摘要:

We have derived an analytical model for the postcollapse equilibrium structure of cosmological halos as nonsingular truncated isothermal spheres (TIS) and compared this model with observations and simulations of cosmological halos on all scales. Our model is in good agreement with the observations of the internal structure of dark-matter-dominated halos from dwarf galaxies to X-ray clusters. It reproduces many of the average properties of halos in CDM simulations to good accuracy, including the density profiles outside the central region, while avoiding the possible discrepancy at small radii between observed galaxy and cluster density profiles and the singular density profiles predicted by N-body simulations of the CDM model. While much attention has been focused lately on this possible discrepancy, we show that the observed galaxy rotation curves and correlations of halo properties nevertheless contain valuable additional information with which to test the theory, despite this uncertainty at small radii. The available data allows us to constrain the fundamental cosmological parameters and also to put a unique constraint on the primordial density fluctuation power spectrum at large wave numbers (i.e. small mass scale). ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1419545

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

The crisis of the cold dark matter and problems of the self-interacting dark matter models is resolved by postulating flavor mixing of dark matter particles. Flavor-mixed particles segregate in the gravitational field to form dark halos composed of heavy mass eigenstates. Since these particles are mixed in the interaction basis, elastic collisions convert some of heavy eigenstates into light ones which leave dense central regions of the halo. This annihilation-like process will soften dense central cusps of halos. The proposed model accumulates most of the attractive features of self-interacting and annihilating dark matter models, but does not suffer from their severe drawbacks. This model is natural; it does not require fine tuning. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1419546

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

We present a parameter study of offset mergers between clusters of galaxies, examining the effect of a cuspy dark matter profile on luminosity and temperature evolution and turbulence. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1419547

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1419548

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

As part of a 4-year Cosmology and Particle Astrophysics (CosPA) Research Excellence Initiative in Taiwan, AMiBA—a 19-element dual-channel 85–105 GHz interferometer array is being specifically built to search for high redshift clusters of galaxies via the Sunyaev-Zeldovich Effect (SZE). In addition, AMiBA will have full polarization capabilities, in order to probe the polarization properties of the Cosmic Microwave Background. AMiBA, to be sited on Mauna Kea in Hawaii or in Chile, will reach a sensitivity of ∼1 mJy or 9 &mgr;K in 1 hour. The project involves extensive international scientific and technical collaborations. The construction of AMiBA is scheduled to start operating in early 2004. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1419549

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

The Cosmic Background Imager (CBI) is an instrument designed to measure intrinsic anisotropies in the cosmic microwave background (CMB) on angular scales from about 3 arc minutes to one degree (spherical harmonics ofl∼4250tol∼400). The CBI is a 13 element interferometer mounted on a 6 meter platform operating in ten 1-GHz frequency bands from 26 to 36 GHz. We present a review of the capabilities of the instrument and a discussion of observations which have been taken over the past year from the Atacama desert of Chile. We also present first results from the CBI which show a strong cutoff in the power spectrum betweenl=600andl=1200which is consistent with the photon-diffusive damping predicted by most models of structure formation in the early universe. We discuss future topics which the CBI will address. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1419550

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

Galactic synchrotron will be an important contaminant for forthcoming experiments on CMB polarization. We investigate the angular power spectra of polarized Galactic synchrotron in several surveys (Parkes at 2.4 GHz, Effelsberg at 2.7 GHz and 1.4 GHz), showing that partial sky coverage analysis may lead to largely different results. Reasonable extrapolations to tens of GHz allow us to find a region in the(v,l)plane where the CMB polarized signal is expected to prevail largely. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1419551

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

We propose an analytical method to calculate the vorticity power spectrum of the intergalactic gas peculiar momentum in the non-linear regime and thus to calculate the kinetic Sunyaev Zel’dovich effect. Our results show that the KSZ power spectrum peaks aroundl=3000with&Dgr;T≃1.5&hthinsp;&mgr;K.©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1419552

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

We review the general primordial perturbation valid at early times in a universe with no new physics and consisting of four regular isocurvature modes in addition to an adiabatic growing mode. The prospects for testing the adiabaticity of the cosmic microwave background (CMB) anisotropy using MAP and PLANCK are then discussed. The role of CMB polarization in constraining the presence of primordial isocurvature modes is investigated. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1419553

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

A conflict has been reported between the baryon density inferred from deuterium observations and that found from recent CMB observations by BOOMERanG and MAXIMA. Despite the flurry of papers that attempt to resolve this conflict by adding new physics to the early universe, we will show that it can instead be resolved via a more careful usage of statistics. Indeed, the Bayesian analyses that produce this conflict are by their nature poorly suited for drawing this type of conclusion. A properly defined frequentist analysis can address this question directly and appears not to find a conflict. Finally, a conservative accounting of systematic uncertainties in measuring the deuterium abundance could reduce what is nominally a 3&sgr; conflict to 1&sgr;. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1419554

出版商:AIP    

年代:1901

数据来源: AIP