1307.4398
Constraints on neutrino density and velocity isocurvature modes from WMAP-9 data
Savelainen et al
WMAP9 and other CMB data to constraint cosmological models where the primordial perturbations have both an adiabatic and a (possibly correlated) neutrino density (NDI), neutrino velocity (NVI), or cold dark matter density (CDI) isocurvature component. For NDI and CDI use both a phenomenological approach, where primordial perturbations are parameterized in terms of amplitudes at two scales, and a slow-roll two-field inflation approach, where slow-roll parameters are used as primary parameters. For NVI use only the phenomenological approach, since it is difficult to imagine a connection with inflation. Find that in the NDI and NVI cases, larger isocurvature fractions are allowed than in the corresponding models with CDI. For uncorrelated perturbations, the upper limit to the primordial NDI (NVI) fraction is 24% (20%) at k=0.002 /Mpc and 28% (15%) at k=0.01 /Mpc. For maximally correlated (anticorrelated) perturbations, the upper limit to the NDI fraction is 0.3% (0.9%). The nonadiabatic contribution to the CMB temperature variance can be as large as 10% (-13%) for the NDI (NVI) modes. Bayesian model comparison favors pure adiabatic initial mode over the mixed primordial adiabatic and NDI, NVI, or CDI perturbations. At the best, the betting odds for a mixed model (uncorrelated NDI) are 1:3.4 compared to the pure adiabatic model. For the phenomenological generally correlated mixed models the odds are about 1:100, whereas the slow-roll approach leads to 1:13 (NDI) and 1:51 (CDI).
1307.4399
Joint likelihood function of cluster number counts and weak lensing power spectrum
Takada, Spergel
A coherent over- or under-density contrast across a finite survey volume causes an upward- or downward- fluctuation in the number of haloes. This fluctuation in halo number adds a significant covariant scatter in the observed amplitudes of WL PS at NL, small scales. Because of this covariance, the amount of information that can be extracted from a measurement of theWL PS is significantly smaller than naive estimates. In this paper, show that by measuring both the number counts of clusters and the PS in the same survey region, can mitigate this loss of information and significantly enhance the scientific return from the upcoming surveys. First, using the halo model approach, derive the joint likelihood function of the halo number counts and the WL PS, taking into account the super-sample covariance effect on the two observables. Show that the analytical model matches the distributions measured from 1000 realizations for a LCDM model. Then develop a method of combining the observed number counts of massive haloes with a measurement of the WL PS, in order to suppress or correct for the super-sample variance effect. Adding the observed number counts of massive haloes with M>1e14 Ms/h can significantly improve the information content of WL PS, almost recovering the Gaussian information of the initial density field up to l_max~1000. When combined with the halo number counts for M > 3 or 1e14 Ms/h, the improvement is up to a factor of 1.4 or 2 at angular modes of l_max~1000-2000, equivalent to a 2x or 4x larger survey volume, compared to the PS measurement without the Gaussianization method. The improvements are larger for surveys with higher number densities of galaxies.
1307.4402
zCOSMOS 20k: satellite galaxies are the main drivers of environmental effects in the galaxy population at least to z~0.7
Kovac, Lilly, ... et al
Explore the role of environment in the evolution of galaxies over 0.1<z<0.7 using the final zCOSMOS-bright data set. Using the red fraction of galaxies as a proxy for the quenched population, find that the fraction of red galaxies increases with the environmental overdensity and with the stellar mass, consistent with previous works. As at lower redshift, the red fraction appears to be separable in mass and environment, suggesting the action of two processes: mass and environmental quenching. The parameters describing these appear to be essentially the same at z~0.7 as locally. Explore the relation between red fraction, mass and environment also for the central and satellite galaxies separately, paying close attention to the effects of impurities in the central-satellite classification and using carefully constructed samples matched in stellar mass. There is little evidence for a dependence of the red fraction of centrals on overdensity. Satellites are consistently redder at all overdensities, and the satellite quenching efficiency increases with overdensity at 0.1<z<0.4. This is less marked at higher redshift, but both are nevertheless consistent with the equivalent local measurements. At a given stellar mass, the fraction of galaxies that are satellites also increases with the over density. At a given overdensity and mass, the obtained relation between the environmental quenching and the satellite fraction agrees well with the satellite quenching efficiency, demonstrating that the environmental quenching in the overall population is consistent with being entirely produced through the satellite quenching processes at least up to z=0.7. However, despite the unprecedented size of high-z samples, the associated statistical uncertainties are still significant and these statements should be understood as approximations to physical reality, rather than physically exact.
Constraints on neutrino density and velocity isocurvature modes from WMAP-9 data
Savelainen et al
WMAP9 and other CMB data to constraint cosmological models where the primordial perturbations have both an adiabatic and a (possibly correlated) neutrino density (NDI), neutrino velocity (NVI), or cold dark matter density (CDI) isocurvature component. For NDI and CDI use both a phenomenological approach, where primordial perturbations are parameterized in terms of amplitudes at two scales, and a slow-roll two-field inflation approach, where slow-roll parameters are used as primary parameters. For NVI use only the phenomenological approach, since it is difficult to imagine a connection with inflation. Find that in the NDI and NVI cases, larger isocurvature fractions are allowed than in the corresponding models with CDI. For uncorrelated perturbations, the upper limit to the primordial NDI (NVI) fraction is 24% (20%) at k=0.002 /Mpc and 28% (15%) at k=0.01 /Mpc. For maximally correlated (anticorrelated) perturbations, the upper limit to the NDI fraction is 0.3% (0.9%). The nonadiabatic contribution to the CMB temperature variance can be as large as 10% (-13%) for the NDI (NVI) modes. Bayesian model comparison favors pure adiabatic initial mode over the mixed primordial adiabatic and NDI, NVI, or CDI perturbations. At the best, the betting odds for a mixed model (uncorrelated NDI) are 1:3.4 compared to the pure adiabatic model. For the phenomenological generally correlated mixed models the odds are about 1:100, whereas the slow-roll approach leads to 1:13 (NDI) and 1:51 (CDI).
1307.4399
Joint likelihood function of cluster number counts and weak lensing power spectrum
Takada, Spergel
A coherent over- or under-density contrast across a finite survey volume causes an upward- or downward- fluctuation in the number of haloes. This fluctuation in halo number adds a significant covariant scatter in the observed amplitudes of WL PS at NL, small scales. Because of this covariance, the amount of information that can be extracted from a measurement of theWL PS is significantly smaller than naive estimates. In this paper, show that by measuring both the number counts of clusters and the PS in the same survey region, can mitigate this loss of information and significantly enhance the scientific return from the upcoming surveys. First, using the halo model approach, derive the joint likelihood function of the halo number counts and the WL PS, taking into account the super-sample covariance effect on the two observables. Show that the analytical model matches the distributions measured from 1000 realizations for a LCDM model. Then develop a method of combining the observed number counts of massive haloes with a measurement of the WL PS, in order to suppress or correct for the super-sample variance effect. Adding the observed number counts of massive haloes with M>1e14 Ms/h can significantly improve the information content of WL PS, almost recovering the Gaussian information of the initial density field up to l_max~1000. When combined with the halo number counts for M > 3 or 1e14 Ms/h, the improvement is up to a factor of 1.4 or 2 at angular modes of l_max~1000-2000, equivalent to a 2x or 4x larger survey volume, compared to the PS measurement without the Gaussianization method. The improvements are larger for surveys with higher number densities of galaxies.
1307.4402
zCOSMOS 20k: satellite galaxies are the main drivers of environmental effects in the galaxy population at least to z~0.7
Kovac, Lilly, ... et al
Explore the role of environment in the evolution of galaxies over 0.1<z<0.7 using the final zCOSMOS-bright data set. Using the red fraction of galaxies as a proxy for the quenched population, find that the fraction of red galaxies increases with the environmental overdensity and with the stellar mass, consistent with previous works. As at lower redshift, the red fraction appears to be separable in mass and environment, suggesting the action of two processes: mass and environmental quenching. The parameters describing these appear to be essentially the same at z~0.7 as locally. Explore the relation between red fraction, mass and environment also for the central and satellite galaxies separately, paying close attention to the effects of impurities in the central-satellite classification and using carefully constructed samples matched in stellar mass. There is little evidence for a dependence of the red fraction of centrals on overdensity. Satellites are consistently redder at all overdensities, and the satellite quenching efficiency increases with overdensity at 0.1<z<0.4. This is less marked at higher redshift, but both are nevertheless consistent with the equivalent local measurements. At a given stellar mass, the fraction of galaxies that are satellites also increases with the over density. At a given overdensity and mass, the obtained relation between the environmental quenching and the satellite fraction agrees well with the satellite quenching efficiency, demonstrating that the environmental quenching in the overall population is consistent with being entirely produced through the satellite quenching processes at least up to z=0.7. However, despite the unprecedented size of high-z samples, the associated statistical uncertainties are still significant and these statements should be understood as approximations to physical reality, rather than physically exact.
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