arXiv subjects

C. Hernandez-Monteagudo

Publications and source records attributed to C. Hernandez-Monteagudo.

40 records · Page 3Linked to original sources

arXiv2003

CMB Observations and the Production of Chemical Elements at the End of the Dark Ages

The metallicity evolution and ionization history of the universe must leave its imprint on the Cosmic Microwave Background through resonant scattering of CMB photons by atoms, ions and molecules. These transitions partially erase original temperature anisotropies of the CMB, and also generate new fluctuations. In this paper we propose a method to determine the abundance of these heavy species in low density (over-densities less than $10^4-10^5$) optically thin regions of the universe by using the unprecedented sensitivity of current and future CMB experiments. In particular, we focus our analysis on the sensitivity of the PLANCK HFI detectors in four spectral bands. We also present results for l=220 and 810 which are of interest for balloon and ground-based instruments, like ACT, APEX and SPT. We use the fine-structure transitions of atoms and ions as a source of frequency dependent optical depth ($τ_ν$). These transitions give different contributions to the power spectrum of CMB in different observing channels. By comparing results from those channels, it is possible to {\it avoid} the limit imposed by the cosmic variance and to extract information about the abundance of corresponding species at the redshift of scattering. For PLANCK HFI we will be able to get strong constraints ($10^{-4}-10^{-2}$ solar fraction) on the abundances of neutral atoms like C, O, Si, S, and Fe in the redshift range 1-50. Fine-structure transitions of ions like CII, NII or OIII set similar limits in the very important redshift range 3-25 and can be used to probe the ionization history of the universe. Foregrounds and other frequency dependent contaminants may set a serious limitation for this method.

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arXiv2003

Using peak distribution of the cosmic microwave background for MAP and Planck data analysis: formalism and simulations

We implement and further refine the recently proposed method (Kashlinsky, Hernández-Monteagudo & Atrio-Barandela, 2001 - KHA) for a time efficient extraction of the power spectrum from future cosmic microwave background (CMB) maps. The method is based on the clustering properties of peaks and troughs of the Gaussian CMB sky. The procedure takes only ${1/2}[f(ν)]^2N^2$ steps where $f(ν)$ is the fraction of pixels with $|δT|\geqν$ standard deviations in the map of $N$ pixels. We use the new statistic introduced in KHA, $ξ_ν$, which characterizes spatial clustering of the CMB sky peaks of progressively increasing thresholds. The tiny fraction of the remaining pixels (peaks and troughs) contains the required information on the CMB power spectrum of the entire map. The threshold $ν$ is the only parameter that determines the accuracy of the final spectrum. We performed detailed numerical simulations for parameters of the two-year WMAP and Planck CMB sky data including cosmological signal, inhomogeneous noise and foreground residuals. In all cases we find that the method can recover the power spectrum out to the Nyquist scale of the experiment channel. We discuss how the error bars scale with $ν$ allowing to decide between accuracy and speed. The method can determine with significant accuracy the CMB power spectrum from the upcoming CMB maps in only $\sim(10^{-5}-10^{-3})\times N^2$ operations.

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arXiv2003

On the Presence of Thermal SZ Induced Signal in the First Year WMAP Temperature Maps

Using available optical and X-ray catalogues of clusters and superclusters of galaxies, we build templates of tSZ emission as they should be detected by the WMAP experiment. We compute the cross-correlation of our templates with WMAP temperature maps, and interpret our results separately for clusters and for superclusters of galaxies. For clusters of galaxies, we claim 2-5 $σ$ detections in our templates built from BCS Ebeling et al. (1998), NORAS (Boehringer et al. 2000) and de Grandi et al. (1999) catalogues. In these templates, the typical cluster temperature decrements in WMAP maps are around 15-35 $μ$K in the RJ range (no beam deconvolution applied). Several tests probing the possible influence of foregrounds in our analyses demonstrate that our results are robust against galactic contamination. On supercluster scales, we detect a diffuse component in the V & W WMAP bands which cannot be generated by superclusters in our catalogues (Einasto et al. 1994, 1997), and which is not present in the clean map of Tegmark, de Oliveira-Costa & Hamilton (2003). Using this clean map, our analyses yield, for Einasto's supercluster catalogues, the following upper limit for the comptonization parameter associated to supercluster scales: $y_{SC} < 2.18 \time s 10^{-8}$ at the 95% confidence limit.

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arXiv2000

Limits on Hot Intracluster Gas Contributions to the Tenerife Temperature Anisotropy Map

We limit the contribution of the hot intracluster gas, by means of the Sunyaev-Zel'dovich effect, to the temperature anisotropies measured by the Tenerife experiment. The data is cross-correlated with maps generated from the ACO cluster catalogue, the ROSAT PSPC catalogue of clusters of galaxies, a catalogue of superclusters and the HEAO 1 A-1 map of X-ray sources. There is no evidence of contamination by such sources at an rms level of $\sim 8μ$K at 99% confidence level at $5^o$ angular resolution. We place an upper limit on the mean Comptonization parameter of $ y \le 1.5\times 10^{-6}$ at the same level of confidence. These limits are slightly more restrictive than those previously found by a similar analysis on the COBE/DMR data and indicate that most of the signal measured by Tenerife is cosmological.

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