40 research outputs found
Environment, morphology and stellar populations of bulgeless low surface brightness galaxies
Based on the Sloan Digital Sky Survey DR 7, we investigate the environment,
morphology and stellar population of bulgeless low surface brightness (LSB)
galaxies in a volume-limited sample with redshift ranging from 0.024 to 0.04
and . The local density parameter is used to
trace their environments. We find that, for bulgeless galaxies, the surface
brightness does not depend on the environment. The stellar populations are
compared for bulgeless LSB galaxies in different environments and for bulgeless
LSB galaxies with different morphologies. The stellar populations of LSB
galaxies in low density regions are similar to those of LSB galaxies in high
density regions. Irregular LSB galaxies have more young stars and are more
metal-poor than regular LSB galaxies. These results suggest that the evolution
of LSB galaxies may be driven by their dynamics including mergers rather than
by their large scale environment.Comment: 12 pages, 13 figures, Accepted by A&
Premixed Turbulent Flame Propagation in Microgravity
Papers included address the following topics: (1) Turbulent premixed flame propagation in microgravity; (2) The effect of gravity on turbulent premixed flame propagation - a preliminary cold flow study; and (3) Characteristics of a subgrid model for turbulent premixed combustion
Characterizing the red optical sky background fluctuations from narrow-band imaging
The detection and characterization of the physical properties of very distant
galaxies will be one the prominent science case of all future Extremely Large
Telescopes, including the 39m E-ELT. Multi-Object Spectroscopic instruments are
potentially very important tools for studying these objects, and in particular
fiber-based concepts. However, detecting and studying such faint and distant
sources will require subtraction of the sky background signal (i.e., between OH
airglow lines) with an accuracy of ~1%. This requires a precise and accurate
knowledge of the sky background temporal and spatial fluctuations. Using FORS2
narrow-band filter imaging data, we are currently investigating what are the
fluctuations of the sky background at ~9000A. We present preliminary results of
sky background fluctuations from this study over spatial scales reaching ~4
arcmin, as well as first glimpses into the temporal variations of such
fluctuations over timescales of the order of the hour. This study (and other
complementary on-going studies) will be essential in designing the
next-generation fiber-fed instruments for the E-ELT.Comment: To be published in Proc SPIE 8446: Ground-based & Airborne
Instrumentation for Astronomy IV; 12 pages, 3 tables, 8 figure
The XMM-LSS survey. Survey design and first results
We have designed a medium deep large area X-ray survey with XMM - the XMM
Large Scale Structure survey, XMM-LSS - with the scope of extending the
cosmological tests attempted using ROSAT cluster samples to two redshift bins
between 0<z<1 while maintaining the precision of earlier studies. Two main
goals have constrained the survey design: the evolutionary study of the
cluster-cluster correlation function and of the cluster number density. The
results are promising and, so far, in accordance with our predictions as to the
survey sensitivity and cluster number density. The feasibility of the programme
is demonstrated and further X-ray coverage is awaited in order to proceed with
a truly significant statistical analysis. (Abridged)Comment: Published in Journal of Cosmology and Astroparticle Physic
The WIRCam Ultra Deep Survey (WUDS) I. Survey overview and UV luminosity functions at z similar to 5 and z similar to 6
The aim of this paper is to introduce the WIRCam Ultra Deep Survey (WUDS), a near-IR photometric survey carried out at the CFH Telescope in the field of the CFHTLS-D3 field (Groth Strip). WUDS includes four near-IR bands (Y, J, H and Ks) over a field of view of âŒ400 arcmin2. The typical depth of WUDS data reaches between âŒ26.8 in Y and J, and âŒ26 in H and Ks (AB, 3Ï in 1.3âł aperture), whereas the corresponding depth of the CFHTLS-D3 images in this region ranges between 28.6 and 29 in ugr, 28.2 in i and 27.1 in z (same S/N and aperture). The area and depth of this survey were specifically tailored to set strong constraints on the cosmic star formation rate and the luminosity function brighter or around Lâ in the zââŒâ6â
ââ
10 redshift domain, although these data are also useful for a variety of extragalactic projects. This first paper is intended to present the properties of the public WUDS survey in details: catalog building, completeness and depth, number counts, photometric redshifts, and global properties of the galaxy population. We have also concentrated on the selection and characterization of galaxy samples at zââŒâ[4.5â
ââ
7] in this field. For these purposes, we include an adjacent shallower area of âŒ1260 arcmin2 in this region, extracted from the WIRCam Deep Survey (WIRDS), and observed in J, H and Ks bands. UV luminosity functions were derived at zââŒâ5 and zââŒâ6 taking advantage from the fact that WUDS covers a particularly interesting regime at intermediate luminosities, which allows a combined determination of Mâ and Ίâ with increased accuracy. Our results on the luminosity function are consistent with a small evolution of both Mâ and Ίâ between zâ=â5 and zâ=â6, irrespective of the method used to derive them, either photometric redshifts applied to blindly-selected dropout samples or the classical Lyman Break Galaxy color-preselected samples. Our results lend support to higher Ίâ determinations at zâ=â6 than usually reported. The selection and combined analysis of different galaxy samples at zââ„â7 will be presented in a forthcoming paper, as well as the evolution of the UV luminosity function between zââŒâ4.5 and 9. WUDS is intended to provide a robust database in the near-IR for the selection of targets for detailed spectroscopic studies, in particular for the EMIR/GTC GOYA Survey
4MOST: Project overview and information for the First Call for Proposals
We introduce the 4-metre Multi-Object Spectroscopic Telescope (4MOST), a new high-multiplex, wide-field spectroscopic survey facility under development for the four-metre-class Visible and Infrared Survey Telescope for Astronomy (VISTA) at Paranal. Its key specifications are: a large field of view (FoV) of 4.2 square degrees and a high multiplex capability, with 1624 fibres feeding two low-resolution spectrographs (), and 812 fibres transferring light to the high-resolution spectrograph (). After a description of the instrument and its expected performance, a short overview is given of its operational scheme and planned 4MOST Consortium science; these aspects are covered in more detail in other articles in this edition of The Messenger. Finally, the processes, schedules, and policies concerning the selection of ESO Community Surveys are presented, commencing with a singular opportunity to submit Letters of Intent for Public Surveys during the first five years of 4MOST operations
The main sequence of star-forming galaxies at z ⌠0.6: reinstating major mergers
International audienc
The 5Â Gyr evolution of sub-M* galaxies
International audienc