Abstracts


Name: Maria Carmen Toribio
Title: VLA observations and Tully-Fisher distances of gas-poor spiral galaxies in the Virgo Cluster Region
Abstract:
The Virgo cluster region spirals NGC 4307, NGC 4356, NGC 4411B, and NGC 4492 were identified in a previous statistical study of the three-dimensional distribution of the atomic hydrogen in these region of the sky as objects with a substantial dearth of HI that could be lying outside the main body of the cluster. Here we present the results of our high-sensitivity, high-resolution Very Large Array observations in the 21 cm line of fields centered on the selected galaxies. Our measurements, together with data from the literature, are also used to emphasize the substantial uncertainties affecting the Tully-Fisher radial distance estimates to these objects. Authors: M. Carmen Toribio Josep M. Solanes

Name: Breezy Ocaña Flaquer
Title: Molecular gas in radio-galaxies.
Abstract:
Powerful radio-AGN are normally hosted by massive elliptical galaxies which are usually very poor in molecular gas. Nevertherless the central black hole needs molecular gas to feed the nuclear activity. Thus it is important to study the origin, the distribution and the kinematics of the molecular gas in such objects. We have performed at the IRAM-30m telescope, a survey of the CO(1-0) and CO(2-1) emission in the most powerful radio galaxies of the Local Universe, selected only on the basis of their radiocontinuum fluxes. The main result of that survey is the very low content in molecular gas of such galaxies compared to Seyfert galaxies. The median value of the molecular gas mass is 4x108 solar masses. Moreover, the CO spectra indicate the presence of a central molecular gas disk in these radio galaxies. Our results contrast with previous surveys, mainly selected through the FIR emission, with a larger mass of molecular gas observed. The first results indicate that minor mergers are good candidates to fuel the central part of the radio galaxies of our sample. We complement the CO survey with photometric data of Spitzer (both the Infrared Array Camera -IRAC, and the Multi-band Imager Photometer for Spitzer -MIPS), as well as the IRAS satelite fluxes and all centimetric data found in NED, with the purpose of studyng the dust (Spectral Energy Diagram (SED), morphology) and its relation with the molecular gas and the AGN. Also we will analize the HI content of these radio galaxies to study possible interactions and to compare with the molecular gas content.

Name: Sanchayeeta Borthakur
Title: Nature and Origin of the Neutral Intra-group medium in Compact Group Environments
Abstract:
We present the results of our 21cm GBT/VLA study discovering a significant diffuse neutral intra-group medium (IGM) (on an average 39% of the total HI mass of the groups) in a sample of 18 Hickson Compact Groups (HCGs). HCGs are dense concentration of galaxies where strong tidal interactions coupled with low velocity dispersions are at work to constantly change the gas distribution and morphology in galaxies and in the IGM. HCGs are found to be deficient in HI although our new detections have reduced the previously estimated deficiency values considerably. In our study, we compared HI detected by the GBT (single dish) and the VLA (interferometer) and found significant excess (77%) in the GBT spectra, which is well beyond the scope of any calibration error. The GBT detected broad HI wings rather than discrete features thus suggesting the presence of a fainter component over a large velocity range. By comparing the instrumental properties of the two instruments we conclude that this excess must be in the form of a diffuse neutral intra-group medium that is most likely being fed by the ISM of individual galaxies. With the presence of a significant IGM, processes like ram-pressure stripping, large scale shocking of the gas as the galaxies ram through the IGM can be very crucial and would aid in gas stripping along with tidal forces. We found a statistically significant correlation between the percentage of diffuse gas in a system and its HI deficiency, Hubble type of the central galaxy and the evolutionary stage of the group, which advocates the gradual dispersion of neutral gas into the IGM.

Name: Danielle Lucero
Title: The HI-H2 Pressure Relation In Early-Type Galaxies
Abstract:
Authors: Danielle Lucero, Lisa Young Galaxies which are rich in cold gas tend to have roughly equal amounts of gas in the atomic and in the molecular phase. But, to the best of our knowledge, star formation only occurs in the molecular phase. Therefore, the global balance between atomic and molecular gas is crucial to the long-term evolution of galaxies and their stellar populations. Recently, studies of the gas content of a large sample of nearby spiral galaxies have shown that the ratio of molecular to atomic gas is a very tight function of the midplane hydrostatic pressure. We present the results of a study that aims to determine whether this pressure relation holds for galaxies in cluster environments as well as in early-type galaxies. Atomic and molecular column densities have been obtained from VLA HI observations and existing CO data for a sample of eleven early-type galaxies which reside in a variety of environments. We estimate the hydrostatic pressure at the midplane of an axisymmetric early-type galaxy, taking the gravitational potential of our sample galaxies from 2MASS K band images using the multi-Gaussian Expansion method of Cappellari (2002). This work fills an important niche in the larger-scale study of gas and galaxy evolution by helping to disentangle the effects of the environment and morphology (Hubble type) on the interstellar medium.

Name: Salman Hameed
Title: Tracing evolution of early-type spirals through the neutral hydrogen window
Abstract:
Early-type (Sa-Sab) spirals are slowly gaining a reputation of being highly dynamic systems representing diverse range of properties, perhaps a consequence of past interactions. Neutral hydrogen window provides an opportunity to identify galaxies with recent galactic encounters. We have looked for interaction signatures in large scale neutral hydrogen distribution for 22 nearby Sa-Sab galaxies displaying a wide range of star formation rates. We find that 10 out of these 22 galaxies show HI anomalies that can be attributed to a recent interaction. While our sample is slightly biased towards high rates of star formation, our results support claims regarding recent dynamic history of these large bulge spiral galaxies.

Name: Joe Helmboldt
Title: The HI content of elliptical and lenticular galaxies with recent star formation
Abstract:
As a first step toward constraining the efficiency of the star formation episodes that lead to elliptical (E) and lenticular (S0) K+A galaxies, a survey for HI within a sample of E and S0 K+A galaxies and their likely progenitors (i.e., actively star forming E and S0 galaxies) has been conducted with the NRAO Green Bank Telescope (GBT). The sample was taken from a larger parent sample drawn from the Sloan Digital Sky Survey (SDSS). Here, the GBT data and initial results are discussed. Over half (19 out of 30) of all observed galaxies have detectable 21-cm emission. It was found that both the K+A and star forming early-type (SFE) galaxies were on average more gas poor than disk galaxies at the same luminosity while being more gas rich than more typical E and S0 galaxies with detected 21-cm emission. The gas richness of K+A galaxies appears to be similar to that of SFE galaxies. The star formation rates and estimated star formation time scales of the SFE galaxies imply that they are capable of only marginally changing their atomic hydrogen content. Follow-up observations are required to explore these same issues in terms of molecular gas, which is more likely to actively participate in the star formation process. Kinematic data for the HI gas, the warm ionised gas, and the stars within the galaxies combined with the SDSS g and i band surface brightness profiles imply that the atomic hydrogen is most likely spatially coincident with the star forming regions within ~1 kpc of the galaxies' centers.

Name: Jana Grcevich
Title: HI in Local Group Dwarf Galaxies
Abstract:
The HI content of the newly discovered satellites of the Milky Way has not been previously studied. We use HIPASS (HI Parkes All Sky Survey), LAB (Leiden/Argentine/Bonn), and GALFA (Galactic Arecibo L-band Feed Array) survey data to explore HI in the environment of the newly discovered dwarf galaxies and add this information to what was previously known about HI in the dwarf spheroidal and lower mass dwarf irregular galaxies of the Local Group. All of the new satellites discovered in the Sloan Digital Sky Survey data have limits on their HI masses which range from < 13 Solar Masses to 30,000 Solar Masses, except for Leo T, which has an HI mass of approximately 10^5 Solar Masses. Galaxies within 300 kpc of the Milky Way or Andromeda are all undetected in HI to low limits, or have ambiguous detections, while those further than 300 kpc are predominantly detected with masses > 10^5 Solar Masses. The most favored explanation for the lack of HI in dwarf galaxies at small galactocentric distances is ram pressure stripping of the gas in the dwarf galaxy by the larger galaxy's hot halo gas. The HI content will also be discussed in terms of the fuel it provides to the Milky Way and the star formation history of the dwarfs. Finally, I will discuss the discovery in the GALFA data of discrete HI clouds with characteristics similar to known dwarf galaxies.

Name: Roban Kramer
Title: The Thickness of High-Redshift Quasar Ionization Fronts as a Constraint on the Ionizing Spectral Energy Distribution
Abstract:
High-redshift quasars (z >~ 6) drive ionization fronts into the intergalactic medium (IGM), with the thickness of the front generally increasing with the hardness of ionizing spectrum. If the thickness of the front can be measured, it can provide a novel constraint on the ionizing spectral energy distribution (SED), uniquely available for sources prior to the end of reionization. Here we follow the propagation of an I-front into a uniform IGM, and compute its thickness for a range of possible spectra and ages of the quasar, neutral hydrogen density and clumping of the IGM. We also explore the effects of non-uniform ionizing backgrounds. We find that even for hard spectra, the fronts are initially thin, with a thickness much smaller than the mean free path of ionizing photons. The front gradually thickens as it approaches equilibrium in 10^8 10^9 years, and the thickness of its outer part can eventually significantly exceed simple estimates based on the mean free path. With a sufficiently high intrinsic hydrogen column density obscuring the source (log(N_H) >~ 19.2) or a sufficiently hard power-law spectrum combined with some obscuration (d(log F_\nu)/d(log nu) >~ -1.2 at log(N_H) = 18.0), the outer thickness of the front exceeds ~1 physical Mpc and may be measurable from the three-dimensional morphology of its redshifted 21cm signal. We find that the highly ionized inner part of the front, which may be probed by Lyman line absorption spectra, remains thin for bright quasars unless a large obscuring column (log(N_H) >~ 19.2) removes most of their ionizing photons up to ~40 eV. However, for sources with log(N_H) >~ 19.8, the black Lyman-alpha trough (where the neutral fraction is ~10^-3) underestimates the size of the HII region by a factor of ~4.

Name: Jesse Miner
Title: Environmental dependence of HI content in spirals.
Abstract:
We have investigated the dependence of the HI content of spiral galaxies on local density, using the Arecibo catalog made public by Springob et al (2005). We define the HI content with the DEF parameter (Solanes et al 1996), which is the ratio of HI mass expected from a sample of "normal" spirals of the same morphological type to the observed HI mass. Our sample of normal spirals is slightly different than those used by Solanes et al, and includes only galaxies below a local density threshold. The local density is calculated using a volume-limited sample from the Updated Zwicky Catalog (Falco et al, 1999), with an adaptive spherical volume which depends on the mean distance to the six nearest neighbors. Because both the calculated densities and HI fluxes are affected by Malmquist-type biases, our analysis has required careful examination of any selection effects which may influence the correlation of DEF with local density. Our results show that there is a slight but statistically insignificant increase of DEF with local density up to the cluster density regime, where the DEF increases rapidly. This is in agreement with cluster studies which show an increase in gas deficient galaxies with decreasing cluster-centric distance. We also include the Virgo and Pegasus clusters for comparison to the large survey, because they are well-studied and represent two different cluster density regimes.

Name: Adrienne Stilp
Title: Tools for Creating HI Data from N-body/SPH Simulations
Abstract:
We present results from a project to create HI data cubes from N-body/SPH simulations run by the University of Washington's N-body Shop. The cubes can be smoothed to mimic any resolution available at radio telescopes. Using the "observed" data cubes, IDL tools have been implemented to create maps of total HI mass, velocity field, and velocity dispersion, as well as radial profiles and spectra as a function of position. The eventual goal of the project is correlate the temporal and spatial affects of star formation on the neutral ISM gas by comparing simulated galaxies with both VLA HI data and HST data of spatially- and temporally-resolved star formation for galaxies within 4 Mpc.

Name: Zhong Wang
Title: Infrared and Ultraviolet Observations in the Outer Disk of NGC 4254
Abstract:
We report observations of the outer disk of NGC 4254 in the Virgo cluster, in connection to the potential dark galaxy VIRGOHI21 first reported by Minchin et al., with the Spitzer and Galex telescopes. The upper limits set by the mid-infrared observations at the location of the dark HI cloud are consistent with it being diffuse gas of tidal origin, instead of self-gravitating dense clouds. On the other hand, the excess UV emission found in the vicinity of the tidally-disrupted areas appears to suggest a history of more recent star formation. We discuss these observations in light of the existing models of galaxy interaction and ram pressure stripping, and show how environmental factors can be of crucial importance to star formation in the outer disk.

Name: D.J. Pisano
Title: The HI properties of the local analogs to z~1 star-forming galaxies.
Abstract:
Luminous Compact Blue Galaxies (LCBGs) are common at z~1, representing ~20% of the galaxy population and contributing ~40% of the total star formation rate density at that time, but are a factor of ten rarer by the present day. While we know that LCBGs are rapidly evolving, we do not know what drives their evolution or into what type of galaxy they evolve. We present original and archival HI data from Arecibo, the Green Bank Telescope (GBT), Nancay, and Parkes for a sample of local analogs to the intermediate redshift LCBGs. These data provide us with a measure of the fuel for future star formation and the dynamical masses of LCBGs; information that we can not currently obtain for z~1 LCBGs. The data reveal that LCBGs are a diverse collection of galaxies. LCBGs are gas-rich and prolifically forming stars, such that, at their current SFR, the majority will consume their HI within 5 Gyr. LCBGs have dynamical masses consistent with low-mass galaxies, such as dwarf ellipticals, dwarf irregular or late-type spirals. If intermediate redshift LCBGs have similar physical properties to their local counterparts, then it is unlikely that they will evolve into today's population of massive ellipticals and grand-design spirals nor into dwarf spheroidal galaxies. Our observations provide a first look at what the SKA will detect from the dominant star-forming population at a redshift of one.

Name: Eva Manthey
Title: IC 10 - a cosmic bluebottle
Abstract:
IC 10 is one of the nearest starbursting dwarf galaxies. Therefore, this galaxy is ideal to study the connection between the ongoing starburst and the interstellar medium. . We obtained a deep HI mosaic using the Westerbork Interferometer to study in particular faint structures in the surroundings of IC 10. We found a complex and disturbed HI distribution covering almost 1 deg^2. Several tail-like structures with a chaotic velocity field are observed. These data allow us to investigate whether the extended HI features occur due to starburst-driven superwinds, which sweep the gas away from the galaxy, or if they reflect accretion of (primordial) intergalactic material, which might fuel the starburst.

Name: Judd Bowman
Title: Observing Neutral Hydrogen Above Redshift 6: The “Global” Perspective
Abstract:
Above redshift 6, the dominant source of neutral hydrogen in the Universe shifts from localized clumps in and around galaxies and filaments to a pervasive, diffuse component of the intergalactic medium (IGM). This transition tracks the global neutral fraction of hydrogen in the IGM and can be studied, in principle, through the redshifted 21 cm hyperfine transition line. During the last half of the reionization epoch, the mean (global) brightness temperature of the redshifted 21 cm emission is proportional to the neutral fraction, but at earlier times (10 < z < 25), the mean brightness temperature should probe the spin temperature of neutral hydrogen in the IGM. Measuring the (approximately 30 mK) mean brightness temperature of the redshifted 21 cm line as a function of frequency (and hence redshift) would chart the evolution of galaxies through the heating and ionizing of the IGM by their stellar populations. The timing and duration of several expected features in the global brightness temperature could provide valuable constraints on the nature of early stars. Experiments are already underway to accomplish this task or, at least, provide basic constraints on the evolution of the mean brightness temperature. I will provide a brief overview of one of these experiments and discuss prospects for future results.

Name: Bjorn Emonts
Title: Large-scale HI and the merger history of different types of radio galaxies
Abstract:
Large-scale HI gas is an excellent tool to trace galaxy mergers and interactions. Powerful radio-loud AGN have often been suggested to be triggered by such gas-rich mergers. In order to investigate a possible relation between galaxy mergers and radio source triggering, we studied the large-scale HI properties of complete samples of nearby radio galaxies. We find that the host galaxies of different types of radio sources (compact, FR-I and FR-II) appear to have fundamentally different large-scale HI properties: the more powerful radio galaxies (Fanaroff & Riley type-II, with relativistic jets ending in bright hot-spots) often appear to show tidal HI structures, indicative of a recent galaxy merger or collision, while the lower power radio galaxies (FR-I, with sub-relativistic, edge-darkened jets) are devoid of large amounts of extended HI. The host galaxies of several low power compact radio sources contain a giant HI disk or ring, possibly a relic of an old merger. Our HI results suggest that different types of radio galaxies may have had a different formation history, which could indicate a fundamental difference in the triggering mechanism of the radio source. If confirmed by larger statistical studies with future radio telescopes, this means that radio source properties may be an excellent indicator for the properties and formation history of the underlying host galaxy. This is particularly important for understanding galaxy evolution in the high-redshift Universe, where powerful radio sources can be observed as beacons for galaxies that are often too faint to be studied in detail at optical wavelengths. In this respect, I will also discuss an upcoming project, in which we aim to study the cold neutral and molecular hydrogen gas in high-z radio galaxies with existing radio telescopes.

Name: Pang Xiaoying
Title: Open Clusters in the Milky Way, Global Properties
Abstract:
This research has made use of the WBETA database of 2007, operated at the Institute for Astronomy of the University of Vienna.The data of open clusters in the Galaxy consists of 970 open clusters, in which 911 open clusters have age determination, 920 have distance to the Sun, 911 have color excess data. Base on the statistics analysis of global properties of open clusters, we aim at deriving disk properties, height above the Galactic plane of the Sun. It turns out that old open clusters (age> 1 Gyr ) are preferentially located far from the galactic plane with <|z| >~ 394.5 pc and in the outer part of the galactic disk, which was first noticed by Van den Bergh (1958) for 4 open clusters which were known at that time. The young open clusters are distributed on the Galactic plane almost symmetrically about the Sun with a scale height perpendicular to the galactic plane of 50.2 pc. The open cluster age distribution can be fit approximately with a two-component exponential decay function: one component has an age scale factor of 167Myr, and the other consists of longer-lived clusters with an age scale of 1.2 Gyr, which are smaller than those derived by Janes & Phelps (1994), 200Myr and 4 Gyr for the young and old OCs respectively. As a consequence of the completeness effects, the observed radial distribution of OCs with respect to Galactocentric distance does not follow the expected exponential profile, instead it falls of both for regions external to the Solar circle and more sharply towards the Galactic center, which is probably due the giant molecular cloud disruption in the center. We simulate the effects of completeness using two models, in which the intrinsic number of observable stars are distributed: (i) assuming the actual positions of the OCs in the sample, and (ii)random selection of OC positions. As a result we derive completeness-corrected radial distributions which agree with exponential disks throughout the observed Galactocentric distance in the range of 5 ~ 15 kpc, with scale lengths in the range of RD = 1.6 ~ 2.8 kpc.

Name: Eva Manthey
Title: HI in SAURON early-type galaxies
Abstract:
ntegral-field spectroscopy usinig the SAURON spectrograph was obtained to investigate the stars and the ionised gas. Here we present first results from our HI survey of the SAURON galaxies. So far, we observed 34 galaxies with the Westerbork Radio Synthesis Telescope to map the neutral hydrogen distribution and study the kinematics of the cold gas. Both field and cluster galaxies were included in the sample to search for environment effects. HI was detected in 60% of the field galaxies, whereas only in one cluster galaxy HI could be found. We also investigated the dependence on the continuum emission and the dynamical type of the galaxies. Furthermore, we used the existing optical 2D spectroscopic data taken with the SAURON spectrograph to compare the kinematics of the cold neutral gas with the ionised gas and the stars. While the ionised and neutral gas typically show the same rotation sense, we found several cases in which the gas counter-rotates compared to the rotation of the stars.

Name: Erik Muller
Title: Zooming into the ISM of the SMC
Abstract:
We present the highest-available resolution observations of the neutral hydrogen ISM in the most active and turbulent part of the nearby Small Magellanic Cloud. These ATCA observations of the South-West SMC are combined with existing datasets to extend the previous resolution limits down to ~2 pc. In doing so, we have contiguously sampled scales from ~kpc down to the parsec level. At these smaller scales, we are now probing the scales over which star formation is expected to directly shape and modify the ISM by the action of stellar winds, planetary nebulae, and SNe.

Name: Trish Henning
Title: The ALFA Zone of Avoidance Survey
Abstract:
The Extragalactic ALFA Zone of Avoidance team is mapping the distribution of low-Galactic-latitude galaxies and large scale structures through detection of galaxies' 21-cm emission with ALFA. This Zone of Avoidance survey finds new HI galaxies which lie hidden behind the Milky Way, and also provides redshifts for partially-obscured galaxies known at other wavelengths. In this way, we are illuminating the large scale structure in the local Universe in the low-Galactic-latitude sky where it is currently poorly mapped. Two precursor regions have been observed to date, totalling 140 square degrees. The results from these early observations will be presented, and prospects for the full survey discussed.

Name: Steven Gibson
Title: Mapping Hydrogen in the Galaxy, Galactic-Halo and Local Group with the Galactic Arecibo L-Band Feed Array (GALFA)
Abstract:
The GALFA-HI Survey will map the entire Arecibo sky at 21-cm over a velocity range of -700 to +700 km/s with a resolution of 0.2 km/s and 3.4 arcminutes using the Arecibo L-Band Feed Array. This poster presents highlights from the TOGS (Turn on GALFA Survey) portion of GALFA-HI, which covers a large portion of the Arecibo sky with commensal drift scan observing with ALFALFA and AGES.

Name: Barbara Catinella
Title: The GALEX - Arecibo SDSS Survey (GASS)
Abstract: The GALEX Arecibo SDSS Survey (GASS; PI: D. Schiminovich) is a large targeted survey to be carried out at Arecibo. GASS is designed to measure the neutral hydrogen content of a representative sample of massive, transitional galaxies (i.e., in transition from the blue cloud to the red sequence), uniformly selected from the SDSS spectroscopic and GALEX imaging surveys. GASS will prodcue the first statistically significant sample of massive transition galaxies with homogeneously measured stellar masses, star formation rates and gas properties. The final database will include optical, UV and HI parameters for ~1000 galaxies with stellar mass greater than 1010 solar masses and gas mass fractions as low as 1.5%. The analysis of this sample will allow us to investigate if and how the cold gas responds to a variety of different physical conditions in the galaxy, thus yielding insights on the physical processes responsible for the transition between blue, star-forming and red, passively evolving galaxies. GASS will be of considerably legacy value not only in isolation but also by complementing on-going HI-selected surveys.

Name: Wim van Driel
Title: NIBLES: an HI census of local SDSS galaxies
Abstract:
NIBLES (Nancay Interstellar Baryons Legacy Extragalactic Survey) is a Key Project proposed for the 100m-class Nancay Radio Telescope (NRT) in France. Its aim is a census of the HI gas content and dynamics of 4,000 Sloan Digital Sky Survey galaxies in the Local Volume (900
Name: Marco Grossi
Title: The HI distribution in the outskirts of M33 with the ALFALFA survey
Abstract:
Spiral galaxies appear to be dynamical systems whose disks are still forming at the current epoch and which continue to accrete mass. The most likely source of accretion would be the reservoirs of gas observed outside nearly all spiral disks. The blue disk of the Local Group galaxy M33 seems to indicate that to sustain its star formation activity it needs to accrete gas at a rate of one solar mass per year. We present the analysis of the ALFALFA survey data in the region of M33 aimed at searching high velocity clouds around this galaxy.

Name: Suzanne Linder
Title: Absorption in varying galactic environments seen in HI surveys
Abstract:
Numerous studies have shown that stronger Ly-alpha absorbers are more closely associated with galaxies, while weaker absorbers arise in the intragroup medium surrounding concentrations of galaxies near the absorber redshift. What can absorbers tell us about the properties of the intragroup medium in varying galactic environments? I compare the properties of absorbers in varying galactic environments, starting with those studied by AGES and other recent HI surveys.

Name: B. Winkel
Title: The Effelsberg-Bonn HI Survey (EBHIS) using the new L-band 7-beam-array
Abstract:
Within the next few months an L-band 7-Feed-Array will be operated at the 100-m radio telescope at Effelsberg. This receiver is going to perform an unbiased, fully sampled HI survey of the whole northern hemisphere observing both the galactic and extragalactic sky (SDSS-area) in parallel. The integration time per position will be 10 min towards the SDSS area and 2 min for the rest of the sky, pushing sensitivity to be competitive with the Arecibo ALFALFA and GALFA surveys which are limited to much smaller sky portions.
The use of state-of-the-art FPGA-based Digital Fast Fourier Transform spectrometers --- superior in dynamic range (14-bit) and makes fast dumping of spectra possible (1 sec.) --- allowing sophisticated RFI mitigation to be applied. Software products for stray-radiation correction, RFI mitigation, and source detection are already tested and working, as well as an implementation of the Least-Squares Frequency Switching (LSFS) scheme for the bandpass calibration.
Both surveys will be extremely valuable for a broad range of scientific disciplines ranging from the study of the low-mass end of the HI mass function (HIMF) in the local volume, as well as, environmental and evolutionary effects on the HIMF, the search for galaxies near low-redshift Lyman-alpha absorbers, to the analysis of multiphase and extra-planar gas, HI shells, and ultra-compact high-velocity-clouds.

Name: Sperello di Serego Alighieri
Title: Early-type galaxies with neutral hydrogen in the Virgo cluster from the ALFALFA survey
Abstract:
We are evaluating the HI content of Early-Type Galaxies (ETG), as a function of galaxy mass and environment, in a complete and unbiased way, using the ALFALFA survey. The first results on the Virgo cluster show a very low detection rate: only 2.3% of the VCC ETG with B_T < 18.0 are detected in HI down to 3.5 and 7.6 x 10^7 solar masses of HI for dwarf and giant ETG, respectively. We will present new results obtained on a similar sample of field ETG, allowing the study of the dependence with the environment. We will briefly discuss the interplay of the cold, warm and hot phases of the ISM in ETG, in an attempt to shed light on their evolution, in particular on their star formation history.