Novae: X-ray observations as a test of mass loss and

evolution(constraining… or complicating the

parameters space?)

Marina OrioINAF-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)≤1036 erg/s, usually ≤1034 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)~1033-34 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 19.97 A (emissivity peak at T=3MK; but alsoN 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 ~1500-2000 km/s, except Fe XII 3540 km/s.

RS Oph inFebruary:The wind

Collisional ionization or photoionization?From (f+i)/r ~1 we infer a collisionally ionized plasmaAre 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 Teff vs. tturn off

In this regionflux goes to zero if C>=0.01 C(sol)in model atmospheresbecause of CVIedge @ 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 rapidvariability 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-radialg-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 tojets? Correlation with WD rotation?Rapid spin period predicted.

Prolonged ejectionof 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 ~10-11 mo.

• 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 streamtouches 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 & Orio2005)Non magneticLow mdot8.00 ×10-11 mO yr-1

CP Pup

Mdot<1.6 x 10-10mo/yr

Consistent with very luminous moderately fast nova

Tmax>60 K

Massive WD

Magnetic?