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Shatter or not: Role of temperature and metallicity in the evolution of thermal instability

Das, HK and Choudhury, PP and Sharma, P (2021) Shatter or not: Role of temperature and metallicity in the evolution of thermal instability. In: Monthly Notices of the Royal Astronomical Society, 502 (4). pp. 4935-4952.

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Official URL: https://doi.org/10.1093/mnras/stab382


We test how metallicity variation (a background gradient and fluctuations) affects the physics of local thermal instability using analytical calculations and idealized, high-resolution 1D hydrodynamic simulations. Although the cooling function (Λ[T, Z]) and the cooling time (tcool) depend on gas temperature and metallicity, we find that the growth rate of thermal instability is explicitly dependent only on the derivative of the cooling function relative to temperature (∂ln Λ/∂ln T) and not on the metallicity derivative (∂ln Λ/∂ln Z). For most of 104 K ≲ T ≲ 107 K, both the isobaric and isochoric modes (occurring at scales smaller and larger than the sonic length covered in a cooling time [cstcool], respectively) grow linearly, and at higher temperatures (≳107 K) the isochoric modes are stable. We show that even the non-linear evolution depends on whether the isochoric modes are linearly stable or unstable. For the stable isochoric modes, we observe the growth of small-scale isobaric modes but this is distinct from the non-linear fragmentation of a dense cooling region. For unstable isochoric perturbations we do not observe large density perturbations at small scales. While very small clouds (∼min[cstcool]) form in the transient state of non-linear evolution of the stable isochoric thermal instability, most of them merge eventually.

Item Type: Journal Article
Publication: Monthly Notices of the Royal Astronomical Society
Publisher: Oxford University Press
Additional Information: The copyright for this article belongs to the author.
Keywords: galaxies: clusters: intracluster medium; galaxies: evolution; galaxies: haloes; hydrodynamics; instabilities; intergalactic medium; Physical data and process
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 04 Aug 2023 08:48
Last Modified: 04 Aug 2023 08:48
URI: https://eprints.iisc.ac.in/id/eprint/82706

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