Novae: X-ray observations as a test of mass loss and evolution (constraining… or complicating the parameters space?) Marina Orio INAF-Padova (Italy) and U Wisconsin (USA)

1.Novae in outburst (recent work with A. Bianchini, T. Nelson, G.Anzolin, F. Tamburini, & previous work with with many others) Phase 1: shell emission, shocks L(x) ≤ erg/s, usually ≤ erg/s (grating spectra only for RS Oph). Phase 2: the WD as a luminous SSS. Only 8 novae monitored, 4(+1) grating spectra. Phase 3: residual SSS emission lines, sometimes harder emission (V351 Pup, GK Per). L(X)~ erg/s.

Two weeks after outburst: rich emission line spectrum; resonance lines of He-l like and H-like ions of Fe, S, Si, Mg and Ne. Wide range of plasma temperatures: coolest transition O VIII Lyman alpha doublet at A (emissivity peak at T=3MK; but also N VII in RGS ), hottest is Fe XXV 1s2p-1s2 resonance line (emissivity peak at T=60MK). Lines are blue shifted with velocity inversely dependent on ionization state! FWHM ~ km/s, except Fe XII 3540 km/s. RS Oph in February: The wind

Collisional ionization or photoionization? From (f+i)/r ~1 we infer a collisionally ionized plasma Are there shocks within the ejecta? Is it all due to collision with RG wind? => Implicatiosn for SNe Ia theories..

Ways to test the theories of accreting and nuclear Burning, e.g. correlation T eff vs. t turn off

In this region flux goes to zero if C>=0.01 C(sol) in model atmospheres because of CVI 25.3 AA CNO cycle: most of C(12) is transformed into N(14) We are observing material processed BEFORE the outburst => it was not ejected => The WD mass is growing V4743 Sgr RS Oph

No wonder novae appear luminous also in X-rays ! The most surprising fact is the rapid variability of the SSS, on different time scales. PERIODIC & APERIODIC. Minutes: ~35 s for RS Oph (erratic period during SSS phase, stabilizing to Low end of values as mass loss ceases. N Cyg 1992 ~Half hour oscillations. WD spin + non-radial g-mode pulsations? (V1494 Aql, V4743 Sgr). Obscurations and flares.

A variety of SSS light curves:

RS Oph at onset of supersoft phase 35 s P appears New mass ejection episode: related to jets? Correlation with WD rotation? Rapid spin period predicted.

Prolonged ejection of mass in a jet?

V4743 Sgr P(orb)=6.7 hrs observed for longer with XMM: never repeated

Possible explanations: Not related with the orbital period or WD spin period. Keep in mind V4743 Sgr is a polar (6.7 hours, 22 min. spin?). Flame did not propagate? (Unlikely) Was it a clump? Size has to be comparable to WD size (very large clumps possible). Mass ~ m o. Why does the clump appear only after 6 months and then disappears? New shell ejection seems only explanation in his case. Or should we think of a triple system instead?

V1494 Aql (Chandra LETG) P=3.23 hours

V5116 Sgr: XMM+ Chandra LETG

N VII OVIII N VII 5 times RGS Twice (LETG)

Constraints set by fast rise and “stunted” high state Rise always in ~200 s High states repeated every “putative”obital period of 2.9 hours Flickering in low state, “stunted behaviour” in high state One missed high state Constant T(eff) with possible mild increase of N(H) but lower luminosity when it is “low” Can it be a warped disk? Not consistent with rise! No eclipses observed Overall shape similar to polars (VV Pup) Flame not propagated? (Unlikely)

Large polar cap with “spongy” atmosphere” in a polar system. “Craters” form on atmophere in area where accretion stream touches surface (UV emitting surf.)

Cartoon model for V5116 Sgr (2) Predicted to be a polar.

2. X-ray observations of novae at quiescence : ongoing and recent projects RS Oph returned to quiescence: emission lines: Ne IX, O VIII, O VII and N VII. Ongoing wind. V4743 Sgr returned to quiescence: very soft for a polar, composite spectrum. EY Cyg: a dwarf nova with nova signatures, well studied in UV. CP Pup (with Mukai, Bianchini, di Martino,Howell) V603 Aql (Mukai & Orio 2003)

Why we want to observe post- outburst novae: X-rays are a probe of accretion => direct way to study evolution Shocked accreted material has T~M(WD) (results with cooling flow model) Mdot parameter in models - can also be compared with results inferred in UV Studying novae with known outburst properties we test the theoretical predictions

EY Cyg

V603 Aql (Mukai & Orio 2005) Non magnetic Low mdot 8.00 × m O yr -1

CP Pup Mdot <1.6 x m o /yr Consistent with very luminous moderately fast nova T max >60 K  Massive WD Magnetic?