ﻻ يوجد ملخص باللغة العربية
By using N-body hydrodynamical cosmological simulations in which the chemistry of major metals and molecules is consistently solved for, we study the interaction of metallic fine-structure lines with the CMB. Our analysis shows that the collisional induced emissions in the OI 145 $mu$m and CII 158 $mu$m lines during reionization introduce a distortion of the CMB spectrum at low frequencies ($ u < 300$ GHz) with amplitudes up to $Delta I_{ u}/B_{ u}(T_{rm CMB})sim 10^{-8}$-$10^{-7}$, i.e., at the $sim 0.1$ percent level of FIRAS upper limits. Shorter wavelength fine-structure transitions (OI 63 $mu$m, FeII 26 $mu$m, and SiII 35 $mu$m) typically sample the reionization epoch at higher observing frequencies ($ u > 400$ GHz). This corresponds to the Wien tail of the CMB spectrum and the distortion level induced by those lines may be as high as $Delta I_{ u}/B_{ u}(T_{rm CMB})sim 10^{-4}$. The angular anisotropy produced by these lines should be more relevant at higher frequencies: while practically negligible at $ u=145 $GHz, signatures from CII 158 $mu$m and OI 145 $mu$m should amount to 1%-5% of the anisotropy power measured at $l sim 5000$ and $ u=220 $GHz by the ACT and SPT collaborations (after assuming $Delta u_{rm obs}/ u_{rm obs}simeq 0.005$ for the line observations). Our simulations show that anisotropy maps from different lines (e.g., OI 145 $mu$m and CII 158 $mu$m) at the same redshift show a very high degree ($>0.8$) of spatial correlation, allowing for the use of observations at different frequencies to unveil the same snapshot of the reionization epoch. Finally, our simulations demonstrate that line-emission anisotropies extracted in narrow frequency/redshift shells are practically uncorrelated in frequency space, thus enabling standard methods for removal of foregrounds that vary smoothly in frequency, just as in HI 21 cm studies.
We compute the spectral distortions of the Cosmic Microwave Background (CMB) polarization induced by non-linear effects in the Compton interactions between CMB photons and cold intergalactic electrons. This signal is of the $y$-type and is dominated
The neutral hydrogen (HI) and its 21 cm line are promising probes to the reionization process of the intergalactic medium (IGM). To use this probe effectively, it is imperative to have a good understanding on how the neutral hydrogen traces the under
Voyage 2050 White Paper highlighting the unique science opportunities using spectral distortions of the cosmic microwave background (CMB). CMB spectral distortions probe many processes throughout the history of the Universe. Precision spectroscopy, p
Since the measurements of COBE/FIRAS in the mid-90s we know that the energy spectrum of the cosmic microwave background (CMB) is extremely close to that of a perfect blackbody at an average temperature T0~2.726K. However, a number of early-universe p
The intergalactic medium is expected to be at its coldest point before the formation of the first stars in the universe. Motivated by recent results from the EDGES experiment, we revisit the standard calculation of the kinetic temperature of the neut