Quark StarsQuark Stars

Kyle DolanKyle DolanAstronomy 4001Astronomy 4001

10 December 200710 December 2007

NASA/Dane Berry

OutlineOutline

• 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 StarsOverview of Neutron Stars

• Core of a massive star that remains after a supernova explosion

• Average Density: ~1014

g/cm3

• Rotational frequency may range up to 1122 Hz (XTE J1739-285)

• Magnetic field strength can be ~108-1014 times that of Earth

• Exotic Physics!

http://science.nasa.gov/

Quark Stars (QS)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 1.5-

1.8MSun are likely candidates http://chandra.harvard.edu

Significance of Quark StarsSignificance 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 CharacteristicsQuark 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

RXJ1856.5-3754: Possible QS• Discovered in 1996

• Diameter of ≤10km.

• Data suggests that the star is too small to be made of normal neutrons, and could be made of strange matter.

ESO/VLT

XTE J1739-285: XTE J1739-285: Record-Setting PulsarRecord-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 ~700Hz

• High frequency indicates a more compact star, possibly made of strange matter

• May contradict theories of gravitational waves braking rotational speeds

NASA/Dana Berry

3C58 – Possible Quark Nova 3C58 – Possible Quark Nova RemnantRemnant

• 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

• 3C58 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 2006gy: Possible Quark NovaSN 2006gy: 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 2006gy as a quark nova

NASA/CXC/M Weiss

ControversyControversy

• Possible contradiction of the QS theory:– EXO 0748-676, neutron star with possible mass ~2.1MSun,

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

• 3C58 may be older than the SN 1181 remnant, due to the lack of variation in its radio emissions

ConclusionsConclusions

• 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

SourcesSources“3C58: Pulsar Gives Insight on Ultra Dense Matter and Magnetic Fields.” chandra.harvard.edu. 30 August 2006.

http://chandra.harvard.edu/photo/2004/3c58/

Blaschke, D.B. et al. “Color superconducting quark matter in compact stars.”. arXiv:0712.0117v1. 2 December 2007

Drake, J. J. et al. “Is RX J185635-375 a Quark Star?” arXiv:astro-ph/0204159v1 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/dn11221?DCMP=NLC-nletter&nsref=dn11221

Shiga, David. “Massive neutron star rules out exotic matter.” newscientist.com. 28 June 2006. http://space.newscientist.com/article/dn9428-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/dn12514-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.” arXiv:0709.0214v1. 3 September 2007.

Zhang, C.M. et al. “Does Sub-millisecond Pulsar XTE J1739-285 Contain a Low Magnetic Neutron Star or Quark Star?” arXiv:0708.3566v2. 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=9D04E7DB1F3DF932A25757C0A9649C8B63&sec=&spon=&pagewanted=print