arXiv subjects

Matteo Viel

Publications and source records attributed to Matteo Viel.

At least 145 records · Page 8Linked to original sources

arXiv2014

Suite of Hydrodynamical Simulations for the Lyman-Alpha Forest with Massive Neutrinos

The signature left in quasar spectra by the presence of neutral hydrogen in the Universe allows one to constrain the sum of the neutrino masses with improved sensitivity, with respect to laboratory experiments, and may shed a new light on the neutrino mass hierarchy and on the absolute mass scale of neutrinos. Constraints on cosmological parameters and on the dark energy equation of state can also be derived, from a joint parameter estimation procedure. However, this requires a detailed modeling of the line-of-sight power spectrum of the transmitted flux in the Lyman-Alpha (LyA) forest on scales ranging from a few to hundreds of Mpcs, which in turns demands the inclusion and careful treatment of cosmological neutrinos. To this end, we present here a suite of state-of-the-art hydrodynamical simulations with cold dark matter, baryons and massive neutrinos, specifically targeted for modeling the low-density regions of the IGM as probed by the LyA forest at high-redshift. The simulations span volumes ranging from (25 Mpc/h)^3 to (100 Mpc/h)^3, and are made using either 3 X 192^3~21 millions or 3 X 768^3~1.4 billion particles. The resolution of the various runs can be further enhanced, so that we can reach the equivalent of 3 X 3072^3~87 billion particles in a (100 Mpc/h)^3 box size. The chosen cosmological parameters are compatible with the latest Planck (2013) results, although we also explore the effect of slight variations in the main cosmological and astrophysical parameters. We adopt a particle-type implementation of massive neutrinos, and consider three degenerate species having masses M_nu =0.1, 0.2, 0.3, 0.4 and 0.8 eV, respectively. We improve on previous studies in several ways, in particular with updated routines for IGM radiative cooling and heating processes, and initial conditions based on 2LPT rather than the Zeldovich approximation.

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arXiv2014

Quasar-Lyman $α$ Forest Cross-Correlation from BOSS DR11 : Baryon Acoustic Oscillations

We measure the large-scale cross-correlation of quasars with the Lyman alpha forest absorption, using over 164,000 quasars from Data Release 11 of the SDSS-III Baryon Oscillation Spectroscopic Survey. We extend the previous study of roughly 60,000 quasars from Data Release 9 to larger separations, allowing a measurement of the Baryonic Acoustic Oscillation (BAO) scale along the line of sight $c/(H(z=2.36) ~ r_s) = 9.0 \pm 0.3$ and across the line of sight $D_A(z=2.36) / ~ r_s = 10.8 \pm 0.4$, consistent with CMB and other BAO data. Using the best fit value of the sound horizon from Planck data ($r_s=147.49 Mpc$), we can translate these results to a measurement of the Hubble parameter of $H(z=2.36) = 226 \pm 8 km/s / Mpc$ and of the angular diameter distance of $D_A(z=2.36) = 1590 \pm 60 Mpc$. The measured cross-correlation function and an update of the code to fit the BAO scale (baofit) are made publicly available.

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arXiv2014

Massive Neutrinos and the Non-linear Matter Power Spectrum

We perform an extensive suite of N-body simulations of the matter power spectrum, incorporating massive neutrinos in the range M = 0.15-0.6 eV, probing the non-linear regime at scales k < 10 hMpc-1 at z < 3. We extend the widely used HALOFIT approximation to account for the effect of massive neutrinos on the power spectrum. In the strongly non-linear regime HALOFIT systematically over-predicts the suppression due to the free-streaming of the neutrinos. The maximal discrepancy occurs at k ~ 1 hMpc-1, and is at the level of 10% of the total suppression. Most published constraints on neutrino masses based on HALOFIT are not affected, as they rely on data probing the matter power spectrum in the linear or mildly non-linear regime. However, predictions for future galaxy, Lyman-alpha forest and weak lensing surveys extending to more non-linear scales will benefit from the improved approximation to the non-linear matter power spectrum we provide. Our approximation reproduces the induced neutrino suppression over the targeted scales and redshifts significantly better. We test its robustness with regard to changing cosmological parameters and a variety of modelling effects.

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arXiv2014

The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: weighing the neutrino mass using the galaxy power spectrum of the CMASS sample

We measure the sum of the neutrino particle masses using the three-dimensional galaxy power spectrum of the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS) Data Release 9 (DR9) CMASS galaxy sample. Combined with the cosmic microwave background (CMB), supernova (SN) and additional baryonic acoustic oscillation (BAO) data, we find upper 95 percent confidence limits of the neutrino mass $Σm_ν<0.340$ eV within a flat $Λ$CDM background, and $Σm_ν<0.821$ eV, assuming a more general background cosmological model. The number of neutrino species is measured to be $N_{\rm eff}=4.308\pm0.794$ and $N_{\rm eff}=4.032^{+0.870}_{-0.894}$ for these two cases respectively. We study and quantify the effect of several factors on the neutrino measurements, including the galaxy power spectrum bias model, the effect of redshift-space distortion, the cutoff scale of the power spectrum, and the choice of additional data. The impact of neutrinos with unknown masses on other cosmological parameter measurements is investigated. The fractional matter density and the Hubble parameter are measured to be $Ω_M=0.2796\pm0.0097$, $H_0=69.72^{+0.90}_{-0.91}$ km/s/Mpc (flat $Λ$CDM) and $Ω_M=0.2798^{+0.0132}_{-0.0136}$, $H_0=73.78^{+3.16}_{-3.17}$ km/s/Mpc (more general background model). Based on a Chevallier-Polarski-Linder (CPL) parametrisation of the equation-of-state $w$ of dark energy, we find that $w=-1$ is consistent with observations, even allowing for neutrinos. Similarly, the curvature Ω_K and the running of the spectral index $α_s$ are both consistent with zero. The tensor-to-scaler ratio is constrained down to $r<0.198$ (95 percent CL, flat $Λ$ CDM) and $r<0.440$ (95 percent CL, more general background model).

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arXiv2014

Cosmic Degeneracies I: Joint N-body Simulations of Modified Gravity and Massive Neutrinos

We present the first suite of cosmological N-body simulations that simultaneously include the effects of two different and theoretically independent extensions of the standard $Λ$CDM cosmological scenario - namely an $f(R)$ theory of Modified Gravity (MG) and a cosmological background of massive neutrinos - with the aim to investigate their possible observational degeneracies. We focus on three basic statistics of the large-scale matter distribution, more specifically the nonlinear matter power spectrum, the halo mass function, and the halo bias, for which we determine the deviation with respect to the fiducial $Λ$CDM cosmology in the context of both separate and combined simulations of $f(R)$ MG and massive neutrinos scenarios. Our results show that while these two extended models separately determine very prominent and potentially detectable features in all the three statistics, when we allow them to be simultaneously at work these features are strongly suppressed, resulting in much weaker deviations from the standard model's predictions. In particular, when an $f(R)$ gravity model with $f_{R0}=-1\times 10^{-4}$ is combined with a total neutrino mass of $Σ_{i}m_{ν_{i}}=0.4$ eV, the resulting matter power spectrum, halo mass function, and bias at z=0 are found to be consistent with the standard model's predictions at the 10%, 20%, and 5% accuracy levels, respectively. Therefore, our results imply an intrinsic theoretical limit to the effective discriminating power of present and future observational data sets with respect to these widely considered extensions of the standard cosmological scenario in the absence of independent measurements of the neutrino masses from laboratory experiments, even though the high-redshift evolution might still allow to partially break the degeneracy [Abridged].

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arXiv2014

The SDSS-III Baryonic Oscillation Spectroscopic Survey: Constraints on the Integrated Sachs Wolfe effect

In the context of the study of the Integrated Sachs Wolfe effect (ISW), we construct a template of the projected density distribution up to $z\simeq 0.7$ by using the Luminous Galaxies (LGs) from the Sloan Digital Sky Survey DR8. We use a photo-z catalogue trained with more than a hundred thousand galaxies from BOSS in the SDSS DR8 imaging area. We consider two different LG samples whose selection matches that of SDSS-III/BOSS: the LOWZ sample ($z\in [0.15,0.5]$) and the CMASS sample ($z\in[0.4,0.7]$). When building the LG density maps we use the information from star density, survey footprint, seeing conditions, sky emission, dust extinction and airmass to explore the impact of these artifacts on the two LG samples. In agreement with previous studies, we find that the CMASS sample is particularly sensitive to Galactic stars, which dominate the contribution to the auto-angular power spectrum below $\ell=7$. Other potential systematics affect mostly the low multipole range ($\ell\in[2,7]$), but leave fluctuations on smaller scales practically unchanged. The resulting power spectra in the multipole range $\ell\in[2,100]$ for the LOWZ, CMASS and LOWZ+CMASS samples are compatible with linear $Λ$CDM expectations and constant bias values of $b=1.98 \pm 0.11$, $2.08\pm0.14$ and $1.88\pm 0.11$, respectively, with no traces of non-Gaussianity: $f_{\rm NL}^{\rm local}=59\pm 75$ at 95% confidence level for the full LOWZ+CMASS sample in the range $\ell\in[4,100]$. After cross-correlating WMAP-9yr data with the LOWZ+CMASS LG density field, the ISW signal is detected at the level of 1.62--1.69$\,σ$. While this result is in close agreement with predictions from Monte Carlo simulations in the concordance $Λ$CDM model, it cannot rule out by itself an Einstein-de Sitter scenario, and has a moderately low signal compared to previous studies conducted on subsets of this LG sample.

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arXiv2014

Simulated star formation rate functions at z~4-7, and the role of feedback in high-z galaxies

We study the role of feedback from supernovae and black holes in the evolution of the star formation rate function (SFRF) of z~4-7 galaxies. We use a new set of cosmological hydrodynamic simulations, ANGUS (AustraliaN GADGET-3 early Universe Simulations), run with a modified and improved version of the parallel TreePM-smoothed particle hydrodynamics code GADGET-3 called P-GADGET3(XXL), that includes a self-consistent implementation of stellar evolution and metal enrichment. In our simulations both Supernova (SN) driven galactic winds and Active Galactic Nuclei (AGN) act simultaneously in a complex interplay. The SFRF is insensitive to feedback prescription at z>5, meaning that it cannot be used to discriminate between feedback models during reionisation. However, the SFRF is sensitive to the details of feedback prescription at lower redshift. By exploring different SN driven wind velocities and regimes for the AGN feedback, we find that the key factor for reproducing the observed SFRFs is a combination of "strong" SN winds and early AGN feedback in low mass galaxies. Conversely, we show that the choice of initial mass function and inclusion of metal cooling have less impact on the evolution of the SFRF. When variable winds are considered, we find that a non-aggressive wind scaling is needed to reproduce the SFRFs at z>4. Otherwise, the amount of objects with low SFRs is greatly suppressed and at the same time winds are not effective enough in the most massive systems.

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arXiv2013

A consistent determination of the temperature of the intergalactic medium at redshift z=2.4

We present new measurements of the thermal state of the intergalactic medium (IGM) at $z\sim2.4$ derived from absorption line profiles in the Ly$α$ forest. We use a large set of high-resolution hydrodynamical simulations to calibrate the relationship between the temperature-density ($T$--$Δ$) relation in the IGM and the distribution of HI column densities, $N_{\rm HI}$, and velocity widths, $b_{\rm HI}$, of discrete Ly$α$ forest absorbers. This calibration is then applied to the measurement of the lower cut-off of the $b_{\rm HI}$--$N_{\rm HI}$ distribution recently presented by Rudie et al. (2012). We infer a power-law $T$--$Δ$ relation, $T=T_{0}Δ^{γ-1}$, with a temperature at mean density, $T_{0}=[1.00^{+0.32}_{-0.21}]\times10^{4}\rm\,K$ and slope $(γ-1)=0.54\pm0.11$. The slope is fully consistent with that advocated by the analysis of Rudie et al (2012); however, the temperature at mean density is lower by almost a factor of two, primarily due to an adjustment in the relationship between column density and physical density assumed by these authors. These new results are in excellent agreement with the recent temperature measurements of Becker et al. (2011), based on the curvature of the transmitted flux in the Ly$α$ forest. This suggests that the thermal state of the IGM at this redshift is reasonably well characterised over the range of densities probed by these methods.

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arXiv2013

Cosmology with massive neutrinos III: the halo mass function and an application to galaxy clusters

We use a suite of N-body simulations that incorporate massive neutrinos as an extra-set of particles to investigate their effect on the halo mass function. We show that for cosmologies with massive neutrinos the mass function of dark matter haloes selected using the spherical overdensity (SO) criterion is well reproduced by the fitting formula of Tinker et al. (2008) once the cold dark matter power spectrum is considered instead of the total matter power, as it is usually done. The differences between the two implementations, i.e. using $P_{\rm cdm}(k)$ instead of $P_{\rm m}(k)$, are more pronounced for large values of the neutrino masses and in the high end of the halo mass function: in particular, the number of massive haloes is higher when $P_{\rm cdm}(k)$ is considered rather than $P_{\rm m}(k)$. As a quantitative application of our findings we consider a Planck-like SZ-clusters survey and show that the differences in predicted number counts can be as large as $30\%$ for $\sum m_ν= 0.4$ eV. Finally, we use the Planck-SZ clusters sample, with an approximate likelihood calculation, to derive Planck-like constraints on cosmological parameters. We find that, in a massive neutrino cosmology, our correction to the halo mass function produces a shift in the $σ_8(Ω_{\rm m}/0.27)^γ$ relation which can be quantified as $Δγ\sim 0.05$ and $Δγ\sim 0.14$ assuming one ($N_ν=1$) or three ($N_ν=3$) degenerate massive neutrino, respectively. The shift results in a lower mean value of $σ_8$ with $Δσ_8 = 0.01$ for $N_ν=1$ and $Δσ_8 = 0.02$ for $N_ν=3$, respectively. Such difference, in a cosmology with massive neutrinos, would increase the tension between cluster abundance and Planck CMB measurements.

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arXiv2013

Lyman-α Forest and Cosmic Weak Lensing in a Warm Dark Matter Universe

We review the current state of the theory of large scale structure in a warm dark matter (WDM) cosmological model. In particular, we focus on the non-linear modelling of the matter power spectrum and on the mass function of dark matter haloes. We describe the results of N-body simulations with WDM and mention the effects that could be induced by baryonic physics. We also examine the halo model of large scale structure and its recently suggested modifications for a WDM cosmology, which account for the small scale smoothness of the initial matter density field and better fit the results of N-body simulations. Having described the theoretical models, we discuss the current lower limits on the WDM particle mass, m_w, which correspond to upper limits on the WDM temperature under the assumption that the particles are thermal relics. The best such constraints come from the Lyα forest and exclude all masses below 3.3 keV at the 2σ confidence level. We finally review the forecasts for future lensing surveys, which will be of the same order of magnitude as the already existing constraints from the Lyα forest data but explore a different redshift regime.

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arXiv2013

The one-dimensional Ly-alpha forest power spectrum from BOSS

We have developed two independent methods to measure the one-dimensional power spectrum of the transmitted flux in the Lyman-$α$ forest. The first method is based on a Fourier transform, and the second on a maximum likelihood estimator. The two methods are independent and have different systematic uncertainties. The determination of the noise level in the data spectra was subject to a novel treatment, because of its significant impact on the derived power spectrum. We applied the two methods to 13,821 quasar spectra from SDSS-III/BOSS DR9 selected from a larger sample of over 60,000 spectra on the basis of their high quality, large signal-to-noise ratio, and good spectral resolution. The power spectra measured using either approach are in good agreement over all twelve redshift bins from $ = 2.2$ to $ = 4.4$, and scales from 0.001 $\rm(km/s)^{-1}$ to $0.02 \rm(km/s)^{-1}$. We determine the methodological and instrumental systematic uncertainties of our measurements. We provide a preliminary cosmological interpretation of our measurements using available hydrodynamical simulations. The improvement in precision over previously published results from SDSS is a factor 2--3 for constraints on relevant cosmological parameters. For a $Λ$CDM model and using a constraint on $H_0$ that encompasses measurements based on the local distance ladder and on CMB anisotropies, we infer $σ_8 =0.83\pm0.03$ and $n_s= 0.97\pm0.02$ based on \ion{H}{i} absorption in the range $2.1<z<3.7$.

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arXiv2013

The Sloan Digital Sky Survey quasar catalog: tenth data release

We present the Data Release 10 Quasar (DR10Q) catalog from the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey III. The catalog includes all BOSS objects that were targeted as quasar candidates during the first 2.5 years of the survey and that are confirmed as quasars via visual inspection of the spectra. The catalog also includes known quasars (mostly from SDSS-I and II) that were reobserved by BOSS. The catalog contains 166,583 quasars (74,454 are new discoveries since SDSS-DR9) detected over 6,373 deg$^{2}$ with robust identification and redshift measured by a combination of principal component eigenspectra. The number of quasars with $z>2.15$ (117,668) is $\sim$5 times greater than the number of $z>2.15$ quasars known prior to BOSS. Redshifts and FWHMs are provided for the strongest emission lines (CIV, CIII, MgII). The catalog identifies 16,461 broad absorption line quasars and gives their characteristics. For each object, the catalog presents five-band (u, g, r, i, z) CCD-based photometry with typical accuracy of 0.03 mag and information on the optical morphology and selection method. The catalog also contains X-ray, ultraviolet, near-infrared, and radio emission properties of the quasars, when available, from other large-area surveys. The calibrated digital spectra cover the wavelength region 3,600-10,500Å at a spectral resolution in the range 1,300$<$R$<$2,500; the spectra can be retrieved from the SDSS Catalog Archive Server. We also provide a supplemental list of an additional 2,376 quasars that have been identified among the galaxy targets of the SDSS-III/BOSS.

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arXiv2013

Cosmology with massive neutrinos I: towards a realistic modeling of the relation between matter, haloes and galaxies

By using a suite of large box-size N-body simulations that incorporate massive neutrinos as an extra set of particles, we investigate the impact of neutrino masses on the spatial distribution of dark matter haloes and galaxies. We compute the bias between the spatial distribution of dark matter haloes and the overall matter and cold dark matter distributions using statistical tools such as the power spectrum and the two-point correlation function. Overall we find a scale-dependent bias on large scales for the cosmologies with massive neutrinos. However, our results indicate that the scale-dependence in the bias is reduced if the latter is computed with respect to the cold dark matter distribution only. We find that the value of the bias on large scales is reasonably well reproduced by the Tinker fitting formula once the linear cold dark matter power spectrum is used, instead of the total matter power spectrum. We investigate whether scale-dependent bias really comes from purely neutrino's effect or from nonlinear gravitational collapse of haloes. For this purpose, we address the $Ω_ν$-$σ_8$ degeneracy and find that such degeneracy is not perfect, implying that neutrinos imprint a slight scale dependence on the large-scale bias. Finally, by using a simple halo occupation distribution (HOD) model, we investigate the impact of massive neutrinos on the distribution of galaxies within dark matter haloes. We use the main galaxy sample in the Sloan Digital Sky Survey II Data Release 7 to investigate if the small-scale galaxy clustering alone can be used to discriminate among different cosmological models with different neutrino masses. Our results suggest that different choices of the HOD parameters can reproduce the observational measurements relatively well, and we quantify the difference between the values of the HOD parameters between massless and massive neutrino cosmologies.

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arXiv2013

Kinetic or thermal AGN feedback in simulations of isolated and merging disk galaxies calibrated by the M-sigma relation

(Abridged) We investigate two modes of coupling the feedback energy from a central AGN to the neighboring gas in galaxy simulations: kinetic - velocity boost, and thermal - heating. We formulate kinetic feedback models for energy-driven wind (EDW) and momentum-driven wind (MDW), using two free parameters: feedback efficiency epsilon_f, and AGN wind velocity v_w. A novel numerical algorithm is implemented in the SPH code GADGET-3, to prevent the expansion of a hole in the gas distribution around the BH. We perform simulations of isolated evolution and merger of disk galaxies, of Milky-Way mass as well as lower and higher masses. We find that in the isolated galaxy BH kinetic feedback generates intermittent bipolar jet-like gas outflows. We infer that current prescriptions for BH subgrid physics in galaxy simulations can grow the BH to observed values even in an isolated disk galaxy. The BH growth is enhanced in a galaxy merger. Comparing the [M_BH - sigma_star] relation obtained in our simulations with observational data, we conclude that it is possible to find parameter sets for a fit in all the models, except for the case with MDW feedback in a galaxy merger, in which the BH is always too massive. The BH thermal feedback implementation of Springel, Di Matteo & Hernquist (2005) within the multiphase star-formation model is found to have negligible impact on gas properties; and the effect claimed in all previous studies is attributed to gas depletion around the BH by the creation of an artificial hole. The BH mass accretion rate in our simulations exhibit heavy fluctuations. The star formation rate is quenched with feedback by removal of gas. The CGM gas at galactocentric distances (20 - 100)/h kpc are found to give the best metallicity observational diagnostic to distinguish between BH models.

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arXiv2013

Turbulence driven by structure formation in the circum-galactic medium

The injection of turbulence in the circum-galactic medium at redshift z = 2 is investigated using the mesh-based hydrodynamic code Enzo and a subgrid-scale (SGS) model for unresolved turbulence. Radiative cooling and heating by a uniform Ultraviolet (UV) background are included in our runs and compared with the effect of turbulence modelling. Mechanisms of gas exchange between galaxies and the surrounding medium, as well as metal enrichment, are not taken into account, and turbulence is here driven solely by structure formation (mergers and shocks). We find that turbulence, both at resolved and SGS scales, impacts mostly the warm-hot intergalactic medium (WHIM), with temperature between 10^5 and 10^7 K, mainly located around collapsed and shock heated structures, and in filaments. Typical values of the ratio of turbulent to thermal pressure is 0.1 in the WHIM, corresponding to a volume-weighted average of the SGS turbulent to thermal Doppler broadening b_t / b_therm = 0.26, on length scales below the grid resolution of 25 kpc/h. In the diffuse intergalactic medium (IGM), defined in a range of baryon overdensity δ between 1 and 50, the importance of turbulence is smaller, but grows as a function of gas density, and the Doppler broadening ratio is fitted by the function b_t / b_therm = 0.023 δ^{0.58}.

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arXiv2013

Measurement of Baryon Acoustic Oscillations in the Lyman-alpha Forest Fluctuations in BOSS Data Release 9

We use the Baryon Oscillation Spectroscopic Survey (BOSS) Data Release 9 (DR9) to detect and measure the position of the Baryonic Acoustic Oscillation (BAO) feature in the three-dimensional correlation function in the Lyman-alpha forest flux fluctuations at a redshift z=2.4. The feature is clearly detected at significance between 3 and 5 sigma (depending on the broadband model and method of error covariance matrix estimation) and is consistent with predictions of the standard LCDM model. We assess the biases in our method, stability of the error covariance matrix and possible systematic effects. We fit the resulting correlation function with several models that decouple the broadband and acoustic scale information. For an isotropic dilation factor, we measure 100x(alpha_iso-1) = -1.6 ^{+2.0+4.3+7.4}_{-2.0-4.1-6.8} (stat.) +/- 1.0 (syst.) (multiple statistical errors denote 1,2 and 3 sigma confidence limits) with respect to the acoustic scale in the fiducial cosmological model (flat LCDM with Omega_m=0.27, h=0.7). When fitting separately for the radial and transversal dilation factors we find marginalised constraints 100x(alpha_par-1) = -1.3 ^{+3.5+7.6 +12.3}_{-3.3-6.7-10.2} (stat.) +/- 2.0 (syst.) and 100x(alpha_perp-1) = -2.2 ^{+7.4+17}_{-7.1-15} +/- 3.0 (syst.). The dilation factor measurements are significantly correlated with cross-correlation coefficient of ~ -0.55. Errors become significantly non-Gaussian for deviations over 3 standard deviations from best fit value. Because of the data cuts and analysis method, these measurements give tighter constraints than a previous BAO analysis of the BOSS DR9 Lyman-alpha forest sample, providing an important consistency test of the standard cosmological model in a new redshift regime.

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arXiv2013

Neutrino Signatures on the High Transmission Regions of the Lyman-alpha Forest

We quantify the impact of massive neutrinos on the statistics of low density regions in the intergalactic medium (IGM) as probed by the Lyman-alpha forest at redshifts z=2.2--4. Based on mock but realistic quasar (QSO) spectra extracted from hydrodynamic simulations with cold dark matter, baryons and neutrinos, we find that the probability distribution of weak Lyman-alpha absorption features, as sampled by Lyman-alpha flux regions at high transmissivity, is strongly affected by the presence of massive neutrinos. We show that systematic errors affecting the Lyman-alpha forest reduce but do not erase the neutrino signal. Using the Fisher matrix formalism, we conclude that the sum of the neutrino masses can be measured, using the method proposed in this paper, with a precision smaller than 0.4 eV using a catalog of 200 high resolution (S/N~100) QSO spectra. This number reduces to 0.27 eV by making use of reasonable priors in the other parameters that also affect the statistics of the high transitivity regions of the Lyman-alpha forest. The constraints obtained with this method can be combined with independent bounds from the CMB, large scale structures and measurements of the matter power spectrum from the Lyman-alpha forest to produce tighter upper limits on the sum of the masses of the neutrinos.

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arXiv2013

High-z cosmography at a glance

Cosmography is the tool that makes possible to untie the interpretation of cosmological observations from the definition of any dynamical prior. We review the constraints on the cosmographic parameter obtained using the most thorough data set ensemble available. We focus on some specific topics about the statistically based selection of the most stringent fitting expansion.

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