My question is that:
For any prime $p>7$, is there a mod $ p $ representation $ \bar{\rho}:G_{\mathbb{Q}}\to \operatorname{GL}_{2}(\mathbb{F}_{q}) $ of the absolute Galois group $ G_{\mathbb{Q}} $ of the rational number field $ \mathbb{Q} $ where $ \mathbb{F}_{q} $ is a finite field of characteristic $p$ such that
- $ \bar{\rho} $ is unramified at $ p $;
- $ \bar{\rho} $ is even, i.e. the determinant of the image of a complex conjugation $ c $ is $ 1 $;
- the image $ \operatorname{Im}(\bar{\rho}) $ of $ \bar{\rho} $ contains $ \operatorname{SL}_{2}(\mathbb{F}_{q}) $?
My motivation for asking this question comes from Theorem 1 in Allen and Calegari - Finiteness of unramified deformation rings. The paragraph following Theorem 1 in the above paper states that if the mod $p$ representation $ \bar{\rho} $ contains $ \operatorname{SL}_n(\mathbb{F}_q)$ , then …. I asked myself, does such $ \bar{\rho} $ really exist (especially in even case)?
If we drop conditions 1 and 2, then it is a special case of inverse Galois problem for $\mathbb{Q}$, and it seems that it has an affirmative answer, cf. Wiese - On projective linear groups over finite fields as Galois groups over the rational numbers.
If we drop condition 2 and the condition 1 is weakened in the sense that we only consider the tame representation (but not unramified at $p$), then it's called the Tame Inverse Galois Problem, and it seems that it has an affirmative answer, cf. Sara Arias de Reyna's Ph. D. thesis "Galois Representations and Tame Galois realizations".
I think the most serious assumption here is 1.