Embed Size (px)
Citation preview
Fridolin Weber San Diego State University
San Diego, California USA
IAU Symposium 291 Neutron Stars and Pulsars: Challenges and OpportuniEes aFer 80 years
IAU General Assembly XXVIII — 20-‐31 August 2012, Beijing, China
Ø Strange Quark Stars versus “Neutron” Stars
Ø Explore Testable Predic<ons
q Rapid rotaEon
q Ultra-‐high electric fields
q OscillaEons of electron sea
q Meissner effect (vortex expulsion)
q Pycnonuclear reacEons
Ø Summary
F. Weber (SDSU, 2012)
I
Surface● Hydrogen/Helium plasma ● Iron nuclei
Outer Crust ● Ions● Electron gas
Inner Crust ● Heavy ions ● Relativistic electron gas● Superfluid neutrons
Outer Core ● Neutrons, protons● Electrons, muons
Inner Core● Neutrons● Superconducting protons ● Electrons, muons● Hyperons (Σ, Λ, Ξ)● Deltas (Δ)● Boson (π, K) condensates● Deconfined (u,d,s) quarks / color- superconducting quark matter
sun
Radii > 10 kmRadii < 10 km
Masses ~1 to 2 M
Outer Crust
Surface
Strange Quark Star Neutron Star
Core● Electrons ● u,d,s quarks
(color-superconducting)
Quark Stars* vs “Neutron” Stars
Ø Made enErely of deconfined
quarks and leptons
Ø Self-‐bound (M ~ R3)
Ø Baryon number O(1) < B < 1057
Ø Electron sea at surface
(super-‐high electric fields)
Ø May posses outer crusts
Ø No inner crusts
Ø Two-‐parameter stellar sequences
Ø May contain deconfined quark
maaer only in stellar core
Ø Bound by gravity
Ø 1056 to 1057
Ø Absent
Ø Outer crusts
Ø Inner crusts
Ø One-‐parameter stellar sequence
*E. Wiaen, Phys. Rev. D 30 (1984) 272; Alcock, Farhi, Olinto, ApJ 310 (1986) 261; Alcock & Olinto, Ann. Rev. Nucl. Part. Sci. 38 (1988) 161; Madsen, Lecture Notes Phys. 516 (1999) 162.
100 101 102 103 104 105
R (km)
10−3
10−2
10−1
100
101
M/M
sun
Neutronstars White
dwarfsunstable
configurationsequilibrium
1
2
3
voidof compactstars
Planets
Blackholes
Mass-‐radius relaEonship of neutron stars
d
a
b
a
a
b
b
b
d c
Mass-‐radius relaEonship of neutron stars and strange quark stars
RotaEon at Sub-‐Millisecond Periods
Strange quark stars
Observed masses and rotaEonal periods
Neutron stars
Kep
ler P
erio
d (m
sec)
Electrically Charged Quark Stars
T�µ = (P + ⇤)u�u
µ + P ��µ +
1
4⇥
✓FµlF�l +
1
4⇥��
µFklFkl
◆
Energy density of electric field is of same order as energy density of quark maaer!
R. Negreiros, FW, M. Malheiro, V. Usov, PRD 80 (2009) 083006
GravitaEonal mass Increases by up to 15%. Radius increases by up to 5%.
ideal fluid
Electron sphere may be differenEally rotaEng!
Electrically Charged Quark Stars (cont.)
Could explain observed magneEc fields of CCOs
R. Negreiros, I. Mishustin, S. Schramm, FW, PRD 82 (2010) 103010
I = �(⇥+ � ⇥�)
B = const E (�+ � ��)R
Electron sea may perform global (hydrodynamical cyclotron) oscillaEons
Frequency spectrum calculated by R. X. Xu et al.*
*R. X. Xu, Bastrukov, FW, Yu, Molodtsova, PRD 85 (2012) 023008
*G. F. Bignami, P. A. Caraveo, A. De Luca, & S. Mereghen, Nature 423 (2003) 725
AbsorpEon features in spectrum of 1E 1207.4-‐5209 at 0.7, 1.4 and 2.1 keV*
0.5 1.0 2.0
0.7 keV 1.4 keV
2.1 keV
Meissner Effect in Quark Stars made of CFL Quark Maaer
Vortex expulsion reheats the quark star
Cooling of CFL Quark Stars via Vortex Expulsion
SGRs/AXPs
Negreiros, Niebergal, Ouyed, FW, PRD 81 (2010) 043005
Negreiros, Niebergal, Ouyed, FW, PRD 81 (2010) 043005
Neutron stars
SGRs/AXPs
Pycnonuclear Reactions in the Crusts of Neutron Stars White dwarf
Neutron star crust
Pycnonuclear reactions
Neutron star
Pycnonuclear Reactions in the Crusts of Neutron Stars White dwarf
Neutron star
Strange quark matter nuggets embedded in the nuclear crust
Strange Quark Matter Nuggets
l Nu ~ Nd ~ Ns l A > Amin (~10 to 100) l Charge-to-baryon number ratio depends on whether SQM
is made of Ø “ordinary” quark matter, Z ≈ 0.1 (m150)
2 A, or
Ø color superconducting quark matter, Z ≈ 0.3 m150 A2/3
Farhi & Jaffe, PRD 30 (1984) 2379; Berger & Jaffe, PRC 35 (1987) 213; Alcock, Farhi, Olinto, ApJ 310 (1986) 261; Madsen, PRL 87 (2001) 172003
Madsen, PRL 87 (2001) 172003; Rajagopal & Wilczek, PRL 86 (2001) 3492; Oertel & Urban PRD 77 (2008) 074015
! !
!! "#$% "&%'()" #
&#*$&
*$*
*
#&##
*
% $& % &+ '' '(*#("( ')& ((&
!"#!$%&'()*
+"#,-,'(*.'#'/&*0,
1"#2&33#4526,*
7"#2&33#8,43.(9
:"#.4;,*3,#-,40(/#<&*&2,(,*
6)89#',4(,*,8#'56.'#=6''>#-&((.',
Gasques et al. PRC 72 (2005) 025806 Yakovlev et al. PRC 74 (2006) 035803
R = (lattice pairs) x TCoulomb barrier x S x E-1
B. Golf, J. Hellmers, F. Weber, PRC 80 (2009) 015804
Impact of quark maaer nuggets on pycnonuclear reacEon rates
q True ground state of the strong interacEon is not known
q Key differences between neutron stars and quark stars emerge
from the fact that quark stars are self-‐bound and possess
electron seas at their surfaces.
q Peculiar stellar properEes/phenomena to watch out for:
superfast rotaEon, unusually small objects (CCOs), unusually hot
objects (SGRs, AGRs), absorpEon features (XDIN, CCOs),
superbursts, driFing sub-‐pulses (R. X. Xu) , quark novae (R.
Ouyed), . . . ?
q Need more observed data (e.g. SkA, FAST)
