Wednesday. Happy New Year!
1212.6491
The GAMA panchromatic survey
Driver
In operation for 5 years, gathering spectroscopic redshifts for five regions of sky spanning 300 sq deg in total depth of r<19.8 mag. Over 225k spectroscopic z, 3rd largest z campaign after SDSS and BOSS. Unique-ness: (1) complete and uniform sampling to a fixed flux limit regardless of galaxy clustering due to multiple-visits to each region, enabling the construction of high-fidelity catalogues of groups and paris, (2) co-ordination with diverse imaging campaigns which together sample an extremely broad range along the EM spectrum, from GALEX (UV) through optical (VST KiDS), NIR (VIKING), mid-IR (WISE), FIR (Herschel-Atlas), 1m (GMRT), and 20cm continuum and rest-fram 21cm line measurements (ASCAP DINGO). GAMA DR2 scheduled for end of Jan, 2013.
1212.6267
Constraints on cosmology from the cosmic microwave background power spectrum of the 2500-square degree SPT-SZ survey
Hou, Reichardt, .. de Putter, .. Dodelson, et al
Adding WMAP7 to SPT significantly improves constraints on LCDM model; the addition of low-z measurements of H0 and BAO leads to further improvements. Before combination, check for consistency in the LCDM model between measurements of CMB, H0 and BAO, and find evidence for some tension between the datasets. Within CMB along, find only weak support for physics beyond LCDM model due to slight trend of decreasing power at smaller angular scales, relative to the prediction of the LCDM model. This trend could be due to a log scale dependence of the power-law index of the primordial power spectrum, n_run. Alternatively, the trend could arise either from adjustments at small or large scales. The power at small scales is sensitive to the damping scale which is influenced by both the He abundance and the effective number of neutrino species. These extensions have similar observational consequences and are partially degenerate when considered simultaneously. These degeneracies can weaken or enhance the apparent deviation of any single extension from the LCDM model. Of the 6 one-parameter model extensions considered, find the CMB data to have the largest statistical preference for running within [-0.046, -0.003] at 95% CL.
1212.6651
Effects of baryon removal on the structure of dwarf spheroidal galaxies
Arraki, Klypin, More, Trujillo-Gomez
Dwarf spheroidal galaxies (dSphs) are extremely gas poor, DM dominated galaxies, which make them ideal to test the predictions of the CDM model. Argue that the removal of a small baryonic component from the central regions of forming dSphs may substantially reduce their central DM density. Thus it may play an important role in alleviate one of the problems of the CDM model related with the structure of relatively massive satellite galaxies of the MW. Traditionally, collisionless cosmological N-body simulations are used when confronting theoretical predictions with observations. However, these simulations assume that the baryon fraction is equal to the cosmic mean, and assumption which can be incorrect for dSphs. Find that the combination of (i) the lower baryon fraction in dSphs compared to the cosmic mean and (ii) the concentration of baryons in the inner part of the MW halo can go a long way towards explaining the observed circular velocity profiles of dSphs. Find that the blowing away of baryons by ram pressure, when the dwarfs fall into larger galaxies, lowers the circular velocity profile of the satellite. In the ~200-500 pc region of the galaxies the DM density is expected to decline by a factor of 0.5. In addition, the enhanced baronic mass in the central regions of the parent galaxy generates tidal forces, which are larger than those experienced by subhaloes in traditional N-body simulations. Increased tidal forces substantially alter circular velocity profiles for satellites that come as close as 50 kpc. Show that these two effects are strong enough to bring the observed structure of dSphs into agreement with predictions of the subhaloes in CDM simulations, regardless of the details of the baryonic processes.
1212.6700
Large size scatter of passive evolving lensed galaxies at z~2 in CLASH
Fan, Chen, Er, Li, Kong
High-z galaxies are small, but their size distribution shows a large scatter; this must be carefully taken into account in galaxy evolution model predictions. [how many galaxies did they use? they are from 11 cluster fields]
1212.6491
The GAMA panchromatic survey
Driver
In operation for 5 years, gathering spectroscopic redshifts for five regions of sky spanning 300 sq deg in total depth of r<19.8 mag. Over 225k spectroscopic z, 3rd largest z campaign after SDSS and BOSS. Unique-ness: (1) complete and uniform sampling to a fixed flux limit regardless of galaxy clustering due to multiple-visits to each region, enabling the construction of high-fidelity catalogues of groups and paris, (2) co-ordination with diverse imaging campaigns which together sample an extremely broad range along the EM spectrum, from GALEX (UV) through optical (VST KiDS), NIR (VIKING), mid-IR (WISE), FIR (Herschel-Atlas), 1m (GMRT), and 20cm continuum and rest-fram 21cm line measurements (ASCAP DINGO). GAMA DR2 scheduled for end of Jan, 2013.
1212.6267
Constraints on cosmology from the cosmic microwave background power spectrum of the 2500-square degree SPT-SZ survey
Hou, Reichardt, .. de Putter, .. Dodelson, et al
Adding WMAP7 to SPT significantly improves constraints on LCDM model; the addition of low-z measurements of H0 and BAO leads to further improvements. Before combination, check for consistency in the LCDM model between measurements of CMB, H0 and BAO, and find evidence for some tension between the datasets. Within CMB along, find only weak support for physics beyond LCDM model due to slight trend of decreasing power at smaller angular scales, relative to the prediction of the LCDM model. This trend could be due to a log scale dependence of the power-law index of the primordial power spectrum, n_run. Alternatively, the trend could arise either from adjustments at small or large scales. The power at small scales is sensitive to the damping scale which is influenced by both the He abundance and the effective number of neutrino species. These extensions have similar observational consequences and are partially degenerate when considered simultaneously. These degeneracies can weaken or enhance the apparent deviation of any single extension from the LCDM model. Of the 6 one-parameter model extensions considered, find the CMB data to have the largest statistical preference for running within [-0.046, -0.003] at 95% CL.
1212.6651
Effects of baryon removal on the structure of dwarf spheroidal galaxies
Arraki, Klypin, More, Trujillo-Gomez
Dwarf spheroidal galaxies (dSphs) are extremely gas poor, DM dominated galaxies, which make them ideal to test the predictions of the CDM model. Argue that the removal of a small baryonic component from the central regions of forming dSphs may substantially reduce their central DM density. Thus it may play an important role in alleviate one of the problems of the CDM model related with the structure of relatively massive satellite galaxies of the MW. Traditionally, collisionless cosmological N-body simulations are used when confronting theoretical predictions with observations. However, these simulations assume that the baryon fraction is equal to the cosmic mean, and assumption which can be incorrect for dSphs. Find that the combination of (i) the lower baryon fraction in dSphs compared to the cosmic mean and (ii) the concentration of baryons in the inner part of the MW halo can go a long way towards explaining the observed circular velocity profiles of dSphs. Find that the blowing away of baryons by ram pressure, when the dwarfs fall into larger galaxies, lowers the circular velocity profile of the satellite. In the ~200-500 pc region of the galaxies the DM density is expected to decline by a factor of 0.5. In addition, the enhanced baronic mass in the central regions of the parent galaxy generates tidal forces, which are larger than those experienced by subhaloes in traditional N-body simulations. Increased tidal forces substantially alter circular velocity profiles for satellites that come as close as 50 kpc. Show that these two effects are strong enough to bring the observed structure of dSphs into agreement with predictions of the subhaloes in CDM simulations, regardless of the details of the baryonic processes.
1212.6700
Large size scatter of passive evolving lensed galaxies at z~2 in CLASH
Fan, Chen, Er, Li, Kong
High-z galaxies are small, but their size distribution shows a large scatter; this must be carefully taken into account in galaxy evolution model predictions. [how many galaxies did they use? they are from 11 cluster fields]
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