235 research outputs found
BUDHIES I: characterizing the environments in and around two clusters at z~0.2
We present the optical spectroscopy for the Blind Ultra Deep HI Environmental
Survey (BUDHIES). With the Westerbork Synthesis Radio Telescope, BUDHIES has
detected HI in over 150 galaxies in and around two Abell clusters at z~0.2.
With the aim of characterizing the environments of the HI-detected galaxies, we
obtained multi-fiber spectroscopy with the William Herschel Telescope. In this
paper, we describe the spectroscopic observations, report redshifts and EW[OII]
measurements for ~600 galaxies, and perform an environmental analysis. In
particular, we present cluster velocity dispersion measurements for 5 clusters
and groups in the BUDHIES volume, as well as a detailed substructure analysis.Comment: v2: Typos and small corrections after proofs added. 14 pages (plus
small appendix), 12 figures. Accepted for publication in MNRAS. Adobe Acrobat
Reader is required to correctly display the (3D) animated figures (Fig. 9).
Full data tables and supporting videos are also available at the BUDHIES
project website: http://www.astro.rug.nl/budhies
WSRT Ultra-Deep Neutral Hydrogen Imaging of Galaxy Clusters at z=0.2, a Pilot Survey of Abell 963 and Abell 2192
A pilot study with the powerful new backend of the Westerbork Synthesis Radio
Telescope (WSRT) of two galaxy clusters at z=0.2 has revealed neutral hydrogen
emission from 42 galaxies. The WSRT probes a total combined volume of 3.4x10^4
Mpc^3 at resolutions of 54x86 kpc^2 and 19.7 km/s, surveying both clusters and
the large scale structure in which they are embedded. In Abell 963, a
dynamically relaxed, lensing Butcher-Oemler cluster with a high blue fraction,
most of the gas-rich galaxies are located between 1 and 3 Mpc in projection,
northeast from the cluster core. Their velocities are slightly redshifted with
respect to the cluster, and this is likely a background group. None of the blue
galaxies in the core of Abell 963 are detected in HI, although they have
similar colors and luminosities as the HI detected galaxies in the cluster
outskirts and field. Abell 2192 is less massive and more diffuse. Here, the
gas-rich galaxies are more uniformly distributed. The detected HI masses range
from 5x10^9 to 4x10^10 Msun. Some galaxies are spatially resolved, providing
rudimentary rotation curves useful for detailed kinematic studies of galaxies
in various environments. This is a pilot for ultra-deep integrations down to HI
masses of 8x10^8 Msun, providing a complete survey of the gas content of
galaxies at z=0.2, probing environments ranging from cluster cores to voids.Comment: 5 pages, 6 figures + 1 Plate, accepted for publication in the
Astrophysical Journal Letter
Criticism of the Use of Coomassie Brilliant Blue G-250 for the Quantitative Determination of Proteins
Peer Reviewe
ORFEUS-II Far-Ultraviolet Observations of 3C273: 1. Interstellar and Intergalactic Absorption Lines
We present the first intermediate-resolution (lambda / 3000) spectrum of the
bright quasi-stellar object 3C273 at wavelengths between 900 and 1200 A.
Observations were performed with the Berkeley spectrograph aboard the
ORFEUS-SPAS II mission. We detect Lyman beta counterparts to
previously-identified intergalactic Lyman-alpha features at cz = 19900, 1600,
and 1000 km/s; counterparts to other putative Lyman-alpha clouds along the
sight line are below our detection limit. The strengths of the two very low
redshift Lyman-beta features, which are believed to arise in Virgo intracluster
gas, exceed preflight expectations, suggesting that the previous determination
of the cloud parameters may underestimate the true column densities. A
curve-of-growth analysis sets a minimum H I column density of 4 E14/cm^2 for
the 1600 km/s cloud. We find marginally significant evidence for Galactic H_2
along the sight line, with a total column density of about 1 E15/cm^2. We
detect the stronger interstellar O VI doublet member unambiguously; the weaker
member is blended with other features. If the Doppler b value for O VI is
comparable to that determined for N V then the O VI column density is 7 +/- 2
E14/cm^2, significantly above the only previous estimate. The O VI / N V ratio
is about 10, consistent with the low end of the range observed in the disk.
Additional interstellar species detected for the first time toward 3C273 (at
modest statistical significance) include P II, Fe III, Ar I, and S III.Comment: LaTeX file, 11 pages, 4 encapsulated PostScript figures. Uses
aaspp4.sty and astrobib.sty. (Astrobib is available from
http://www.stsci.edu/software/TeX.html .) The ORFEUS telescope is described
at http://sag-www.ssl.berkeley.edu/orfeus/ . To appear in ApJ (Letters
The Disk and Dark Halo Mass of the Barred Galaxy NGC 4123. I. Observations
The non-circular streaming motions in barred galaxies are sensitive to the
mass of the bar and can be used to lift the degeneracy between disk and dark
matter halo encountered when fitting axisymmetric rotation curves of disk
galaxies. In this paper, we present photometric and kinematic observations of
NGC 4123, a barred galaxy of modest size (V_rot = 130 km/sec, L = 0.7 L_*),
which reveal strong non-circular motions. The bar has straight dust lanes and
an inner Lindblad resonance. The disk of NGC 4123 has no sign of truncation out
to 10 scale lengths, and star-forming regions are found well outside R_25. A
Fabry-Perot H-alpha velocity field shows velocity jumps of >100 km/sec at the
location of the dust lanes within the bar, indicating shocks in the gas flow.
VLA observations yield the velocity field of the H I disk. Axisymmetric mass
models yield good fits to the rotation curve outside the bar regionfor disk
I-band M/L of 2.25 or less, and dark halos with either isothermal or power-law
profiles can fit the data well. In a companion paper, we model the full 2-D
velocity field, including non-circular motions, to determine the stellar M/L
and the mass of the dark halo.Comment: accepted by ApJ, 16 pages, 9 figures (1 color), uses emulateapj.sty,
onecolfloat.st
BUDHIES IV:Deep 21-cm neutral Hydrogen, optical, and UV imaging data of Abell 963 and Abell 2192 at z ≃ 0.2
In this paper, we present data from the Blind Ultra-Deep H I Environmental Survey (BUDHIES), which is a blind 21-cm H I spectral line imaging survey undertaken with the Westerbork Synthesis Radio Telescope. Two volumes were surveyed, each with a single pointing and covering a redshift range of 0.164 < z < 0.224. Within these two volumes, this survey targeted the clusters Abell 963 and Abell 2192, which are dynamically different and offer unique environments to study the process of galaxy evolution within clusters. With an integration time of 117 × 12 h on Abell 963 and 72 × 12 h on Abell 2192, a total of 166 galaxies were detected and imaged in H I. While the clusters themselves occupy only 4 per cent of the 73 400 Mpc3 surveyed by BUDHIES, most of the volume consists of large-scale structures in which the clusters are embedded, including foreground and background overdensities and voids. We present the data processing and source detection techniques and counterpart identification based on a wide-field optical imaging survey using the Isaac Newton Telescope and deep ultraviolet (UV) Galaxy Evolution Explorer (GALEX) imaging. Finally, we present H I and optical catalogues of the detected sources as well as atlases of their global H I properties, which include integrated column density maps, position-velocity diagrams, global H I profiles, and optical and UV images of the H I sources
GMRT Detection of HI 21 cm-line Absorption from the Peculiar Galaxy in Abell 2125
Using the recently completed Giant Meterwave Radio Telescope, we have
detected the HI 21 cm-line absorption from the peculiar galaxy C153 in the
galaxy cluster Abell 2125. The HI absorption is at a redshift of 0.2533, with a
peak optical depth of 0.36. The full width at half minimum of the absorption
line is 100 km/s. The estimated column density of atomic Hydrogen is
0.7e22(Ts/100K) per sq. cm. The HI absorption is redshifted by ~ 400 km/s
compared to the [OIII] emission line from this system. We attribute this to an
in-falling cold gas, or to an out-flowing ionised gas, or to a combination of
both as a consequence of tidal interactions of C153 with either a cluster
galaxy or the cluster potential.Comment: 9 pages, 2 figures, uses jaa.sty (included
A Search for HI in E+A Galaxies
We present the results of HI line and radio continuum observations of five
nearby E+A galaxies. These galaxies have spectra that are dominated by a young
stellar component but lack the emission lines characteristic of significant,
on-going star formation. They are selected from a unique sample of 21 E+A's
identified by Zabludoff et al.(1996) in their spectroscopic search for E+A
galaxies using the Las Campanas Redshift Survey, where over 11,000 nearby
galaxies were examined. The five E+A galaxies span a range of environments:
three are in the field and two are in clusters. Only one system was detected in
HI emission, the field E+A galaxy EA1, with a total flux of 0.30 +/- 0.02 Jy
km/s and an HI mass of (3.5 +/- 0.2) 10^9 h^(-2) M_sun. The HI morphology and
kinematics of EA 1 suggest a galaxy-galaxy interaction, with a dynamical age of
about 6 x 10^8 h^(-1) yr inferred from the HI tail lengths and velocities. This
age estimate is consistent with the interpretation drawn from optical
spectroscopy that starbursts in E+A galaxies began (and subsequently ended)
within the last 10^9 yr. Our HI detection limits are such that if the other
E+A's in our sample had the HI properties of EA 1, we would have detected (or
marginally detected) them. We conclude that E+A galaxies have a range of HI
properties. None of the galaxies were detected in radio continuum emission,
with upper limits to the radio power of about 10^21 h^(-2) W/Hz. Our limits
exclude the possibility that these E+A's are dust-enshrouded massive starburst
galaxies, but are insufficient to exclude modest star formation rates of less
than a few h^(-2) M_sun per yr.Comment: 21 Latex pages, including 5 figures and 6 tables. Uses Aastex. To
appear in AJ, April 2001; minor changes to text and Figure
The MeerKAT Fornax Survey
We present the science case and observations plan of the MeerKAT Fornax
Survey, an HI and radio continuum survey of the Fornax galaxy cluster to be
carried out with the SKA precursor MeerKAT. Fornax is the second most massive
cluster within 20 Mpc and the largest nearby cluster in the southern
hemisphere. Its low X-ray luminosity makes it representative of the environment
where most galaxies live and where substantial galaxy evolution takes place.
Fornax's ongoing growth makes it an excellent laboratory for studying the
assembly of clusters, the physics of gas accretion and stripping in galaxies
falling in the cluster, and the connection between these processes and the
neutral medium in the cosmic web.
We will observe a region of 12 deg reaching a projected distance of 1.5
Mpc from the cluster centre. This will cover a wide range of environment
density out to the outskirts of the cluster, where gas-rich in-falling groups
are found. We will: study the HI morphology of resolved galaxies down to a
column density of a few times 1e+19 cm at a resolution of 1 kpc; measure
the slope of the HI mass function down to M(HI) 5e+5 M(sun); and attempt to
detect HI in the cosmic web reaching a column density of 1e+18 cm at a
resolution of 10 kpc.Comment: Proceedings of Science, "MeerKAT Science: On the Pathway to the SKA",
Stellenbosch, 25-27 May 201
Gas Reservoirs and Star Formation in a Forming Galaxy Cluster at zbsime0.2
We present first results from the Blind Ultra Deep HI Environmental Survey
(BUDHIES) of the Westerbork Synthesis Radio Telescope (WSRT). Our survey is the
first direct imaging study of neutral atomic hydrogen gas in galaxies at a
redshift where evolutionary processes begin to show. In this letter we
investigate star formation, HI-content, and galaxy morphology, as a function of
environment in Abell 2192 (at z=0.1876). Using a 3-dimensional visualization
technique, we find that Abell 2192 is a cluster in the process of forming, with
significant substructure in it. We distinguish 4 structures that are separated
in redshift and/or space. The richest structure is the baby cluster itself,
with a core of elliptical galaxies that coincides with (weak) X-ray emission,
almost no HI-detections, and suppressed star formation. Surrounding the
cluster, we find a compact group where galaxies pre-process before falling into
the cluster, and a scattered population of "field-like" galaxies showing more
star formation and HI-detections. This cluster proves to be an excellent
laboratory to understand the fate of the HI gas in the framework of galaxy
evolution. We clearly see that the HI gas and the star formation correlate with
morphology and environment at z=0.2. In particular, the fraction of
HI-detections is significantly affected by the environment. The effect starts
to kick in in low mass groups that pre-process the galaxies before they enter
the cluster. Our results suggest that by the time the group galaxies fall into
the cluster, they are already devoid of HI.Comment: 6 pages, 4 figures. Accepted for publication in ApJL. An animated
version of Figure 2 is available at:
http://www.nottingham.ac.uk/~ppxyj/Jaffe_ApJL_2012_Fig2_movie.mpeg. (v2.
minor corrections/typos added
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