Related papers: How Dark Matter Reionized The Universe
The evidence is that the mass of the universe is dominated by an exotic nonbaryonic form of matter largely draped around the galaxies. It approximates an initially low pressure gas of particles that interact only with gravity, but we know…
Dark Matter annihilation (DMA) may yield an excess of gamma rays and antimatter particles, like antiprotons and positrons, above the background from cosmic ray interactions. Several signatures, ranging from the positron excess, as observed…
The possibility that population III stars have reionized the Universe at redshifts greater than 6 has recently gained momentum with WMAP polarization results. Here we analyse the role of early dust produced by these stars and ejected into…
In popular cold dark matter cosmological scenarios, stars may have first appeared in significant numbers around a redshift of 10 or so, as the gas within protogalactic halos with virial temperatures in excess of 20,000 K (corresponding to…
Recent preliminary results from the PAMELA experiment indicate the presence of an excess of cosmic ray positrons above 10 GeV. In this letter, we consider possibility that this signal is the result of dark matter annihilations taking place…
It has recently been argued that the PAMELA, ATIC and PPB-BETS data showing an anomalous excess of high-energy cosmic ray positrons and electrons might be explained by dark matter annihilating in the Galactic halo with a cross section…
Annihilation of clumped superheavy dark matter provides an interesting explanation for the origin of ultrahigh energy cosmic rays. The predicted anisotropy signal provides a unique signature for this scenario.
Annihilating dark matter (DM) has been discussed as a possible source of gamma-rays from the galactic center (GC) and contributing to the extragalactic gamma-ray background (EGB). Assuming universality of the density profile of DM halos, we…
In the current paradigm of cosmic structure formation, dark matter plays a key role on the formation and evolution of galaxies through its gravitational influence. On microscopic scales, dark matter particles are expected to annihilate…
The primordial gas in the earliest dark matter halos, collapsing at redshifts around z=20, with masses M_halo=10^6 M_sun, and virial temperatures T_vir<10^4K, relied on the presence of molecules for cooling. Several theoretical studies have…
The epoch of reionization probes the state of our universe when the very first stars formed and ionized the hydrogen atoms in the surrounding medium. Since the epoch has not yet been probed observationally, it is often called the "final…
We derive new constraints on models of decaying and annihilating dark matter (DM) by requiring that the energy injected into the intergalactic medium (IGM) not overheat it at late times, when measurements of the Lyman-$\alpha$ forest…
Annihilating dark matter (DM) models offer promising avenues for future DM detection, in particular via modification of astrophysical signals. However when modelling such potential signals at high redshift the emergence of both dark matter…
We assess a model of late cosmic reionization in which the ionizing background radiation arises entirely from high redshift quasars and other active galactic nuclei (AGNs). The low optical depth to Thomson scattering reported by the Planck…
Understanding the detailed process of cosmic reionization is one of the remaining problems in astrophysics and cosmology. Here we construct a model of cosmic reionization that includes contribution from high-$z$ galaxies and active galactic…
A problem still unsolved in cosmology is the identification of the sources of radiation able to reionize HI in the intergalactic medium (IGM) by z~6. Theoretical works and observations seem to indicate that the fraction, f_esc, of HI…
Some seventy five years ago, the concept of dark matter was introduced by Zwicky to explain the anomaly of galactic rotation curves, though there is no clue to its identity or existence to date. In 1997, the author had introduced a model of…
If dark matter decays to electromagnetically-interacting particles, it can inject energy into the baryonic gas and thus affect the processes of recombination and reionization. This leaves an imprint on the cosmic microwave background (CMB):…
One of the next decade's most exciting prospects is to explore the cosmic "dark ages," during which the first stars in the Universe formed, with the 21 cm line of neutral hydrogen. At z>6, this light redshifts into the low-frequency radio…
A possible explanation of the present discrepancy between the abundance of galactic subhaloes predicted by N-Body simulations with those observed in the Local Group is presented. We study the impact of an early reionization on the baryonic…