Shocking Arms

This composite image of galaxy NGC 4258 shows two spiral arms that intersect its plane. The x-rays, in blue, were imaged by NASA’s Chandra X-ray Observatory; the radio waves in purple were imaged by the Very Large Array; the optical light in blue and yellow was imaged by the Hubble Space Telescope; and finally the red is infrared light imaged by the Spitzer Space Telescope. Recently astronomers have discovered shock waves in the arms, perhaps created by jets from the galaxy’s supermassive black hole.