PETERBOROUGH, N.H.- There is no greater luxury for a writer than a residency at MacDowell, the artists’ colony founded in 1907 by American composer Edward MacDowell and his wife Marian. I am writing this in my studio, a little stone cottage in the woods where I have been working on a book for the past month. My desk looks out on enormous dark hemlock trees and the bare trunks of old birches and oaks. Occasionally I notice a squirrel or chipmunk, and in the afternoon a group of deer will wander by, nosing the frozen ground in search of food. But from morning until dinnertime, those are the only creatures I see. Nobody bothers me, nobody knocks. Lunch is dropped off on my studio doorstep in a picnic basket. There is no Internet connection, no phone service. On good days and bad days, I’m alone with my work. But even alone, I have company. Like all of MacDowell’s 32 studios, mine is lined with peaked rectangular wooden plaques, known as “tombstones,’’ signed by all of the artists who have worked here over the years.