Heat the olive oil in a 10- to 11- inch straight sided saute pan over medium heat. Add the fennel and garlic, and cook, stirring occasionally, until the fennel starts to soften and brown, about 5 minutes.
Stir in 1 cup water and the cream, low-salt chicken broth, sun-dried tomatoes, red pepper flakes and 1 teaspoon salt. Bring to a boil, reduce the heat and simmer briskly uncovered, until the tomatoes are plump and soft, about 15 minutes.
Remove from the heat and stir in the Pernod if using. Let cool slightly, then puree in a blender until smooth. Wipe out the skillet, return the sauce to the skillet, season to taste with salt and keep hot.
Bring a large pot of well-salted water to a boil. Cook the rigatoni until just barely al dente, 1-2 minutes less than the package instructions. Drain well and return to the pot. Add the sauce and toss over medium-low heat for a minute or two so the pasta finishes cooking and absorbs some of the sauce.