OUTER GALACTIC DISKS AND A QUANTITATIVE TEST OF GRAVITY AT LOW ACCELERATIONS
- Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)
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 H{alpha} 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 >4{sigma} level with a reasonable investment of observational resources.
- OSTI ID:
- 21452848
- Journal Information:
- Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 720; ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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