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Multiwavelength Spectroscopy of High Accretion Rate Polars

This study investigates the multiwavelength spectroscopy of high accretion rate polars, focusing on their magnetic field, accretion stream, and cyclotron cooling. It also explores issues for XMM/Chandra observations and the temperature and density structure of the accretion column. The study concludes with the need for further data and support for X-ray Doppler tomography.

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Multiwavelength Spectroscopy of High Accretion Rate Polars

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  1. Multiwavelength spectroscopy of high accretion rate polars Axel SchwopeAstrophysical 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 heatinghard 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/orlow 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 ~ 3ol~ 450 km h~ 0.015 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 2004Fischer & Beuermann 2001

  12. High accretion rate polars • Duty cycle ~ 50% (cf. Ramsay et al 2004) • The XMM-Newton conspiracyNONE of the ‚classical‘ bright polars was observed in a high accretion state • XMM triggers (V834 Cen AO5, VV Pup AO6)

  13. Patterson et al 1984 Schwope et al 1995 VV Pup – the soft X-ray machine 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 PupSMARTS optical monitoring

  16. Simultaneous optical-UV-Xobservation 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 phaseX-ray spectrum bbody (30eV)+mekal(12keV)need warm absorberdon‘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 EINSTEIN EUVE RGS FUSE EPIC ROSAT ROSAT & EUVE agree, EINSTEIN high Lx ruled out by FUSEBoth 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

  30. Spectral energy distribution: 2XMMp1312+1736Vogel+08, astroph 0804.3946

  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)

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