PSR J0737-3039

Double Pulsars

Artist's impression. The objects are not shown to scale: if they were depicted as the size of marbles, they would be 225 m (750 ft) apart. See also MPEG animation (2.4 MB)
Observation data Epoch J2000      Equinox J2000
Constellation	Puppis
Right ascension	07h 37m 51.247s
Declination	-30° 39' 40.74 "'
Characteristics
Spectral type	Pulsar
U−B color index	?
B−V color index	?
Variable type	None
Astrometry
Distance	1600 - 2000 Ly (600 parsecs)
Details
Mass	1.24 M☉
Radius	? R☉
Luminosity	? L☉
Temperature	? K
Metallicity	?
Rotation	2.77346077 s[1]
Age	? years

PSR J0737-3039B

Details
Mass	1.35 M☉
Radius	? R☉
Luminosity	? L☉
Temperature	? K
Metallicity	?
Rotation	22.6993786 ms[1]
Age	? years
Other designations
PSR J0737-3039A, PSR J0737-3039, [CGB2005] J073751.248-303940.83.

PSR J0737-3039 is currently the only known double pulsar, it consists of two neutron stars emitting electromagnetic waves in the radio wavelength in a relativistic binary system. The two Pulsars are known as PSR J0737-3039A and PSR J0737-3039B. It was discovered in 2003 at Australia's Parkes Observatory by an international team led by the radio astronomer Marta Burgay during a high-latitude pulsar survey.^[2]

Lone Pulsars

A pulsar is the collapsed core of a star that has ended its life as a supernova explosion. Weighing more than our sun, yet only a few kilometers across, these extremely dense objects rotate on their axes, producing highly focused electromagnetic waves which sweep around the sky in a lighthouse effect at speeds that can reach a few hundred times per second. They are formed when a star erupts in a supernova, and consequently the remnant becomes a neutron star. If a neutron star is rotating at a high velocity it is likely to be a pulsar, however the beam emitted from its poles is unseen and undetected due to the orientation of the poles being away from the earth.

Double pulsar

A double pulsar is a binary system that is composed of two rotating and pulsating neutron stars. The mass makes it spin due to angular momentum. It spins and becomes stable, the other star also turns into a neutron star also but is much slower and orbits the spinning primary pulsar.

Known double pulsars

PSR J0737-3039 is a relativistic binary pulsar system, the first known double pulsar, discovered in 2003 by a team led by Dr Marta Burgay using the CSIRO's Parkes radio telescope in Australia.

PSR J0737-3039

The orbital period of J0737-3039 (2.4 hours) is the shortest yet known for such an object (one-third that of the Taylor-Hulse object), which enables the most precise tests yet. In 2005, it was announced that measurements had shown an excellent agreement between general relativity theory and observation. In particular, the predictions for energy loss due to gravitational waves appear to match the theory.

As a result of energy loss due to gravitational waves, the common orbit shrinks by 7 mm per day. The two components will coalesce in about 85 million years.

Property	Pulsar A	Pulsar B
Spin period	23 milliseconds	2.8 seconds
Mass	1.337 solar masses	1.250 solar masses
Orbital period	2.4 hours

The pulses from Pulsar B are only detectable for about 20 minutes in each orbit.

Discovery

PSR J0737-3039A was discovered in 2003, along with its partner at Australia's 65m Parkes Radio Observatory, however J0737-3039B was not identified as a pulsar until a second observation. The system was originally observed by an international team during a high-latitude multibeam survey organized in order to discover more pulsars in the night sky.^[3] Initially this system was thought to be an ordinary pulsar detection. The first detection showed one pulsar with a period of 23 milliseconds in orbit around a neutron star. Only after follow up observations that a weaker second pulsar was detected with a pulse of 2.8 seconds from the companion star.

Although over 1400 pulsars have been detected since their discovery 1967 by Anthony Hewish and Jocelyn Bell in Cambridge university, this particular system has caused a lot of excitement. Previous observations have recorded a pulsar orbiting a neutron star, but never two pulsars orbiting each other .^[4]

Implications

The double pulsar system PSR J0737-3039 is being studied in order to test out Einstein's General Theory of Relativity put forward in 1915. The investigation of double pulsars is a great opportunity as the environment created by warped space-time due to the shift of intense masses is extremely rare, and thus perfect for the testing of Einstein's theory and the observation of theoretical Gravitational Waves.^[5]

Eclipses

Another great discovery from the double pulsar is the observation of an eclipse from a conjunction of the both superior and weaker pulsar. This happens when the doughnut shaped magnetosphere of one pulsar, which is filled with absorbing plasma, blocks the companion pulsar's light for 30+ seconds. Blockage is not complete, due to the geometrical configuration and limited size of the weaker pulsar's magnetosphere; some of the stronger pulsar's light can still be detected during the eclipse.

Similar pulsars

The object is similar to PSR B1913+16, which was discovered in 1974 by Taylor and Hulse, and for which the two won the 1993 Nobel Prize in Physics. Objects of this kind enable precise testing of Einstein's theory of general relativity, because relativistic effects can be seen in the timing of the pulsar pulses. However most such binary systems are merely known to consist of one pulsar and one neutron star; J0737-3039 is the first case where both components are known to be not just neutron stars but pulsars.

Other binary systems

A whole range of differing two-body systems can occur, where a pulsar exists. Other than a double pulsar system, these systems also occur:

A pulsar-white dwarf system; Such as the PSR B1620-26 binary star.

A pulsar-neutron star system, such as PSR B1913+16.

pulsar and a normal star; E.g, PSR J0045-7319, a system that is composed of a pulsar and main-sequence B star

A pulsar-black hole binary system is possible, but such a system is yet to be discovered. A Pulsar-black hole system will be perfect to test Einstein's theory of General Relativity, due to the immense gravitational forces exerted by both celestial objects. The Square Kilometre Array, a planned Radio Telescope due to be constructed in the southern hemisphere in 2012, will observe binary pulsar systems. It will also search for Pulsar-Black hole systems in order to test General Relativity.^[6]

References

1. ^ ^{a b} ATNF Pulsar Catalogue database [1].
2. ^ "An increased estimate of the merger rate of double neutron stars from observations of a highly relativistic system"- Retrieved 2010-07-07
3. ^ "The first double pulsar"-List of the team. Retrieved 2010-07-07
4. ^ "The Double Pulsar" Retrieved 2010-07-07
5. ^ J. H. Taylor, Philos. Trans. R. Soc. London Ser. A 341, 117 (1992). "Pulsar Timing and Relativistic Gravity"
6. ^ "Strong field tests of gravity using pulsars and black holes" Retrieved 2010-07-06.

External links

• http://skyandtelescope.com/news/article_1124_1.asp (discovery)
• http://skyandtelescope.com/news/article_1473_1.asp (verification of general relativity)
• http://www.physicsweb.org/articles/world/18/3/6/1
• http://www.jb.man.ac.uk/news/doublepulsar/
• http://www.atnf.csiro.au/research/highlights/2003/manchester/manchester.html -list of the Parkes Pulsar Survey team members.
• http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=PSR+J0737-3039&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id
• http://www.portaldoastronomo.org/noticia.php?id=354
• http://www.ufn.ru/en/news/2004/1/
• http://www.atnf.csiro.au/research/highlights/2003/manchester/manchester.html
• http://www.physics.mcgill.ca/~bretonr/doublepulsar/

Pulsar video: http://www.physics.mcgill.ca/~bretonr/doublepulsar/doublepulsar_artistic_small.mov

Sound clip http://www.physics.mcgill.ca/~bretonr/doublepulsar/doublepulsar_sound.mp3