[Tex/LaTex] How to draw a ring-like diagram with some labels on its arcs

Question

I would like to draw a figure that looks like the following scenario:

Consider a circle of radius $r$, described parametrically by $x = cos(t) and y = sin(t)$. I'd like to draw a figure where the 90 to 180 degrees arc and the 270 to 360 arc are stretched by adding 1 to the previous point, while keeping the figure connected. Here is a sketch of the figure below: (x and y axis should not be included in the final figure).

The respective labels are $\Omega_1$, $\partial \varphi(1)$, $\partial \varphi (1)$, $t=0$, $t=1$, $t=0$, $t=1$, $\phi^2$, $\Omega_2$

Any help would be greatly appreciated.

Here is part of the picture that I have drawn:

\begin{pspicture}(-.5,-.5)(3.5,3.5)
\psaxes[labels=none,ticks=none]{->}(0,0)(-.5,-.5)(3,3)[$x$,0][$y$,90]
\pscustom[fillstyle=solid,fillcolor=lightgray]
{
 \psarc(0,0){2.5}{0}{90}
 \psarcn(0,0){1.5}{90}{0}
 \closepath
   }
   \rput(2;45){$\Delta \mathfrak{M}$}
    \end{pspicture}

I'd also like to have an additional label $\Delta \mathfrak{M}$ in each annulus as well as for them to be shaded.

Answer 1

\documentclass[tikz,margin=10pt]{standalone}
\usepackage{mathtools,amssymb}
\begin{document}
\begin{tikzpicture}[scale=2,transform shape]
\draw (1,0) arc (0:90:1);
\draw (-1,0) arc (180:270:1);
\draw[fill=gray!30] (-1,0) -- (-2,0) arc (180:90:2) -- (0,1) arc (90:180:1);
\draw[fill=gray!30] (1,0) -- (2,0) arc (0:-90:2) -- (0,-1) arc (-90:0:1);
\node at (0.2,0.75) {\tiny $\phi^2$};
\node[rotate=50] at (-0.7,0.5) {\tiny $t=0$};
\node[rotate=50] at (0.7,-0.5) {\tiny $t=0$};
\node[rotate=50] at (-1.45,1.2) {\tiny $t=1$};
\node[rotate=50] at (1.45,-1.2) {\tiny $t=1$};
\node[rotate=50] at (-1.6,1.4) {\tiny $\partial \varphi (1)$};
\node[rotate=50] at (1.6,-1.4) {\tiny $\partial \varphi (1)$};
\node at (-2,2) {\tiny $\Omega_1$};
\node at (2,-2) {\tiny $\Omega_2$};
\node at (-1,1) {\tiny $\Delta \mathfrak{M}^2$};
\node at (1,-1) {\tiny $\Delta \mathfrak{M}^2$};
\end{tikzpicture}

\end{document}