Saturday. Need to catch up for about 4 days worth, in the next 2 days. Actually, Monday.
1301.2596
Obscured star formation in Ly-alpha blobs at z=3.1
Tamura et al
Results suggest that LABs on average have little ultra-luminous obscured star-formation, in contrast to a long-believed picture that LABs undergo an intense episode of dusty SF activities with SFR of 1e3 Msun/yr. Observations with ALMA are needed to directly study the obscured part of SF activity in the LABs.
1301.2670
What's up in the Milky Way? The orientation of the disc relative to the triaxial halo
Debattista, ... Moore, et al
Models of Sag Stream consistently find that MW disc is oriented such that its symmetry axis is along the intermediate axis of the triaxial DM halo. Attempt to build models of disc galaxies in such an orientation. First 2/3 models: rigidly grow a disc in a triaxial halo such that the disc ends up perpendicular to the intermediate axis. Also attempt to coax a disc to form in an intermediate-axis orientation by producing a gas+dark matter triaxial system with gas angular momentum about the intermediate axis. In all cases fail to produce systems which remain with stellar angular momentum aligned with the halo's intermediate axis. For one of these unstable simulations, show that the potential is even rounder than the models of MW potential in the region probed by Sagittarius Stream. Conclude that the MW disc is very unlikely to be in an intermediate axis orientation. Find that a disc can persist off one of the principal planes of the potential. Propose that the disc of MW must be tilted relative to the principal axis of DM halo. Direct confirmation of this prediction would constitute a critical test of MOND.
1301.2685
Confronting predictions of the galaxy stellar mass function with observations at high-redshift
Wilkins et al
Galaxy stellar mass function evolution at z>=5 using large cosmo hydro sims. Observational determinations of galaxy stellar mass function at very-high z typically assume a relation between the observed UV luminosity and stellar M/L ratio, which is applied to high-z samples in order to estimate stellar masses; this relation can be measured from the simulations. Find 2 significant differences with the usual observational assumption: It evolves strongly with z and has a different shape. Using this relation to make a consistent comparison between galaxy stellar mass functions, find that at z=6 and above, the simulation predictions arei n good agreement with observed data over the whole mass range. Without using the correct UV luminosity and stellar M/L ratio, the discrepancy would be up to 2 orders of mag for galaxies >1e10 Msun/h. At z=5, however, th stellar mass function for low mass < 1e9 Msun/h galaxies is overpredicted by a factor of few, consistent with the behaviour of the UV LF, and perhaps a sign that feedback in the simulation is not efficient enough for these galaxies.
1301.2744
Structure of dark matter haloes in warm dark matter models and in models with long-lived charged massive particles
Kamada, et al
Study the formation of NL structure in WDM models and in a Long-Lived Charged Massive Particle (CHAMP) model. CHAMPs with a decay lifetime of ~1yr induce characteristic suppression in the matter power spectrum at subgalactic scales through acoustic oscillations in the thermal background. ... such models resolve the so-called "missing satellite problem".
1301.3010
A new method to improve photometric redshift reconstruction. Applications to the Large Synoptic Survey Telescope
Gorecki et al
Use magnitude to apply priors for catastrophic outliers. Try combining template and neural network methods. Conclude that the photometric redshifts will be accurately estimated with the LSST if a Bayesian prior probability and a calibration sample are used.
1301.3069
New organizations to support astroinformatics and astrostatistics
Feigelson, Ivezic, Hilbe, Borne
Share info. As the title says.
1301.3092
AGN-driven quenching of star formation: morphological and dynamical implications for early-type galaxies
Dubois, Gavazzi, Peirani, Silk
To understand the physical mechanisms during the formation of massive early-type galaxies, perform 6 zoomed hydro cosmo sims of halos of 4.3e12<(M_vir/Msun)<8.0e13 at z=0, using RAMSES (Adaptive Mesh Refinement code). Explore the role of AGN, through jets powered by the accretion onto SMBH on the formation of massive elliptical galaxies. In the absence of AGN feedback, large amounts of stars accumulate in the central galaxies to form overly massive, blue, compact and rotation-dominated galaxies. Powerful AGN jets transform the central galaxies into red extended and dispersion-dominated galaxies. This morphological transformation is driven by the efficient quenching of the in situ SF due to AGN feedback, which transform these galaxies into systems built up by accretion. For such galaxies, the proportion of stars deposited farther away from the center increases, and galaxies have larger sizes. The accretion is also directly responsible for randomizing the stellar orbits, increasing the amount of dispersion over rotation of stars as a function of time. Find that the galaxies with AGN feedback better match the observed scaling laws, such as the size-mass, velocity dispersion-mass, fundamental plane relations, and slope of the total density profiles at z~0, from dynamical and strong lensing constraints.
1301.2596
Obscured star formation in Ly-alpha blobs at z=3.1
Tamura et al
Results suggest that LABs on average have little ultra-luminous obscured star-formation, in contrast to a long-believed picture that LABs undergo an intense episode of dusty SF activities with SFR of 1e3 Msun/yr. Observations with ALMA are needed to directly study the obscured part of SF activity in the LABs.
1301.2670
What's up in the Milky Way? The orientation of the disc relative to the triaxial halo
Debattista, ... Moore, et al
Models of Sag Stream consistently find that MW disc is oriented such that its symmetry axis is along the intermediate axis of the triaxial DM halo. Attempt to build models of disc galaxies in such an orientation. First 2/3 models: rigidly grow a disc in a triaxial halo such that the disc ends up perpendicular to the intermediate axis. Also attempt to coax a disc to form in an intermediate-axis orientation by producing a gas+dark matter triaxial system with gas angular momentum about the intermediate axis. In all cases fail to produce systems which remain with stellar angular momentum aligned with the halo's intermediate axis. For one of these unstable simulations, show that the potential is even rounder than the models of MW potential in the region probed by Sagittarius Stream. Conclude that the MW disc is very unlikely to be in an intermediate axis orientation. Find that a disc can persist off one of the principal planes of the potential. Propose that the disc of MW must be tilted relative to the principal axis of DM halo. Direct confirmation of this prediction would constitute a critical test of MOND.
1301.2685
Confronting predictions of the galaxy stellar mass function with observations at high-redshift
Wilkins et al
Galaxy stellar mass function evolution at z>=5 using large cosmo hydro sims. Observational determinations of galaxy stellar mass function at very-high z typically assume a relation between the observed UV luminosity and stellar M/L ratio, which is applied to high-z samples in order to estimate stellar masses; this relation can be measured from the simulations. Find 2 significant differences with the usual observational assumption: It evolves strongly with z and has a different shape. Using this relation to make a consistent comparison between galaxy stellar mass functions, find that at z=6 and above, the simulation predictions arei n good agreement with observed data over the whole mass range. Without using the correct UV luminosity and stellar M/L ratio, the discrepancy would be up to 2 orders of mag for galaxies >1e10 Msun/h. At z=5, however, th stellar mass function for low mass < 1e9 Msun/h galaxies is overpredicted by a factor of few, consistent with the behaviour of the UV LF, and perhaps a sign that feedback in the simulation is not efficient enough for these galaxies.
1301.2744
Structure of dark matter haloes in warm dark matter models and in models with long-lived charged massive particles
Kamada, et al
Study the formation of NL structure in WDM models and in a Long-Lived Charged Massive Particle (CHAMP) model. CHAMPs with a decay lifetime of ~1yr induce characteristic suppression in the matter power spectrum at subgalactic scales through acoustic oscillations in the thermal background. ... such models resolve the so-called "missing satellite problem".
1301.3010
A new method to improve photometric redshift reconstruction. Applications to the Large Synoptic Survey Telescope
Gorecki et al
Use magnitude to apply priors for catastrophic outliers. Try combining template and neural network methods. Conclude that the photometric redshifts will be accurately estimated with the LSST if a Bayesian prior probability and a calibration sample are used.
1301.3069
New organizations to support astroinformatics and astrostatistics
Feigelson, Ivezic, Hilbe, Borne
Share info. As the title says.
1301.3092
AGN-driven quenching of star formation: morphological and dynamical implications for early-type galaxies
Dubois, Gavazzi, Peirani, Silk
To understand the physical mechanisms during the formation of massive early-type galaxies, perform 6 zoomed hydro cosmo sims of halos of 4.3e12<(M_vir/Msun)<8.0e13 at z=0, using RAMSES (Adaptive Mesh Refinement code). Explore the role of AGN, through jets powered by the accretion onto SMBH on the formation of massive elliptical galaxies. In the absence of AGN feedback, large amounts of stars accumulate in the central galaxies to form overly massive, blue, compact and rotation-dominated galaxies. Powerful AGN jets transform the central galaxies into red extended and dispersion-dominated galaxies. This morphological transformation is driven by the efficient quenching of the in situ SF due to AGN feedback, which transform these galaxies into systems built up by accretion. For such galaxies, the proportion of stars deposited farther away from the center increases, and galaxies have larger sizes. The accretion is also directly responsible for randomizing the stellar orbits, increasing the amount of dispersion over rotation of stars as a function of time. Find that the galaxies with AGN feedback better match the observed scaling laws, such as the size-mass, velocity dispersion-mass, fundamental plane relations, and slope of the total density profiles at z~0, from dynamical and strong lensing constraints.
No comments:
Post a Comment