![]() ![]() So much so that they essentially overwhelm the combined light of every star in an entire galaxy. When situated exactly behind a galaxy, quasars tend to disrupt our view of foreground galaxies because they are so immensely bright. He and his team have spotted several absorbing galaxies by parsing light from reddened quasars, but once this is done, they are faced with a much more challenging task: hunting for light emitted by the absorbing galaxy itself. "Because star dust tends to absorb the blue light but not the red, if there is a dusty galaxy in the foreground, the quasar will be reddened." "To find absorbing galaxies, we first look for quasars that are particularly red," Johan Fynbo, an astronomer at the Cosmic Dawn Center, said in a statement. In other words, light in those "gaps" would've been absorbed by a foreground object on the way to our vantage point. And because chemical elements absorb light at specific wavelengths, looking for gaps in the light output - or spectra - from a background source can tell astronomers what that light had passed through on its way to our telescopes. ![]() As light passes through a background galaxy toward a foreground galaxy, for instance, gas and dust in the foreground galaxy will absorb some of the background one's wavelengths. Galaxies put out light waves found across the entire electromagnetic spectrum, and different telescopes are able to observe these cosmic objects in different wavelengths of light to form a full picture.īut, when a galaxy is located along the same line of sight as another, more distant, source of bright light, there's another way to go about these galactic observations. Just as we see a light bulb via the light it emits, astronomers usually observe galaxies using the light their stars emit.
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