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Since Pan-STARRS surveys the whole sky every few days, it offers
an unprecedented opportunity to discover and monitor those rare,
explosive objects that challenge the limits of our understanding
of astrophysics. Some of these events will be discovered as a result
of Pan-STARRS routine monitoring of the whole sky, while fainter
ones will be searched for with directed deeper surveys.
Supernova Science
Type Ia supernovae are astronomy's most luminous "standard
candle."
By monitoring the apparent brightness of these rare events we can
estimate the distance to a galaxy independent of its redshift,
and hence determine if and how Hubble's law has changed over the
history of the Universe. It was measurements of Type Ia supernova
distances that provided the first clues that rate of expansion
of the Universe may be accelerating, and the first hint of the
existence of "dark energy." Supernova distances are still
one of the very few ways of studying this mysterious pressure,
which appears to be the dominant form of energy in the Universe.
Pan-STARRS will find many candidate Type Ia supernovae in the course
of its regular sky monitoring; but these discoveries will need
to be followed up on other telescopes. By monitoring a few patches
of sky every four days for a year, however, we can expect
to discover and obtain light curves for about 5000 Type Ia supernovae,
without using any other instrument.
Gamma-Ray Bursts
Gamma ray bursts are the most powerful known events in the Universe,
and are believed to arise from the gravitational collapse of massive
stars . The bursts themselves are detected by satellites, but the
afterglow from a burst can be watched visually for about a day after
the event.
The hundreds of afterglows that Pan-STARRS will detect will provide
a statistical basis for determining the astrophysical environments
that foster their birth.
Active Galactic Nuclei
Active galactic nuclei (AGNs), such as quasars, are our main beacons from
the early Universe. These objects are so luminous that they can be
detected at distances corresponding to z = 7. At this redshift
we are looking back nearly to the age of recombination, the time
at which ultraviolet light from the first generation of stars became
strong enough to ionize the hydrogen in the Universe and make it
transparent.
Pan-STARRS will detect AGNs by both color and variablity. The most
distant ones will require a dedicated deep survey to magnitude 29.
Next: Galaxies and Cosmology
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