Abstract

Massive elliptical galaxies are often quiescent in star formation, despite hosting large amounts of -10 million K gas in their ISM , which can cool in a few 100 Myr and fuel star formation. Many of these elliptical galaxies also host massive kpc-scale filaments of cooler atomic (10^4 K) and molecular gas (~10 K) which coexist with the hot ISM .

Two of the outstanding problems related to these systems are – (1) when and how do these cold filaments form? and (2) what keeps the rest of the ISM of the elliptical galaxies hot?

In the first part of this presentation, I will discuss the results of our latest local patch simulations with gravity, turbulence, and radiative cooling physics included. I will present a new condensation criterion to form cold gas from the hot ISM , which takes the effect of turbulence, cooling, and buoyancy into account. (https://arxiv.org/abs/2302.09380)

In the inner few kilo-parsecs (kpc) of the elliptical galaxies, the net heating due to type 1a supernovae (SNIa) is comparable to the net radiative cooling rate and can help maintain the ISM hot. In the second part of the talk, I will present the results from our 1 kpc ISM -patch simulations with individually resolved type SNIa bubbles. I will discuss how these SNIa heat the ISM and drive turbulence in it. Finally, I will compare our results against more commonly implemented smooth heating models in previous theoretical studies. (arxiv: https://arxiv.org/abs/2402.03613)