Since this document is fairly technical for most of the readers, allow me to write some excerpts and make the reading easier and understandable.
Radio Transient Universe The SKA will produce the first, unbiased survey
of the variable radio sky at centimeter wavelengths. A useful comparison is to gamma-ray bursts (GRBs), which were detected only because a previously
unexplored region of parameter space for gammaray observations (namely all-sky, high time resolution observations) were conducted. After 30 yr of
mystery, GRBs may now prove to be useful probes of the star formation history of the Universe and the intergalactic medium. Based on the known
populations of radio transient sources, such a survey could reveal populations of radio pulsars in 1 nearby galaxies (via the emission of giant pulses
like those of the Crab pulsars), possibly as distant as the Virgo Cluster. A byproduct of the detection of such pulsars would be direct detection of
the ionized local intergalactic medium. In turn, this would allow study of the bulk of the baryons in the local Universe. Such a survey could also
reveal microquasars throughout the Local Super-cluster. We emphasize, however, that these predictions are based on the known populations of transient
sources. The greatest return from such a survey will (should!) be the detection of currently unknown populations of sources.
Galactic Pulsar Census Radio pulsars provide unparallelled probes of
fundamental physics, and their signals provide unique diagnostics of
intervening media. For example, their pulse periods, particularly those
near 1 ms, constrain the nuclear equation of state; discovery of a pulsar with a pulse period below 1 ms would provide even tighter constraints.
Neutron star-neutron star binaries have provided indirect detection of gravitational waves; discovery of neutron star-neutron star binaries in tighter
orbits or, particularly, black hole-neutron star binaries would enable more precise tests of strong-field gravity. A timing array of millisecond
pulsars could be used to search for gravitational waves with frequencies inaccessible to LIGO and LISA.
SETI Even without detailed knowledge of the luminosity function of ETI
transmitters nor of ETI signal structure, it is almost self-evident that the SKA will allow unprecendented characterization of the ETI sky.
Sensitivity of course allows probing to greater distances for a given transmitter strength. For example, the SKA would enable detection of
transmitters with radiated powers comparable to that of terrestrial TV stations over parsec-scale distances. Perhaps of far greater importance is the
ability to identify and remove terrestrial radio-frequency interference, whose diversity in signal structure may be similar to that of ETI signals.
The key traits of the SKA for this purpose are the multiple-beaming capabilities from a station along with an array of stations at widely spaced
sites.
In this section we discuss SKA specifications, both as they are baselined and
as needed to accomplish the scientific goals described here.
The picture above is the Projection onto the Galactic plane of a simulated SKA survey at 1.4 GHz for pulsars. The blue dots show the number of pulsars
detected by the SKA (∼104), assuming 1024 channels across a 400 MHz with a 600 s integration time per pointing. The open circles and black dots
show
known pulsars from the Parkes Multibeam survey and Princeton catalog,
respectively. Also shown are the spiral arms as defined in the Cordes-Lazio
electron density model (Cordes & Lazio 2002, in preparation). In the simulation, pulsars are born preferentially in spiral arms but move away from the
arms and from the galactic plane according to a velocity distribution
consistent with that of known radio pulsars.
[edit on 2/19/2008 by JacKatMtn]
