2,703 research outputs found
The central region of the Fornax cluster -- II. Spectroscopy and radial velocities of member and background galaxies
Radial velocities of 94 galaxies brighter than about V_tot = 20 mag in the
direction of the central Fornax cluster have been measured. Except for 8 Fornax
members, all galaxies lie in the background. Among the 8 members, there are 5
nucleated dwarf ellipticals that are already listed in the FCC (Ferguson 1989,
AJ 98, 367). Two of the 3 ``new'' members are very compact and have surface
brightnesses comparable to globular clusters, however their luminosities are in
the range of dwarf elliptical nuclei. The measured line indices (especially
Mg2, H beta, and iron) of the brighter of the compact objects suggest a solar
metallicity, whereas the fainter compact object as well as the dE,Ns have line
indices that are similar to those of old metal-poor globular clusters (GCs).
However, with these data it is not possible to clearly classify the compact
objects either as very bright globular clusters, isolated nuclei of dE,Ns, or
even compact ellipticals. A background galaxy cluster at z = 0.11 has been
found just behind the center of the Fornax cluster. This explains the excess
population of galaxies reported in Paper I. The brightest galaxy of the
background cluster lies only 1.1 arcmin south of NGC 1399 and is comparable in
absolute luminosity with the central Fornax galaxy itself.Comment: 12 pages, LaTeX2e, uses aa.cls, including 9 PostScript figures;
accepted for publication in A&AS, also available at
http://www.astro.puc.cl/~mhilker/publication.htm
The central region of the Fornax cluster -- I. A catalog and photometric properties of galaxies in selected CCD fields
We present a photometric catalog (based on V and I photometry) of galaxies in
the central regions of the Fornax galaxy cluster. Our 11 CCD fields cover 0.17
degrees in total. The limiting surface brightness is around 24 mag arsec^-2,
similar to that of Ferguson's (1989, AJ 98, 367) catalog, whereas our limiting
total magnitude is around V = 22 mag, about two magnitudes fainter. It is the
surface brightness limit, however, that prevents us from detecting the
counterparts of the faintest Local Group dwarf spheroidals. The photometric
properties of all objects are presented as a catalog. The properties and fit
parameters of the surface brightness profiles for a sub-sample are presented as
a second catalog (both catalogs are available in electronic form at the CDS).
We can only add 4 new dwarf galaxies to Ferguson's catalog. However, we confirm
that the dwarf galaxies in Fornax follow a similar surface brightness-magnitude
relation as the Local Group dwarfs. They also follow the color (metallicity) -
relation seen in other galaxy clusters. A formerly suspected excess of dwarf
galaxies surrounding the central cD galaxy NGC 1399 can finally be ruled out.
An enhanced density of objects around NGC 1399 can indeed be seen, but it
appears displaced with respect to the central galaxy and is identified as a
background cluster at z = 0.11 in Paper II of these series, which will discuss
spectroscopic results for our sample.Comment: 15 pages, LaTeX2e, uses aa.cls, including 10 PostScript figures, 1
additional gif figure; accepted for publication in A&AS, also available at
http://www.astro.puc.cl/~mhilker/publication.htm
The Globular Cluster System of NGC 1399: III. VLT Spectroscopy and Database
Radial velocities of 468 globular clusters around NGC 1399, the central
galaxy in the Fornax cluster, have been obtained with FORS2 and the Mask
Exchange Unit (MXU) at the ESO Very Large Telescope. This is the largest sample
of globular cluster velocities around any galaxy obtained so far. The mean
velocity uncertainty is 50 km/sec. This data sample is accurate and large
enough to be used in studies of the mass distribution of NGC 1399 and the
properties of its globular cluster system. Here we describe the observations,
the reduction procedure, and discuss the uncertainties of the resulting
velocities. The complete sample of cluster velocities which is used in a
dynamical study of NGC 1399 is tabulated. A subsample is compared with
previously published values.Comment: 34 pages, 9 figures, 2 tables, accepted by A
Strong Clustering of Faint Galaxies at Small Angular Scales
The 2-point angular correlation function of galaxies, \wt, has been computed
on equatorial fields observed with the CTIO 4m prime focus, within a total area
of 2.31 deg. In the magnitude range , corresponding to
, we find an excess of power in \wt at scales over what would be expected from an extrapolation of \wt measured at
larger . The significance of this excess is . At
larger scales, , the amplitude of \wt is 1.6 times
smaller than the standard no evolutionary model. At these scales there is
remarkable agreement between the present data and Infante \& Pritchet (1995).
At large angular scales () the data is best described
by a model where clustering evolution in has taken place. Strong
luminosity evolution cannot be ruled out with the present data. At smaller
scales, , our data are formally fit by models where
Mpc) or Mpc
. If the mean redshift of our sample is 0.35 then our
data show a clear detection of the scale () where the
clustering evolution approaches a highly non linear regime, i.e., .
The rate at which galaxies merge has been computed. If this rate is
proportional to , then .Comment: 10 pages, LaTeX text, 2 Postscript figures, To appear in ApJ Let
The Ionized Gas Kinematics of the LMC-Type Galaxy NGC 1427A in the Fornax Cluster
NGC 1427A is a LMC-like irregular galaxy in the Fornax cluster with an
extended pattern of strong star formation around one of its edges, which is
probably due to some kind of interaction with the cluster environment. We
present H-alpha velocities within NGC 1427A, obtained through long-slit
spectroscopy at seven different positions, chosen to fall on the brightest HII
regions of the galaxy. Due to its location very near the center of the cluster
this object is an excellent candidate to study the effects that the cluster
environment has on gas-rich galaxies embedded in it. The rotation of NGC 1427A
is modeled in two different ways. The global ionized gas kinematics is
reasonably well described by solid-body rotation, although on small scales it
shows a chaotic behaviour. In this simple model, the collision with a smaller
member of the cluster as being responsible for the peculiar morphology of NGC
1427A is very unlikely, since the only candidate intruder falls smoothly into
the general velocity pattern of the main galaxy. In a more elaborate model, for
which we obtain a better solution, this object does not lie in the same plane
of NGC 1427A, in which case we identify it as a satellite bound to the galaxy.
These results are discussed in the context of a normal irregular versus one
interacting with some external agent. Based on several arguments and
quantitative estimates, we argue that the passage through the hot intracluster
gas of the Fornax cluster is a very likely scenario to explain the
morphological properties of NGC 1427A.Comment: 31 pages, LaTeX2e, uses aas2pp4.sty and psfig.sty, including 7
Postscript figures; accepted for publication in ApJ, Vol. 530, February 200
Providing healthcare for people with chronic illness: the views of Australian GPs
The document attached has been archived with permission from the editor of the Medical Journal of Australia (26 April 2007). An external link to the publisherâs copy is included.OBJECTIVES: To explore general practitioners' views on chronic-disease care: the difficulties and rewards, the needs of patients, the impact of government incentive payments, and the changes needed to improve chronic-disease management. DESIGN: Qualitative study, involving semi-structured questions administered to 10 focus groups of GPs, conducted from April to October 2002. PARTICIPANTS AND SETTING: 54 GPs from both urban and rural practices in New South Wales and South Australia. RESULTS: Consistent themes emerged about the complex nature of chronic-disease management, the tension between patients' and GPs' goals for care, the time-consuming aspects of care (exacerbated by federal government requirements), and the conflicting pressures that prevent GPs engaging in structured multidisciplinary care (ie, team-based care involving systems for patient monitoring, recall, and care planning). CONCLUSIONS: Structured multidisciplinary care for people with chronic conditions can be difficult to provide. Barriers include the lack of fit between systems oriented towards acute care and the requirements of chronic-disease care, and between bureaucratic, inflexible structures and the complex, dynamic nature of GPâpatient relationships. These problems are exacerbated by administrative pressures associated with federal government initiatives to improve chronic-illness management. Changes are needed in both policies and attitudes to enable GPs to move from episodic care to providing structured long-term care as part of a multidisciplinary team.John Oldroyd, Judith Proudfoot, Fernando A Infante, Gawaine Powell Davies, Tanya Bubner, Chris Holton, Justin J Beilby and Mark F Harri
The ALMA Frontier Fields Survey - IV. Lensing-corrected 1.1 mm number counts in Abell 2744, MACSJ0416.1-2403 and MACSJ1149.5+2223
[abridged] Characterizing the number counts of faint, dusty star-forming
galaxies is currently a challenge even for deep, high-resolution observations
in the FIR-to-mm regime. They are predicted to account for approximately half
of the total extragalactic background light at those wavelengths. Searching for
dusty star-forming galaxies behind massive galaxy clusters benefits from strong
lensing, enhancing their measured emission while increasing spatial resolution.
Derived number counts depend, however, on mass reconstruction models that
properly constrain these clusters. We estimate the 1.1 mm number counts along
the line of sight of three galaxy clusters, i.e. Abell 2744, MACSJ0416.1-2403
and MACSJ1149.5+2223, which are part of the ALMA Frontier Fields Survey. We
perform detailed simulations to correct these counts for lensing effects. We
use several publicly available lensing models for the galaxy clusters to derive
the intrinsic flux densities of our sources. We perform Monte Carlo simulations
of the number counts for a detailed treatment of the uncertainties in the
magnifications and adopted source redshifts. We find an overall agreement among
the number counts derived for the different lens models, despite their
systematic variations regarding source magnifications and effective areas. Our
number counts span ~2.5 dex in demagnified flux density, from several mJy down
to tens of uJy. Our number counts are consistent with recent estimates from
deep ALMA observations at a 3 level. Below 0.1 mJy, however,
our cumulative counts are lower by 1 dex, suggesting a flattening in
the number counts. In our deepest ALMA mosaic, we estimate number counts for
intrinsic flux densities 4 times fainter than the rms level. This
highlights the potential of probing the sub-10 uJy population in larger samples
of galaxy cluster fields with deeper ALMA observations.Comment: 19 pages, 14 figures, 3 tables. Accepted for publication in A&
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