Cosmological implications of the full shape of anisotropic clustering measurements in BOSS and eBOSS

We present the analysis of the full shape of anisotropic clustering measurement from the extended Baryon Oscillation Spectroscopic Survey (eBOSS) quasar sample together with the combined galaxy sample from the Baryon Oscillation Spectroscopic Survey (BOSS), re-analysed using an updated recipe for the non-linear matter power spectrum and the non-local bias parameters. We obtain constraints for flat Lambda cold dark matter cosmologies, focusing on the cosmological parameters that are independent of the Hubble parameter h. Our recovered value for the Root Mean Square (RMS) linear perturbation theory variance as measured on the scale of 12 Mpc is sigma(12) = 0.805 +/- 0.049, while using the traditional reference scale of 8 h(-1) Mpc gives sigma(8) = 0.815 +/- 0.044. We quantify the agreement between our measurements and the latest cosmic microwave background data from Planck using the suspiciousness metric, and find them to be consistent within 0.64 +/- 0.03 sigma. Combining our clustering constraints with the 3 x 2pt data sample from the Dark Energy Survey Year 1 release slightly degrades this agreement to the level of 1.54 +/- 0.08 sigma, while still showing an overall consistency with Planck. We furthermore study the effect of imposing a Planck - like prior on the parameters that define the shape of the linear matter power spectrum, and find significantly tighter constraints on the parameters that control the evolution of density fluctuations. In particular, the combination of low-redshift data sets prefers a value of the physical dark energy density omega(DE) = 0.335 +/- 0.011, which is 1.7 sigma higher than the one preferred by Planck.

Cosmology with Large Scale Structures using Massive Spectroscopic Surveys

Amélie Tamone

Spectroscopic surveys aim to map large fractions of the Universe to study the Large Scale Structures (LSS). LSS evolution traces the distribution of matter as a result of the tension between the expansion of the Universe and the gravitational forces, which means that LSS can be used to test cosmological and gravity model, in particular the standard model of cosmology (

\Lambda

CDM) with General Relativity (GR). One usual way to study those LSS is to quantify the clustering of the galaxies with the 2-point correlation function (2PCF). The Baryon Acoustic Oscillations (BAO) signature is characterised as a peak in the 2PCF, whose position is related to the Hubble parameter. Moreover, Redshift Space Distortions (RSD) are imprinted in the 2PCF and are used to measure the growth rate of structure of the Universe. In this thesis I measured the growth rate of structure of the emission line galaxy (ELG) sample of the extended Baryon Oscillation Spectroscopic Survey (eBOSS) from RSD in configuration space. I was able along with the Sloan Digital Sky Survey (SDSS) collaboration to participate to the final cosmological implication of the past 20 years of SDSS. By a combination of probes, the current cosmological parameters were then constrained with a high precision, outpassing the expected constraints for Stage-III dark energy experiment.Moreover I performed a BAO analysis with voids, tracing the underdensities in the quasars (QSO) sample of eBOSS. While the method was shown to bring great improvement on other tracers, it reveals itself more difficult to deal with quasars due to their low density. I was nevertheless able to detect a BAO signal and to provide forecast for a QSO sample from a DESI-like (Dark Energy Spectroscopic Instrument) experiment.

EPFL2022

NEAR-ULTRAVIOLET SPECTROSCOPY OF STAR-FORMING GALAXIES FROM eBOSS: SIGNATURES OF UBIQUITOUS GALACTIC-SCALE OUTFLOWS

Johan Comparat, Timothée Guy Olivier Delubac, Jean-Paul Richard Kneib, Jeffrey Newman, Anand Stéphane Raichoor

We present rest-frame near-ultraviolet (NUV) spectroscopy of star-forming galaxies (SFGs) at 0.6 < z < 1.2 from the Extended Baryon Oscillation Spectroscopic Survey (eBOSS) in SDSS-IV. One of the eBOSS programs is to obtain 2 ''. (about 15 kpc) fiber spectra of about 200,000 emission-line galaxies (ELGs) at redshift z greater than or similar to 0.6. We use the data from the pilot observations of this program, including 8620 spectra of SFGs at 0.6 < z < 1.2. The median composite spectra of these SFGs at 2200 angstrom < lambda < 4000 angstrom feature asymmetric, preferentially blueshifted non-resonant emission, Fe II*, and blueshifted resonant absorption, e.g., Fe II and Mg II, indicating ubiquitous outflows driven by star formation at these redshifts. For the absorption lines, we find a variety of velocity profiles with different degrees of blueshift. Comparing our new observations with the literature, we do not observe the non-resonant emission in the small-aperture (< 40 pc) spectra of local star-forming regions with the Hubble Space Telescope, and find the observed line ratios in the SFG spectra to be different from those in the spectra of local star-forming regions, as well as those of quasar absorption-line systems in the same redshift range. We introduce an outflow model that can simultaneously explain the multiple observed properties and suggest that the variety of absorption velocity profiles and the line ratio differences are caused by scattered fluorescent emission filling in on top of the absorption in the large-aperture eBOSS spectra. We develop an observation-driven, model-independent method to correct the emission infill to reveal the true absorption profiles. Finally, we show that the strengths of both the non-resonant emission and the emission-corrected resonant absorption increase with [O II] lambda lambda 3727, 3730 rest equivalent width and luminosity, with a slightly larger dependence on the former. Our results show that the eBOSS and future dark-energy surveys (e.g., Dark Energy Spectroscopic Instrument survey and Prime Focus Spectrograph survey) will provide rich data sets of rest-frame NUV spectroscopy for astrophysical applications.

Iop Publishing Ltd2015