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ABSTRACT The orbits of satellite galaxies encode rich information about their histories. We investigate the orbital dynamics and histories of satellite galaxies around Milky Way (MW)-mass host galaxies using the FIRE-2 cosmological simulations, which, as previous works have shown, produce satellite mass functions and spatial distributions that broadly agree with observations. We first examine trends in orbital dynamics at z = 0, including total velocity, specific angular momentum, and specific total energy: the time of infall into the MW-mass halo primarily determines these orbital properties. We then examine orbital histories, focusing on the lookback time of first infall into a host halo and pericentre distances, times, and counts. Roughly 37 per cent of galaxies with $$M_{\rm star}\lesssim 10^7\, {\rm M}_{\odot }$$ were ‘pre-processed’ as a satellite in a lower-mass group, typically $$\approx 2.7\, {\rm Gyr}$$ before falling into the MW-mass halo. Half of all satellites at z = 0 experienced multiple pericentres about their MW-mass host. Remarkably, for most (67 per cent) of these satellites, their most recent pericentre was not their minimum pericentre: the minimum typically was ∼40 per cent smaller and occurred $$\sim 6\, {\rm Gyr}$$ earlier. These satellites with growing pericentres appear to have multiple origins: for about half, their specific angular momentum gradually increased over time, while for the other half, most rapidly increased near their first apocentre, suggesting that a combination of a time-dependent MW-mass halo potential and dynamical perturbations in the outer halo caused these satellites’ pericentres to grow. Our results highlight the limitations of idealized, static orbit modelling, especially for pericentre histories.
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Grenzziehungen in der Leere: Die ersten Satelliten und die Generierung eines Außenraums
During the early Cold War, outer space became a politically contested space, and changes in its spatial perception were related to political and ideological controversies. The article highlights the specific relevance of Euclidean geometry in representations of outer space. Focusing on illustrations and expositions in both postwar German States, it argues that shifts within the spatial imagination and representation of space corresponded with the first satellite missions and condensed debates about the future of technology and the moral legacies of the Second World War. In October 1957, Sputnik I, the first artificial satellite to orbit the Earth and a Soviet construction, urged engineers, scientists, and illustrators to find new ways of depicting and communicating the spaces of outer space to the public and to each other. For decades, space fiction had implicitly stifled theories on the relativity of space and time by hinting at traditional motifs of conquest through machines. Early spaceflight, however, was not about immediate flights to other planets, but about the orbit, a space without a traditional place, yet imagined as being of paramount importance for strategic superiority. Driven by political tensions and drawing on representations established in physics and astronomy, the first satellite projects were designed and explained as missions to places that needed to be defined and controlled because they were strange and new.
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- Award ID(s):
- 0707551
- PAR ID:
- 10556408
- Publisher / Repository:
- GESIS - Leibniz Institute for the Social Sciences
- Date Published:
- Journal Name:
- test x
- ISSN:
- 0172-6404
- Subject(s) / Keyword(s):
- Outer space spaceflight spatiality sputnik Cold War
- Format(s):
- Medium: X
- Right(s):
- Creative Commons Attribution 4.0 International
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.12759/hsr.40.2015.1.239-264
