Philips Atlas of the Universe

THE UNIVERSE

 ▼Gravitational lens

effect. The light from a

distant quasar passes by

an intervening, high-mass

galaxy, with the result that

the galaxy acts as a ‘lens’,

and produces multiple

images of the quasar.

In this case the quasar

is almost directly behind

the galaxy, so the effect is

symmetrical; the resulting

picture, imaged by the

Hubble Space Telescope,

is known as the Einstein

Cross, since the effect

was predicted by

Albert Einstein’s theory

of relativity.

▲ Quasar host galaxies:

the top photo shows a tidal

tail of dust and gas beneath

quasar 0316-346 (2200

million light-years from

Earth). The peculiarly shaped

tail suggests that the host

galaxy may have interacted

with a passing galaxy.

The bottom photo shows

evidence of a catastrophic

collision between two

galaxies. The debris from

this collision may be fuelling

quasar IRAS 04505-2958

(3000 million light-years

from Earth). Astronomers

believe that a galaxy plunged

vertically through the plane

of a spiral galaxy, ripping out

its core and leaving the spiral

ring (at the bottom of the

image). The core lies in front

of the quasar, the bright

object in the centre of the

image. Surrounding the core

are star-forming regions.

The distance between the

quasar and spiral ring is

15,000 light-years.

 Quasars and companion

galaxies.The image on the

right reveals the galaxy

associated with the luminous

quasar PKS 2349, which

is 1500 million light-years

from Earth. The image has

enabled astronomers to

peer closer into the galaxy’s

nucleus. Only 11,000 light-

years separate the quasar

and the companion galaxy

(located just above the

quasar). This galaxy is

similar in size and brightness

to the Large Magellanic

Cloud galaxy near our Milky

Way. The galaxy is closer to

the quasar’s centre than our

Sun is to the centre of our

Galaxy. Drawn together by

strong gravitational forces,

the galaxy will eventually

fall into the quasar’s engine,

the black hole. The black

hole will gobble up this

companion galaxy in no

more than 10 million years.

Distant quasar

Intervening

galaxy

Image captured by HST

Gravitational force bends light waves

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