FNAL. We present results on light yield/mip, attenuation, efficiency, homogeneity of response and cross-talk. The data are then compared with Monte Carlo predictions. We measured an average number of 14 photoelectrons per mip and a very low noise level. An efficiency greater than 99% is foreseen for the future double layered tracker.
118292440
Measurement of the angular distribution in anti-p p ---> psi(2S) ---> e+ e-
The authors present the first measurement of the angular distribution for the exclusive process {bar p}p {yields} {psi}(2S) {yields} e{sup +}e{sup -} based on a sample of 6844 events collected by the Fermilab E835 experiment. They find that the angular distribution is well described by the expected functional form dN/d cos {theta}* {proportional_to} 1 + {lambda} cos{sup 2} {theta}*, where {theta}* is the angle between the antiproton and the electron in the center of mass frame, with {lambda} = 0.67 {+-} 0.15(stat.) {+-} 0.04(sys.). The measured value for {lambda} implies a small but non zero {psi}(2S) helicity 0 formation amplitude in {bar p}p, comparable to what is observed in J/{psi} decays to baryon pairs.