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E. Almaraz

Publications and source records attributed to E. Almaraz.

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Testing the nature of Dark Energy with Precision Cosmological constraints

We present a Dark Energy (DE) model with a sound derivation as a natural extension of the Standard Model of particle physics with no free parameters and an excellent fit with current cosmological data improving by 21% the $Λ$CDM fit of the Baryon Acoustic Oscillations (BAO) measurements, specially designed to determine the dynamics of DE. DE corresponds to the lightest bound state scalar particle $ϕ$ with a potential $V=Λ_c^{4+2/3}ϕ^{-2/3}$ dynamically formed at the condensation energy scale $Λ_c$ and scale factor $a_c$. The value of $Λ_c$, the exponent $n=2/3$, and the initial conditions of $ϕ$ are all derived quantities. We obtain an exact constraint $a_cΛ_c/\textrm{eV}=1.0939\times 10^{-4}$ and a theoretical prediction $Λ_c=34 ^{+16}_{-11} \textrm{ eV}$, consistent with the best fit $Λ_c=44.08\pm 0.27 \textrm{ eV}$. We test our model constraint on $a_cΛ_c$ by allowing $a_c$ and $Λ_c$ to vary independently and remarkably our prediction has a relative difference of only 0.2% with the best fit value. Unlike a cosmological constant $Λ$, our DE model predicts the amount of DE and leaves detectable cosmological imprints at different times and scales at a background and perturbation level.

astro-ph.CO

On the sensitivity of the HAWC observatory to gamma-ray bursts

We present the sensitivity of HAWC to Gamma Ray Bursts (GRBs). HAWC is a very high-energy gamma-ray observatory currently under construction in Mexico at an altitude of 4100 m. It will observe atmospheric air showers via the water Cherenkov method. HAWC will consist of 300 large water tanks instrumented with 4 photomultipliers each. HAWC has two data acquisition (DAQ) systems. The main DAQ system reads out coincident signals in the tanks and reconstructs the direction and energy of individual atmospheric showers. The scaler DAQ counts the hits in each photomultiplier tube (PMT) in the detector and searches for a statistical excess over the noise of all PMTs. We show that HAWC has a realistic opportunity to observe the high-energy power law components of GRBs that extend at least up to 30 GeV, as it has been observed by Fermi LAT. The two DAQ systems have an energy threshold that is low enough to observe events similar to GRB 090510 and GRB 090902b with the characteristics observed by Fermi LAT. HAWC will provide information about the high-energy spectra of GRBs which in turn could help to understanding about e-pair attenuation in GRB jets, extragalactic background light absorption, as well as establishing the highest energy to which GRBs accelerate particles.

astro-ph.HE