J/MNRAS/494/2875 A fundamental test for MOND (Marra+, 2020)
A fundamental test for MOND.
Marra V., Rodrigues D.C., de Almeida A.O.F.
<Mon. Not. R. Astron. Soc., 494, 2875-2885 (2020)>
=2020MNRAS.494.2875M 2020MNRAS.494.2875M (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies ; Galaxies, rotation ; Models
Keywords: galaxies: kinematics and dynamic - galaxies: spiral - dark matter
Abstract:
The radial acceleration relation (RAR) shows a strong correlation
between two accelerations associated with galaxy rotation curves. The
relation between these accelerations is given by a non-linear function
that depends on an acceleration scale a+. Some have interpreted this
as an evidence for a gravity model, such as modified Newtonian
dynamics (MOND), which posits a fundamental acceleration scale a0
common to all the galaxies. However, it was later shown, using
Bayesian inference, that this seems not to be the case: the a0
credible intervals for individual galaxies were not found to be
compatible among themselves. A test like the latter is a fundamental
test for MOND as a theory for gravity, since it directly evaluates its
basic assumption and this using the data that most favour MOND: galaxy
rotation curves. Here we improve upon the previous analyses by
introducing a more robust method to assess the compatibility between
the credible intervals, in particular without Gaussian approximations.
We directly estimate, using a Monte Carlo simulation, that the
existence of a fundamental acceleration is incompatible with the data
at more than 5σ. We also consider quality cuts in order to show
that our results are robust against outliers. In conclusion, the new
analysis further supports the claim that the acceleration scale found
in the RAR is an emergent quantity.
Description:
Here we use the SPARC data (Lelli et al. 2016AJ....152..157L 2016AJ....152..157L, Cat.
J/AJ/152/157) for rotationally supported galaxies, which were the same
data used to derive the radial acceleration relation (RAR) (McGaugh et
al. 2016PhRvL.117t1101M 2016PhRvL.117t1101M). The same quality cuts applied to the
original 175 SPARC galaxies are also applied here, namely that
galaxies with inclinations smaller than 30° and those with
relevant asymmetries are not considered (i.e. those with quality flag
Q=3). This leads to a sample of 153 galaxies, which we call the RAR
sample.
This work stresses further the importance of testing the compatibility
between the acceleration scales derived from the individual galaxies,
denoted by A0=log(a0) (km/s). Such test is important for
understanding the meaning of modified Newtonian dynamics (MOND) and
the RAR, and it is a fundamental test for MOND, since it tests one of
the cornerstone assumptions of MOND (the universality of a0) in the
context that most favours MOND, that of rotationally supported
galaxies. This work improves the methodology of Rodrigues et al.
(2018NatAs...2..668R 2018NatAs...2..668R), confirming its results that, in the context of
rotationally supported galaxies, the RAR is an emergent correlation.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 83 153 Results for individual galaxies
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See also:
J/AJ/152/157 : Mass models for 175 disk galaxies with SPARC (Lelli+, 2016)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Galaxy name
13- 19 F7.3 [km/s2] A0 Logarithm of the best fit for the
fundamental acceleration scale a0
21- 28 F8.3 --- chi2 Minimum chi-squared value
30- 32 I3 --- N Number of rotation curve data points
34 A1 --- Q2a [0/1] First part of quality cut Q2 (1)
36 A1 --- Q2b [0/1] Second part of quality cut Q2 (1)
38- 44 F7.3 --- A0mode The mode of the marginalized A0 posterior
46- 51 F6.3 --- 1s-A0mode 1σ lower limit of the A0 credible
interval
53- 57 F5.3 --- 1s+A0mode 1σ upper limit of the A0 credible
interval
59- 64 F6.3 --- 3s-A0mode 3σ lower limit of the A0 credible
interval
66- 70 F5.3 --- 3s+A0mode 3σ upper limit of the A0 credible
interval
72- 77 F6.3 --- 5s-A0mode 5σ lower limit of the A0 credible
interval
79- 83 F5.3 --- 5s+A0mode 5σ upper limit of the A0 credible
interval
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Note (1): To pass Q2, both Q2a and Q2b need to be 1. Quality cut as follows:
1 = passes
0 = does not pass
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 30-May-2023