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Satellites around Milky Way Analogs: Tension in the Number and Fraction of Quiescent Satellites Seen in Observations versus Simulations

Karunakaran, Ananthan; Spekkens, Kristine; Oman, Kyle A.; Simpson, Christine M.; Fattahi, Azadeh; Sand, David J.; Bennet, Paul; Crnojević, Denija; Frenk, Carlos S.; Gómez, Facundo A.; Grand, Robert J.J.; Jones, Michael G.; Marinacci, Federico; Mutlu-Pakdil, Burçin; Navarro, Julio F.; Zaritsky, Dennis

Satellites around Milky Way Analogs: Tension in the Number and Fraction of Quiescent Satellites Seen in Observations versus Simulations Thumbnail


Authors

Ananthan Karunakaran

Kristine Spekkens

Kyle A. Oman

Christine M. Simpson

Azadeh Fattahi

David J. Sand

Paul Bennet

Denija Crnojević

Facundo A. Gómez

Robert J.J. Grand

Michael G. Jones

Federico Marinacci

Burçin Mutlu-Pakdil

Julio F. Navarro

Dennis Zaritsky



Abstract

We compare the star-forming properties of satellites around Milky Way (MW) analogs from the Stage II release of the Satellites Around Galactic Analogs Survey (SAGA-ii) to those from the APOSTLE and Auriga cosmological zoom-in simulation suites. We use archival GALEX UV imaging as a star formation indicator for the SAGA-ii sample and derive star formation rates (SFRs) to compare with those from APOSTLE and Auriga. We compare our detection rates from the NUV and FUV bands to the SAGA-ii Hα detections and find that they are broadly consistent with over 85% of observed satellites detected in all three tracers. We apply the same spatial selection criteria used around SAGA-ii hosts to select satellites around the MW-like hosts in APOSTLE and Auriga. We find very good overall agreement in the derived SFRs for the star-forming satellites as well as the number of star-forming satellites per host in observed and simulated samples. However, the number and fraction of quenched satellites in the SAGA-ii sample are significantly lower than those in APOSTLE and Auriga below a stellar mass of M* ∼ 108 M⊙, even when the SAGA-ii incompleteness and interloper corrections are included. This discrepancy is robust with respect to the resolution of the simulations and persists when alternative star formation tracers are employed. We posit that this disagreement is not readily explained by vagaries in the observed or simulated samples considered here, suggesting a genuine discrepancy that may inform the physics of satellite populations around MW analogs.

Citation

Karunakaran, A., Spekkens, K., Oman, K. A., Simpson, C. M., Fattahi, A., Sand, D. J., …Zaritsky, D. (2021). Satellites around Milky Way Analogs: Tension in the Number and Fraction of Quiescent Satellites Seen in Observations versus Simulations. Astrophysical Journal Letters, 916(2), Article L19. https://doi.org/10.3847/2041-8213/ac0e3a

Journal Article Type Article
Acceptance Date Jun 22, 2021
Online Publication Date Aug 2, 2021
Publication Date 2021
Deposit Date Nov 9, 2021
Publicly Available Date Mar 29, 2024
Journal The Astrophysical Journal Letters
Print ISSN 2041-8205
Electronic ISSN 2041-8213
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 916
Issue 2
Article Number L19
DOI https://doi.org/10.3847/2041-8213/ac0e3a

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Copyright Statement
© 2021. The American Astronomical Society. All rights reserved.





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