Spectroscopy of the Stellar Wind in the Cygnus X-1 System

Introduction Cygnus X-1 Data and data analysis Light Curves and Dipping Absorption lines Summary

Spectroscopy of the stellar wind in the Cygnus X-1 system

Ivica Miˇskoviˇcov´a⋆, Manfred Hanke⋆ J. Wilms⋆, M. A. Nowak, K. Pottschmidt, N. S. Schulz

⋆ Dr. Remeis Observatory, Bamberg Erlangen Centre for Astroparticle Physics University Erlangen-Nuremberg, Germany

Black Hole Universe

September 22, 2010

Ivica Miˇskoviˇcov´a:Spectroscopy of the stellar wind in the Cyg X-1 Introduction Cygnus X-1 Data and data analysis Light Curves and Dipping Absorption lines Summary

Outline of the talk

1 Introduction Accretion in X-ray Binaries Stellar wind 2 Cygnus X-1 Cygnus X-1 and its companion HDE 226868 Stellar wind in the Cygnus X-1 Source states Chandra observations 3 Data and data analysis Instruments ObsID 3815, φ ≈ 0.76 4 Light Curves and Dipping Light curves 5 Absorption lines 6 Summary

Ivica Miˇskoviˇcov´a:Spectroscopy of the stellar wind in the Cyg X-1 Introduction Cygnus X-1 Data and data analysis Light Curves and Dipping Absorption lines Summary

Accretion in X-ray Binaries

stellar wind accretion in High Mass X-ray Binaries (HMXB) accretion disk accretion in Low Mass X-ray Binaries (LMXB) eﬃcient energy release, X-ray luminosities ∼ 1038 erg/s

Ivica Miˇskoviˇcov´a:Spectroscopy of the stellar wind in the Cyg X-1 Introduction Cygnus X-1 Data and data analysis Light Curves and Dipping Absorption lines Summary

Stellar wind of HMXBs

hot, O or early B stars: winds driven by absorption lines −6 very strong: mass loss rate ∼ 10 M⊙/year

Theory: two components of the wind: cool dense clumps embedded by hot photoionized gas (Castor, Abbot, Klein, 1975; Sako et al. 2002)

Ivica Miˇskoviˇcov´a:Spectroscopy of the stellar wind in the Cyg X-1 Introduction Cygnus X-1 Data and data analysis Light Curves and Dipping Absorption lines Summary

Stellar wind of HMXBs

hot, O or early B stars: winds driven by absorption lines −6 very strong: mass loss rate ∼ 10 M⊙/year

Theory: two components of the wind: cool dense clumps embedded by hot photoionized gas (Castor, Abbot, Klein, 1975; Sako et al. 2002)

wind structure can be probed directly by Chandra high-resolution spectroscopy (with bright sources like Cyg X-1)

Ivica Miˇskoviˇcov´a:Spectroscopy of the stellar wind in the Cyg X-1 Introduction Cygnus X-1 Data and data analysis Light Curves and Dipping Absorption lines Summary

The high-mass X-ray binary system Cygnus X-1

HDE 226868 O9.7 Iab supergiant M⋆ = 18 M⊙ L⋆ = 250 000 L⊙

black hole

LX ≈ 10 000 L⊙

Ivica Miˇskoviˇcov´a:Spectroscopy of the stellar wind in the Cyg X-1 Introduction Cygnus X-1 Data and data analysis Light Curves and Dipping Absorption lines Summary

Focused stellar wind in the system

0.2 0.3 0.4 0.1 0.7 0.5 0.0 0.8 0.6 Friend & Castor (1982) 0.9 0.5 1.0

phi = / yr sr] "focused

sun wind" M −6 [10 Ω

Cyg HDE 226868 X−1 0 0.2 0.4 0.6

mass loss rate dM/dt/d 0 50 100 150 (M.Hanke,2009) angle θ from binary axis [degrees]

Ivica Miˇskoviˇcov´a:Spectroscopy of the stellar wind in the Cyg X-1 Introduction Cygnus X-1 Data and data analysis Light Curves and Dipping Absorption lines Summary

Hard and Soft State of the Cygnus X-1 hard or soft 20 50

101997 100 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 RXTE−ASM 1.5−12 keV rate [cps] In the low/hard state: hard powerlaw spectrum, low soft X-ray luminosity, high radio ﬂux In the high/soft state: thermal spectral component high soft X-ray luminosity, low radio emission.

Ivica Miˇskoviˇcov´a:Spectroscopy of the stellar wind in the Cyg X-1 Introduction Cygnus X-1 Data and data analysis Light Curves and Dipping Absorption lines Summary

Chandra observations of Cygnus X-1

◦ hard → soft state —TEmode, ··· CC mode i ≈ 35

Ivica Miˇskoviˇcov´a:Spectroscopy of the stellar wind in the Cyg X-1 Introduction Cygnus X-1 Data and data analysis Light Curves and Dipping Absorption lines Summary

Goals and aims of the research

We focus on High Mass X-ray Binaries, especially Cyg X-1 strong and focused stellar wind and its properties source states transitions understanding of the accretion process by detailed study of photoionization of material (high X-ray luminosity) spectral analysis of absorption lines

Ivica Miˇskoviˇcov´a:Spectroscopy of the stellar wind in the Cyg X-1 Introduction Cygnus X-1 Data and data analysis Light Curves and Dipping Absorption lines Summary

Chandra High Energy Transmission Grating (HETG)

two sets of gratings: the High and the Medium Energy Grating (HEG and MEG)

Grating equation: m.λ = p.sinβ

Ivica Miˇskoviˇcov´a:Spectroscopy of the stellar wind in the Cyg X-1 Introduction Cygnus X-1 Data and data analysis Light Curves and Dipping Absorption lines Summary

Data reduction with CIAO 4.2 and order-sorting problem

Ivica Miˇskoviˇcov´a:Spectroscopy of the stellar wind in the Cyg X-1 Introduction Cygnus X-1 Data and data analysis Light Curves and Dipping Absorption lines Summary

Data reduction with CIAO 4.2 and order-sorting problem

Ivica Miˇskoviˇcov´a:Spectroscopy of the stellar wind in the Cyg X-1 Introduction Cygnus X-1 Data and data analysis Light Curves and Dipping Absorption lines Summary

Data reduction with CIAO 4.2 and order-sorting problem

Solution: tg resolve events ⇒ osipﬁle=”none”, osip lo and osip hi

Ivica Miˇskoviˇcov´a:Spectroscopy of the stellar wind in the Cyg X-1 Introduction Cygnus X-1 Data and data analysis Light Curves and Dipping Absorption lines Summary

ObsID 3815 - light curve

Orbital phase of the Cyg X−1

0.7 0.72 0.74 0.76 0.78 0.8 0.82 Count rate [cps] 50 100 150 200 0.4 0.6 0.8 (0.5−1.5)/(1.5−3) 1 2 (0.5−1.5)/(3−10) 1 2 3 (1.5−3)/(3−10) 0 10 20 30 40 50 60 Time since MJD 52702.658 [ks]

Ivica Miˇskoviˇcov´a:Spectroscopy of the stellar wind in the Cyg X-1 Introduction Cygnus X-1 Data and data analysis Light Curves and Dipping Absorption lines Summary

Telemetry saturation

Fractional exposure CCD 4 0 0.5 1 CCD 5 0 0.5 1 CCD 6 0 0.5 1 CCD 7 0 0.5 1 CCD 8 0 0.5 1 CCD 9 0 0.5 1 0 10 20 30 40 50 Time since MJD 52702.665 [ks]

Ivica Miˇskoviˇcov´a:Spectroscopy of the stellar wind in the Cyg X-1 Introduction Cygnus X-1 Data and data analysis Light Curves and Dipping Absorption lines Summary

ObsID 3815 - corrected light curve

Orbital phase of the Cyg X−1

0.7 0.72 0.74 0.76 0.78 0.8 0.82 Count rate [cps] 50 100 150 200 0.4 0.6 0.8 (0.5−1.5)/(1.5−3) 1 2 (0.5−1.5)/(3−10) 1 2 3 (1.5−3)/(3−10) 0 10 20 30 40 50 60 Time since MJD 52702.658 [ks]

Ivica Miˇskoviˇcov´a:Spectroscopy of the stellar wind in the Cyg X-1 Introduction Cygnus X-1 Data and data analysis Light Curves and Dipping Absorption lines Summary

ObsID 3815 - corrected light curve

Orbital phase of the Cyg X−1

0.7 0.72 0.74 0.76 0.78 0.8 0.82 Count rate [cps] 50 100 150 200 0.4 0.6 0.8 (0.5−1.5)/(1.5−3) 1 2 (0.5−1.5)/(3−10) 1 2 3 (1.5−3)/(3−10) 0 10 20 30 40 50 60 Time since MJD 52702.665 [ks]

Ivica Miˇskoviˇcov´a:Spectroscopy of the stellar wind in the Cyg X-1 Introduction Cygnus X-1 Data and data analysis Light Curves and Dipping Absorption lines Summary

Compared Chandra observations of Cygnus X-1

Ivica Miˇskoviˇcov´a:Spectroscopy of the stellar wind in the Cyg X-1 Introduction Cygnus X-1 Data and data analysis Light Curves and Dipping Absorption lines Summary

Light curves of Cyg X-1 at prominent phases

500 500 ObsID 3814 ObsID 8525 ObsID 9847 ObsID 11044 200 2003-04-19/20 2008-04-18/19 2008-04-19 2010-01-14 200

100 100

50 50

20 ObsID 3815 20 2003-03-04/05

0.5–10 keV count rate (c/s) 10 10 8 8 58 ks 48 ks 30 ks 19 ks 30 ks 4 4

2 2

1 1

0.5 0.5 0.3 0.3 (0.5–3 keV) / (3–100.2 keV) 0.2 0.7 0.75 0.8 -0.05 0 0.05 0.2 0.5 0.55 Orbital phase φ (At φ=0, Cyg X-1 is only seen through the densest part of the donor’s stellar wind.)

φ≈0: violent absorption dips dipping occurs already at φ≈0.7 and has not ceased at φ≈0.2 φ≈0.5: totally free of dips!

Ivica Miˇskoviˇcov´a:Spectroscopy of the stellar wind in the Cyg X-1 Introduction Cygnus X-1 Data and data analysis Light Curves and Dipping Absorption lines Summary

ObsID 3815 - Color-color diagram

Orbital phase of the Cyg X−1 0.7 0.72 0.74 0.76 0.78 0.8 0.82 0.5 1 1.5 2 (0.5−1.5)/(3−10) Ratio (1.5−3 keV)/(3−10 keV) 1 1.5 2 2.5 3

0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 Ratio (0.5−1.5 keV)/(1.5−3 keV)

Ivica Miˇskoviˇcov´a:Spectroscopy of the stellar wind in the Cyg X-1 Introduction Cygnus X-1 Data and data analysis Light Curves and Dipping Absorption lines Summary

Color-color diagrams - comparison

3.5 ObsID 3815 ObsID 11044 3

2.5

1.5

0.5 2

1.5 ObsID 3814 1 ObsID 8525 ObsID 9847

0.5

0 “Hard” (1.5–3 keV rate) / (3–10 keV rate)0 Softness Ratio 0.2 0.4 0.6 0.8 0 0.2 0.4 0.6 0.8 “Soft” (0.5–1.5 keV rate) / (1.5–3 keV rate) Softness Ratio

Ivica Miˇskoviˇcov´a:Spectroscopy of the stellar wind in the Cyg X-1 Introduction Cygnus X-1 Data and data analysis Light Curves and Dipping Absorption lines Summary

Absorption lines

Spectrum absorption lines χ −5 0 5

2 4 6 8 10 12 14 Wavelength [Å]

Ivica Miˇskoviˇcov´a:Spectroscopy of the stellar wind in the Cyg X-1 Introduction Cygnus X-1 Data and data analysis Light Curves and Dipping Absorption lines Summary

Absorption and P Cygni proﬁles of Si xiv, Mg xii, Ne x

Wavelength [A]˚ Wavelength [A]˚ Wavelength [A]˚ 6.14 6.16 6.18 6.2 6.22 8.4 8.45 12.05 12.1 12.15 12.2 2.2 2 3 2 1.8 1.8 2.5 1.6 1.6 2 1.4 1.4 1.5 1.2 1.2 1 1 1

Data /0.8 Model (Continuum) + oﬀset -2000 -1000 0 1000 2000 -2000 -1000 0 1000 2000 -2000 -1000 0 1000 2000 Velocity (Si xiv α) [km/s] Velocity (Mg xii α) [km/s] Velocity (Ne x α) [km/s]

φ≈0: strong absorption lines, vrad≈0 φ≈0.5: P Cygni proﬁles: strong emission at vrad≈0 and weak absorption tail blueshifted by ∼ 500 − 1 000 km/s ⇒ if the same plasma is observed in both cases ⇒ the real velocity has to be small ⇒ we see a dense wind close to the stellar surface φ≈0.7: absorption lines, but redshifted by ∼ 200 − 300km/s

Ivica Miˇskoviˇcov´a:Spectroscopy of the stellar wind in the Cyg X-1 Introduction Cygnus X-1 Data and data analysis Light Curves and Dipping Absorption lines Summary

Si absorption lines Energy [keV] 2 1.9 1.8 1.7

Si XIV Si XIII Si XIISi XI Si XSi IXSi VIIISi VII ε δ γ /Å] 2 Mg XIIAl XIIIMg XI Mg XI Mg XI 0.1 0.2 0.5 Chandra−HETGS Flux [photons/s/cm

6.2 6.4 6.6 6.8 7 7.2 7.4 Wavelength [Å] non-dip spectrum: Si xiv and Si xiii dip spectrum: additional absorption lines of Si xii-vii

Ivica Miˇskoviˇcov´a:Spectroscopy of the stellar wind in the Cyg X-1 Introduction Cygnus X-1 Data and data analysis Light Curves and Dipping Absorption lines Summary

Si absorption lines Energy [keV] 2 1.9 1.8 1.7 theoretical ← Si Kα lines /Å]

2 discrepancy → XIII XII XI X IX VIII VII II−VI (House, 1969)

Si XVI Si XIII

Mg AlXII XIII ×3 ×1.5

Mg XI 0.02 0.05 0.2 0.5 (Pileup−corrected) Chandra−HETGS Flux [photons/s/cm

0.016.5 0.1 7 7.5 Wavelength [Å] Ivica Miˇskoviˇcov´a:Spectroscopy of the stellar wind in the Cyg X-1 Introduction Cygnus X-1 Data and data analysis Light Curves and Dipping Absorption lines Summary

Summary

Comparison of φ≈0, φ≈0.2, φ≈0.5, φ≈0.7 Strong absorption dips around φ≈0, while NO dips at φ≈0.5 P Cygni proﬁles observed for the ﬁrst time in Cyg X-1! at φ≈0.5 in contrast to strong pure absorption at φ≈0⇒ environment close to stellar surface Si absorption lines of lower ionization stages present only in dip spectra⇒ inhomogeneities of lower temperature in the wind

Outlook Photoionization modeling Wind structure modeling

Ivica Miˇskoviˇcov´a:Spectroscopy of the stellar wind in the Cyg X-1 The high-mass X-ray binary HDE 226868/Cygnus X-1

HDE 226868 parameters: O9.7 Iab supergiant Binary system parameters:

M⋆ = 18 M⊙ orbital period P = 5.6 d Teﬀ = 32 000 K distance d ≈ 2.5 kpc

L⋆ = 250 000 L⊙ binary separation a = 41 R⊙ R⋆ ≈ 17 R⊙ v sin i = 76 km/s Cyg X-1 parameters: ﬁlls ≈90 % of Roche lobe MBH = 10 M⊙ volume LX ≈ 10 000 L⊙ −6 M˙ ⋆ = 3×10 M⊙/yr

Ivica Miˇskoviˇcov´a:Spectroscopy of the stellar wind in the Cyg X-1 Advanced CCD Imaging Spectrometer (ACIS) focal plane ACIS FLIGHT FOCAL PLANE

~22 pixels ~11" not constant with Z

I0 I1 w203c4r w193c2 0 1 ACIS-I 22 pixels x (aimpoint on I3 = (949, 978)) = 11" I2 I3 } w158c4r w215c2r 2 3 330 pixels = 163"

S0 S1 S2 S3 S4 S5 + w168c4r w140c4r w182c4r w134c4r w457c4 w201c3r ACIS-S 4 5 6 7 8 9 } (aimpoint on S3 = (235, 497))

∆ + Y Target 18 pixels = 8".8 +Z +Z Offset Coordinates BI chip indicator Top

column Pointing one two three + ∆ Z

node zero row Coordinates Image Region Bottom . . -Z Pixel (0,0) +Y Sim Motion Frame Store Coordinate CCD Key Node Row/Column Definitions Definition Orientations

Ivica Miˇskoviˇcov´a:Spectroscopy of the stellar wind in the Cyg X-1