TY - JOUR
T1 - Outer galactic disks and a quantitative test of gravity at low accelerations
AU - Zaritsky, Dennis
AU - Psaltis, Dimitrios
N1 - Copyright:
Copyright 2015 Elsevier B.V., All rights reserved.
PY - 2010/9/1
Y1 - 2010/9/1
N2 - We use the recent measurement of the velocity dispersion of star-forming, outer-disk knots by Herbert-Fort et al. in the nearly face-on galaxy NGC 628, in combination with other data from the literature, to execute a straightforward test of gravity at low accelerations. Specifically, the rotation curve at large radius sets the degree of non-standard acceleration and then the predicted scale height of the knots at that radius provides the test of the scenario. For our demonstration, we presume that the Hα knots, which are young (age < 10 Myr), are distributed like the gas from which they have recently formed and find a marginal (>97% confidence) discrepancy with a modified gravity scenario given the current data. More interestingly, we demonstrate that there is no inherent limitation that prevents such a test from reaching possible discrimination at the >4σ level with a reasonable investment of observational resources.
AB - We use the recent measurement of the velocity dispersion of star-forming, outer-disk knots by Herbert-Fort et al. in the nearly face-on galaxy NGC 628, in combination with other data from the literature, to execute a straightforward test of gravity at low accelerations. Specifically, the rotation curve at large radius sets the degree of non-standard acceleration and then the predicted scale height of the knots at that radius provides the test of the scenario. For our demonstration, we presume that the Hα knots, which are young (age < 10 Myr), are distributed like the gas from which they have recently formed and find a marginal (>97% confidence) discrepancy with a modified gravity scenario given the current data. More interestingly, we demonstrate that there is no inherent limitation that prevents such a test from reaching possible discrimination at the >4σ level with a reasonable investment of observational resources.
KW - Galaxies: kinematics and dynamics
KW - Gravitation
UR - http://www.scopus.com/inward/record.url?scp=78649304976&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=78649304976&partnerID=8YFLogxK
U2 - 10.1088/2041-8205/720/1/L11
DO - 10.1088/2041-8205/720/1/L11
M3 - Article
AN - SCOPUS:78649304976
VL - 720
SP - L11-L14
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
SN - 2041-8205
IS - 1 PART 2
ER -