相关论文: The Wouthuysen Field Absorption Trough in Cosmic S…
In previous works we discussed the 21 cm signature of a single cosmic string wake. However the 21 cm brightness temperature is influenced by a network of cosmic string wakes, and not one single wake. In this work we consider the signal from…
The analysis of the 21 cm signature of cosmic string wakes is extended in several ways. First we consider the constraints on $G\mu$ from the absorption signal of shock heated wakes laid down much later than matter radiation equality.…
A cosmic string wake produces a distinct non-Gaussian signal in 21-cm intensity maps at redshifts above that of reionization. While the string signal is (locally) larger in amplitude than the signal of the Gaussian fluctuations of the…
We discuss the signature of a cosmic string wake in 21cm redshift surveys. Since 21cm surveys probe higher redshifts than optical large-scale structure surveys, the signatures of cosmic strings are more manifest in 21cm maps than they are…
We present results of a cosmological hydrodynamical study of gravitational accretion in cosmic string wakes and filaments. Cosmic string wakes are formed by fast moving (v ~ c) strings. A conical deficit angle in the string spacetime…
Cosmic strings are generically predicted in many extensions of the Standard Model of particle physics. We propose a new avenue for detecting cosmic strings through their effect on the filamentary structure in the cosmic web. Using…
I compute the 3-D non-linear evolution of gas and dark matter fluids in the neighbourhood of cosmic string wakes which are formed at high redshift ($z\simeq 2240$) for a ``realistic'' scenario of wake formation. These wakes are the ones…
We consider cosmic string cusp annihilations as a possible source of enhancement to the global background radiation temperature in $21$-cm photons at reionization. A soft photon spectrum is induced via the Bremsstrahlung and Synchrotron…
The first UV sources in the universe are expected to have coupled the HI spin temperature to the gas kinetic temperature via scattering in the Lyman-alpha resonance [the Wouthuysen-Field (WF) effect]. By establishing an HI spin temperature…
Superconducting cosmic strings emit electromagnetic waves between the times of recombination and reionization. Hence, they have an effect on the global 21cm signal. We compute the resulting absorption features, focusing on strings with…
Cosmic strings moving through matter produce wakes where density is higher than the background density. We investigate the effects of such wakes occurring at the time of a first order quark-hadron transition in the early universe and show…
We calculate the contribution of cosmic strings arising from a phase transition in the early universe, or cosmic superstrings arising from brane inflation, to the cosmic 21 cm power spectrum at redshifts z > 30. Future experiments can…
The EDGES experiment recently announced evidence for a broad absorption feature in the sky-averaged radio spectrum around 78 MHz, as may result from absorption in the 21 cm line by neutral hydrogen at z~15-20. If confirmed, one implication…
We study the effect of weak lensing by cosmic (super-)strings on the higher-order statistics of the cosmic microwave background (CMB). A cosmic string segment is expected to cause weak lensing as well as an integrated Sachs-Wolfe (ISW)…
In this paper, we describe the results of N-body simulation runs, which include a cosmic string wake of tension $G\mu= 4 \times 10^{-8}$ on top of the usual $\Lambda CDM$ fluctuations. To obtain a higher resolution of the wake in the…
Cosmic string loops lead to nonlinear baryon overdensities at early times, even before the time which in the standard LCDM model corresponds to the time of reionization. These overdense structures lead to signals in 21cm redshift surveys at…
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…
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…
We examine the structure of baryonic wakes in the cosmological fluid which would form behind GUT-scale cosmic strings at early times (redshifts z > 100) in a neutrino-dominated universe. We show, using simple analytical arguments as well as…
A recent observation by the EDGES collaboration shows a strong absorption signal in the global 21-cm spectrum from around a redshift of $z = 17$. This absorption is stronger than the maximum prediction by existing models and indicates that…