Patrick Petitjean

New reaction rates for improved primordial D/H calculation and the cosmic evolution of deuterium

Primordial or big bang nucleosynthesis (BBN) is one of the three historically strong evidences for the big bang model. Standard BBN is now a parameter-free theory, since the baryonic density of the Universe has been deduced with an unprecedented precision from observations of the anisotropies of the cosmic microwave background radiation. There is a good agreement between the primordial abundances of He4, D, He3, and Li7 deduced from observations and from primordial nucleosynthesis calculations. However, the Li7 calculated abundance is significantly higher than the one deduced from spectroscopic observations and remains an open problem. In addition, recent deuterium observations have drastically reduced the uncertainty on D/H, to reach a value of 1.6%. It needs to be matched by BBN predictions whose precision is now limited by thermonuclear reaction rate uncertainties. This is especially important as many attempts to reconcile Li observations with models lead to an increased D prediction. Here, we reevaluate the d(p,γ)He3, d(d,n)He3, and d(d,p)H3 reaction rates that govern deuterium destruction, incorporating new experimental data and carefully accounting for systematic uncertainties. Contrary to previous evaluations, we use theoretical ab initio models for the energy dependence of the S factors. As a result, these rates increase at BBN temperatures, leading to a reduced value of D/H=(2.45±0.10)×10-5 (2σ), in agreement with observations.

The sloan digital sky survey reverberation mapping project: no evidence for evolution in the M.-sigma(*) relation to z similar to 1

We present host stellar velocity dispersion measurements for a sample of 88 broad-line quasars at 0.1 0.6) from the Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) project. High signal-to-noise ratio coadded spectra (average S/N~30 per 69 km/s pixel) from SDSS-RM allowed decomposition of the host and quasar spectra, and measurement of the host stellar velocity dispersions and black hole (BH) masses using the single-epoch (SE) virial method. The large sample size and dynamic range in luminosity (L5100=10^(43.2-44.7) erg/s) lead to the first clear detection of a correlation between SE virial BH mass and host stellar velocity dispersion far beyond the local universe. However, the observed correlation is significantly flatter than the local relation, suggesting that there are selection biases in high-z luminosity-threshold quasar samples for such studies. Our uniform sample and analysis enable an investigation of the redshift evolution of the M-sigma relation free of caveats by comparing different samples/analyses at disjoint redshifts. We do not observe evolution of the M-sigma relation in our sample, up to z~1, but there is an indication that the relation flattens towards higher redshifts. Coupled with the increasing threshold luminosity with redshift in our sample, this again suggests certain selection biases are at work, and simple simulations demonstrate that a constant M-sigma relation is favored to z~1. Our results highlight the scientific potential of deep coadded spectroscopy from quasar monitoring programs, and offer a new path to probe the co-evolution of BHs and galaxies at earlier times.

Measurement of BAO correlations at

Author(s): Bautista, JE; Busca, NG; Guy, J; Rich, J; Blomqvist, M; Du Mas Des Bourboux, H; Pieri, MM; Font-Ribera, A; Bailey, S; Delubac, T; Kirkby, D; Le Goff, JM; Margala, D; Slosar, A; Vazquez, JA; Brownstein, JR; Dawson, KS; Eisenstein, DJ; Miralda-Escude, J; Noterdaeme, P; Palanque-Delabrouille, N; Pâris, I; Petitjean, P; Ross, NP; Schneider, DP; Weinberg, DH; Yeche, C | Abstract:

z=2.3

Abstract We review recent results on the high-redshift Universe and the cosmic evolution obtained using Gamma-Ray Bursts (GRBs) as tracers of high-redshift galaxies. Most of the results come from photometric and spectroscopic observations of GRB host galaxies once the afterglow has faded away but also from the analysis of the GRB afterglow line of sight as revealed by absorptions in their optical spectrum.

with SDSS DR12 \lya-Forests

We study the mean absorption spectrum of the Damped Lyman alpha population at

Gamma-ray bursts as probes of the distant Universe

z\sim 2.6

The Mean Metal-line Absorption Spectrum of Damped Lyα Systems in BOSS

by stacking normalized, rest-frame shifted spectra of

[O ii] nebular emission from Mg ii absorbers: star formation associated with the absorbing gas

\sim 27\,000

The cosmic evolution of dust-corrected metallicity in theneutral gas

DLAs from the DR12 of BOSS/SDSS-III. We measure the equivalent widths of 50 individual metal absorption lines in 5 intervals of DLA hydrogen column density, 5 intervals of DLA redshift, and overall mean equivalent widths for an additional 13 absorption features from groups of strongly blended lines. The mean equivalent width of low-ionization lines increases with

Baryon Acoustic Oscillations in the Lyforest of BOSS quasars

N_{\rm HI}