GCRT J1745-3009

Starbox observe
epoch=J2000.0
constell=Scorpius
ra=RA|17|45|5.1
dec=DEC|-30|09|56

GCRT J1745-3009 is a newly-discovered transient, bursting low-frequency radio source which lies in the direction of the galactic center.

Discovery

A group of astronomers from Sweet Briar College and the Naval Research Laboratory detected transient emission from two sources in 1998 while studying the Galactic Center. They then began monitoring the region specifically looking for transient sources and detected five bursts of radio waves about 1 meter in wavelength (frequency 330 MHz) during a seven-hour period from September 30 to October 1, 2002.The five bursts were of equal brightness, with each lasting about 10 minutes, and occurring every 77 minutes.cite journal | author=Scott D. Hyman, T. Joseph W. Lazio, Namir E. Kassim, Paul S. Ray, Craig B. Markwardt and Farhad Yusef-Zadeh | title=A powerful bursting radio source towards the Galactic Centre | journal=Nature | volume=434 | issue=7029 | year=2005 | pages=50–52 | pmid=15744294 | doi=10.1038/nature03400 [http://www.nature.com/nature/journal/v434/n7029/full/nature03400.html Text at "Nature".] ] Like an earlier low-frequency transient discovered by the same group [Low-Frequency Radio Transients in the Galactic Center, Scott D. Hyman, T. Joseph W. Lazio, Namier E. Kassim, and Ashlee L. Bartleson, "Astronomical Journal" 123, #3 (March 2002), pp. 1497–1501. [http://adsabs.harvard.edu/abs/2002AJ....123.1497H Paper at ADSABS] ] , it was given the designation "GCRT", an abbreviation for "Galactic Center Radio Transient". The source was also nicknamed a "burper".cite journal | author=S. R. Kulkarni and E. Sterl Phinney | title=Astronomy: blasts from the radio heavens | journal=Nature | volume=434 | issue=7029 | year=2005 | pages=28–29 | pmid=15744281 | doi=10.1038/434028a [http://www.nature.com/nature/journal/v434/n7029/full/434028a.html Text at "Nature".] ] The group found no X-ray or γ-ray counterpart to the object.

Another burst from the source was later found in data recorded September 28, 2003 [A New Radio Detection of the Transient Bursting Source GCRT J1745-3009, Scott D. Hyman, T. Joseph W. Lazio, Subhashis Roy, Paul S. Ray, Namir E. Kassim, and Jennifer L. Neureuther, "Astrophysical Journal" 639, #1 (March 2006), pp. 348–353. [http://adsabs.harvard.edu/abs/2006ApJ...639..348H Paper at ADSABS] ; also [http://arxiv.org/abs/astro-ph/0508264 arXiv:astro-ph/0508264] .] , and a weaker burst was found in data recorded March 20, 2004. As of January 2007, no other bursts have been found.

tructure

The discoverers argue that if the source is further than 70 parsecs away, its high brightness temperature would require it to be powered by a coherent emission process. (If within 70 parsecs, the source could be either coherent or incoherent.) They also claim that most known coherent emission processes are unlikely explanations for the source. Models proposed by others include a nulling pulsar, a pair of orbiting neutron stars [Is the Bursting Radio Source GCRT J1745-3009 a Double Neutron Star Binary?, R. Turolla, A. Possenti and A. Treves, "Astrophysical Journal" 628, #1 (July 2005), pp. L49–L52. [http://adsabs.harvard.edu/abs/2005ApJ...628L..49T Paper at ADSABS] ; also, [http://arxiv.org/abs/astro-ph/0506199 arXiv:astro-ph/0506199] .] , a radio-emitting white dwarf [GCRT J1745-3009 as a Transient White Dwarf Pulsar, Bing Zhang and Janusz Gil, "Astrophysical Journal" 631, #2 (October 2005), pp. L143–L146. [http://adsabs.harvard.edu/abs/2005ApJ...631L.143Z Paper at ADSABS] ; also, [http://arxiv.org/abs/astro-ph/0508213 arXiv:astro-ph/0508213] .] , and a pulsar precessing with a period of 77 minutes. [GCRT J1745-3009: a precessing radio pulsar?, W. W. Zhu and R. X. Xu, "Monthly Notices of the Royal Astronomical Society" 365, #1 (pp. L16–L20). [http://adsabs.harvard.edu/abs/2006MNRAS.365L..16Z Paper at ADSABS] ; also, [http://arxiv.org/abs/astro-ph/0504251 arXiv:astro-ph/0504251] .]

References

External links

* [http://www.aztlan.net/rumblings_center_galaxy.htm Strange Rumblings at the Center of our Galaxy]

* [http://xweb.nrl.navy.mil/personnel/paulr/images/BBCradioInterv.mpeg BBC Radio interview with Scott Hyman] (MPEG)

* [http://www.sciencedaily.com/releases/2005/03/050309125109.htm Science Daily]

* [http://www.earthfiles.com/news/news.cfm?ID=1160&category=Science Mysterious Radio Bursts]