J/MNRAS/422/3370 Spatial variation in fine-structure constant (King+, 2012)
Spatial variation in the fine-structure constant - new results from VLT/UVES.
King J.A., Webb J.K., Murphy M.T., Flambaum V.V., Carswell R.F.,
Bainbridge M.B., Wilczynska M.R., Koch F.E.
<Mon. Not. R. Astron. Soc., 422, 3370-3414 (2012)>
=2012MNRAS.422.3370K 2012MNRAS.422.3370K
ADC_Keywords: QSOs ; Redshifts ; Spectroscopy
Keywords: methods: data analysis - quasars: absorption lines -
cosmology: observations
Abstract:
Quasar absorption lines provide a precise test of whether the
fine-structure constant, α, is the same in different places and
through cosmological time. We present a new analysis of a large sample
of quasar absorption-line spectra obtained using the Ultraviolet and
Visual Echelle Spectrograph (UVES) on the Very Large Telescope (VLT)
in Chile. We apply the many-multiplet method to derive values of
{DELTA}α/α≡(αz-α0)/α0 from 154
absorbers, and combine these values with 141 values from previous
observations at the Keck Observatory in Hawaii.
Description:
We have used publicly available spectra from VLT/UVES, in Chile (at
25° south), to generate an MM sample similar in size to the Keck
sample.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea1.dat 56 295 Table of all VLT and Keck da/a values
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq Sequential number
5- 18 A14 --- QSO QSO name (JHMMSS+DDMMSS)
20- 24 F5.3 --- zem Emission redshift
26- 32 F7.5 --- zabs Absorption redshift
34- 40 F7.3 10-5 da/a Value of (Δα)/α
= (αzα0)/α0
(αz at the zabs redshift)
42- 47 F6.3 10-5 e_da/a Error on da/a
49- 52 A4 --- Sample Sample (Keck or VLT)
54 I1 --- Flag [1/3] sigrandflag value (1)
56 I1 --- Out [0/1] indicates whether the system was
identified as an outlier and removed from
consideration (2)
--------------------------------------------------------------------------------
Note (1): The value of sigma_rand depends on the model under consideration.
Some 11 models are considered in the paper, each with its own sigma_rand
value. The values of sigma_rand used are given in Table 2. For a particular
model, the sigma_rand values given in Table 2 should be added in quadrature
with the "err" values according to the "sigrandflag" column:
* sig_rand(VLT) => sigrandflag = 3
* sig_rand(Keck LC) => sigrandflag = 1
* sig_rand(Keck HC) => sigrandflag = 2
where LC and HC refer to "low contrast" and "high contrast"
subsamples of the Keck sample. The particular case of a weighted
mean requires:
* sig_rand(VLT) = 0.905
* sig_rand(Keck LC) = 0
* sig_rand(Keck HC) = 1.743
[these values are in units of 10-5]
There are 27 Keck "high contrast" (sigrandflag=2) absorbers.
All the other Keck absorbers have sigrandflag=1, whilst
all the VLT absorbers have sigrandflag=3.
Note (2): In the analysis in the paper, two outliers are identified through
the Least Trimmed Squares analysis. These outliers were removed from
consideration before any further statistical analysis. These can be
identified by the presence of a "1" in the "Outlier" column (all
other absorbers have "0" in the Outlier column).
--------------------------------------------------------------------------------
Table 2: sig_rand values used in each model.
--------------------------------------------------------------------------------
I Sample + model sig_rand(VLT) sig_rand(Keck LC) sig_rand(Keck HC)
(10-5) (10-5) (10-5)
--------------------------------------------------------------------------------
1 Keck04-dipole N/A 0 1.630
2 #1 with no monopole N/A 0 1.668
3 VLT-weighted mean 0.905 N/A N/A
4 Combined weighted mean 0.905 0 1.743
5 VLT-dipole 0.905 N/A N/A
6 #5 with no monopole 0.882 N/A N/A
7 Combined dipole 0.905 0 1.630
8 #7 with no monopole 0.882 0 1.668
9 Combined r-dipole 0.858 0 1.630
10 #9 with no monopole 0.858 0 1.630
11 zβ dipole 0.812 0 1.592
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 24-Jan-2013