| 1131. |
- Muller, Sebastien, 1976, et al.
(författare)
-
A precise and accurate determination of the cosmic microwave background temperature at z = 0.89
- 2013
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 551, s. A109 (pp. 1-13)
-
Tidskriftsartikel (refereegranskat)abstract
- Context. According to the Big Bang theory and as a consequence of adiabatic expansion of the Universe, the temperature of the cosmic microwave background (CMB) increases linearly with redshift. This relation is, however, poorly explored, and detection of any deviation would directly lead to (astro-)physics beyond the standard model.Aims. We aim to measure the temperature of the CMB with an accuracy of a few percent at z = 0.89 toward the molecular absorber in the galaxy lensing the quasar PKS 1830−211.Methods. We adopted a Monte-Carlo Markov chain approach, coupled with predictions from the non-LTE radiative transfer code RADEX, to solve the excitation conditions of a set of various molecular species directly from their spectra.Results. We determine TCMB = 5.08 ± 0.10 K at 68% confidence level. Our measurement is consistent with the value TCMB = 5.14 K predicted by the standard cosmological model with adiabatic expansion of the Universe. This is the most precise determination of TCMB at z > 0 to date.
|
|
| 1132. |
- Muller, Sebastien, 1976, et al.
(författare)
-
A study of submillimeter methanol absorption toward PKS 1830-211:: Excitation, invariance of the proton-electron mass ratio, and systematics
- 2021
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 652
-
Tidskriftsartikel (refereegranskat)abstract
- Context. Methanol is an important tracer to probe physical and chemical conditions in the interstellar medium of galaxies. Methanol is also the most sensitive target molecule for probing potential space-time variations of the proton-electron mass ratio, μ, a dimensionless constant of nature. Aims. We present an extensive study of the strongest submillimeter absorption lines of methanol (with rest frequencies between 300 and 520 GHz) in the z = 0.89 molecular absorber toward PKS 1830-211, the only high-redshift object in which methanol has been detected. Our goals are to constrain the excitation of the methanol lines and to investigate the cosmological invariance of μ based on their relative kinematics. Methods. We observed 14 transitions of methanol, five of the A-form and nine of the E-form, and three transitions of A-13CH3OH, with ALMA. We analyzed the line profiles with a Gaussian fitting and constructed a global line profile that is able to match all observations after allowing for variations of the source covering factor, line opacity scaling, and relative bulk velocity offsets. We explore methanol excitation by running the non local thermal equilibrium radiative transfer code RADEX on a grid of kinetic temperatures and H2 volume densities. Results. Methanol absorption is detected in only one of the two lines of sight (the southwest) to PKS 1830-211. There, the excitation analysis points to a cool (∼10 - 20 K) and dense (∼104 - 5 cm-3) methanol gas. Under these conditions, several methanol transitions become anti-inverted, with excitation temperatures below the temperature of the cosmic microwave background. In addition, we measure an abundance ratio A/E = 1.0 ± 0.1, an abundance ratio CH3OH/H2 ∼ 2 × 10-8, and a 12CH3OH/13CH3OH ratio 62 ± 3. Our analysis shows that the bulk velocities of the different transitions are primarily correlated with the observing epoch due to morphological changes in the background quasar's emission. There is a weaker correlation between bulk velocities and the lower level energies of the transitions, which could be a signature of temperature-velocity gradients in the absorbing gas. As a result, we do not find evidence for variations of μ, and we estimate Δμ/μ=(-1.8 ± 1.2) × 10-7 at 1-σ from our multivariate linear regression. Conclusions. We set a robust upper limit |Δμ/μ| < 3.6 × 10-7 (3σ) for the invariance of μ at a look-back time of half the present age of the Universe. Our analysis highlights that systematics need to be carefully taken into account in future radio molecular absorption studies aimed at testing Δμ/μ below the 10-7 horizon.
|
|
| 1133. |
- Muller, Sebastien, 1976, et al.
(författare)
-
An ALMA Early Science survey of molecular absorption lines toward PKS 1830-211 Analysis of the absorption profiles
- 2014
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 566
-
Tidskriftsartikel (refereegranskat)abstract
- We present the first results of an ALMA spectral survey of strong absorption lines for common interstellar species in the z = 0.89 molecular absorber toward the lensed blazar PKS 1830-211. The dataset brings essential information on the structure and composition of the absorbing gas in the foreground galaxy. In particular, we find absorption over large velocity intervals (greater than or similar to 100 km s(-1)) toward both lensed images of the blazar. This suggests either that the galaxy inclination is intermediate and that we sample velocity gradients or streaming motions in the disk plane, that the molecular gas has a large vertical distribution or extraplanar components, or that the absorber is not a simple spiral galaxy but might be a merger system. The number of detected species is now reaching a total of 42 different species plus 14 different rare isotopologues toward the SW image, and 14 species toward the NE line-of-sight. The abundances of CH, H2O, HCO+, HCN, and NH3 relative to H-2 are found to be comparable to those in the Galactic diffuse medium. Of all the lines detected so far toward PKS 1830-211, the ground-state line of ortho-water has the deepest absorption. We argue that ground-state lines of water have the best potential for detecting diffuse molecular gas in absorption at high redshift.
|
|
| 1134. |
- Muller, Sebastien, 1976, et al.
(författare)
-
Detection of chloronium and measurement of the Cl-35/Cl-37 isotopic ratio at z=0.89 toward PKS 1830-211
- 2014
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 566
-
Tidskriftsartikel (refereegranskat)abstract
- We report the first extragalactic detection of chloronium (H2Cl+) in the z = 0.89 absorber in front of the lensed blazar PKS 1830-211. The ion is detected through its 1(11)-0(00) line along two independent lines of sight toward the North-East and South-West images of the blazar. The relative abundance of H2Cl+ is significantly higher (by a factor similar to 7) in the NE line of sight, which has a lower H-2/H fraction, indicating that H2Cl+ preferably traces the diffuse gas component. From the ratio of the (H2Cl+)-Cl-35 and (H2Cl+)-Cl-37 absorptions toward the SW image, we measure a Cl-35/Cl-37 isotopic ratio of 3.1(-0.2)(+0.3) at z = 0.89, similar to that observed in the Galaxy and the solar system.
|
|
| 1135. |
- Muller, Sebastien, 1976, et al.
(författare)
-
Detection of deuterated molecules, but not of lithium hydride, in the z=0.89 absorber toward PKS 1830-211
- 2020
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 637
-
Tidskriftsartikel (refereegranskat)abstract
- Deuterium and lithium are light elements of high cosmological and astrophysical importance. In this work we report the first detection of deuterated molecules and a search for lithium hydride, (LiH)-Li-7, at redshift z=0.89 in the spiral galaxy intercepting the line of sight to the quasar PKS 1830-211. We used ALMA to observe several submillimeter lines of ND, NH2D, and HDO, and their related isotopomers NH2, NH3, and (H2O)-O-18 H 2 18 O , in absorption against the southwest image of the quasar, allowing us to derive XD/XH abundance ratios. The absorption spectra mainly consist of two distinct narrow velocity components for which we find remarkable differences. One velocity component shows XD/XH abundances that is about 10 times larger than the primordial elemental D/H ratio, and no variability of the absorption profile during the time span of our observations. In contrast, the other component shows a stronger deuterium fractionation. Compared to the first component, this second component has XD/XH abundances that are 100 times larger than the primordial D/H ratio, a deepening of the absorption by a factor of two within a few months, and a rich chemical composition, with relative enhancements of N2H+, CH3OH, SO2 and complex organic molecules. We therefore speculate that this component is associated with the analog of a Galactic dark cloud, while the first component is likely more diffuse. Our search for the (LiH)-Li-7 (1-0) line was unsuccessful and we derive an upper limit (LiH)-Li-7/H-2 = 4x10(-13) (3 sigma) in the z=0.89 absorber toward PKS 1830-211. Besides, with ALMA archival data, we could not confirm the previous tentative detections of this line in the z=0.68 absorber toward B 0218+357; we derive an upper limit (LiH)-Li-7/H-2 = 5x10(-11) (3 sigma), although this is less constraining than our limit toward PKS 1830-211. We conclude that, as in the Milky Way, only a tiny fraction of lithium nuclei are possibly bound in LiH in these absorbers at intermediate redshift.
|
|
| 1136. |
|
|
| 1137. |
|
|
| 1138. |
|
|
| 1139. |
|
|
| 1140. |
|
|
