Spectral spatial fluctuations of CMBR: Strategy and concept of the experiment

Дубрович, В. К.; Bajkova, A. T.; Хайкин, В. Б.

doi:10.1016/j.newast.2007.06.006

Cited by 11 publications

(17 citation statements)

References 40 publications

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“…The gas clouds or halos which have large peculiar velocity along the line of sight are another source of secondary anisotropy: the resonant scattering of CMB quanta by molecules in the moving halos may cause increasing or decreasing of the brightness temperature of the radiation passing through the halo depending on the direction of peculiar velocity relative to the observer. It was predicted by Dubrovich (1977) and possibility of its observation were studied in Maoli et al (1994Maoli et al ( , 1996; Dubrovich et al (2008); Núñez-López et al (2006); Persson et al (2010) and other papers.…”

Section: Introductionmentioning

confidence: 95%

Hydrogen Molecules in the Dark Ages Halos: Thermal Emission versus Resonant Scattering

Novosyadlyj

Shulga

Kulinich

et al. 2019

ApJ

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The emission from dark ages halos in the lines of transitions between lowest rotational levels of hydrogen and hydrogen deuteride molecules is analyzed. It is assumed molecules to be excited by CMB and collisions with hydrogen atoms. The physical parameters of halos and number density of molecules are precalculated in assumption that halos are homogeneous top-hat spheres formed from the cosmological density perturbations in the four-component Universe with post-Planck cosmological parameters. The differential brightness temperatures and differential spectral fluxes in the rotational lines of H 2 -HD molecules are computed for two phenomena: thermal luminescence and resonant scattering of CMB radiation. The results show that expected maximal values of differential brightness temperature of warm halos (T K ∼200-800 K) are at the level of nanokelvins, are comparable for both phenomena, and are below sensitivity of modern sub-millimeter radio telescopes. For hot halos (T K ∼2000-5000 K) the thermal emission of H2-ortho molecules dominates and the differential brightness temperatures are predicted to be of a few microkelvins at the frequencies 300-600 GHz, that could be detectable with telescopes of a new generation.

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Section: Introductionmentioning

confidence: 95%

Hydrogen Molecules in the Dark Ages Halos: Thermal Emission versus Resonant Scattering

Novosyadlyj

Shulga

Kulinich

et al. 2019

ApJ

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“…Jenkins et al 1998). Smaller mass perturbations most likely move with a factor of 2−5 higher peculiar velocity (Dubrovich et al 2008). The present ratio of the peculiar velocity to the speed of light is ∼2 × 10 −3 and decreases with increasing redshift.…”

Section: Linear Phasementioning

confidence: 99%

“…This size will occupy a redshift interval Δz in the Hubble flow, and, assuming a spherical geometry and that every part of the cloud moves with the same peculiar velocity, we have (e.g. Maoli et al 1996;Dubrovich et al 2008)…”

Section: Linear Phasementioning

confidence: 99%

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The first spectral line surveys searching for signals from the dark ages

Persson¹,

Maoli

Encrenaz

et al. 2010

A&A

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Aims. Our aim is to observationally investigate the cosmic Dark Ages in order to constrain star and structure formation models, as well as the chemical evolution in the early Universe. Methods. Spectral lines from atoms and molecules in primordial perturbations at high redshifts can give information about the conditions in the early universe before and during the formation of the first stars in addition to the epoch of reionisation. The lines may arise from moving primordial perturbations before the formation of the first stars (resonant scattering lines), or could be thermal absorption or emission lines at lower redshifts. The difficulties in these searches are that the source redshift and evolutionary state, as well as molecular species and transition are unknown, which implies that an observed line can fall within a wide range of frequencies. The lines are also expected to be very weak. Observations from space have the advantages of stability and the lack of atmospheric features which is important in such observations. We have therefore, as a first step in our searches, used the Odin satellite to perform two sets of spectral line surveys towards several positions. The first survey covered the band 547−578 GHz towards two positions, and the second one covered the bands 542.0−547.5 GHz and 486.5−492.0 GHz towards six positions selected to test different sizes of the primordial clouds. Two deep searches centred at 543.250 and 543.100 GHz with 1 GHz bandwidth were also performed towards one position. The two lowest rotational transitions of H 2 will be redshifted to these frequencies from z ∼ 20−30, which is the predicted epoch of the first star formation. Results. No lines are detected at an rms level of 14−90 and 5−35 mK for the two surveys, respectively, and 2−7 mK in the deep searches with a channel spacing of 1−16 MHz. The broad bandwidth covered allows a wide range of redshifts to be explored for a number of atomic and molecular species and transitions. From the theoretical side, our sensitivity analysis show that the largest possible amplitudes of the resonant lines are about 1 mK at frequencies < ∼ 200 GHz, and a few μK around 500−600 GHz, assuming optically thick lines and no beam-dilution. However, if existing, thermal absorption lines have the potential to be orders of magnitude stronger than the resonant lines. We make a simple estimation of the sizes and masses of the primordial perturbations at their turnaround epochs, which previously has been identified as the most favourable epoch for a detection. This work may be considered as an important pilot study for our forthcoming observations with the Herschel Space Observatory.

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“…In addition, the interaction between the gas and the cosmic microwave background (CMB) plays an important role in regulating the chemistry of the gas, and moreover one which may lead to observable changes in the CMB (see e.g. Maoli, Melchiorri & Tosti 1994;Dubrovich, Bajkova & Khaikin 2008;Schleicher et al 2008). Furthermore, understanding the chemical evolution of the gas at these early epochs is vital if one wants to understand the formation of the first stars and galaxies, given the crucial role played by molecular hydrogen (H 2 ) in this process.…”

Section: Introductionmentioning

confidence: 99%

The Chemistry of the Early Universe

Glover

2011

Proc. IAU

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Abstract. The chemistry of the early Universe is a fascinating field of study. Even in the absence of any elements heavier than lithium, a surprising degree of chemical complexity proves to be possible, giving the topic considerable interest in its own right. In addition, the fact that molecular hydrogen plays a key role in the formation of the first stars and galaxies means that if we want to understand the formation of these objects, we must first develop a good understanding of the chemical evolution of the gas. In this review, I first give a brief introduction to the chemistry occurring in the gas prior to the formation of the first stars and galaxies, and then go on to discuss in more detail the main chemical processes occurring during the gravitational collapse of gas from intergalactic to protostellar densities, and how these processes influence the final outcome of the collapse.

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Spectral spatial fluctuations of CMBR: Strategy and concept of the experiment

Cited by 11 publications

References 40 publications

Hydrogen Molecules in the Dark Ages Halos: Thermal Emission versus Resonant Scattering

Hydrogen Molecules in the Dark Ages Halos: Thermal Emission versus Resonant Scattering

The first spectral line surveys searching for signals from the dark ages

The Chemistry of the Early Universe

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