quark stars renxin xu ( 徐仁新 ) school of physics, peking university talk presented at ccast...

Quark Stars Renxin Xu (徐仁新 )

School of Physics, Peking University

Talk presented at CCAST workshop onDense matter and neutron stars

October 22, 2003, Beijing

“Quark Stars” http://vega.bac.pku.edu.cn/~rxxu R.X. Xu

Quark Stars


I would like to introduce briefly

solid bare strange quark stars

in this talk.

Ref. Xu (astro-ph/0310050) for details.

SUMMARYSUMMARYHistorical notesHistorical notes

Can a Can a starstar be be composed of QMcomposed of QM??

Hadronic stability: Why Hadronic stability: Why strangestrange??

Formation & emission: Why Formation & emission: Why barebare??

Astrophy. appearance: Why Astrophy. appearance: Why solidsolid??

ConclusionConclusion“Quark Stars” http://vega.bac.pku.edu.cn/~rxxu R.X. Xu


Landau 1932

Gell-Mann&ZweigHewish&Bell

Gold 1968 Quark Star? SQS?

What’s the nature of PSRs: NSs? or QSs?

Historical notesHistorical notes


Question: Can a star be composed of QM?

Answer: Possible quark-deconfinement in compact stars should be a straightforward consequence of asymptotic freedomasymptotic freedom.


What’s QM?

T-dominated

Rho 2001

D-dominated




Bowers 2003


Weber(1999) J.Phys.G: 25, R195


Deconfinement occurs probably in NSs

Critical density c?

(4R3/3)-1 ~ 1.5 N



Hadronic instability: Why Hadronic instability: Why strangestrange??

Question: Why are quark stars strange?

Answer: The Bodmer-Witten's conjecture! —— Strange quark matter in bulk is absolutely stableabsolutely stable, although one can hardly justify it from the first principles (the gauge theory of strong interaction, QCD).

A simple argument for B -W’s conjecturemu ~ 5

md ~ 10

ms ~150

=1.5N

F ~ 400

Farhi & Jaffe (1984) Greiner et al 1998





Strange stars are QSs with strangeness

Strangeness S is a quantum number for strange quark: S(s) = -1, S(s) = 1

Strange quarks are actually not strange, we have really a lot of strange virtual quarks in our bodies (protons & neutrons)

proton = {uud; uu, dd, ss; g}, neutron = {udd; uu, dd, ss; g}

Note: strange stars could be ...

o crusted

o bare



Electric field:

E ~ 1017V/cm



Question: Should quark stars be bare?

Answer: Very likely! This is because of (1)(1) detonation, (2)(2) high temperature, and (3)(3) rapid rotation and strong magnetic fields, although a realistic simulation of SNE with a quark phase transition is difficult and does not appear (ref. Xu: astro-ph/0211563).

PSR 0943+10 Deshpande & Rankin 1999


Evidence for bare SSs from radio pulses


Ruderman-Sutherland (1975) modelVaccum-gap sparking Vd ~ c (EB/B2)RS requires: EB>~10keV & B<0

Difficulties in RS modelBounding energy of neutron stars: EB<10keVWhy haven’t we observe two distinct kinds of _pulsar radio emission (B<0, >0)?Strong complicated multipolar magnetic _fields? (Gil & Mitra, 2001, ApJ, 550, 383)



Advantages of the bare strange star idealEB for any Bkeeps the RS scenario of vacuum gap sparking

ConclusionDrifting subpulses are consistent with the RS-_type vacuum gap sparking model.

It is quite natural for bare strange stars, but _requires special conditions for neutron stars.





Question: Are quark stars in a solid state?

Answer: This possibility can not be rule out by the first principles; furthermore, competition evidence for solid QSsevidence for solid QSs may exist.

Please see Xu (2003, ApJ, L59; or, astro-ph/0302165) for details.

An experimental example: water and ice

Temperature-density diagram of pure water

E.U. FranckE.U. Franckin: The physics and chemistry of aqueous ionic solutions, p.337Edited by: M-C. Bellissent-Funel and G.W. Neilson, D. Reidel Publishing Company, 1987



Quark matter with high nB: Fermi gas?No! The interaction between quarks could cause Fermi-sea unable



Condensation: momentummomentum space space vs. positionposition space space

Space homogeneity: 2SC, CFL, LOFF state

Space inhomogeneity? e.g., lattice structure?

CSC after solidification?

No such ambiguous in electric superconductivity

n-quark clusters formed in SQMMulti-quark hadrons (e.g., pentaquark: {uudds}) decays by str. int.Decay of multi-quark clusters in QM is forbidden if B-W is correct



Depth of potential well between n-quark clusters should be

in order to solidify quark matter.

2 2 4 2 1/30 b( / ) , ~ [ /(3 )]V c l m c mc kT l n n

Xu: astro-ph/0202365, ApJL


Evidence for solid & bare QSs: featureless spec.


NASA News release (2002/4/10): RX J1856 a strange star?

Chandra



But we do observe lines: Atomic transition lines?

0.7keV 1.4keV

Sanwal et al: astro-ph/0206195


Xu et al: astro-ph/0207079Chandra


“Solid Quark Stars” http://vega.bac.pku.edu.cn/~rxxu R.X. Xu

Bignami et al.Nature, 423 (2003) 725

Cyclotron absorption: confirmed?

0.7、 1.4、 2.1

2.8?

XMM-Newton



Fit the spectr. by solid bare QS model: RX J1856

Zhang, Xu, Zhang (2003)

Results:T = 59.30.5 eV

R > 7.4 km

> 1.21018s -1

>10-20 s , ee~ 10-16 s

Chandra



Zhu WW (2003)

Results:~(1.55.9)1015s -

1

single T ~ 227eV

Fit the spectr. by solid bare QS model: 1E 1207

XMM-Newton



Efforts to understand the spectra in NS models


Turolla, Zane, & Drake 2003: condensation?1, to be consistant in thermodynamics? 2, can not fit

Ho & Lai 2003: vaccum polarization?A satisfactory fit of the data is still not possible.

Walter 2003: rapid rotating?Can RX J1856 become radio quiet (below deathline)?

How to calm down magnetospheric activity?e.g., AXP/SGR-like persistent and burst X-ray emission? radio pulsation?


Evidence: Glitches and free precession?


Discrepancy: vertex-pinning vs. free preces.Pinning in precession NSs is much weaker than that predicted by current glitch models

Link 2003: no coexistence of n-vortex and p-fluxSolid strange quark stars:

No difficuty with free precession of radio pulsarsGlitch due to global starquake

( ) (0) exp( )t t


Other astrophysical implications of solid QM

Asteroseismology: r-mode instability?

B-filed origin: ferromagnetism domain?

Cooling T: energy release when solidifying


ConclusionConclusion

Three issues are challenging the conventional neutron stars models:1, Drifting subpulses2, Thermal spectra of NSs3, Free precession of radio pulsars

They may be naturally understood

if NSs are actually solid bare SSs!“Quark Stars” http://vega.bac.pku.edu.cn/~rxxu R.X. Xu

and in the future ...Phenomenological study for solid quark matter

Ferromagnetic origin of pulsar strong field?

Yang & Luo (1983): Curie Tc ~ 100MeV

Tatsumi (2000): spontaneous mag. instab.

Cooling behavior of strange stars“Quark Stars” http://vega.bac.pku.edu.cn/~rxxu R.X. Xu

ConclusionConclusion

SUMMARYSUMMARYHistorical notesHistorical notes


Hadronic stability: Why Hadronic stability: Why strangestrange??



ConclusionConclusion“Quark Stars” http://vega.bac.pku.edu.cn/~rxxu R.X. Xu

谢谢各位！

quark stars renxin xu ( 徐仁新 ) school of physics, peking university talk presented at ccast...

Documents