Multiwavelength spectroscopy of high accretion rate polars

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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)

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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

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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)
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Issues for XMM/Chandra

• Temperature and density structure of accretion
  column (if there is one) ? X-ray line
  diagnostic

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Line diagnostics in AM Her(Girish et al 2007)
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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

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HU Aqr fit to X-ray and UV-light curves
(Schwope01)
Eclipse resolved
Q 3o l 450 km h 0.015 Rwd 120 km
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XMM-Newton observation of HU Aqr (May 17, 2002)
Schwope et al 2004, ASP
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HU Aqr Simultaneous observations XMM
VLT(ULTRACAM) 16.5.2005

• VLT-UT3(ULTRACAM g)
• XMM EPIC pn

Schwarz et al 2008, AA
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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

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

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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)

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VV Pup the soft X-ray machine?

• MSSL polar survey
• Weak instationary accretion
• Thermal plasma 4keV
• (Pandel et al 2005)

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VV PupSMARTS optical monitoring
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Simultaneous optical-UV-Xobservation of VV Pup
Oct 20, 2007
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VV Pup multi-epoch optical and X-ray light
curves
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SED low state
HST (Araujo-Betancor05) XMM/OM (Pandel05) VLT
(Mason07)
.
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High state, main pole cyclotron (bright
faint)

• kTcyc 10 keV
• Fcyc 2e-11 cgs

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High state, bright phaseX-ray spectrum
bbody (30eV)mekal(12keV)need warm
absorberdont need abs, reflect (?)
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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 ---

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VV Pup high state SED
ROSAT EUVE agree, EINSTEIN high Lx ruled out by
FUSEBoth poles in ROSAT brighter than in XMM
epoch
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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

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V834 Cen multispectral data Jan 31, 2007
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V834 Cen viewing geometry and multispectral
light curves
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V834 Cen non-dip spectrum
wabsabsori (bbody(25eV) mekal_cool(lt1keV)
mekal_hot(12keV))need reflection
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V834 Cen SED
kT (cyc) 10 keV Fcyc 1e-11 cgs
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V834 Cen SED through high and low states
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SED results
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Spectral energy distribution 2XMMp13121736Vogel
08, astroph 0804.3946
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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)