Constraint on a Cosmological Variation in the Proton-to-Electron Mass Ratio From Electronic Co Absorption

Daprà, M.; Niu, Mei; Salumbides, E. J.; Murphy, Michael T.; Ubachs, Wim

doi:10.3847/0004-637x/826/2/192

Cited by 27 publications

(40 citation statements)

References 78 publications

(141 reference statements)

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“…Evans et al 2014), solar twin stars (e.g. Daprà et al 2015Daprà et al , 2016 or spectra of the same object on better-calibrated spectrographs (e.g. Kotuš et al 2017).…”

Section: Wavelength Scale Shifts and Distortionsmentioning

confidence: 99%

The UVES Spectral Quasar Absorption Database (SQUAD) data release 1: the first 10 million seconds

Murphy

Kacprzak

Savorgnan

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We present the first data release (DR1) of the UVES Spectral Quasar Absorption Database (SQUAD), comprising 467 fully reduced, continuum-fitted high-resolution quasar spectra from the Ultraviolet and Visual Echelle Spectrograph (UVES) on the European Southern Observatory's Very Large Telescope. The quasars have redshifts z = 0-5, and a total exposure time of 10 million seconds provides continuum-to-noise ratios of 4-342 (median 20) per 2.5km s −1 pixel at 5500 Å. The SQUAD spectra are fully reproducible from the raw, archival UVES exposures with open-source software, including our _ tool for combining multiple extracted echelle exposures which we document here. All processing steps are completely transparent and can be improved upon or modified for specific applications. A primary goal of SQUAD is to enable statistical studies of large quasar and absorber samples, and we provide tools and basic information to assist three broad scientific uses: studies of damped Lyman-α systems (DLAs), absorption-line surveys and time-variable absorption lines. For example, we provide a catalogue of 155 DLAs whose Lyman-α lines are covered by the DR1 spectra, 18 of which are reported for the first time. The H column densities of these new DLAs are measured from the DR1 spectra. DR1 is publicly available and includes all reduced data and information to reproduce the final spectra.

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“…Evans et al 2014), solar twin stars (e.g. Daprà et al 2015Daprà et al , 2016 or spectra of the same object on better-calibrated spectrographs (e.g. Kotuš et al 2017).…”

Section: Wavelength Scale Shifts and Distortionsmentioning

confidence: 99%

The UVES Spectral Quasar Absorption Database (SQUAD) data release 1: the first 10 million seconds

Murphy

Kacprzak

Savorgnan

et al. 2018

Monthly Notices of the Royal Astronomical Society

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“…Salumbides et al (2012) reported high-accuracy laboratory wavelength measurements, with an accuracy of ∆λ/λ = 3 × 10 −7 , for this band system, allowing to extract a constraint on a varying µ at a level of ∼ 10 −5 . Daprà et al (2016) reported the first measurement of ∆µ/µ = (0.7 ± 1.6 stat ± 0.5 syst ) × 10 −5 from electronic CO absorption only in the system SDSS J123714.60+064759.5, which was then combined with the ∆µ/µ value derived from H 2 absorption. Noterdaeme et al (2017) presented a detailed study of the absorption system towards J0000+0048, including CO, H 2 , deuterated molecular hydrogen, HD, as well as atomic species and dust, in order to understand the chemical and physical properties of the absorbing gas.…”

Section: Introductionmentioning

confidence: 99%

Analysis of carbon monoxide absorption at zabs ≃ 2.5 to constrain variation of the proton-to-electron mass ratio

Daprà

Noterdaeme

Vonk

et al. 2017

Monthly Notices of the Royal Astronomical Society

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Absorption by carbon monoxide in the spectrum of quasar SDSS J000015.16+004833.2 is investigated in order to derive a constraint on the temporal variation of the proton-to-electron mass ratio, µ. The spectrum was recorded using VLT/UVES, and it was partially corrected for long-range wavelength scale distortions using the supercalibration technique. Eight vibrational CO singlet-singlet bands belonging to the A 1 Π-X 1 Σ + electronic absorption system, and the perturbing d 3 ∆-X 1 Σ + (5, 0) singlet-triplet band are detected in the damped Lyman-α system at z abs ≃ 2.52. The spectra are modelled using a comprehensive fitting technique, resulting in a final value of ∆µ/µ = (1.8 ± 2.2 stat ± 0.4 syst ) × 10 −5 , which is consistent with no variation over a look-back time of ∼ 11.2 Gyrs.

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“…The J = 4 lines are at the noise level for most bands, but included in the fit. We used the updated molecular data summarised in Daprà et al (2016). Accurate wavelengths were obtained through calibration by laser and VUV synchrotron studies (Salumbides et al 2012;Niu et al 2013Niu et al , 2015, while oscillator strengths and damping constants were carefully re-evaluated taking into account an updated perturbation analysis.…”

Section: Carbon Monoxidementioning

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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Constraint on a Cosmological Variation in the Proton-to-Electron Mass Ratio From Electronic Co Absorption

Cited by 27 publications

References 78 publications

The UVES Spectral Quasar Absorption Database (SQUAD) data release 1: the first 10 million seconds

The UVES Spectral Quasar Absorption Database (SQUAD) data release 1: the first 10 million seconds

Analysis of carbon monoxide absorption at zabs ≃ 2.5 to constrain variation of the proton-to-electron mass ratio

Discovery of a Perseus-like cloud in the early Universe

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