Very hard X-ray binaries containing white dwarfs Marina Orio Collaborators: D. de Martino, A. Bianchini, K. Mukai, T. Nelson, J. Sokoloski

Classes of interacting WD binaries emitting hard X-rays: Symbiotics: a red, cool secondary. Not all symbiotics have WD… perhaps 90%? 7 NS stars symbiotics are hard. But… also 4 WD symbiotics are very hard sources. Main sequence secondary: disk (low luminosity hard X-rays possible), magnetic mass transfer only (polars), magnetic accretion+disk (intermediate polars) White dwarfs MS or RG with thermonuclear burning: novae, recurrent novae, “steady burners”? High mass binaries: probably very soft only Products of HMB evolution with brown dwarf, WD or NS: hard sources if they are merging? Probably not! All these binaries, but specially novae and symbiotics, are detected in external galaxies. Novae can be indicators of binary star formation and pop. evolution.

Hard X-rays in outburst: RS Oph outburst on February 12 2006

RS Ophiuchi is a recurrent nova and a symbiotic system (WD + red giant). It was observed in outburst in 1898, 1933, 1958, 1967, 1985 and in February of 2006. The AAVSO light curve is shown above, and on the left is Williamina Fleming, who studied the system after the first outburst. RS Oph was also extensively studied by Annie Jump Cannon. 34000 AAVSO observations in 2000.

Early days of outburst: blast wave 1036 erg/s in hard X-rays! Initially >50 keV? Deceleration after 1.7 days (low mass shell) and rapid cooling, implications for H-content of SNe Ia.

Plot by J. Drake February 26 2006: 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), hottest is Fe XXV 1s2p-1s2 resonance line (emissivity peak at T=60MK). Broadening of the lines => approximately 2000 km/s at half maximum. Broadening increases with . Larger blue shift proportionate to ionization state and proportional to  Interaction with red giant wind.

Quiescent evolution: CVs in hard X-ray surveys SWIFT/BAT: INTEGRAL IBIS: 421 sources (~5% are CVs) 461 sources (~6% are CVs) 7

Emission in post-shock region For both magnetic and non magnetic accretion, hard X-rays. Stationary cooling flow, with highest T ~ gravitational potential well. 7 times deeper for 1.35 M than for 0.6 M WD Hard X-rays are the best way to select potential Sne Ia candidates among WD systems! MCV have “vertical” shocks and no radiation from disk. IP’s have larger mdot and, due to lower B, no large blobs penetrating the post-shock region => much brighter in hard X-rays

Hard X-ray CVs Most RXTE, INTEGRAL & SWIFT CVs are IP’s (Barlow et al. 2006; Bonnet-Bidaud et al.2006; 2007; Mukai et al.2007; Bodaghee et al. 2007; Shafter et al. 2008; Bonnet-Bidaud et al. 2009; de Martino et al. 2009……follow-up on-going…..) 9

MCVs: a hidden population of Galactic XRBs? Chandra survey of the Galactic center (Muno et al.2004; Ruiter et al 2006): - 1500 over 2000 Faint Sources: Lx < 1031 – 1033 erg/s - Hard spectra: kT > 8keV, Fe H-like and He-like emissions - Affected by local absorption - Variable: periods 300sec – 4.5hrs => IPs thought to be the dominant population: ~800 to be detected with NHXM RXTE & INTEGRAL surveys of the Milky Way (Sazonov et al. 2006; Revnivtsev et al. 2008; 2009): - XLF [2-10keV] at L<1034erg/s from coronal sorces (65%) and CVs (35%) - XLF of CVs [2-12keV] similar to XLF[16-60keV] => Galactic Ridge emission at E>20keV dominated by MCVs 10

Most SDSS emission line objects Most Hard X-ray surveys ORBITAL PERIOD DISTRIBUTION Census: Polars IPs Pre-Rosat 18 (60%) 12 (40%) Post-Rosat 55 (70%) 25 (30%) Today 94 (54%) 79(46%) Most SDSS emission line objects Most Hard X-ray surveys

Polar CV emitting hard X-rays: INTEGRAL & SWIFT hard X-ray polars NAME B (MG) SYNCHRO P_orb (hr) V834 Cen 23 YES 1.7 SwiftJ2319+26 ? NO: 3.0 BY Cam 41 NO 3.4 V1432 Aql 28-35 The asynchronous polars are post-outburst novae? (Massive WD yield novae more often) 12

WD Symbiotics Kennea et al. 2009, Luna 2007-2008: 4 symbiotics with large X-ray luminosity (several 1033 erg/s) detected with Swift-BAT up to 50 keV T Cr Bor is a recurrent nova => surely a WD Like the other 3 systems it does not show a spin period of the WD Evidence hat they are all very massive WD with large(1012-1013 cm) disks Type Ia SN progenitors? stochastic variability, “partial” absorber

Same criterion can be used to select massive WD in quiescent novae CP Puppis is the hardest quiescent WD so far Outburst consistent with very massive nova Very luminous and only moderately fast => low mdot, not SN progenitor Novae are far, we need deeper X-ray observations