Clumped stellar winds in supergiant HMXBs

ArXiv: 1201.1951v1Oskinova et. al.

Reporter: Zhang Zhen2012.3.13

Outlines

• Introduction

• The CAK model

• Bondi-Hoyle-Lyttleton accretion

• Simulations and paradox

• Modification and results

• Conclusion

Introduction

• Theories about clumpy wind• CAK: line scattering

2500km/s

• Owocki et al. 1988: numerical simulation

Small-amplitude perturbation Highly structured wind

• Runacres & Owocki 2002

Evolution of wind structures Inhomogeneous

7 110 sunM M yr

Introduction

• Observations about clumpy wind

• Prinja & Massa (2010)

Introduction• Clumpy wind in supergiant HMXBs

• van der Meer et al. (2005): 4U1700-37

• SFXT

• Furst et al. (2010): Vela X-1

Purpose

• Bridge the gap between detailed models of inhomogeneous stellar winds in single stars and the phenomenological description of donor winds in supergiant high-mass X-ray binaries (HMXBs).

CAK model

CAK

• Main idea: scattering of line radiation

• Basic equations for the stellar envelope • Mass conservation:• Momentum balance:

• Equation of state

2 2

1[1 ( )]

4ge

dpLdv Gmv M tdr r r c dr

24 tandm

r v cons tdt

About

• Castor, 1974, MNRAS, 169, 279

( )erad

Ff M t

c

( )M t

( )M t kt

CAK result

(1 )/ 1/ 1/ (1 )/4(1 ) (1 )

e th

dm Gmk

dt v

Results

• For a class O5 6

11

60

9.66 10

0.4449290

9.585 10 13.8

sun

sun

e

eff

sun

m m

L L

L

GmcT K

R cm R

20 14.16 10dm

gsdt

1 1

4 3mst dm

m dt

Bondi accretion

BHL accretion

• Reviewed by

Edgar (2004) & Negueruela (2009)

• Bondi radius:

• Accretion rate 24 acc wM r v

Simulations and paradox

HYDRODYNAMICAL SIMULATIONS

• Feldmeier et al. (1997a,b): hydrodynamical simulations of the line driven stellar wind

L_x: a change up to eight orders of magnitude

Modification and results

Background

• Microclumping: optically thin

Leads to smaller mass-loss rate Hillier 1991; Hamann & Koesterke 1998 Bouret e

t al. (2005) and Fullerton et al. (2006)

• Modification:

Photo-ionization

Absorption

Photo-ionization

• Neglecting absorption, the mean primary photon intensity at frequency v at a distance r:

•

• Photo-ionization parameter:

Absorption

Calculation

• 2_D stochastic wind model: Oskinova et al. (2004) Feldmeier et al. (1997a,b) + Absorption

• Notation: 1. spherically symmetric 2. solid angle 3. “balls” & “pancakes” 4. no self-absorption & no re-emission. 5. edge on system

Results

Thanks