Variations in the fundamental constants in the QSO host J1148+5251 at z = 6.4 and the BR1202−0725 system at z = 4.7

Monthly Notices of the Royal Astronomical Society, Apr 2013

We use sensitive observations of three high-redshift sources: [C ii] $^2\text{P}_{3/2}$ → $^2\text{P}_{1/2}$ fine-structure and CO (J = 2 → 1) rotational transitions for the z = 6.4 quasar (QSO) host galaxy J1148+5251 taken with the Plateau de Bure Interferometer (PdBI) and Jansky Very Large Array, respectively, and [C ii] and CO (J = 5 → 4) transitions from the QSO BR1202−0725 and its companion sub-millimetre galaxy (SMG) at z = 4.7 taken with the Atacama Large Millimeter Array and the PdBI. We use these observations to place constraints on the quantity $\Delta z = z_{\rm CO} - z_{\text{C}{\,\small {ii}}}$ for each source where zCO and $z_{\text{C}{\,\small {ii}}}$ are the observed redshifts of the CO rotational transition and [C ii] fine-structure transition, respectively, using a combination of approaches: (1) modelling the emission line profiles using ‘shapelets’ – a complete orthonormal set of basis functions that allow us to recreate most physical line shapes – to compare both the emission redshifts and the line profiles themselves, in order to make inferences about the intrinsic velocity differences between the molecular and atomic gas, and (2) performing a marginalization over all model parameters in order to calculate a non-parametric estimate of Δz. We derive 99 per cent confidence intervals for the marginalized posterior of Δz of (−1.9 ± 1.3) × 10−3, (−3 ± 8) × 10−4 and (−2 ± 4) × 10−3 for J1148+5251, and the BR1202−0725 QSO and SMG, respectively. We show that the [C ii] and CO (J = 2 → 1) line profiles for J1148+5251 are consistent with each other within the limits of the data, whilst the [C ii] and CO (J = 5 → 4) line profiles from the BR1202−0725 QSO and SMG, respectively, have 65 and >99.9 per cent probabilities of being inconsistent, with the CO (J = 5 → 4) lines ∼30 per cent wider than the [C ii] lines. Therefore, whilst the observed values of Δz can correspond to variations in the quantity ΔF/F with cosmic time, where F = α2/μ, with α the fine-structure constant and μ the proton-to-electron mass ratio, of both (−3.3 ± 2.3) × 10−4 for a look-back time of 12.9 Gyr and of (−5 ± 15) × 10−5 for a look-back time of 12.4 Gyr, we propose that they are the result of the two species of gas being spatially separated as indicated by the inconsistencies in their line profiles.

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Variations in the fundamental constants in the QSO host J1148+5251 at z = 6.4 and the BR1202−0725 system at z = 4.7

L. Lentati 3 ‹ C. Carilli 1 P. Alexander 3 R. Maiolino 0 3 R. Wang 1 P. Cox 7 D. Downes 7 R. McMahon 0 6 K. M. Menten 5 R. Neri 7 D. Riechers 4 J. Wagg 3 9 F. Walter 8 A. Wolfe 2 0 Kavli Institute for Cosmology, University of Cambridge , Madingley Road, Cambridge CB3 OHA , UK 1 National Radio Astronomy Observatory , PO Box O, Socorro, NM 87801 , USA 2 Department of Physics, Centre for Astrophysics & Space Sciences, University of California , San Diego, CA 92093 , USA 3 Astrophysics Group, Cavendish Laboratory , JJ Thomson Avenue, Cambridge, CB3 0HE , UK 4 Astronomy Department, California Institute of Technology , MC 249-17, 1200 East California Boulevard, Pasadena, CA 91125 , USA 5 Max-Planck-Institut fu ̈r Radioastronomie , Auf dem Hu ̈gel 69, D-53121 Bonn , Germany 6 Institute of Astronomy, University of Cambridge , Madingley Road, Cambridge, CB3 0HA , UK 7 Institut de Radio Astronomie Millimetrique , 300 Rue de la Piscine, Domaine Universitaire, 38406 Saint Martin d'He ́res , France 8 Max-Planck-Institut fu ̈r Astronomie , Ko ̈nigstuhl 17, D-69117 Heidelberg , Germany 9 European Southern Observatory , Alonso de Cordova 3107, Vitacura, Casilla 19001, Santiago 19 , Chile A B S T R A C T We use sensitive observations of three high-redshift sources: [C II] 2P3/2 → 2P1/2 finestructure and CO (J = 2 → 1) rotational transitions for the z = 6.4 quasar (QSO) host galaxy J1148+5251 taken with the Plateau de Bure Interferometer (PdBI) and Jansky Very Large Array, respectively, and [C II] and CO (J = 5 → 4) transitions from the QSO BR1202−0725 and its companion sub-millimetre galaxy (SMG) at z = 4.7 taken with the Atacama Large Millimeter Array and the PdBI. We use these observations to place constraints on the quantity z = zCO − zC II for each source where zCO and zC II are the observed redshifts of the CO rotational transition and [C II] fine-structure transition, respectively, using a combination of approaches: (1) modelling the emission line profiles using 'shapelets' - a complete orthonormal set of basis functions that allow us to recreate most physical line shapes - to compare both the emission redshifts and the line profiles themselves, in order to make inferences about the intrinsic velocity differences between the molecular and atomic gas, and (2) performing a marginalization over all model parameters in order to calculate a non-parametric estimate of z. We derive 99 per cent confidence intervals for the marginalized posterior of z of (−1.9 ± 1.3) × 10−3, (−3 ± 8) × 10−4 and (−2 ± 4) × 10−3 for J1148+5251, and the BR1202−0725 QSO and SMG, respectively. We show that the [C II] and CO (J = 2 → 1) line profiles for J1148+5251 are consistent with each other within the limits of the data, whilst the [C II] and CO (J = 5 → 4) line profiles from the BR1202−0725 QSO and SMG, respectively, have 65 and >99.9 per cent probabilities of being inconsistent, with the CO (J = 5 → 4) lines ∼30 per cent wider than the [C II] lines. Therefore, whilst the observed values of z can correspond to variations in the quantity F/F with cosmic time, where F = α2/μ, with α the fine-structure constant and μ the proton-to-electron mass ratio, of both (−3.3 ± 2.3) × 10−4 for a look-back time of 12.9 Gyr and of (−5 ± 15) × 10−5 for a look-back time of 12.4 Gyr, we propose that they are the result of the two species of gas being spatially separated as indicated by the inconsistencies in their line profiles. line; profiles - methods; data analysis - quasars; emission lines - cosmology; observations - One of the most important principles that underlie much of modern physics is that of Copernicus; that our location in space and time is not special, such that the laws of physics do not change from one point in space–time to another. All these laws contain within them a relationship to the fundamental constants; electromagnetic interactions involve the fine-structure constant α, gravitational interactions depend on the gravitational constant G and so on. It is therefore a natural question to ask whether these constants are constant with cosmic epoch. This question is not a new one, being proposed some 70 years ago by Dirac (1937) and Milne (1935). Since then however it has become of particular interest with the development of physical models that seek to unify the fundamental forces via extra dimensions, such as Kaluza–Klein, or superstring theories. For a recent review, both of the theoretical models that allow for variations in the fundamental constants, and constraints placed on the variations by both terrestrial and astrophysical methods, see Uzan (2011). Below we will describe only in brief what is needed to aid further discussion. In short, the extra dimensions predicted by these theories would have only manifested themselves in the first instant of time following the big bang (∼10−43 s, or energies of ∼1019 GeV) before compactifying to the Planck scale during the cosmic expansion that followed. Over cosmic time variations in the sca (...truncated)


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L. Lentati, C. Carilli, P. Alexander, R. Maiolino, R. Wang, P. Cox, D. Downes, R. McMahon, K. M. Menten, R. Neri, D. Riechers, J. Wagg, F. Walter, A. Wolfe. Variations in the fundamental constants in the QSO host J1148+5251 at z = 6.4 and the BR1202−0725 system at z = 4.7, Monthly Notices of the Royal Astronomical Society, 2013, pp. 2454-2463, 430/3, DOI: 10.1093/mnras/stt070