A Quasar Portrait Gallery
9.03.2002

Quasars (QUASi-stellAR objects) lie near the edge of the observable Universe. Discovered in 1963, astronomers were astounded that such objects could be visible across billions of light-years, as this implies they must emit prodigious amounts of energy. Where does the energy come from?

The Galaxy and the Quasar
7.10.2002

Is the galaxy in the center connected to the quasar on the upper right? Disagreements about systems like this have raged for decades and have been used to challenge the foundations of modern cosmology.

A Quasar-Galaxy Collision?
22.10.1995

In 1963 astronomers were astounded to discover that certain faint, star-like objects have very large redshifts. The large redshifts imply that these objects, now known as quasars (QUASi-stellAR objects), lie near the edge of the observable Universe.

High Redshift Quasars
11.12.1998

Each red speck indicated above is a powerful quasar estimated to be over 100 times brighter than a galaxy. Yet in these Sloan Digital Sky Survey discovery images the quasars appear faint because they are extremely distant.

A Network of Microlensing Caustics
24.08.1999

A virtual sky map like this would be of interest to astronomers studying gravitational microlensing. In microlensing, the gravity of stars near the line of sight can act to magnify the light of background objects such as distant stars, or quasars. Nowhere is this magnification greater than near a gravitational lensing caustic.

The Lyman Alpha Forest
24.02.1998

We live in a forest. Strewn throughout the universe are "trees" of hydrogen gas that absorb light from distant objects. These gas clouds leave numerous absorption lines in a distant quasar's spectra, together called the Lyman-alpha forest.

The Lyman Alpha Forest
12.11.2000

We live in a forest. Strewn throughout the universe are "trees" of hydrogen gas that absorb light from distant objects. These gas clouds leave numerous absorption lines in a distant quasar's spectra, together called the Lyman-alpha forest.

PKS 1127 145: Quasar View
8.02.2002

The quasar known as PKS 1127-145 lies ten billion light-years from our fair planet. A Hubble Space Telescope view in the left panel shows this quasar along with other galaxies as they appear in optical light. The quasar itself is the brightest object in the lower right corner.

A Five Quasar Gravitational Lens
24.05.2006

What's happening near the center of this cluster of galaxies? At first glance, it appears that several strangely elongated galaxies and fully five bright quasars exist there. In reality, an entire cluster of galaxies is acting as a gigantic gravitational lens that distorts and multiply-images bright objects that occur far in the distance.

The Most Distant X Ray Jet
28.11.2003

A false-color x-ray image inset at upper left reveals emission from a cosmic jet of high-energy particles, 100,000 light-years in length, emerging from quasar GB1508+5714. An estimated 12 billion (12,000,000,000) light-years away, this appears to be the most distant energetic jet in the known Universe.