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Detection of Strong Epicyclic Density Spikes in the GD-1 Stellar Stream: An Absence of Evidence for the Influence of Dark Matter Subhalos?

Abstract : The density variations in thin stellar streams may encode important information on the nature of the dark matter. For instance, if dark matter aggregates into massive sub-halos, these perturbers are expected to scatter stars out of dynamically cold stellar streams, possibly leading to detectable gaps in those structures. Here we reexamine the density variations in the GD-1 stream, using Gaia DR2 astrometry, Pan-STARRS photometry, together with high precision radial velocities measured with the CFHT/ESPaDOnS and VLT/UVES instruments and complemented with public radial velocity catalogs. We show that after correcting for projection effects, the density profile exhibits high contrast periodic peaks, separated by 2.64 ± 0.18 kpc. An N-body simulation is presented that reproduces this striking morphology with simple epicyclic motion in a smooth Galactic potential. We also discuss the reliability of measuring density variations using ground-based photometric surveys, and for the particular case of GD-1 we highlight some of the artifacts present in the Gaia DR2 catalog along its track. Massive dark subhalos do not appear to be required to explain the density clumping along GD-1.
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Contributor : Benoit Famaey Connect in order to contact the contributor
Submitted on : Sunday, November 1, 2020 - 4:56:00 PM
Last modification on : Wednesday, November 3, 2021 - 6:48:14 AM
Long-term archiving on: : Tuesday, February 2, 2021 - 7:37:31 PM

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Rodrigo Ibata, Guillaume Thomas, Benoit Famaey, Khyati Malhan, Nicolas Martin, et al.. Detection of Strong Epicyclic Density Spikes in the GD-1 Stellar Stream: An Absence of Evidence for the Influence of Dark Matter Subhalos?. The Astrophysical Journal, American Astronomical Society, 2020, 891 (2), pp.161. ⟨10.3847/1538-4357/ab7303⟩. ⟨hal-02984975⟩

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