1307.0001
Leakage of power from dipole to higher multipoles due to non-symmetric WMAP beam
Das, Souradeep
Power at the low mutlipoles in CMB PS are lower than their theoretically predicted values. Possible angular correlation between the orientations of these low multipoles have also been claimed. Important to investigate the possibility that the power deficiency at low multipoles may not be of primordial origin and is only an observation artifact coming from the scan procedure adapted in the WMAP or Planck satellites. Any observational artifacts that can mimic them? The CMB dipole which is 550x higher than the quadrupole can leak into the higher multipoles due to the non-symmetric beam shape of WMAP. In this paper, a formalism has been developed and simulations are carried out to study the effect of the non-symmetric beam on this power transfer. A small but non-negligible amount of power from the dipole can get transferred to the quadrupole and the higher multipoles due to the non-symmetric beam. In case of WMAP scan strategy, the shape of the quadrupole coming due to this power leakage is much similar to the observed quadrupole from WMAP data. Simulations also carried out for Planck scan strategy. It is seen that for Planck scan strategy, the power transfer is not only limited to the quadrupole but also to a few higher low multipoles. Since the actual beam shapes of Planck are not publicly available, present results in terms of upper limits on asymmetric beam parameters that would contaminate the quadrupole power at the level of 1uK.
1307.0003
Larger sizes of massive quiescent early-type galaxies in clusters than in the field at 0.8<z<1.5
Delaye, ..., Mei, Bernardi, Tanaka, et al
The mass-size relation of ETGs has been studied to probe the mass assembly of the most massive objects in the Universe. In this paper, focus on the mass-size relation of quiescent massive ETGs (Mstar/Msol > 3e10) living in massive clusters (M_200~1e14 Mstar [mistake? Msun, I think]) at 0.8<z<1.5, as compared to those living in the field at the same epoch. Sample contains ~400 ETGs in clusters and the same number in the field. Therefore, sample is approximately an order of magnitude larger than previous studies in the same redshift range for galaxy clusters. Find that ETGs living in clusters are between ~30-50% larger than galaxies with the same stellar mass residing in the field. Parameterize the size using the mass-normalized size, gamma=Re/Mstar^0.57. The gamma distributions in both environments peak at the same position but the distributions in clusters are more skewed towards larger sizes. Since this size difference is not observed in the loac Universe, the size evolution at fixed stellar mass from z~1.5 of cluster galaxies is less steep ((1+z)-0.53pm0.04) than the evolution of field galaxies ((1+z)-0.92pm0.04). The size difference eseems to be essentially driven by the galaxies residing in the cluster cores (R<0.5*R200). If part of the size evolution is due to mergers, the difference we wee between cluster and field galaxies could be due to higher merger rates in clusters at higher redshift, probably during the formation phase of the clusters when velocity dispersions are lower. Cannot exclude however that the difference is driven by newly quenched galaxies which are quenced more efficiently in clusters. The implications of these results for the hierarchical growth of ETGs will be discussed in a companion paper.
1307.0008
Streams in the Aquarius stellar haloes
Gomez, ... Frenk, Navarro, White
In Aquarius, study the phase-space distribution of halo stars in "solar neighbourhood"-like volumes. Find ~300-600 streams, easily identified from velocity space. Agrees with analytical predictions, even in the presence of chaotic mixing. The fraction of particles linked to (massive) stellar streams can be as large as 84%. Streams decrease as a power-law with galactocentric radius.
Leakage of power from dipole to higher multipoles due to non-symmetric WMAP beam
Das, Souradeep
Power at the low mutlipoles in CMB PS are lower than their theoretically predicted values. Possible angular correlation between the orientations of these low multipoles have also been claimed. Important to investigate the possibility that the power deficiency at low multipoles may not be of primordial origin and is only an observation artifact coming from the scan procedure adapted in the WMAP or Planck satellites. Any observational artifacts that can mimic them? The CMB dipole which is 550x higher than the quadrupole can leak into the higher multipoles due to the non-symmetric beam shape of WMAP. In this paper, a formalism has been developed and simulations are carried out to study the effect of the non-symmetric beam on this power transfer. A small but non-negligible amount of power from the dipole can get transferred to the quadrupole and the higher multipoles due to the non-symmetric beam. In case of WMAP scan strategy, the shape of the quadrupole coming due to this power leakage is much similar to the observed quadrupole from WMAP data. Simulations also carried out for Planck scan strategy. It is seen that for Planck scan strategy, the power transfer is not only limited to the quadrupole but also to a few higher low multipoles. Since the actual beam shapes of Planck are not publicly available, present results in terms of upper limits on asymmetric beam parameters that would contaminate the quadrupole power at the level of 1uK.
1307.0003
Larger sizes of massive quiescent early-type galaxies in clusters than in the field at 0.8<z<1.5
Delaye, ..., Mei, Bernardi, Tanaka, et al
The mass-size relation of ETGs has been studied to probe the mass assembly of the most massive objects in the Universe. In this paper, focus on the mass-size relation of quiescent massive ETGs (Mstar/Msol > 3e10) living in massive clusters (M_200~1e14 Mstar [mistake? Msun, I think]) at 0.8<z<1.5, as compared to those living in the field at the same epoch. Sample contains ~400 ETGs in clusters and the same number in the field. Therefore, sample is approximately an order of magnitude larger than previous studies in the same redshift range for galaxy clusters. Find that ETGs living in clusters are between ~30-50% larger than galaxies with the same stellar mass residing in the field. Parameterize the size using the mass-normalized size, gamma=Re/Mstar^0.57. The gamma distributions in both environments peak at the same position but the distributions in clusters are more skewed towards larger sizes. Since this size difference is not observed in the loac Universe, the size evolution at fixed stellar mass from z~1.5 of cluster galaxies is less steep ((1+z)-0.53pm0.04) than the evolution of field galaxies ((1+z)-0.92pm0.04). The size difference eseems to be essentially driven by the galaxies residing in the cluster cores (R<0.5*R200). If part of the size evolution is due to mergers, the difference we wee between cluster and field galaxies could be due to higher merger rates in clusters at higher redshift, probably during the formation phase of the clusters when velocity dispersions are lower. Cannot exclude however that the difference is driven by newly quenched galaxies which are quenced more efficiently in clusters. The implications of these results for the hierarchical growth of ETGs will be discussed in a companion paper.
1307.0008
Streams in the Aquarius stellar haloes
Gomez, ... Frenk, Navarro, White
In Aquarius, study the phase-space distribution of halo stars in "solar neighbourhood"-like volumes. Find ~300-600 streams, easily identified from velocity space. Agrees with analytical predictions, even in the presence of chaotic mixing. The fraction of particles linked to (massive) stellar streams can be as large as 84%. Streams decrease as a power-law with galactocentric radius.
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