dorsal/arxiv
View SchemaLocal Group analogues in a cosmological context -- I. Relating velocity structure to the cosmic web
| Authors | Kai Wang, Peder Norberg, Azadeh Fattahi, Louis E. Strigari |
|---|---|
| Categories | |
| ArXiv ID | 2601.08419vv1 |
| URL | https://arxiv.org/abs/2601.08419 |
| License | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ |
Abstract
Our Local Group, dominated in mass by the Milky Way (MW) and M31, provides a unique laboratory for testing $\Lambda$CDM cosmology on small scales owing to its proximity. However, its connection to the surrounding large-scale environment, which is essential for interpreting its properties, is inadequately understood. In this work, we explore the connection between Local Group analogues (LGAs) and their surrounding large-scale environments using the ABACUSSUMMIT simulation suite, highlighting the key role of the coupling energy of the MW-M31 orbit, $E_{\rm coupling}$. We find that LGAs with high $E_{\rm coupling}$ preferentially reside in denser regions, whereas those with low $E_{\rm coupling}$ tend to occupy low-density environments. Furthermore, LGAs with low $E_{\rm coupling}$ exhibit strong alignment with cosmic filaments, manifested as a pronounced polar anisotropy in the distribution of tracer haloes. By contrast, LGAs with high $E_{\rm coupling}$ show a weaker polar anisotropy but an enhanced azimuthal anisotropy, with large-scale tracer haloes preferentially lying in the plane spanned by the halo pair and the orbital spin vector. Within this framework, our Local Group is characterised by typical $E_{\rm coupling}$ residing in a relatively under-dense environment, yet it remains consistent with the 95\% range of analogue systems identified in the simulation.
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"abstract": "Our Local Group, dominated in mass by the Milky Way (MW) and M31, provides a unique laboratory for testing $\\Lambda$CDM cosmology on small scales owing to its proximity. However, its connection to the surrounding large-scale environment, which is essential for interpreting its properties, is inadequately understood. In this work, we explore the connection between Local Group analogues (LGAs) and their surrounding large-scale environments using the ABACUSSUMMIT simulation suite, highlighting the key role of the coupling energy of the MW-M31 orbit, $E_{\\rm coupling}$. We find that LGAs with high $E_{\\rm coupling}$ preferentially reside in denser regions, whereas those with low $E_{\\rm coupling}$ tend to occupy low-density environments. Furthermore, LGAs with low $E_{\\rm coupling}$ exhibit strong alignment with cosmic filaments, manifested as a pronounced polar anisotropy in the distribution of tracer haloes. By contrast, LGAs with high $E_{\\rm coupling}$ show a weaker polar anisotropy but an enhanced azimuthal anisotropy, with large-scale tracer haloes preferentially lying in the plane spanned by the halo pair and the orbital spin vector. Within this framework, our Local Group is characterised by typical $E_{\\rm coupling}$ residing in a relatively under-dense environment, yet it remains consistent with the 95\\% range of analogue systems identified in the simulation.",
"arxiv_id": "2601.08419",
"authors": [
"Kai Wang",
"Peder Norberg",
"Azadeh Fattahi",
"Louis E. Strigari"
],
"categories": [
"astro-ph.GA",
"astro-ph.CO"
],
"license": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
"title": "Local Group analogues in a cosmological context -- I. Relating velocity structure to the cosmic web",
"url": "https://arxiv.org/abs/2601.08419",
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