arXiv subjects

R. F. L. Holanda

Publications and source records attributed to R. F. L. Holanda.

At least 55 records · Page 3Linked to original sources

arXiv2018

Is the non-isothermal double $β$-model incompatible with no time evolution of galaxy cluster gas mass fraction ?

In this paper, we propose a new method to obtain the depletion factor $γ(z)$, the ratio by which the measured baryon fraction in galaxy clusters is depleted with respect to the universal mean. We use exclusively galaxy cluster data, namely, X-ray gas mass fraction ($f_{gas}$) and angular diameter distance measurements from Sunyaev-Zel'dovich effect plus X-ray observations. The galaxy clusters are the same in both data set and the non-isothermal spherical double $β$-model was used to describe their electron density and temperature profiles. In order to compare our results with those from recent cosmological hydrodynamical simulations, we suppose a possible time evolution for $γ(z)$, such as, $γ(z) = γ_0(1 + γ_1z)$. As main conclusions we found that: the $γ_0$ value is in full agreement with the simulations. { On the other hand, although the $γ_1$ value found in our analysis is compatible with $γ_1=0$ within 2$σ$ c.l., our results show a non-negligible time evolution for the depletion factor, unlike the results of the simulations. However, we also put constraints on $γ(z)$ by using the $f_{gas}$ measurements and angular diameter distances obtained from the flat $Λ$CDM model (Planck results) and from a sample of galaxy clusters described by a elliptical profile. For these cases no significant time evolution for $γ(z)$ was found. Then, if a constant depletion factor is an inherent characteristic of these structures, our results show that the spherical double $β$-model used to describe the galaxy clusters considered does not affect the quality of their $f_{gas}$ measurements.

astro-ph.CO↗

arXiv2018

Cosmic transparency and acceleration

In this paper, by considering an absorption probability independent of photon wavelength, we show that current type Ia supernovae (SNe Ia) and gamma ray burst (GRBs) observations plus high-redshift measurements of the cosmic microwave background (CMB) radiation temperature support cosmic acceleration regardless of the transparent-universe assumption. Two flat scenarios are considered in our analyses: the $Λ$CDM model and a kinematic model. We consider $τ(z)=2\ln(1+z)^{\varepsilon}$, where $τ(z)$ denotes the opacity between an observer at $z=0$ and a source at $z$. This choice is equivalent to deforming the cosmic distance duality relation as $D_LD^{-1}_A = (1 + z)^{2+\varepsilon}$ and, if the absorption probability is independent of photon wavelength, the CMB temperature evolution law is $T_{CMB}(z)=T_0(1+z)^{1+2\varepsilon/3 }$. By marginalizing on the $\varepsilon$ parameter, our analyses rule out a decelerating universe at 99.99 \% c.l. for all scenarios considered. Interestingly, by considering only SNe Ia and GRBs observations, we obtain that a decelerated universe indicated by $Ω_Λ \leq 0.33$ and $q_0 > 0$ is ruled out around 1.5$σ$ c.l. and 2$σ$ c.l., respectively, regardless of the transparent-universe assumption.

astro-ph.CO↗

arXiv2018

Astronomical Distance Determination in the Space Age. Secondary distance indicators

The formal division of the distance indicators into primary and secondary leads to difficulties in description of methods which can actually be used in two ways: with, and without the support of the other methods for scaling. Thus instead of concentrating on the scaling requirement we concentrate on all methods of distance determination to extragalactic sources which are designated, at least formally, to use for individual sources. Among those, the Supernovae Ia is clearly the leader due to its enormous success in determination of the expansion rate of the Universe. However, new methods are rapidly developing, and there is also a progress in more traditional methods. We give a general overview of the methods but we mostly concentrate on the most recent developments in each field, and future expectations.

astro-ph.GA↗

arXiv2017

Cosmological constraints on the gas depletion factor in galaxy clusters

The evolution of the X-ray emitting gas mass fraction ($f_{gas}$) in massive galaxy clusters can be used as an independent cosmological tool to probe the expansion history of the Universe. Its use, however, depends upon a crucial quantity, i.e., the depletion factor $γ$, which corresponds to the ratio by which $f_{gas}$ is depleted with respect to the universal baryonic mean. This quantity is not directly observed and hydrodynamical simulations performed in a specific cosmological model (e.g., a flat $Λ$CDM cosmology) have been used to calibrate it. In this work, we obtain for the first time self-consistent observational constraints on the gas depletion factor combining 40 X-ray emitting gas mass fraction measurements and luminosity distance measurements from type Ia supernovae. Using Gaussian Processes to reconstruct a possible redshift evolution of $γ$, we find no evidence for such evolution, which confirms the current results from hydrodynamical simulations. Moreover, our constraints on $γ$ can be seen as a data prior for cosmological analyses on different cosmological models. The current measurements are systematic limited, so future improvements will depend heavily on a better mass calibration of galaxy clusters and their measured density profiles.

astro-ph.CO↗

arXiv2017

Testing the cosmic conservation of photon number with type Ia supernovae and ages of old objects

In this paper, we obtain luminosity distances by using ages of 32 old passive galaxies distributed over the redshift interval $0.11 < z < 1.84$ and test the cosmic conservation of photon number by comparing them with 580 distance moduli of type Ia supernovae (SNe Ia) from the so-called Union 2.1 compilation. Our analyses are based on the fact that the method of obtaining ages of galaxies relies on the detailed shape of galaxy spectra but not on galaxy luminosity. Possible departures from cosmic conservation of photon number is parametrized by $τ(z) = 2 εz$ and $τ(z) = εz/(1+z)$ (for $ε=0$ the conservation of photon number is recovered). We find $ε=0.016^{+0.078}_{-0.075}$ from the first parametrization and $ε=-0.18^{+0.25}_{-0.24}$ from the second parametrization, both limits at 95\% c.l. In this way, no significant departure from cosmic conservation of photon number is verified. In addition, by considering the total age as inferred from Planck (2015) analysis, we find the incubation time $t_{inc}=1.66\pm0.29$ Gyr and $t_{inc}=1.23\pm0.27$ Gyr at 68\% c.l. for each parametrization, respectively.}

astro-ph.CO↗

arXiv2017

Evolution of the universe driven by a mass dimension one fermion field

This paper study the evolution of the universe filled with a neutral mass dimension one fermionic field, sometimes called Elko. The numerical analysis of the coupled system of equations furnish a scale factor growth and energy density evolution that correctly reproduces the inflationary phase of the universe. After that, supposing a mechanism of energy transference to ordinary matter, the initial conditions generated after inflation drives the radiation dominated phase and also the subsequent dark matter evolution, since the Elko field is a good dark matter candidate. The energy density of the field at the end of inflation, at the end of radiation phase and for present time are in agreement to the standard model estimates. The analysis was performed with a potential containing a quadratic mass term plus a quartic self-interaction term, which follows naturally from the theory of mass dimension one fermions. It is interesting to notice that inflation occurs when the field makes a kind of transition around the Planck mass scale. The number of e-foldings during inflation was found to be strongly dependent on the initial conditions of the Elko field, as occurs in chaotic inflationary models. An upper mass limit for Elko field has been obtained as $m<10^9$GeV. A possible interpretation of both inflationary phase and recent cosmic acceleration as a consequence of a kind of Pauli exclusion principle is presented at the end.

gr-qc↗

arXiv2017

Probing the distance-duality relation with high-$z$ data

Measurements of strong gravitational lensing jointly with type Ia supernovae (SNe Ia) observations have been used to test the validity of the cosmic distance duality relation (CDDR), $D_L(z)/[(1+z)^2D_A(z)]=η=1$, where $D_L(z)$ and $D_A(z)$ are the luminosity and the angular diameter distances to a given redshift $z$, respectively. However, several lensing systems lie in the interval $1.4 \leq z \leq 3.6$ i.e., beyond the redshift range of current SNe Ia compilations ($z \approx 1.50$), which prevents this kind of test to be fully explored. In this paper, we circumvent this problem by testing the CDDR considering observations of strong gravitational lensing along with SNe Ia and { a subsample from} the latest gamma-ray burst distance modulus data, whose redshift range is $0.033 \leq z \leq 9.3$. { We parameterize their luminosity distances with a second degree polynomial function and search for possible deviations from the CDDR validity by using four different $η(z)$ functions: $η(z)=1+η_0z$, $η(z)=1+η_0z/(1+z)$, $η(z)=(1+z)^{η_0}$ and $η(z)=1+η_0\ln(1+z)$. Unlike previous tests done at redshifts lower than $1.50$, the likelihood for $η_0$ depends strongly on the $η(z)$ function considered, but we find no significant deviation from the CDDR validity ($η_0=0$). However, our analyses also point to the fact that caution is needed when one fits data in higher redshifts to test the CDDR as well as a better understanding of the mass distribution of lenses also is required for more accurate results.

astro-ph.CO↗

arXiv2017

Improved constraints on violations of the Einstein equivalence principle in the electromagnetic sector with complementary cosmic probes

Recent results have shown that a field non-minimally coupled to the electromagnetic Lagrangian can induce a violation of the Einstein equivalence principle. { This kind of coupling is present in a very wide class of gravitation theories.} In a cosmological context, this would break the validity of the cosmic distance duality relation as well as cause a time variation of the fine structure constant. Here, we improve constraints on this scenario by using four different observables: the luminosity distance of type Ia supernovae, the angular diameter distance of galaxy clusters, the gas mass fraction of galaxy clusters and the temperature of the cosmic microwave background at different redshifts. We consider four standard parametrizations adopted in the literature and show that, due to a high complementarity of the data, the errors are shrunk between 20\% and 40\% depending on the parametrization. We also show that our constraints are weakly affected by the geometry considered to describe the galaxy clusters. In short, no violation of the Einstein equivalence principle is detected up to redshifts $\sim$ 3.

gr-qc↗

arXiv2017

Constraints on a possible evolution of mass density power-law index in strong gravitational lensing from cosmological data

In this work, by using strong gravitational lensing (SGL) observations along with Type Ia Supernovae (Union2.1) and gamma ray burst data (GRBs), we propose a new method to study a possible redshift evolution of $γ(z)$, the mass density power-law index of strong gravitational lensing systems. In this analysis, we assume the validity of cosmic distance duality relation and the flat universe. In order to explore the $γ(z)$ behavior, three different parametrizations are considered, namely: (P1) $γ(z_l)=γ_0+γ_1 z_l$, (P2) $γ(z_l)=γ_0+γ_1 z_l/(1+z_l)$ and (P3) $γ(z_l)=γ_0+γ_1 \ln(1+z_l)$, where $z_l$ corresponds to lens redshift. If $γ_0=2$ and $γ_1=0$ the singular isothermal sphere model is recovered. Our method is performed on SGL sub-samples defined by different lens redshifts and velocity dispersions. For the former case, the results are in full agreement with each other, while a 1$σ$ tension between the sub-samples with low ($\leq 250$ km/s) and high ($>250$ km/s) velocity dispersions was obtained on the ($γ_0$-$γ_1$) plane. By considering the complete SGL sample, we obtain $γ_0 \approx 2$ and $ γ_1 \approx 0$ within 1$σ$ c.l. for all $γ(z)$ parametrizations. However, we find the following best fit values of $γ_1$: $-0.085$, $-0.16$ and $-0.12$ for P1, P2 and P3 parametrizations, respectively, suggesting a mild evolution for $γ(z)$. By repeating the analysis with Type Ia Supernovae from JLA compilation, GRBs and SGL systems this mild evolution is reinforced.

gr-qc↗

arXiv2017

Probing the cosmic distance duality relation using time delay lenses

The construction of the cosmic distance-duality relation (CDDR) has been widely studied. However, its consistency with various new observables remains a topic of interest. We present a new way to constrain the CDDR $η(z)$ using different dynamic and geometric properties of strong gravitational lenses (SGL) along with SNe Ia observations. We use a sample of $102$ SGL with the measurement of corresponding velocity dispersion $σ_0$ and Einstein radius $θ_E$. In addition, we also use a dataset of $12$ two image lensing systems containing the measure of time delay $Δt$ between source images. Jointly these two datasets give us the angular diameter distance $D_{A_{ol}}$ of the lens. Further, for luminosity distance, we use the $740$ observations from JLA compilation of SNe Ia. To study the combined behavior of these datasets we use a model independent method, Gaussian Process (GP). We also check the efficiency of GP by applying it on simulated datasets, which are generated in a phenomenological way by using realistic cosmological error bars. Finally, we conclude that the combined bounds from the SGL and SNe Ia observation do not favor any deviation of CDDR and are in concordance with the standard value ($η=1$) within $2σ$ confidence region, which further strengthens the theoretical acceptance of CDDR.

astro-ph.CO↗

arXiv2017

Searching for deviations from the General Relativity Theory with gas mass fraction of galaxy clusters and complementary probes

Nowadays, thanks to the improved precision of cosmological data, it has been possible to search for deviation from the general relativity theory with tests on large cosmic scales. Particularly, there is a class of modified gravity theories that breaks the Einstein equivalence principle (EEP) in the electromagnetic sector, generating variations of the fine structure constant, violations of the cosmic distance duality relation and the evolution law of the cosmic microwave background (CMB) radiation. In recent papers, this class of theories has been tested with angular diameter distances from galaxy clusters, type Ia supernovae and CMB temperature. In this work we propose a new test by considering the most recent X-ray surface brightness observations of galaxy clusters jointly with type Ia supernovae and CMB temperature. {The crucial point here is that we take into account the dependence of the X-ray gas mass fraction of galaxy clusters on possible variations of the fine structure constant and violations of the cosmic distance duality relation.} Our basic result is that this new approach is competitive with the previous one and it also does not show significant deviations from the general relativity.

astro-ph.CO↗

arXiv2017

Limits on evolution of the fine-structure constant in runaway dilaton models from Sunyaev-Zeldovich Observations

In this paper, new bounds on possible variations of the fine structure constant, $α$, for a class of runaway dilaton models are performed. By considering a possible evolution with redshift, $z$, such as $\frac{Δα}α=-γ\ln(1+z)$, where in $γ$ are the physical properties of the model, we constrain this parameter by using a deformed cosmic distance duality relation jointly with gas mass fraction (GMF) measurements of galaxy clusters and luminosity distances of type Ia supernovae. The GMF's used in our analyses are from cluster mass data from 82 galaxy clusters in the redshift range $0.12<z<1.36$, detected via the Sunyaev-Zeldovich effect at 148 GHz by the Atacama Cosmology Telescope. The type Ia supernovae are from the Union2.1 compilation. We also explore the dependence of the results from four models used to describe the galaxy clusters. As a result no evidence of variation was obtained.

astro-ph.CO↗

arXiv2016

Can galaxy clusters, type Ia supernovae and cosmic microwave background rule out a class of modified gravity theories?

In this paper we study cosmological signatures of modified gravity theories that can be written as a coupling between a extra scalar field and the electromagnetic part of the usual Lagrangian for the matter fields. In these frameworks all the electromagnetic sector of the theory is affected and variations of fundamental constants, of the cosmic distance duality relation and of the evolution law of the cosmic microwave background radiation (CMB) are expected and are related each other. In order to search these variations we perform jointly analyses with angular diameter distances of galaxy clusters, luminosity distances of type Ia supernovae and $T_{CMB}(z)$ measurements. We obtain tight constraints with no indication of violation of the standard framework.

astro-ph.CO↗

arXiv2016

The robustness of angular diameter distances to the lens in the B1608+656 and RXJ1131-1231 systems

The angular diameter distance of lens, $D_{Aol}$, of strong gravitational lensing systems has been claimed as a cosmic standard ruler. The first measurements for this distance were recently obtained to two well-known systems: B1608+656 and RXJ1131-1231. However, there is a range of possible systematic uncertainties which must be addressed in order to turn these systems into useful cosmic probes. In this paper, we confront $D_{Aol}$ with luminosity distances of type Ia supernovae and angular diameter distances of galaxy clusters to search for tensions between these cosmological measurements using the cosmic distance duality relation. No tension was verified with the present data, showing the robustness of the assumptions used to describe the lens systems.

astro-ph.CO↗

arXiv2016

Galaxy clusters, type Ia supernovae and the fine structure constant

As is well known, measurements of the Sunyaev-Zeldovich effect can be combined with observations of the X-ray surface brightness of galaxy clusters to estimate the angular diameter distance to these structures. In this paper, we show that this technique depends on the fine structure constant, $α$. Therefore, if $α$ is a time-dependent quantity, e.g., $α=α_0 ϕ(z)$, where $ϕ$ is a function of redshift, we argue that current data do not provide the real angular diameter distance, $D_{\rm{A}}(z)$, to the cluster but instead $D_A^{data}(z) = ϕ(z)^2 D_{\rm{A}}(z)$. We use this result to derive constraints on a possible variation of $α$ for a class of dilaton runaway models considering a sample of 25 measurements of $D_A^{data}(z)$ in redshift range $0.023 < z < 0.784$ and estimates of $D_{\rm{A}}(z)$ from current type Ia supernovae observations. We find no significant indication of variation of $α$ with the present data.

astro-ph.CO↗

arXiv2016

Searching for cosmological signatures of the Einstein equivalence principle breaking

Modifications of gravity generated by a multiplicative coupling of a scalar field to the electromagnetic Lagrangian lead to a breaking of Einstein equivalence principle (EEPB) as well as to variations of fundamental constants. In these theoretical frameworks, deviations of standard values of the fine structure constant, $Δα/α=ϕ$, and of the cosmic distance duality relation, $D_L(1+z)^{-2}/D_A=η=1$, where $D_L$ and $D_A$ are the luminosity and angular diameter distances, respectively, are unequivocally linked. In this paper, we search for cosmological signatures of the EEPB by using angular diameter distance from galaxy clusters, obtained via their Sunyaev-Zeldovich effect (SZE) and X-ray observations, and distance modulus of type Ia supernovae (SNe Ia). The crucial point here is that we take into account the dependence of the SZE/X-ray technique with $ϕ$ and $η$. Our new results show no indication of the EEPB.

astro-ph.CO↗

arXiv2016

Constraints on a possible variation of the fine structure constant from galaxy cluster data

We propose a new method to probe a possible time evolution of the fine structure constant $α$ from X-ray and Sunyaev-Zeldovich measurements of the gas mass fraction ($f_{gas}$) in galaxy clusters. Taking into account a direct relation between variations of $α$ and violations of the distance-duality relation, we discuss constraints on $α$ for a class of dilaton runaway models. Although not yet competitive with bounds from high-$z$ quasar absorption systems, our constraints, considering a sample of 29 measurements of $f_{gas}$, in the redshift interval $0.14 < z < 0.89$, provide an independent estimate of $α$ variation at low and intermediate redshifts. Furthermore, current and planned surveys will provide a larger amount of data and thus allow to improve the limits on $α$ variation obtained in the present analysis.

astro-ph.CO↗

arXiv2016

Probing the cosmic distance duality with strong gravitational lensing and supernovae Ia data

We propose and perform a new test of the cosmic distance-duality relation (CDDR), $D_L(z) / D_A(z) (1 + z)^{2} = 1$, where $D_A$ is the angular diameter distance and $D_L$ is the luminosity distance to a given source at redshift $z$, using strong gravitational lensing (SGL) and type Ia Supernovae (SNe Ia) data. We show that the ratio $D=D_{A_{12}}/D_{A_2}$ and $D^{*}=D_{L_{12}}/D_{L_{2}}$, where the subscripts 1 and 2 correspond, respectively, to redshifts $z_1$ and $z_2$, are linked by $D/D^*=(1+z_1)^2$ if the CDDR is valid. We allow departures from the CDDR by defining two funcions for $η(z_1)$, which equals unity when the CDDR is valid. We find that combination of SGL and SNe Ia data favours no violation of the CDDR at 1$σ$ confidence level ($η(z) \simeq 1$), in complete agreement with other tests and reinforcing the theoretical pillars of the CDDR.

astro-ph.CO↗