相关论文: 21cm absorption signal from charge sequestration
The Dark Ages, probed by the redshifted 21-cm signal, is the ideal epoch for a new rigorous test of the standard LCDM cosmological model. Divergences from that model would indicate new physics, such as dark matter decay (heating) or…
We evaluate the ratio of baryon and electric-charge cumulants at second order from the recent experimental results at $\sqrt{s_{_{NN}}}=200$ GeV by the STAR Collaboration. The baryon number cumulant is reconstructed from the proton number…
While the $\mathbb{Z}_3$ symmetric dark matter models have shown tremendous prospects in addressing a number of (astro-)particle physics problems, they can leave interesting imprints on cosmological observations as well. We consider two…
The redshifted 21-cm signal of neutral Hydrogen is a promising probe into the period of evolution of our Universe when the first stars were formed (Cosmic Dawn), to the period where the entire Universe changed its state from being…
Apart from its anomalously large depth, the cosmological 21-cm absorption signal measured by the EDGES collaboration also has a shape that is distinctly different from theoretical predictions. Models with non-traditional components such as…
We present here 21 cm predictions from high dynamic range simulations for a range of reionization histories that have been tested against available Lyman-alpha and CMB data. We assess the observability of the predicted spatial 21 cm…
The existence of millicharged dark matter (mDM) can leave a measurable imprint on 21-cm cosmology through mDM-baryon scattering. However, the minimal scenario is severely constrained by existing cosmological bounds on both the fraction of…
An absorption dip in the spectrum of the cosmic microwave background observed by the EDGES experiment suggests an unexplained reduction of the hydrogen spin temperature at cosmic redshift z ~ 17. The mass of dark-matter axions could…
The recent detection of the "cosmic dawn" redshifted 21 cm signal at 78 MHz by the EDGES experiment differs significantly from theoretical predictions. In particular, the absorption trough is roughly a factor of two stronger than the most…
The cosmic radio-frequency spectrum is expected to show a strong absorption signal corresponding to the 21-centimetre-wavelength transition of atomic hydrogen around redshift 20, which arises from Lyman-alpha radiation from some of the…
Before the universe was reionized, it was likely that the spin temperature of intergalactic hydrogen was decoupled from the CMB by UV radiation from the first stars through the Wouthuysen-Field effect. If the IGM had not yet been heated…
The recent tentative detection by the EDGES Low-Band antenna of the hydrogen 21-cm line from cosmic dawn, if confirmed, is the first ever signature observed from the epoch of primordial star formation. However, the magnitude and the shape…
We investigate a high-$z$ cosmological model to compute the co-moving sound horizon $r_s$ at baryon-velocity freeze-out towards the end of hydrogen recombination. This model assumes a replacement of the conventional CMB photon gas by…
Accurate simulations of the 21-cm signal from the Epoch of Reionization require the generation of maps at specific frequencies given the values of astrophysical and cosmological parameters. The peculiar velocities of the hydrogen atoms…
The resonance scattering of Ly$\alpha$ photons with neutral hydrogen atoms in the intergalactic medium not only couples the spin temperature to the kinetic temperature but also leads to a heating of the gas. We investigate the impact of…
This paper presents a systematic study of the photoionization and thermodynamic properties of the cool circumgalactic medium (CGM) as traced by rest-frame ultraviolet absorption lines around 26 galaxies at redshift $z\lesssim1$. The study…
While the origin and composition of dark matter and dark energy remains unknown, it is possible that they might represent two manifestations of a single entity, as occurring in unified dark sector models. On the other hand, advances in our…
We propose a new method to hunt for dark matter using dark forest/absorption features across the whole electromagnetic spectrum from radio to gamma rays, especially in the bands where there is a desert i.e. regions where no strong lines…
The recent EDGES collaboration detection of an absorption signal at a central frequency of $\nu = 78 \pm 1$ MHz points to the presence of a significant Lyman-$\alpha$ background by a redshift of $z=18$. The timing of this signal constrains…
The 21cm line refers to a forbidden transition in neutral hydrogen associated with alignment of spins of the proton and electron. It is a very low energy transition that is emitted whenever there is neutral hydrogen in the Universe. Since…