Skip to main content Accessibility help
×
Home

FOSSILs in the Galactic Halo

  • Carl J. Grillmair (a1)

Abstract

We use a matched filter to detect compact groups of old, metal-poor stars that we term FOSSILs (Fragments of Old Stellar Systems in Limbo). With size scales on the order of 10 arcminutes, distances ranging from 2 to 200 kpc, and memberships ranging from a handful to several dozen stars, these FOSSILs stand out from the surrounding field and are presumably signatures of, or debris from, ancient star clusters and dwarf galaxies. They may be localized concentrations of stars within more extensive tidal streams, and in some cases may be the signatures of extant but heretofore undetected ultrafaint galaxies. Using magnitudes and colors from the Pan-STARRs survey, we detect ∼ 70 such FOSSILs at 5 σ or greater in a 2200 square degree region in the vicinity of the north Galactic pole. A subsample of more populous FOSSILs that could be candidate ultrafaint dwarf galaxies suggests a total population of 200 such objects within 200 kpc of the Galactic center. Spectroscopic and astrometric follow-up of these FOSSILs will be required to determine the nature of these structures, deepen our understanding of the make-up and accretion history of the Galactic halo, and perhaps alleviate the missing satellites problem.

Copyright

References

Hide All
Chambers, K, Magnier, E. A., Metcalfe, N. et al. 2016, arXiv:1612.05560
Grillmair, C. J., & Dionatos, O. 2006 ApJ, 643, L17
Grillmair, C. J., & Carlin, J. L. 2016, in: Newberg, H. J. & Carlin, J. L. (eds.), Tidal Streams in the Local Group and Beyond (Switzerland: Springer), p. 87
Grillmair, C. J. 2017, ApJ, 834, 98
Klypin, A., Kravtsom, A. V., Valenzuela, O., & Prada, F. 1999, ApJ, 522, 82
Moore, B., Ghigna, S., Governato, F., Lake, G., Quinn, T., Stadel, J., & Tozzi, P., 1999 ApJ, 524, L19
Piffl, T., Scannapieco, C., Binney, J., et al. 2014, Astr. Ap., 562, 91
Shipp, N., Drlica-Wagner, A., Balbinot, E. et al. 2018, ApJ, 862, 114
MathJax
MathJax is a JavaScript display engine for mathematics. For more information see http://www.mathjax.org.

Keywords

FOSSILs in the Galactic Halo

  • Carl J. Grillmair (a1)

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed