Gaps in the GD-1 Star Stream

May 2013 • 2013ApJ...768..171C

Authors • Carlberg, R. G. • Grillmair, C. J.

Abstract • GD-1 is a long, thin, Milky Way star stream that has readily visible density variations along its length. We quantify the locations, sizes, and statistical significance of the density structure, i.e., gaps, using a set of scaled filters. The shapes of the filters are based on the gaps that develop in simulations of dark matter sub-halos crossing a star stream. The high Galactic latitude 8.4 kpc long segment of GD-1 that we examine has 8 ± 3 gaps of 99% significance or greater, with the error estimated on the basis of tests of the gap-filtering technique. The cumulative distribution of gaps more than three times the width of the stream is in good agreement with predictions for dark matter sub-halo encounters with cold star streams. The number of gaps narrower than three times the width of the GD-1 stream falls well below the cold stream prediction which is taken into account for the gap creation rate integrated over all sizes. Simple warm stream simulations scaled to GD-1 show that the falloff in gaps is expected for sub-halos below a mass of 10⁶ M _⊙. The GD-1 gaps requires 100 sub-halos >10⁶ M _⊙ within 30 kpc, the apocenter of GD-1 orbit. These results are consistent with LCDM sub-halo predictions but further improvements in stream signal-to-noise and gap modeling will be welcome.

Links

• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2013ApJ...768..171C
• PDF https://iopscience.iop.org/article/10.1088/0004-637X/768/2/171/pdf
• PDF https://stacks.iop.org/0004-637X/768/171/pdf
• PREPRINT http://arxiv.org/abs/1303.4342
• ELECTR https://doi.org/10.1088%2F0004-637X%2F768%2F2%2F171