Combine the chicken carcass, onions, celery, carrots, peppercorns, thyme
, and bay leaves in a large, heavy stockpot. Pour in the wine, then cover the chicken and vegetables with the cold water. Bring to a boil over medium-high heat, then immediately decrease the heat to medium-low and simmer, covered, for 12 to 14 hours, adding water as necessary to keep the bones submerged. From time to time, skim away any scum that might rise to the surface. The foamy scum isn’t harmful, but it can leave the broth with a very faintly acrid or dirty flavor.