Deuterium at high redshift

Noterdaeme, P.; López, Sebastián; Dumont, Vincent; Ledoux, C.; Molaro, P.; Petitjean, P.

doi:10.1051/0004-6361/201219453

Cited by 55 publications

(53 citation statements)

References 39 publications

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“…Its abundance can accurately be measured in highredshift low-metallicity QSO Lyα absorption systems. Although the data are still scarce -there are only ten absorption systems for which such a D/H measurement has been carried out (Pettini & Cooke 2012) -the measurements appear to converge to a mean primordial value D/H ∼ (2.5 -2.9) × 10 −5 , which corresponds to Ω b h 2 ∼ 0.0222 -0.0223 (Iocco et al 2009;Noterdaeme et al 2012;Pettini & Cooke 2012;Cooke et al 2014). This estimate of Ω b h 2 is in excellent agreeement with the value of 0.0221 -0.0222 obtained from studies of the fluctuations of the cosmic microwave background (CMB) with WMAP and Planck (Keisler et al 2011;Ade et al 2013).…”

Section: Introductionmentioning

confidence: 99%

A new determination of the primordial He abundance using the He i λ10830 Å emission line: cosmological implications

Izotov¹,

Thuan²,

Гусева³

2014

Monthly Notices of the Royal Astronomical Society

255

355

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We present near-infrared spectroscopic observations of the high-intensity He i λ10830Å emission line in 45 low-metallicity H ii regions. We combined these NIR data with spectroscopic data in the optical range to derive the primordial He abundance. The use of the He i λ10830Å line, the intensity of which is very sensitive to the density of the H ii region, greatly improves the determination of the physical conditions in the He + zone. This results in a considerably tighter Y -O/H linear regression compared to all previous studies. We extracted a final sample of 28 H ii regions with Hβ equivalent width EW(Hβ) 150Å, excitation parameter O 2+ /O 0.8, and with helium mass fraction Y derived with an accuracy better than 3%. With this final sample we derived a primordial 4 He mass fraction Y p = 0.2551 ± 0.0022. The derived value of Y p is higher than the one predicted by the standard big bang nucleosynthesis (SBBN) model. Using our derived Y p together with D/H = (2.53±0.04)×10 −5 , and the χ 2 technique, we found that the best agreement between these light element abundances is achieved in a cosmological model with a baryon mass density Ω b h 2 = 0.0240±0.0017 (68% CL), ±0.0028 (95.4% CL), ±0.0034 (99% CL) and an effective number of neutrino species N eff = 3.58±0.25 (68% CL), ±0.40 (95.4% CL), ±0.50 (99% CL). A non-standard value of N eff is preferred at the 99% CL, implying the possible existence of additional types of neutrino species.

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Section: Introductionmentioning

confidence: 99%

A new determination of the primordial He abundance using the He i λ10830 Å emission line: cosmological implications

Izotov¹,

Thuan²,

Гусева³

2014

Monthly Notices of the Royal Astronomical Society

255

355

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“…DLAs have been conjectured to be originating from gas associated with galaxies, in particular since DLAs contain the bulk of the neutral gas at high redshift (e.g. Prochaska et al 2005;Prochaska & Wolfe 2009;Noterdaeme et al 2009bNoterdaeme et al , 2012a and their metallicity is increasing with decreasing redshift (e.g. Rao et al 2006;Rafelski et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Discovery of a Perseus-like cloud in the early Universe

Noterdaeme

Krogager

Balashev

et al. 2017

A&A

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We present the discovery of a molecular cloud at z abs ≈ 2.5255 along the line of sight to the quasar SDSS J 000015.17+004833.3. We use a high-resolution spectrum obtained with the Ultraviolet and Visual Echelle Spectrograph together with a deep multi-wavelength medium-resolution spectrum obtained with X-shooter (both on the Very Large Telescope) to perform a detailed analysis of the absorption lines from ionic, neutral atomic and molecular species in different excitation levels, as well as the broad-band dust extinction.We find that the absorber classifies as a Damped Lyman-α system (DLA) with log N(H i) (cm −2 ) = 20.8 ± 0.1. The DLA has supersolar metallicity (Z ∼ 2.5 Z , albeit to within a factor of two to three) with a depletion pattern typical of cold gas and an overall molecular fraction f = 2N(H 2 )/(2N(H 2 ) + N(H i)) ∼ 50%. This is the highest f -value observed to date in a high-z intervening system. Most of the molecular hydrogen arises from a clearly identified narrow (b ∼ 0.7 km s −1 ), cold component in which carbon monoxide molecules are also found, with log N(CO) ≈ 15. With the help of the spectral synthesis code Cloudy, we study the chemical and physical conditions in the cold gas. We find that the line of sight probes the gas deep after the H i-to-H 2 transition in a ∼4−5 pc-size cloud with volumic density n H ∼ 80 cm −3 and temperature of only 50 K. Our model suggests that the presence of small dust grains (down to about 0.001 µm) and high cosmic ray ionisation rate (ζ H ∼ a few times 10 −15 s −1 ) are needed to explain the observed atomic and molecular abundances. The presence of small grains is also in agreement with the observed steep extinction curve that also features a 2175 Å bump. Interestingly, the chemical and physical properties of this cloud are very similar to what is seen in diffuse molecular regions of the nearby Perseus complex, despite the former being observed when the Universe was only 2.5 Gyr old. The high excitation temperature of CO rotational levels towards J0000+0048 betrays however the higher temperature of the cosmic microwave background. Using the derived physical conditions, we correct for a small contribution (0.3 K) of collisional excitation and obtain T CMB (z = 2.53) ≈ 9.6 K, in perfect agreement with the predicted adiabatic cooling of the Universe.

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“…In short, the technique uses a template matching routine to automatically detect damped Lyman and Werner H 2 lines using the SDSS DLA catalogue (Noterdaeme et al 2012c). A confidence is attributed to each candidate based on a resampling method and using control samples.…”

Section: Introductionmentioning

confidence: 99%

“…H 2 lines towards J 0843+0221 are so saturated that they were initially identified as multiple DLA systems in the automatic DLA search by Noterdaeme et al (2012c). We obtained high-resolution spectroscopic observations of the system using the Ultraviolet and Visual Echelle Spectrograph (UVES) on the VLT.…”

Section: Introductionmentioning

confidence: 99%

CO-dark molecular gas at high redshift: very large H2 content and high pressure in a low-metallicity damped Lyman alpha system

Balashev

Noterdaeme

Rahmani

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We present a detailed analysis of an H 2 -rich, extremely strong intervening damped Ly-α absorption system (DLA) at z abs = 2.786 towards the quasar J 0843+0221, observed with the Ultraviolet and Visual Echelle Spectrograph on the Very Large Telescope. The total column density of molecular (resp. atomic) hydrogen is log N(H 2 )=21.21 ± 0.02 (resp. log N(H i)=21.82 ± 0.11), making it to be the first case in quasar absorption line studies with H 2 column density as high as what is seen in 13 CO-selected clouds in the Milky-Way.We find that this system has one of the lowest metallicity detected among H 2 -bearing DLAs, with [Zn/H] = −1.52 +0.08 −0.10 . This can be the reason for the marked differences compared to systems with similar H 2 column densities in the local Universe: (i) the kinetic temperature, T ∼120 K, derived from the J = 0, 1 H 2 rotational levels is at least twice higher than expected; (ii) there is little dust extinction with A V < 0.1; (iii) no CO molecules are detected, putting a constraint on the X CO factor X CO > 2 × 10 23 cm −2 /(km/s K), in the very low metallicity gas. Low CO and high H 2 contents indicate that this system represents "CO-dark/faint" gas.We investigate the physical conditions in the H 2 -bearing gas using the fine-structure levels of C i, C ii, Si ii and the rotational levels of HD and H 2 . We find the number density to be about n ∼ 260 − 380 cm −3 , implying a high thermal pressure of 3 − 5 × 10 4 cm −3 K. We further identify a trend of increasing pressure with increasing total hydrogen column density. This independently supports the suggestion that extremely strong DLAs (with log N(H) ∼ 22) probe high-z galaxies at low impact parameters.

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Deuterium at high redshift

Cited by 55 publications

References 39 publications

A new determination of the primordial He abundance using the He i λ10830 Å emission line: cosmological implications

A new determination of the primordial He abundance using the He i λ10830 Å emission line: cosmological implications

Discovery of a Perseus-like cloud in the early Universe

CO-dark molecular gas at high redshift: very large H2 content and high pressure in a low-metallicity damped Lyman alpha system

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