arXiv subjects

Axel de la Macorra

Publications and source records attributed to Axel de la Macorra.

At least 163 records · Page 9Linked to original sources

arXiv2020

The Completed SDSS-IV extended Baryon Oscillation Spectroscopic Survey: measurement of the BAO and growth rate of structure of the luminous red galaxy sample from the anisotropic correlation function between redshifts 0.6 and 1

We present the cosmological analysis of the configuration-space anisotropic clustering in the completed Sloan Digital Sky Survey IV (SDSS-IV) extended Baryon Oscillation Spectroscopic Survey (eBOSS) DR16 galaxy sample. This sample consists of luminous red galaxies (LRGs) spanning the redshift range $0.6 < z < 1$, at an effective redshift of $z_{\rm eff}=0.698$. It combines 174 816 eBOSS LRGs and 202 642 BOSS CMASS galaxies. We extract and model the baryon acoustic oscillations (BAO) and redshift-space distortions (RSD) features from the galaxy two-point correlation function to infer geometrical and dynamical cosmological constraints. The adopted methodology is extensively tested on a set of realistic simulations. The correlations between the inferred parameters from the BAO and full-shape correlation function analyses are estimated. This allows us to derive joint constraints on the three cosmological parameter combinations: $D_M(z)/r_d$, $D_H(z)/r_d$ and $fσ_8(z)$, where $D_M$ is the comoving angular diameter distance, $D_H$ is Hubble distance, $r_d$ is the comoving BAO scale, $f$ is the linear growth rate of structure, and $σ_8$ is the amplitude of linear matter perturbations. After combining the results with those from the parallel power spectrum analysis of Gil-Marin et al. 2020, we obtain the constraints: $D_M/r_d = 17.65 \pm 0.30$, $D_H/r_d = 19.77 \pm 0.47$, $fσ_8 = 0.473 \pm 0.044$. These measurements are consistent with a flat $Λ$CDM model with standard gravity.

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arXiv2020

Analytic Fluid Approximation for Warm Dark Matter

We present the full evolution of the velocity of a massive particle, along with the equation of state we can compute the energy density and pressure evolution for the background evolution. It is also natural to compute the perturbation equations for any massive decoupled particle, i.e. warm dark matter (WDM) or neutrinos, in the fluid approximation. Using this approach we analytically compute the time when the WDM stop being relativistic, $a_{nr}$, which is 2.6\% different respect to the exact Boltzmann solution. Using the fluid approximation the matter power spectrum is computed faster and with great accuracy, the cut-off in structure formation due to the free-streaming ($λ_{fs}$) of the particle, characteristic for a WDM particle, is replicated in both matter power spectrum and halo mass function. With this approach, we have a deeper understanding of the WDM physics that lead us to show that the temperature the dark matter can be computed as a function of known properties of the WDM particle. This formulation can be integrated into comprehensive numerical modeling reasonable increasing the performance in the calculations, therefore, we analyze the parameter $a_{nr}$ in a $Λ$WDM model using CMB Planck data combined with matter power spectrum data set of WiggleZ, obtaining a lower bound for the WDM mass $m_{\rm wdm} = 70.3$ eV at 86\% confidence, this value is consistent with WiggleZ data set but more data at small scales or a combination with other observations are needed to stronger constrain the mass value of the WDM particle.

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arXiv2020

The virial mode $k_v$ approach to Structure Formation with Warm Dark Matter

The small scale structure opens a window to constrain the dynamical properties of Dark Matter. Here we study the clustering of warm dark matter (WDM) in a semi-analytical approach and compared the linear power spectrum of WDM with cold dark matter (CDM) employing a new transfer function $T_v(a,k)$ in terms of the viral wave number $k_v=2π/λ_v$ corresponding to a structure with a viral radius $r_v=λ_v/2$, half the size of the free streaming scale radius $r_v=r_{fs}/2=λ_{fs}/4$. The virial mass $M_v$ contained in this structure corresponds to the lightest structure formed for a WDM particle becoming non-relativistic at the scale factor $a_{nr}$ with the corresponding $λ_{fs}$. The viral transfer function $T_v(a,k)=[1+ \left(k/k_v \right)^{β_v }]^{γ_v}$ is given in terms of the viral mode $k_v$ and two constant parameters $β_v$ and $γ_v$. We compare $T_v(a,k)$ with the Boltzmann code CLASS for WDM in the mass range 1-10 keV and we obtain the constraint $β_vγ_v=-18$ with $ν=1.020 \pm 0.025$. In the standard approach the transfer function is given by $T(a,k)=[1+\left(α\, k \right)^β]^γ$ \cite{Viel:2005qj} where $α$ encodes the dynamical properties of WDM and must be numerically adjusted by means of a Boltzmann code. In contrast, in our viral approach the physical quantity $k_v$ is simply given in terms of the free streaming scale $λ_{fs}$ and can be analytically determined. Our viral proposal has a good agreement with CLASS and improves slightly the results from the standard transfer function. To conclude, we have proposed a new physically motivated transfer function $T_v(a,k)$ where the properties of WDM are encoded in the viral wave number $k_v$, is straightforward to determine and improves the prediction of WDM clustering properties.

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arXiv2020

The Sloan Digital Sky Survey Quasar Catalog: Sixteenth Data Release

We present the final Sloan Digital Sky Survey IV (SDSS-IV) quasar catalog from Data Release 16 of the extended Baryon Oscillation Spectroscopic Survey (eBOSS). This catalog comprises the largest selection of spectroscopically confirmed quasars to date. The full catalog includes two sub-catalogs: a "superset" of all SDSS-IV/eBOSS objects targeted as quasars containing 1,440,615 observations and a quasar-only catalog containing 750,414 quasars, including 225,082 new quasars appearing in an SDSS data release for the first time, as well as known quasars from SDSS-I/II/III. We present automated identification and redshift information for these quasars alongside data from visual inspections for 320,161 spectra. The quasar-only catalog is estimated to be 99.8% complete with 0.3% to 1.3% contamination. Automated and visual inspection redshifts are supplemented by redshifts derived via principal component analysis and emission lines. We include emission line redshifts for H$α$, H$β$, Mg II, C III], C IV, and Ly$α$. Identification and key characteristics generated by automated algorithms are presented for 99,856 Broad Absorption Line quasars and 35,686 Damped Lyman Alpha quasars. In addition to SDSS photometric data, we also present multi-wavelength data for quasars from GALEX, UKIDSS, WISE, FIRST, ROSAT/2RXS, XMM-Newton, and Gaia. Calibrated digital optical spectra for these quasars can be obtained from the SDSS Science Archive Server.

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arXiv2020

The Sixteenth Data Release of the Sloan Digital Sky Surveys: First Release from the APOGEE-2 Southern Survey and Full Release of eBOSS Spectra

This paper documents the sixteenth data release (DR16) from the Sloan Digital Sky Surveys; the fourth and penultimate from the fourth phase (SDSS-IV). This is the first release of data from the southern hemisphere survey of the Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2); new data from APOGEE-2 North are also included. DR16 is also notable as the final data release for the main cosmological program of the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), and all raw and reduced spectra from that project are released here. DR16 also includes all the data from the Time Domain Spectroscopic Survey (TDSS) and new data from the SPectroscopic IDentification of ERosita Survey (SPIDERS) programs, both of which were co-observed on eBOSS plates. DR16 has no new data from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey (or the MaNGA Stellar Library "MaStar"). We also preview future SDSS-V operations (due to start in 2020), and summarize plans for the final SDSS-IV data release (DR17).

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arXiv2020

Nonlinear structure formation in Bound Dark Energy

We study nonlinear structure formation in the Bound Dark Energy model (BDE), where dark energy (DE) corresponds to a light scalar meson particle $ϕ$ dynamically formed at a condensation energy scale $Λ_c$. The evolution of this dark-energy meson is determined by the potential $V(ϕ)=Λ_c^{4+2/3}ϕ^{-2/3}$, with a distinguishing phenomenology from other quintessence scenarios. Particularly, the expansion rate of the universe is affected not only at late times, but also when the condensation of $ϕ$ occurs, which in linear theory leads to an enhancement (with respect to standard $Λ$CDM) of matter perturbations on small scales. We study how much of this signature is still present at late times as well as the properties of dark matter halos in the nonlinear regime through N-body simulations. Our results show that nonlinear corrections wash out this feature from the matter power spectrum even before DE becomes dominant. There is, however, a small but clear suppression of the BDE spectrum of $2\%$ today on the largest scales due to the distinct late-time dynamics of DE. The differences on the clustering power between BDE and $Λ$CDM are reflected in the halo mass function, where small halos are more abundant in BDE as opposed to large heavy structures, whose formation is delayed because of the expansion history of the universe. This result is well captured by the semi-analytical Sheth-Tormen formula. However, despite these differences, the halo concentration parameter is essentially the same in both models, which suggest that clustering inside the halos decouple from the general expansion once the halos form.

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arXiv2020

The clustering of the SDSS-IV extended Baryon Oscillation Spectroscopic Survey DR14 LRG sample: structure growth rate measurement from the anisotropic LRG correlation function in the redshift range 0.6 < z < 1.0

We analyze the anisotropic clustering of the Sloan Digital Sky Survey-IV Extended Baryon Oscillation Spectroscopic Survey (eBOSS) Luminous Red Galaxy Data Release 14 (DR14) sample combined with Baryon Oscillation Spectroscopic Survey (BOSS) CMASS sample of galaxies in the redshift range 0.6$<z<$1.0, which consists of 80,118 galaxies from eBOSS and 46,439 galaxies from the BOSS-CMASS sample. The eBOSS-CMASS Luminous Red Galaxy sample has a sky coverage of 1,844 deg$^2$, with an effective volume of 0.9 Gpc$^3$. The analysis was made in configuration space using a Legendre multipole expansion. The Redshift Space Distortion signal is modeled as a combination of the Convolution Lagrangian Perturbation Model and the Gaussian Streaming Model. We constrain the logarithmic growth of structure times the amplitude of dark matter density fluctuations, $f (z_{\rm eff})σ_8(z_{\rm eff})=0.454 \pm0.139 $, and the Alcock-Paczynski dilation scales which constraints the angular diameter distance $D_A(z_{eff})=1466.5 \pm 136.6 (r_s/r_s^{\rm fid})$ and $H(z_{\rm eff})=105.8 \pm 16 (r_s^{\rm fid}/r_s) \mathrm{km\,s^{-1}\,Mpc^{-1}}$, where $r_s$ is the sound horizon at the end of the baryon drag epoch and $r_s^{\rm fid}$ is its value in the fiducial cosmology at an effective redshift $z_{\rm eff}=0.72$. These results are in full agreement with the current $Λ$-Cold Dark Matter ($Λ$-CDM) cosmological model inferred from Planck measurements. This study is the first eBOSS LRG full-shape analysis i.e. including Redshift-Space Distortions (RSD) simultaneously with the Alcock-Paczynski (AP) effect and the Baryon Acoustic Oscillation (BAO) scale.

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arXiv2020

Bound Dark Matter (BDM) towards solving the Small Scale Structure Problem

Cosmological observations such as structure formation, CMB, and cosmic distance ladder set tight constraints to the amount and nature of dark matter (DM). In particular structure formation strongly constraints not only the amount of energy density, but also the time when DM became non-relativistic, anr. Standard cold and thermic warm DM particles have a smooth transition from being relativistic at high energies to a non-relativistic regime since the mass of these particles is constant while the velocity redshifts with the expansion of the universe. However, here we explore the possibility that the DM particle acquires a non-perturbative mass at a phase transition scale and a scale factor ac. This transition acquired a more fundamental meaning for the Bound Dark Matter (BDM) model because they describe a particle getting its mass through a non-perturbative process. These BDM particles may go from being relativistic to non-relativistic at ac, which implies an abrupt transition of the velocity of the particles vc at that time, affecting the equation of state and the cosmological evolution. Here we study the cosmological impact of the values of vc and the scale transition ac and they by reducing the free-streaming scale and therefore the small scale structure. Using CMB Plank, Supernovae SNIa, and BAO data, we constrain the valid region in the parameter space ac-vc putting upper bounds to ac but not restricting vc. For instance, the transition must be ac<$2.66\times10^{-6}$ for vc = 0. We also find that the free-streaming and the Jeans mass of the dark matter particle is highly influenced by the velocity vc, for example, a 3 keV WDM have a Jeans mass of Mfs=$1.97\times10^7$ Msun/h^3 but an equivalent BDM with the same anr but an abrupt transition in the velocity, vc~0 would have a Jeans mass of Mfs=$2.08x10^4$ Msun/h^3 which significantly changes the large scale structure formation.

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arXiv2019

Baryon acoustic oscillations at z = 2.34 from the correlations of Ly$α$ absorption in eBOSS DR14

We measure the imprint of primordial baryon acoustic oscillations (BAO) in the correlation function of Ly$α$ absorption in quasar spectra from the Baryon Oscillation Spectroscopic Survey (BOSS) and the extended BOSS (eBOSS) in Data Release 14 (DR14) of the Sloan Digital Sky Survey (SDSS)-IV. In addition to 179,965 spectra with absorption in the Lyman-$α$ (Ly$α$) region, we use, for the first time, Ly$α$ absorption in the Lyman-$β$ region of 56,154 spectra. We measure the Hubble distance, $D_H$, and the comoving angular diameter distance, $D_M$, relative to the sound horizon at the drag epoch $r_d$ at an effective redshift $z=2.34$. Using a physical model of the correlation function outside the BAO peak, we find $D_H(2.34)/r_d=8.86\pm 0.29$ and $D_M(2.34)/r_d=37.41\pm 1.86$, within 1$σ$ from the flat-$Λ$CDM model consistent with CMB anisotropy measurements. With the addition of polynomial "broadband" terms, the results remain within one standard deviation of the CMB-inspired model. Combined with the quasar-Ly$α$ cross-correlation measurement presented in a companion paper Blomqvist19, the BAO measurements at $z=2.35$ are within 1.7$σ$ of the predictions of this model.

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arXiv2019

The Dark Energy Spectroscopic Instrument (DESI)

We present the status of the Dark Energy Spectroscopic Instrument (DESI) and its plans and opportunities for the coming decade. DESI construction and its initial five years of operations are an approved experiment of the US Department of Energy and is summarized here as context for the Astro2020 panel. Beyond 2025, DESI will require new funding to continue operations. We expect that DESI will remain one of the world's best facilities for wide-field spectroscopy throughout the decade. More about the DESI instrument and survey can be found at https://www.desi.lbl.gov.

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arXiv2019

Imprint of a Steep Equation of State in the growth of structure

We study the cosmological properties of a dynamical of dark energy (DE) component determined by a Steep Equation of State (SEoS) $w(z)=w_0+w_i\frac{(z/z_T)^q}{1+(z/z_T)^q}$. The SEoS has a transition at $z_T$ between two pivotal values ($w_i, w_0$) which can be taken as an early time and present day values of $w$ and the steepness is given by $q$. We describe the impact of this dynamical DE at background and perturbative level. The steepness of the transition has a better cosmological fit than a conventional CPL model with $w=w_0+w_a(1-a)$. Furthermore, we analyze the impact of steepness of the transition in the growth of matter perturbations and structure formation. This is manifest in the linear matter power spectrum, $P(k)$, the logarithmic growth function, $fσ_8(z)$, and the differential mass function $dn/d\log M(z=0)$. The differences in these last three quantities is at a percent-level using the same cosmological baseline parameters in our SEoS and a $ΛCDM$ model. However, we find an increase in the power spectrum, producing a bump at $k\approx k_T$ with $k_T\equiv a_TH(a_T)$ the mode associated to the time of the steep transition ($a_T = 1/(1+z_T)$). Different dynamics of DE lead to a different amount of DM at present time which has an impact in Power Spectrum and accordingly in structure formation.

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arXiv2019

Redshift-weighted constraints on primordial non-Gaussianity from the clustering of the eBOSS DR14 quasars in Fourier space

We present constraints on local primordial non-Gaussianity (PNG), parametrized through $f^{\rm loc}_{\rm NL}$, using the Sloan Digital Sky Survey IV extended Baryon Oscillation Spectroscopic Survey Data Release 14 quasar sample. We measure and analyze the anisotropic clustering of the quasars in Fourier space, testing for the scale-dependent bias introduced by primordial non-Gaussianity on large scales. We derive and employ a power spectrum estimator using optimal weights that account for the redshift evolution of the PNG signal. We find constraints of $-51<f^{\rm loc}_{\rm NL}<21$ at 95% confidence level. These are amont the tightest constraints from Large Scale Structure (LSS) data. Our redshift weighting improves the error bar by 15% in comparison to the unweighted case. If quasars have lower response to PNG, the constraint degrades to $-81<f^{\rm loc}_{\rm NL}<26$, with a 40% improvement over the standard approach. We forecast that the full eBOSS dataset could reach $σ_{f^{\rm loc}_{\rm NL}}\simeq 5\text{-}8$ using optimal methods and full range of scales.

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arXiv2019

Inflation and Dark Energy from spectroscopy at $z > 2$

The expansion of the Universe is understood to have accelerated during two epochs: in its very first moments during a period of Inflation and much more recently, at $z < 1$, when Dark Energy is hypothesized to drive cosmic acceleration. The undiscovered mechanisms behind these two epochs represent some of the most important open problems in fundamental physics. The large cosmological volume at $2 < z < 5$, together with the ability to efficiently target high-$z$ galaxies with known techniques, enables large gains in the study of Inflation and Dark Energy. A future spectroscopic survey can test the Gaussianity of the initial conditions up to a factor of ~50 better than our current bounds, crossing the crucial theoretical threshold of $σ(f_{NL}^{\rm local})$ of order unity that separates single field and multi-field models. Simultaneously, it can measure the fraction of Dark Energy at the percent level up to $z = 5$, thus serving as an unprecedented test of the standard model and opening up a tremendous discovery space.

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arXiv2019

Primordial Non-Gaussianity

Our current understanding of the Universe is established through the pristine measurements of structure in the cosmic microwave background (CMB) and the distribution and shapes of galaxies tracing the large scale structure (LSS) of the Universe. One key ingredient that underlies cosmological observables is that the field that sources the observed structure is assumed to be initially Gaussian with high precision. Nevertheless, a minimal deviation from Gaussianityis perhaps the most robust theoretical prediction of models that explain the observed Universe; itis necessarily present even in the simplest scenarios. In addition, most inflationary models produce far higher levels of non-Gaussianity. Since non-Gaussianity directly probes the dynamics in the early Universe, a detection would present a monumental discovery in cosmology, providing clues about physics at energy scales as high as the GUT scale.

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arXiv2019

Dark Matter Science in the Era of LSST

Astrophysical observations currently provide the only robust, empirical measurements of dark matter. In the coming decade, astrophysical observations will guide other experimental efforts, while simultaneously probing unique regions of dark matter parameter space. This white paper summarizes astrophysical observations that can constrain the fundamental physics of dark matter in the era of LSST. We describe how astrophysical observations will inform our understanding of the fundamental properties of dark matter, such as particle mass, self-interaction strength, non-gravitational interactions with the Standard Model, and compact object abundances. Additionally, we highlight theoretical work and experimental/observational facilities that will complement LSST to strengthen our understanding of the fundamental characteristics of dark matter.

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arXiv2018

Bound Dark Energy: towards understanding the nature of the Dark Energy

We present a complete analysis of the observational constraints and cosmological implications of our Bound Dark Energy (BDE) model aimed to explain the late-time cosmic acceleration of the universe. BDE is derived from particle physics and corresponds to the lightest meson field $ϕ$ dynamically formed at low energies due to the strong gauge coupling constant. The evolution of the dark energy is determined by the scalar potential $V(ϕ)=Λ_c^{4+2/3}ϕ^{-2/3}$ arising from non-perturbative effects at a condensation scale $Λ_c$ and scale factor $a_c$, related each other by $a_cΛ_c/\mathrm{eV}=1.0934\times 10^{-4}$. We present the full background and perturbation evolution at a linear level. Using current observational data, we obtain the constraints $a_c=(2.48 \pm 0.02)\times10^{-6}$ and $Λ_c=(44.09 \pm 0.28) \textrm{ eV}$, which is in complete agreement with our theoretical prediction $Λ_c^{th}=34^{+16}_{-11}\textrm{ eV}$. The bounds on the equation of state today, the dark energy density and the expansion rate are $w_\mathrm{BDE 0}=-0.929\pm 0.007$, $Ω_\mathrm{BDE0}=0.696\pm0.007$ and $H_0=67.82\pm 0.05$ km s$^{-1}$Mpc, respectively. Even though the constraints on the six Planck base parameters are consistent at the 1$σ$ level between BDE and the concordance $Λ$CDM model, BDE improves the likelihood ratio by 2.1 of the Baryon Acoustic Oscillations (BAO) measurements with respect to $Λ$CDM and has an equivalent fit for type Ia supernovae and the Cosmic Microwave Background data. We present the constraints on the different cosmological parameters, and particularly we show the tension between BDE and $Λ$CDM in the BAO distance ratio $r_\mathrm{BAO}$ vs $H_\mathrm{0}$ and the growth index $γ$ at different redshifts, as well as the dark matter density at present time $Ω_ch^2$ vs $H_0$.

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arXiv2018

The clustering of the SDSS-IV extended Baryon Oscillation Spectroscopic Survey DR14 quasar sample: a tomographic measurement of cosmic structure growth and expansion rate based on optimal redshift weights

We develop a new method, which is based on the optimal redshift weighting scheme, to extract the maximal tomographic information of baryonic acoustic oscillations (BAO) and redshift space distortions (RSD) from the extended Baryon Oscillation Spectroscopic Survey (eBOSS) Data Release 14 quasar (DR14Q) survey. We validate our method using the EZ mocks, and apply our pipeline to the eBOSS DR14Q sample in the redshift range of $0.8<z<2.2$. We report a joint measurement of $fσ_8$ and two-dimensional BAO parameters $D_{\rm A}$ and $H$ at four effective redshifts of $z_{\rm eff}=0.98, 1.23, 1.52$ and $1.94$, and provide the full data covariance matrix. Using our measurement combined with BOSS DR12, MGS and 6dFGS BAO measurements, we find that the existence of dark energy is supported by observations at a $7.4σ$ significance level. Combining our measurement with BOSS DR12 and Planck observations, we constrain the gravitational growth index to be $γ=0.580\pm0.082$, which is fully consistent with the prediction of general relativity. This paper is part of a set that analyses the eBOSS DR14 quasar sample.

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arXiv2018

The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the extended Baryon Oscillation Spectroscopic Survey and from the second phase of the Apache Point Observatory Galactic Evolution Experiment

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in operation since July 2014. This paper describes the second data release from this phase, and the fourteenth from SDSS overall (making this, Data Release Fourteen or DR14). This release makes public data taken by SDSS-IV in its first two years of operation (July 2014-2016). Like all previous SDSS releases, DR14 is cumulative, including the most recent reductions and calibrations of all data taken by SDSS since the first phase began operations in 2000. New in DR14 is the first public release of data from the extended Baryon Oscillation Spectroscopic Survey (eBOSS); the first data from the second phase of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2), including stellar parameter estimates from an innovative data driven machine learning algorithm known as "The Cannon"; and almost twice as many data cubes from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous release (N = 2812 in total). This paper describes the location and format of the publicly available data from SDSS-IV surveys. We provide references to the important technical papers describing how these data have been taken (both targeting and observation details) and processed for scientific use. The SDSS website (www.sdss.org) has been updated for this release, and provides links to data downloads, as well as tutorials and examples of data use. SDSS-IV is planning to continue to collect astronomical data until 2020, and will be followed by SDSS-V.

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