Showing papers by "François Levrier published in 2009"

A virtual sky with extragalactic h I and co lines for the square kilometre array and the atacama large millimeter/submillimeter array

Abstract: We present a sky simulation of the atomic HI-emission line and the first 10 rotational CO emission lines of molecular gas in galaxies beyond the Milky Way. The simulated sky field has a comoving diameter of 500 Mpc/h; hence, the actual field-of-view depends on the (user-defined) maximal redshift zmax; e. g., for zmax=10, the field of view yields 4x4 deg^2. For all galaxies, we estimate the line fluxes, line profiles, and angular sizes of the Hi and CO-emission lines. The galaxy sample is complete for galaxies with cold hydrogen masses above 10^8 Msun. This sky simulation builds on a semi-analytic model of the cosmic evolution of galaxies in a Lambda-cold dark matter (Lambda CDM) cosmology. The evolving CDM distribution was adopted from the Millennium Simulation, an N-body CDM-simulation in a cubic box with a side length of 500 Mpc/h. This side length limits the coherence scale of our sky simulation: it is long enough to allow the extraction of the baryon acoustic oscillations in the galaxy power spectrum, yet the position and amplitude of the first acoustic peak will be imperfectly defined. This sky simulation is a tangible aid to the design and operation of future telescopes, such as the Square Kilometre Array, Large Millimeter Telescope, and Atacama Large Millimeter/submillimeter Array. The results presented in this paper have been restricted to a graphical representation of the simulated sky and fundamental dN/dz-analyses for peak flux density limited and total flux limited surveys of Hi and CO. A key prediction is that HI will be harder to detect at redshifts z>2 than predicted by a no-evolution model. The future verification or falsification of this prediction will allow us to qualify the semi-analytic models.

A Virtual Sky with Extragalactic HI and CO Lines for the SKA and ALMA

Abstract: We present a sky simulation of the atomic HI emission line and the first ten CO rotational emission lines of molecular gas in galaxies beyond the Milky Way. The simulated sky field has a comoving diameter of 500/h Mpc, hence the actual field-of-view depends on the (user-defined) maximal redshift zmax; e.g. for zmax=10, the field of view yields ~4x4 sqdeg. For all galaxies, we estimate the line fluxes, line profiles, and angular sizes of the HI and CO emission lines. The galaxy sample is complete for galaxies with cold hydrogen masses above 10^8 Msun. This sky simulation builds on a semi-analytic model of the cosmic evolution of galaxies in a Lambda-cold dark matter (LCDM) cosmology. The evolving CDM-distribution was adopted from the Millennium Simulation, an N-body CDM-simulation in a cubic box with a side length of 500/h Mpc. This side length limits the coherence scale of our sky simulation: it is long enough to allow the extraction of the baryon acoustic oscillations (BAOs) in the galaxy power spectrum, yet the position and amplitude of the first acoustic peak will be imperfectly defined. This sky simulation is a tangible aid to the design and operation of future telescopes, such the SKA, the LMT, and ALMA. The results presented in this paper have been restricted to a graphical representation of the simulated sky and fundamental dN/dz-analyzes for peak flux density limited and total flux limited surveys of HI and CO. A key prediction is that HI will be harder to detect at redshifts z>2 than predicted by a no-evolution model. The future verification or falsification of this prediction will allow us to qualify the semi-analytic models.

Mapping the SKA Simulated Skies with the S3-Tools

Abstract: The S3-Tools are a set of Python-based routines and interfaces whose purpose is to provide user-friendly access to the SKA Simulated Skies (S3) set of simulations, an effort led by the University of Oxford in the framework of the European Union's SKADS program (this http URL) The databases built from the S3 simulations are hosted by the Oxford e-Research Center (OeRC), and can be accessed through a web portal at this http URL This paper focuses on the practical steps involved to make radio images from the S3-SEX and S3-SAX simulations using the S3-Map tool and should be taken as a broad overview For a more complete description, the interested reader should look up the user's guide The output images can then be used as input to instrument simulators, eg to assess technical designs and observational strategies for the SKA and SKA pathfinders