Quark Stars NASADane Berry Kyle Dolan Astronomy 4001

Quark Stars NASA/Dane Berry Kyle Dolan Astronomy 4001 10 December 2007

Outline • • • Introduction to Quark Stars (QS) Significance of QS Characteristics of QS Possible examples of QS Controversy over the existence of QS Possible future observations

Overview of Neutron Stars • Core of a massive star that remains after a supernova explosion • Average Density: ~1014 g/cm 3 • Rotational frequency may range up to 1122 Hz (XTE J 1739 -285) • Magnetic field strength can be ~108 -1014 times that of Earth • Exotic Physics! http: //science. nasa. gov/

Quark Stars (QS) • Stellar core composed of free quarks (strange matter) • Would form through neutron deconfinement • Neutron Star (NS) collapses inward after spinning down, losing centrifugal force • Strange matter would be “softer”, more compressible than neutrons • Smaller, denser than a NS • NS massing from 1. 51. 8 MSun are likely candidates http: //chandra. harvard. edu

Significance of Quark Stars • Opportunity to study strange matter in nature, and its unique behavior • Quark novae may explain gamma ray bursts. NASA/CXC/M Weiss

Quark Star Characteristics • Smaller Size, indicating densities significantly greater than an atomic nucleus • High Rotational Frequency – Conservation of angular momentum allows more compact star to spin faster • Faster Cooling – Higher-density matter allows production of more cooling particles (neutrinos) to carry energy away

RXJ 1856. 5 -3754: Possible QS • Discovered in 1996 • Diameter of ≤ 10 km. • Data suggests that the star is too small to be made of normal neutrons, and could be made of strange matter. ESO/VLT

XTE J 1739 -285: Record-Setting Pulsar • Previously known as a normal neutron star, accreting matter from a companion star • Brightness variations of frequency 1122 Hz observed • Previous record for rotational frequency was ~700 Hz • High frequency indicates a more compact star, possibly made of strange matter • May contradict theories of gravitational waves braking rotational speeds NASA/Dana Berry

3 C 58 – Possible Quark Nova Remnant • Pulsar, possibly the remnant core of SN 1181 • First observed by Chinese and Japanese Astronomers • Remnant cools by internal collisions that release neutrinos to carry away thermal energy • Cooling rate is too fast for matter made only of neutrons • 3 C 58 would have to be ~5 times as dense as a normal neutron star for this cooling rate to make sense Chandra X-Ray Observatory

SN 2006 gy: Possible Quark Nova • First Observed: 18 September 2006 • 100 times brighter than typical Type II novae • Neutron deconfinement would blow the outer layers of the NS away at near light speed, to collide with the original supernova debris. • Observation of elements with A>130 in the debris could confirm 2006 gy as a quark nova NASA/CXC/M Weiss

Controversy • Possible contradiction of the QS theory: – EXO 0748 -676, neutron star with possible mass ~2. 1 MSun, indicates too much rigidity for strange matter – Strange matter is too compressible not to collapse in a mass this large – Mass could be as low as 1. 8 MSun, however, which would still fit QS models • More observations of XTE are needed to confirm its frequency • 3 C 58 may be older than the SN 1181 remnant, due to the lack of variation in its radio emissions

Conclusions • Quark Stars still theoretical, but evidence continues to accumulate to support them • Quark Stars would offer unique opportunities to study exotic matter • Helpful Observations for the Future: – Search for exotic elements in nova remnants – Precise determinations of NS radii and rotational frequency – Close observations of new Supernovae/Quark Novae

Sources “ 3 C 58: Pulsar Gives Insight on Ultra Dense Matter and Magnetic Fields. ” chandra. harvard. edu. 30 August 2006. http: //chandra. harvard. edu/photo/2004/3 c 58/ Blaschke, D. B. et al. “Color superconducting quark matter in compact stars. ”. ar. Xiv: 0712. 0117 v 1. 2 December 2007 Drake, J. J. et al. “Is RX J 185635 -375 a Quark Star? ” ar. Xiv: astro-ph/0204159 v 1 9 Apr 2002. “Quark Stars Could Produce Biggest Bang. ” spacedaily. com. 7 June, 2006. http: //www. spacedaily. com/reports/Quark_Stars_Could_Produce_Biggest_Bang. html Shiga, David. “Fastest spinning star may have exotic heart. ” newscientist. com. 20 February 2007. http: //space. newscientist. com/article/dn 11221? DCMP=NLC-nletter&nsref=dn 11221 Shiga, David. “Massive neutron star rules out exotic matter. ” newscientist. com. 28 June 2006. http: //space. newscientist. com/article/dn 9428 -massive-neutron-star-rules-out-exotic-matter. html Shiga, David. “Was the brightest supernova the birth of a quark star? ” newscientist. com. August 2007. http: //space. newscientist. com/article/dn 12514 -was-the-brightest-supernova-the-birth-of-a-quark-star. html “The leader of the celestial ‘Magnificent Seven. ’” scientificblogging. com. 9 March 2007. http: //www. scientificblogging. com/news/the_leader_of_the_celestial_magnificent_seven Xia et al. “Thermal Evolution of Strange Stars. ” ar. Xiv: 0709. 0214 v 1. 3 September 2007. Zhang, C. M. et al. “Does Sub-millisecond Pulsar XTE J 1739 -285 Contain a Low Magnetic Neutron Star or Quark Star? ” ar. Xiv: 0708. 3566 v 2. 11 September 2007. Wilford, John Noble. “Stars Suggest a Quark Twist And a New Kind of Matter. ” nytimes. com. 11 April, 2002. http: //query. nytimes. com/gst/fullpage. html? res=9 D 04 E 7 DB 1 F 3 DF 932 A 25757 C 0 A 9649 C 8 B 63&sec=&spon=&pagewant ed=print