Superdense stars containing strange quark matterYu.L.Vartanyan, A. R. Harutyunyan

Yerevan State University

Strange quark matterIn pioneer work of V.A.Ambartsumian and G.S. Sahakian [1] it has been

shown that degenerated nuclear plasma may contain, besides neutrons, protons and electrons, also strange baryons – hyperons. In [2] G.S. Sahakian and Yu.L.Vartanian for the first time have shown that taking into account the interaction between baryons makes possible the existence of hyperons in the central regions of stable neutron stars.

A new interest towards strange nuclear plasma has arisen when Witten [3] supposed, that quark-electron plasma with a strangeness -1 per baryon may be absolutely stable state of cold superdense matter.

V.A.Ambartsumian, G.S. Sahakian, Sov.Astron.Zh., 37, 193,1960.G.S.Sahakian, Yu.L.Vartanian, Nuovo Cimento, 30, 82, 1963; Sov.Astron.Zh., 41, 193, 1964.E.Witten, Phys.Rev. D30, 272, 1984.

Strange Stars

Yu.L.Vartanyan, A.R.Arutyunyan, A.K.Grigoryan, Astrofizika, 37, 499,1994

(Astrophysics, 37, 271, 1994);

Yu.L.Vartanyan, A.R.Arutyunyan, A.K.Grigoryan,

Astronomy Letters, 21, 122, 1995.

EoS for Strange Stars

n (fm-3)

E (MeV)

-50

-30

-10

10

30

50

70

90

0 0.2 0.4 0.6 0.8

1.4

1.1

Radius-central density (SS)

0

5

10

15

0 2 4 6 8 10

1.1

7

R (km)

0/c

Mass-radius relationship (SS)

0

0.5

1

1.5

2

2.5

0 5 10 15

R (km)

M / MŸ

1.1

7

Total energy density-distance from star center: 1. M=0.5Msun, 2. M=1.44Msun, 3. M=1.86Msun

MM 5.0

0

2

4

6

8

10

0 3 6 9 12

r (km)

0/

EoS for Neutron Stars with a Strange Quark Core

2 4 6 8 10 12 14

950

975

1000

QM

NM

1/nQ 1/nN

E, Ì

ýÂ

1 / n , Ôì 3

Neutron Stars with a Strange Quark Core

Yu.L.Vartanian, A.R.Harutyunian, G.B.Alaverdyan, in the Plenary Lectures and Contributed Papers, GR 15, Pune, India, December 16-21, 1997, p.159; G.B.Alaverdyan, A.R.Harutyunyan, Yu.L.Vartanyan, Spacetime and Substance, 2, 3(8), 129, 2000; G.B.Alaverdyan, A.R.Harutyunyan, Yu.L.Vartanyan, Astrophysics, 44, 265, 2001;G.B.Alaverdyan, A.R.Arutyunyan, Yu.L.Vartanyan, Astronomy Letters, 28,24, 2002; A.R.Harutyunyan, Astrophysics, 45, 248, 2002; G.B.Alaverdyan, A.R.Harutyunyan, Yu.L.Vartanyan, Astrofizika, 46, 445, 2003.

First-order phase transition

0 2 4 6 8 10

940

960

980

1000

1020

1040

3

2

1

h

gf e

d cb

a

,

МэВ

1/n, Фм3

EoS for NS with a quark core

1014 10150.1

1

10

100

P

, М

эВ/Ф

м3

, г/см3

3a 3b 3c 3d

1 10 1000.0

0.5

1.0

1.5

2.0

2.5

f

Mp

M0

M

M /

M o

Pc , МэВ / Фм3

0.5 1.0 1.5 2.0 2.50.070

0.075

0.080

e

d

c

ba

0.7 0.8 0.9 1.0 1.1 1.2

0.0795

0.080

c

b

a

100

101

102

103

104

106

108

1010

1012

1014

Aen Ae

Конфигурация d

Rnd

=13.24 км

nd=4.3 1011

г / см3

Q

Rcore=1.73 км

,

г

/ см3

r , км

10 100 1000

0.1

1

a

f

e dc

b

M /

M

R , км

0 200 400 600 800 1000 1200 14000.06

0.07

0.08

0.09

0.10

a

e

d

c

b

M /

M

R , êì

1 10 100

10-2

10-1

100

101

102

103

104

Rnd

RNS

Rcore

R, R

nd,

R

core , km

Pc , MeV/fm3

1 10 10010-2

10-1

100

101

102

103

104

105

êì2

I , M

Pc , Ì ýÂ/Ôì

3

1,44

G

F

E

D

C

B

A

M/M

Pc