$\tau$-tilting theory via the morphism category of projective modules I: ICE-closed subcategories

This paper endeavors to explore certain distinguished modules and subcategories within mod$\Lambda$. Let $\mathrm{proj}\mbox{-}\Lambda$ denote the category of all finitely generated projective $\Lambda$-modules and define $\mathcal{P}(\Lambda):=\mathrm{Mor}(\mathrm{proj}\mbox{-}\Lambda)$. Due to the favorable homological properties of $\mathcal{P}(\Lambda)$, we initially examine several noteworthy objects and subcategories of $\mathcal{P}(\Lambda)$, subsequently relating these findings to ${\rm mod}\Lambda$. We demonstrate the existence of a bijection between tilting objects of $\mathcal{P}(\Lambda)$ and support $\tau$-tilting $\Lambda$-modules. This bijection further suggests a correspondence between tilting objects of $\mathcal{P}(\Lambda)$ that possess a specific direct summand and $\tau$-tilting $\Lambda$-modules. We establish a bijection between two-term silting complexes within $\mathbb{K}^{b}({\rm proj}\mbox{-}\Lambda)$ and tilting objects of $\mathcal{P}(\Lambda)$. Following our examination of Image-Cokernel-Extension closed (hereafter referred to as ICE-closed) subcategories of $\mathcal{P}(\Lambda)$, we demonstrate a bijection between rigid objects in $\mathcal{P}(\Lambda)$ and ICE-closed subcategories of $\mathcal{P}(\Lambda)$ with enough Ext-projectives. Subsequently, we present bijections linking rigid objects in $\mathcal{P}(\Lambda)$ with a designated direct summand, $\tau$-rigid pairs within ${\rm mod}\Lambda$, and ICE-closed subcategories of $\mathcal{P}(\Lambda)$ that contain a special object and also have enough Ext-projectives. In order to translate the concept of ICE-closed subcategory from $\mathcal{P}(\Lambda)$ to ${\rm mod}\Lambda$, it is necessary to introduce the framework of ICE-closed subcategories of ${\rm mod}\Lambda$ relative to a projective module.