1. Multiwavelength spectroscopy of high accretion rate polars
Axel Schwope Astrophysical Institute Potsdam
Justus Vogel, Robert Schwarz (AIP)
Fred Walter (SUNY)
Vadim Burwitz (MPE)
Klaus Reinsch (Göttingen)

2. Polars – magnetic CVs main sequence secondary magnetic white dwarf
accretion stream/curtain
magnetic field (10 – 200 MG)
synchronous rotation
no disk
cyclotron cooling
~80 systems known
High/low states

3. Accretion scenarios
3) particle heating hard X-ray supressed (low mass flow rate plus high B field) 1 2
Standard – stationary soft and hard X-rays balanced
Filamentary – instationary
soft X-ray excess (high mass flow rate and/or low magnetic field)

4. Issues for XMM/Chandra
Temperature and density structure of accretion column (if there is one)  X-ray line diagnostic

5. Line diagnostics in AM Her (Girish et al 2007)

6. Issues for XMM/Chandra
Temperature and density structure of accretion column (if there is one)  X-ray line diagnostic
Structure of accretion regions  eclipsing systems

7. HU Aqr: fit to X-ray and UV-light curves (Schwope+01)
Eclipse resolved
Q ~ 3o l ~ 450 km
h ~ Rwd ~ 120 km

8. XMM-Newton observation of HU Aqr (May 17, 2002)
Schwope et al 2004, ASP

9. HU Aqr: Simultaneous observations XMM & VLT(ULTRACAM) 16.5.2005
VLT-UT3 (ULTRACAM g)
XMM EPIC pn
Schwarz et al 2008, A&A

10. Issues for XMM/Chandra
Temperature and density structure of accretion column (if there is one)  X-ray line diagnostic
Extent of emission region  eclipsing systems
Heating and cooling as a function of mass accretion rate  SED of bright systems

11. SEDs – hydro and particle picture
Shock heating
Specific mass flow rate (B, Mwd, geometry, ...)
Particle heating
Beuermann 2004 Fischer & Beuermann 2001

12. High accretion rate polars
Duty cycle ~ 50% (cf. Ramsay et al 2004)
The XMM-Newton conspiracy NONE of the ‚classical‘ bright polars was observed in a high accretion state
XMM triggers (V834 Cen AO5, VV Pup AO6)

13. VV Pup – the soft X-ray machine
Schwope et al 1995
Patterson et al 1984
Porb = 100 min
Two-pole geometry
soft main pole
less soft secondary pole
spectral evolution through bright phase (shoulder)

14. VV Pup – the soft X-ray machine?
MSSL polar survey
Weak instationary accretion
Thermal plasma ~4keV
(Pandel et al 2005)

15. VV Pup SMARTS optical monitoring

16. Simultaneous optical-UV-X observation of VV Pup Oct 20, 2007

17. VV Pup – multi-epoch optical and X-ray light curves

18. SED – low state . HST (Araujo-Betancor+05) XMM/OM (Pandel+05)
VLT (Mason+07) .

19. High state, main pole: cyclotron = (bright – faint)
kTcyc ~ 10 keV
Fcyc ~ 2e-11 cgs

20. High state, bright phase X-ray spectrum
bbody (30eV)+mekal(12keV) need warm absorber don‘t need abs, reflect (?)

21. VV Pup – high & low state high-energy SED
Main pole
XMM: kT ~ 12 keV, 4e-12 cgs
ROSAT/EUVE: ~ 8e-12 cgs
Second pole
XMM: kT ~ 4 keV, 4e-13 cgs
ROSAT/EUVE: ~ 2e-13 cgs
Low state
XMM: kT ~ 4 keV, 5e-14 cgs
ROSAT/EUVE: ---

22. VV Pup – high state SED
FUSE
EUVE
ROSAT
EPIC
RGS
EINSTEIN
ROSAT & EUVE agree, EINSTEIN high Lx ruled out by FUSE Both poles in ROSAT brighter than in XMM epoch

23. VV Pup results Spectra (!) for low states and faint phases
T evolution: Shock vs particle heating
High state SED always dominated by soft X-rays at both poles  additonal blob heating
Low state: No soft component observed

24. V834 Cen – multispectral data Jan 31, 2007

25. V834 Cen viewing geometry and multispectral light curves

26. V834 Cen – non-dip spectrum
wabs*absori (bbody(25eV) + mekal_cool(<1keV) + mekal_hot(12keV)) need reflection

27. V834 Cen – SED
kT (cyc)~ 10 keV
Fcyc ~ 1e-11 cgs

28. V834 Cen – SED through high and low states

29. SED results Pole B (MG) F-bol cgs Fsoft / (Ftp + Fcyc) cgs 100%
V834 Cen low state 22
2e-10 >5e-14
/ ? /
VV P1 X R 31
5e-10 3e-10
/ /
VV P2 X R 56
<e-11 2e-12
< / /
VV low
~5e-13
? /

30. Spectral energy distribution: 2XMMp1312+1736 Vogel+08, astroph 0804

31. Conclusions and outlook
SED fitting: relevance of multi-spectral data
Evolution of spectral parameters for given pole
Evolution of channels of energy release as a function of mass flow rate, B, Mwd and ?
Further insight from phase-resolved X-ray spectral analysis
And yes, we need more data and we do support XEUS (X-ray Doppler tomography)