Title:	Beyond radial profiles: using log-normal distributions to model the multiphase circumgalactic medium
Authors:	Dutta, Alankar Bisht, Mukesh Singh Sharma, Prateek Ghosh, Ritali Roy, Manami Nath, Biman B
Keywords:	methods: analytical methods: data analysis Galaxy: halo, galaxies: haloes quasars: absorption lines software: development
Issue Date:	27-Apr-2024
Publisher:	Monthly Notices of the Royal Astronomical Society
Citation:	Monthly Notices of the Royal Astronomical Society, 2024, Vol. 531 (4), p 5117-5139
Abstract:	Recent observations and simulations reveal that the circumgalactic medium (CGM) surrounding galaxies is multiphase, with the gas temperatures spanning a wide range at most radii, ∼104 K to the virial temperature (∼106 K for Milky Way). Traditional CGM models using simple density profiles are inadequate at reproducing observations that indicate a broad temperature range. Alternatively, a model based on probability distribution functions (PDFs) with parameters motivated by simulations can better match multiwavelength observations. In this work, we use log-normal distributions, commonly seen in the simulations of the multiphase interstellar and circumgalactic media, to model the multiphase CGM. We generalize the isothermal background model by Faerman et al. to include more general CGM profiles. We extend the existing probabilistic models from 1D-PDFs in temperature to 2D-PDFs in density–temperature phase space and constrain its parameters using a Milky Way-like Illustris TNG50-1 halo. We generate various synthetic observables such as column densities of different ions, UV/X-ray spectra, and dispersion and emission measures. X-ray and radio (Fast Radio Burst) observations mainly constrain the hot gas properties. However, interpreting cold/warm phase diagnostics is not straightforward since these phases are patchy, with inherent variability in intercepting these clouds along arbitrary lines of sight. We provide a tabulated comparison of model predictions with observations and plan to expand this into a comprehensive compilation of models and data. Our modelling provides a simple analytical framework that is useful for describing important aspects of the multiphase CGM.
Description:	Open Access. Also available at arXiv.org (one of the alternative locations)
URI:	http://hdl.handle.net/2289/8677
ISSN:	1365-2966
Alternative Location:	https://doi.org/10.48550/arXiv.2310.03717 https://doi.org/10.1093/mnras/stae977
Copyright:	2024 Authors
Additional information:	Collection: RAS Journals
Appears in Collections:	Research Papers (A&A)

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