Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 0810.3649

The CMBR ISW and HI 21-cm Cross-correlation Angular Power Spectrum

Tapomoy Guha Sarkar·Kanan K. Datta·Somnath Bharadwaj
View original source ↗Read source document ↗Export metadata ↓

Abstract

The late-time growth of large scale structures (LSS) is imprinted in the CMBR anisotropy through the Integrated Sachs Wolfe (ISW) effect. This is perceived to be a very important observational probe of dark energy. Future observations of redshifted 21-cm radiation from the cosmological neutral hydrogen (HI) distribution hold the potential of probing the LSS over a large redshift range. We have investigated the possibility of detecting the ISW through cross-correlations between the CMBR anisotropies and redshifted 21-cm observations. Assuming that the HI traces the dark matter, we find that the ISW-HI cross-correlation angular power spectrum at an angular multipole l is proportional to the dark matter power spectrum evaluated at the comoving wave number l/r, where r is the comoving distance to the redshift from which the HI signal originated. The amplitude of the cross-correlation signal depends on parameters related to the HI distribution and the growth of cosmological perturbations. However the cross-correlation is extremely weak as compared to the CMBR anisotropies and the predicted HI signal. As a consequence the cross-correlation signal is smaller than the cosmic variance, and a statistically significant detection is not very likely.

Explore related subjects

astro-ph

Keep this discovery

BibTeXRIS

Tapomoy Guha Sarkar, Kanan K. Datta, Somnath Bharadwaj. 2009-07-22. The CMBR ISW and HI 21-cm Cross-correlation Angular Power Spectrum. https://doi.org/10.1088/1475-7516/2009/08/019

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2014

Interacting Phantom Energy and Avoidance of the Big Rip Singularity

Models of the universe with arbitrary (non gravitational) interaction between the components of the cosmic fluid: the phantom energy and the background, are investigated. A general form of the interaction that is inspired in scalar-tensor theories of gravity is considered. No specific model for the phantom fluid is assumed. We concentrate our investigation on solutions that are free of the coincidence problem. We found a wide region in the parameter space where the solutions are free of the big rip singularity also. Physical arguments, together with arguments based on the analysis of the observational evidence, suggest that phantom models without big rip singularity might be preferred by Nature.

astro-ph↗
arXiv2014

Exploring the Small Magellanic Cloud to the Faintest X-ray Fluxes: Source Catalog, Timing and Spectral Analysis

We present the results of a pair of 100 ksec Chandra observations in the Small Magellanic Cloud to survey high mass X-ray binaries (HMXBs), stars and LMXBs/CVs down to Lx = 4.3 x 10^32 erg/s The two SMC Deep Fields are located in the most active star forming region of the bar, with Deep Field-1 positioned at the most pulsar-rich location identified from previous surveys. Two new pulsars were discovered in outburst: CXOU J004929.7-731058 (P=892s), CXOU J005252.2-721715 (P=326s), and 3 new HMXB candidates were identified. Of 15 Be-pulsars now known in the field, 13 were detected, with pulsations seen in 9 of them. Ephemerides demonstrate that 6 of the 10 pulsars known to exhibit regular outbursts were seen outside their periastron phase, and quiescent X-ray emission at Lx=10^33 - 10^34 is shown to be common. Comparison with ROSAT, ASCA, XMM-Newton catalogs resulted in positive identification of several previously ambiguous sources. Bright optical counterparts exist for 40 of the X-ray sources, of which 33 are consistent with early-type stars Mv<-2, B-V<0.2), and are the subject of a companion paper. The results point to an underlying HMXB population-density up to double that of active systems. The full catalog of 394 point-sources is presented along with detailed analyses of timing and spectral properties.

astro-ph↗
arXiv2014

A Computer Program to Visualize Gravitational Lenses

Gravitational lenses are presently playing an important role in astrophysics. By means of these lenses the parameters of the deflector such as its mass, ellipticity, etc. and Hubble's constant can be determined. Using C, Xforms, Mesa and Imlib a computer program to visualize this lens effect has been developed. This program has been applied to generate sequences of images of a source object and its corresponding images. It has also been used to visually test different models of gravitational lenses.

astro-ph↗