arXiv subjects

Fernando Atrio-Barandela

Publications and source records attributed to Fernando Atrio-Barandela.

14 recordsLinked to original sources

arXiv2026

A possible pathway to UHZ1-type systems at z~10 by heterogeneous mass primordial black holes as dark matter

Recent space-based observations discovered several unusual objects, exhibiting similar properties, at redshifts $z\gtrsim 10$. Among them is the UHZ1 system at $z=10.1$, containing $\sim 10^8M_\odot$ in stars, with a similarly massive central black hole of $\sim 10^{7-8}M_\odot$. Here we propose a possible mechanism for forming such systems which hinges on the presence of primordial black holes (PBHs) covering a range of masses while contributing a significant fraction of the dark matter (DM). We evaluate the accurate expression for the small-scale power responsible for the collapse of the first halos in the presence of the PBH population. The extra power in the matter density field, produced by the granulation term, will cause an earlier collapse of DM halos, populated by PBHs of different masses. In these collapsed and virialized systems the PBHs will undergo 2-body relaxation, driving the more massive PBHs to the halo center under dynamical friction. We quantify this evolution for a distribution of PBH orbital parameters and halo properties. The analysis shows that PBHs can have appropriate mass functions capable of producing systems with parameters similar to what is observed for UHZ1. We suggest that the proposed mechanism could account for a subset of other systems newly discovered with the JWST at high redshifts, including the Little Red Dots.

astro-ph.CO↗

arXiv2015

Probing the Dark Flow signal in WMAP 9 yr and PLANCK cosmic microwave background maps

The "dark flow" dipole is a statistically significant dipole found at the position of galaxy clusters in filtered maps of Cosmic Microwave Background (CMB) temperature anisotropies. The dipole measured in WMAP 3, 5 and 7 yr data releases was 1) mutually consistent, 2) roughly aligned with the all-sky CMB dipole and 3) correlated with clusters' X-ray luminosity. We analyzed WMAP 9 yr and the 1st yr Planck data releases using a catalog of 980 clusters outside the Kp0 mask to test our earlier findings. The dipoles measured on these new data sets are fully compatible with our earlier estimates, being similar in amplitude and direction to our previous results and in disagreement with the results of an earlier study by the Planck Collaboration. Further, in Planck datasets dipoles are found independent of frequency, ruling out the Thermal Sunyaev-Zeldovich as the source of the effect. Both, in WMAP and Planck, we find a clear correlation between the dipole measured at the cluster location in filtered maps with the average anisotropy on the original maps, further proving that the dipole is associated with clusters. The dipole signal is dominated by the most massive clusters, with a statistical significance better than 99\%, slightly larger than in WMAP. Since both data sets differ in foreground contributions, instrumental noise and other systematics, the agreement between WMAP and Planck dipoles argues against them being due to systematic effects in either of the experiments.

astro-ph.CO↗

arXiv2015

Constraining the baryon fraction in the Warm Hot Intergalactic Medium at low redshifts with PLANCK data

We cross-correlate foreground cleaned Planck Nominal Cosmic Microwave Background (CMB) maps with two templates constructed from the Two-Micron All-Sky Redshift Survey of galaxies. The first template traces the large-scale filamentary distribution characteristic of the Warm-Hot Intergalactic Medium (WHIM) out to ~90 Mpc/h. The second traces preferentially the virialized gas in unresolved halos around galaxies. We find a marginal signal from the correlation of Planck data and the WHIM template with a signal-to-noise from 0.84 to 1.39 at the different Planck frequencies, and with a frequency dependence compatible with the thermal Sunyaev-Zel'dovich (tSZ) effect. When we restrict our analysis to the 60% of the sky outside the plane of the Galaxy and known point sources and galaxy clusters, the cross-correlation at zero lag is 0.064 +/- 0.051 muK. The correlation extends out to ~6 deg, which at the median depth of our template corresponds to a physical length of ~ 6-8 Mpc/h. On the same fraction of the sky, the cross-correlation of the CMB data with the second template is <0.17 muK (95% C.L.), providing no statistically significant evidence of a contribution from bound gas to the previous result. This limit translates into a physical constraint on the properties of the shock-heated WHIM of a log-normal model describing the weakly nonlinear density field. We find that our upper limit is compatible with a fraction of 45% of all baryons residing in filaments at overdensities ~1-100 and with temperatures in the range 10^4.5-10^7.5 K, in agreement with the detection at redshift z~0.5 of van Waerbeke et al. (2014).

astro-ph.CO↗

arXiv2014

Probing the epoch of pre-reionization by cross-correlating cosmic microwave and infrared background anisotropies

The epoch of first star formation and the state of the intergalactic medium (IGM) at that time are not directly observable with current telescopes. The radiation from those early sources is now part of the Cosmic Infrared Background (CIB) and, as these sources ionize the gas around them, the IGM plasma would produce faint temperature anisotropies in the Cosmic Microwave Background (CMB) via the thermal Sunyaev-Zeldovich (TSZ) effect. While these TSZ anisotropies are too faint to be detected, we show that the cross-correlation of maps of source-subtracted CIB fluctuations from {\it Euclid}, with suitably constructed microwave maps at different frequencies can probe the physical state of the gas during reionization and test/constrain models of the early CIB sources. We identify the frequency-combined CMB-subtracted microwave maps from space and ground-based instruments to show that they can be cross-correlated with the forthcoming all-sky {\it Euclid} CIB maps to detect the cross-power at scales $\sim 5'-60'$ with the signal/noise of up to $S/N\sim 4-8$ depending on the contribution to the Thomson optical depth during those pre-reionization epochs ($Δτ\simeq 0.05$) and the temperature of IGM (up to $\sim10^4$K). Such a measurement would offer a new window to explore emergence and physical properties of these first light sources.

astro-ph.CO↗

arXiv2013

The effect of Dark Matter and Dark Energy interactions on the peculiar velocity field and the kinetic Sunyaev-Zel'dovich effect

The interaction between Dark Matter and Dark Energy has been proposed as a mechanism to alleviate the coincidence problem. We analyze the effect of the interaction on the evolution of the gravitational field and propose two new observables based on its effect on the matter peculiar velocity field. We find that for different model parameters the matter peculiar velocity could be factor 2 times larger or 5 times smaller than the amplitude of velocity perturbations in the concordance LCDM cosmological model at the same scales. We compare the effect on the peculiar velocities with those on the Integrated Sachs-Wolfe effect and we show that velocities can potentially provide constraints on the strength of the interaction stronger than those currently available. We show that the current upper limits on the amplitude of the kinetic Sunyaev-Zel'dovich power spectrum provide constraints on the coupling within the dark sectors that are consistent with those obtained previously from the CMB and galaxy clusters. In particular, we show that current upper limits from the Atacama Cosmology Telescope and the South Pole Telescope favor Dark Energy decaying into Dark Matter, as required to solve the coincidence problem.

astro-ph.CO↗

arXiv2013

Constraints on the Sunyaev-Zel'dovich signal from the Warm Hot Intergalactic Medium from WMAP and SPT data

The fraction of ionized gas in the Warm Hot Intergalactic Medium induces temperature anisotropies on the Cosmic Microwave Background similar to those of clusters of galaxies. The Sunyaev-Zel'dovich anisotropies due to these low density, weakly non-linear, baryon filaments can not be distinguished from that of clusters using frequency information, but they can be separated since their angular scales are very different. To determine the relative contribution of the WHIM SZ signal to the radiation power spectrum of temperature anisotropies, we explore the parameter space of the concordance LCDM model using Monte Carlo Markov Chains and the Wilkinson Microwave Anisotropy Probe 7yr and South Pole Telescope data. We find marginal evidence of a contribution by diffuse gas, with amplitudes of A_WHIM=10-20 muK^2, but the results are also compatible with a null contribution from the WHIM, allowing to set an upper limit of A_WHIM < 43 muK^2 (95.4% C.L.). The signal produced by galaxy clusters remains at A_CL=4.5 muK^2, a value similar to what is obtained when no WHIM is included. From the measured WHIM amplitude we constrain the temperature-density phase diagram of the diffuse gas, and find it to be compatible with numerical simulations. The corresponding baryon fraction in the WHIM varies from 0.43 to 0.47, depending on model parameters. Planck data could set tighter constraints on the temperature-density relation.

astro-ph.CO↗

arXiv2012

The Matter Power Spectrum of Dark Energy Models and the Harrison-Zel'dovich Prescription

According to the Harrison-Zel'dovich prescription, the amplitude of matter density perturbations at horizon crossing is the same at all scales. Based on this prescription, we show how to construct the matter power spectrum of generic dark energy models from the power spectrum of a $Λ$CDM model without the need of solving in full the dynamical equations describing the evolution of all energy density perturbations. Our approach allows to make model predictions of observables that can be expressed in terms of the matter power spectrum alone, such as the amplitude of matter fluctuations, peculiar velocities, cosmic microwave background temperature anisotropies on large angular scales or the weak lensing convergence spectrum. Then, models that have been tested only at the background level using the rate of the expansion of the Universe can now be tested using data on gravitational clustering and on large scale structure. This method can save a lot of effort in checking the validity of dark energy models. As an example of the accurateness of the approximation used, we compute the power spectrum of different dark energy models with constant equation of state parameter ($w_{DE}=-0.1$, -0.5 and -0.8, ruled out by observations but easy to compare to numerical solutions) using our methodology and discuss the constraints imposed by the low multipoles of the cosmic microwave background.

astro-ph.CO↗

arXiv2012

Measuring the redshift dependence of the CMB monopole temperature with PLANCK data

We study the power of PLANCK data to constrain deviations of the Cosmic Microwave Background black body temperature from adiabatic evolution using the thermal Sunyaev-Zeldovich anisotropy induced by clusters of galaxies. We consider two types of data sets: the cosmological signal is removed in the Time Ordered Information or is removed from the final maps; and two different statistical estimators, based on the ratio of temperature anisotropies at two different frequencies and on a fit to the spectral variation of the cluster signal with frequency. To test for systematics, we construct a template from clusters drawn from a hydro-simulation included in the pre-launch Planck Sky Model. We demonstrate that, using a proprietary catalog of X-ray selected clusters with measured redshifts, electron densities and X-ray temperatures, we can constrain deviations of adiabatic evolution, measured by the parameter $α$ in the redshift scaling $T(z)=T_0(1+z)^{1-α}$, with an accuracy of $σ_α=0.011$ in the most optimal case and with $σ_α=0.016$ for a less optimal case. These results represent a factor 2-3 improvement over similar measurements carried out using quasar spectral lines and a factor 6-20 with respect to earlier results using smaller cluster samples.

astro-ph.CO↗

arXiv2009

The contribution of the kinematic Sunyaev-Zel'dovich Effect from the Warm Hot Intergalactic Medium to the Five-Year WMAP Data

We study the contribution of the kinematic Sunyaev-Zel'dovich (kSZ) effect, generated by the warm-hot intergalactic medium (WHIM), to the cosmic microwave background (CMB) temperature anisotropies in the Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) data. We explore the concordance LambdaCDM cosmological model, with and without this kSZ contribution, using a Markov chain Monte Carlo algorithm. Our model requires a single extra parameter to describe this new component. Our results show that the inclusion of the kSZ signal improves the fit to the data without significantly altering the best-fit cosmological parameters except Obh^2. The improvement is localized at the l>500 multipoles. For the best-fit model, this extra component peaks at l~450 with an amplitude of 129 muK^2, and represents 3.1% of the total power measured by the Wilkinson Microwave Anisotropy Probe. Nevertheless, at the 2-sigma level a null kSZ contribution is still compatible with the data. Part of the detected signal could arise from unmasked point sources and/or Poissonianly distributed foreground residuals. A statistically more significant detection requires the wider frequency coverage and angular resolution of the forthcoming Planck mission.

astro-ph.CO↗

arXiv2008

Dynamics of Interacting Quintessence Models: Observational Constraints

Interacting quintessence models have been proposed to explain or, at least, alleviate the coincidence problem of late cosmic acceleration. In this paper we are concerned with two aspects of these kind of models: (i) the dynamical evolution of the model of Chimento et al. [L.P. Chimento, A.S. Jakubi, D. Pavon, and W. Zimdahl, Phys. Rev. D 67, 083513 (2003).], i.e., whether its cosmological evolution gives rise to a right sequence of radiation, dark matter and dark energy dominated eras, and (ii) whether the dark matter dark energy ratio asymptotically evolves towards a non-zero constant. After showing that the model correctly reproduces these eras, we correlate three data sets that constrain the interaction at three redshift epochs: $z\le 10^{4}$, $z=10^{3}$, and $z=1$. We discuss the model selection and argue that even if the model under consideration fulfills both requirements, it is heavily constrained by observation. The prospects that the coincidence problem can be explained by the coupling of dark matter to dark energy are not clearly favored by the data.

astro-ph↗

arXiv2006

The matter power spectrum as a tool to discriminate dark matterr-dark energy interactions

The coincidence problem of late cosmic acceleration gets significantly alleviated when a suitable interaction between matter and dark energy, either of phantom type or not, enters the picture. We show that a class of models featuring this interaction fares rather well when contrasted with the anisotropies of the CMBR and the matter power spectrum. The latter test is very sensible to the interaction and may be used to discriminate between different models.

astro-ph↗

arXiv2005

Constraining dark energy interacting models with WMAP

We determine the range of parameter space of an interacting quintessence (IQ) model that best fits the luminosity distance of type Ia supernovae data and the recent WMAP measurements of Cosmic Microwave Background temperature anisotropies. Models in which quintessence decays into dark matter provide a clean explanation for the coincidence problem. We focus on cosmological models of zero spatial curvature. We show that if the dark energy (DE) decays into cold dark matter (CDM) at a rate that brings the ratio of matter to dark energy constant at late times, the supernovae data are not sufficient to constrain the interaction parameter. On the contrary, WMAP data constrain it to be smaller than $c^2 < 10^{-2}$ at the $3σ$ level. Accurate measurements of the Hubble constant and the dark energy density, independent of the CMB data, would support/disprove this set of models.

astro-ph↗

arXiv2005

Observational constraints on interacting quintessence models

We determine the range of parameter space of Interacting Quintessence Models that best fits the recent WMAP measurements of Cosmic Microwave Background temperature anisotropies. We only consider cosmological models with zero spatial curvature. We show that if the quintessence scalar field decays into cold dark matter at a rate that brings the ratio of matter to dark energy constant at late times,the cosmological parameters required to fit the CMB data are: Ω_x = 0.43 \pm 0.12, baryon fraction Ω_b = 0.08 \pm 0.01, slope of the matter power spectrum at large scals n_s = 0.98 \pm 0.02 and Hubble constant H_0 = 56 \pm 4 km/s/Mpc. The data prefers a dark energy component with a dimensionless decay parameter c^2 =0.005 and non-interacting models are consistent with the data only at the 99% confidence level. Using the Bayesian Information Criteria we show that this exra parameter fits the data better than models with no interaction. The quintessence equation of state parameter is less constrained; i.e., the data set an upper limit w_x \leq -0.86 at the same level of significance. When the WMAP anisotropy data are combined with supernovae data, the density parameter of dark energy increases to Ω_x \simeq 0.68 while c^2 augments to 6.3 \times 10^{-3}. Models with quintessence decaying into dark matter provide a clean explanation for the coincidence problem and are a viable cosmological model, compatible with observations of the CMB, with testable predictions. Accurate measurements of baryon fraction and/or of matter density independent of the CMB data, would support/disprove these models.

astro-ph↗

arXiv1997

Interacting Hot Dark Matter

We discuss the viability of a light particle ($\sim 30$ eV neutrino) with strong self-interactions as a dark matter candidate. The interaction prevents the neutrinos from free-streaming during the radiation dominated regime so galaxy sized density perturbations can survive. Smaller scale perturbations are damped due to neutrino diffusion. We calculate the power spectrum in the imperfect fluid approximation, and show that it is damped at the length scale one would estimate due to neutrino diffusion. The strength of the neutrino--neutrino coupling is only weakly constrained by observations, and could be chosen by fitting the power spectrum to the observed amplitude of matter density perturbations. The main shortcoming of our model is that interacting neutrinos can not provide the dark matter in dwarf galaxies.

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