Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userAnalytical warm dark matter power spectrum on small scales
135
0
0.0
(
0
)
Added by
Ronaldo Carlotto Batista
Publication date
2021
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
Using the Reduced Relativistic Gas (RRG) model, we analytically determine the matter power spectrum for Warm Dark Matter (WDM) on small scales, $k>1 htext{/Mpc}$. The RRG is a simplified model for the ideal relativistic gas, but very accurate in the cosmological context. In another work, we have shown that, for typical allowed masses for dark matter particles, $m>5 text{keV}$, the higher order multipoles, $ell>2$, in the Einstein-Boltzmann system of equations are negligible on scales $k<10 htext{/Mpc}$. Hence, we can follow the perturbations of WDM using the ideal fluid framework, with equation of state and sound speed of perturbations given by the RRG model. We derive a Meszaros like equation for WDM and solve it analytically in radiation, matter and dark energy dominated eras. Joining these solutions, we get an expression that determines the value of WDM perturbations as a function of redshift and wavenumber. Then we construct the matter power spectrum and transfer function of WDM on small scales and compare it to some results coming from Lyman-$alpha$ forest observations. Besides being a clear and pedagogical analytical development to understand the evolution of WDM perturbations, our power spectrum results are consistent with the observations considered and the other determinations of the degree of warmness of dark matter particles.
rate research
Read More
We compare primordial black hole (PBH) constraints on the power spectrum and mass distributions using the traditional Press Schechter formalism, peaks theory, and a recently developed version of peaks theory relevant to PBHs. We show that, provided the PBH formation criteria and the power spectrum smoothing are treated consistently, the constraints only vary by $sim$10% between methods (a difference that will become increasingly important with better data). Our robust constraints from PBHs take into account the effects of critical collapse, the non-linear relation between $zeta$ and $delta$, and the shift from the PBH mass to the power spectrum peak scale. We show that these constraints are remarkably similar to the pulsar timing array (PTA) constraints impacting the black hole masses detected by the LIGO and Virgo, but that the $mu$-distortion constraints rule out supermassive black hole (SMBH) formation and potentially even the much lighter mass range of $sim$(1-100) $mathrm{M}_odot$ that LIGO/Virgo probes.
This article reviews recent progress in observational determination of the properties of dark matter on small astrophysical scales, and progress towards the European Extremely Large Telescope. Current results suggest some surprises: the central DM density profile is typically cored, not cusped, with scale sizes never less than a few hundred pc; the central densities are typically 10-20GeV/cc; no galaxy is found with a dark mass halo less massive than $sim5.10^7M_{odot}$. We are discovering many more dSphs, which we are analysing to test the generality of these results. The European Extremely Large Telescope Design Study is going forward well, supported by an outstanding scientific case, and founded on detailed industrial studies of the technological requirements.
The latest Planck results reconfirm the existence of a slight but chronic tension between the best-fit Cosmic Microwave Background (CMB) and low-redshift observables: power seems to be consistently lacking in the late universe across a range of observables (e.g.~weak lensing, cluster counts). We propose a two-parameter model for dark energy where the dark energy is sufficiently like dark matter at large scales to keep the CMB unchanged but where it does not cluster at small scales, preventing concordance collapse and erasing power. We thus exploit the generic scale-dependence of dark energy instead of the more usual time-dependence to address the tension in the data. The combination of CMB, distance and weak lensing data somewhat prefer our model to $Lambda$CDM, at $Deltachi^2=2.4$. Moreover, this improved solution has $sigma_8=0.79 pm 0.02$, consistent with the value implied by cluster counts.
An analysis of the physics-rich endgame of reionization at $z=5.7$ is performed, utilizing jointly the observations of the Ly$alpha$ forest, the mean free path of ionizing photons, the luminosity function of galaxies and new physical insight. We find that an upper limit on ${rm tau_e}$ provides a constraint on the minimum mean free path (of ionizing photons) that is primarily due to dwarf galaxies, which in turn yields a new and yet the strongest constraint on the matter power spectrum on $10^6-10^9M_odot$ scales. With the latest Planck measurements of ${rm tau_e = 0.055 pm 0.009}$, we can place an upper limit of $(8.9times 10^6, 3.8times 10^7, 4.2times 10^8)M_odot$ on the lower cutoff mass of the halo mass function, or equivalent a lower limit on warm dark matter particle mass ${rm m_x ge (15.1, 9.8, 4.6)keV}$ or on sterile neutrino mass ${rm m_s ge (161, 90, 33)keV}$, at $(1, 1.4, 2.2)sigma$ confidence level, respectively.
We present a new compilation of inferences of the linear 3D matter power spectrum at redshift $z,{=},0$ from a variety of probes spanning several orders of magnitude in physical scale and in cosmic history. We develop a new lower-noise method for performing this inference from the latest Ly$alpha$ forest 1D power spectrum data. We also include cosmic microwave background (CMB) temperature and polarization power spectra and lensing reconstruction data, the cosmic shear two-point correlation function, and the clustering of luminous red galaxies. We provide a Dockerized Jupyter notebook housing the fairly complex dependencies for producing the plot of these data, with the hope that groups in the future can help add to it. Overall, we find qualitative agreement between the independent measurements considered here and the standard $Lambda$CDM cosmological model fit to the {it Planck} data
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
