Rotationally modulated X-ray emission from the accretion shock in CTTS V2129 Oph Project C. Argiroffi, E. Flaccomio, J. Bouvier, J.-F. Donati, K. V. Getman, S. G. Gregory, G. A. J. Hussain, M. M. Jardine, M. B. Skelly and F. M. Walter V4046 Sgr Project C. Argiroffi, A. Maggio, T. Montmerle, D. P. Huenemoerder, E. Alecian, M. Audard, J. Bouvier, F. Damiani, J.-F. Donati, S. G. Gregory, M. Güdel, G. A. J. Hussain, J. H. Kastner and G. G. Sacco Costanza Argiroffi The X-ray Universe - Berlin, 27 June 2011

ACCRETION IN YOUNG LOW MASS STARS MAGNETOSPHERIC ACCRETION MODEL (Konigl 1991) X-RAYS X-rays from accretion in CTTS: predicted by Ulrich (1976) observational evidences by Kastner et al. (2002) Costanza Argiroffi The X-ray Universe - Berlin, 27 June 2011

WHY STUDY X-RAYS FROM ACCRETION to constrain the total amount of X-rays emitted from CTTS (to constrain the evolution of circumstellar disks) to set the energy balance of the accretion-shock region (to infer the mass accretin rate) to probe the properties (i.e. density, velocity) of the accretion stream (to understand how accretion occurs) to probe the chemical composition of the inner disk (to check the chemical evolution of circumstellar disks) Costanza Argiroffi INAF - OAPA, 27 April 2011

X-RAYS FROM ACCRETION: OPEN ISSUES Observed X-rays significantly lower than predicted Observability of the X-rays from accretion Density vs temperature pattern: observations vs models Costanza Argiroffi INAF - OAPA, 27 April 2011

AIMS: SEARCH FOR ROTATIONAL MODULATION IN X-RAYS Expected periodic variations in: plasma densities plasma average temperatures EM of plasma at temperatures of 1-5 MK Observing programs: Long X-ray monitoring of a CTTS with simultaneous optical observations Projects: V2129 Ophiuchi V4046 Sagittari Costanza Argiroffi The X-ray Universe - Berlin, 27 June 2011

TARGETS: V2129 OPHIUCHI & V4046 SGR Star V2129 Oph V4046 Sgr single binary Mass 1.35 Msun 0.91 + 0.88 Msun ST K5 K5 + K5 Prot 6.53 days 2.42 days age 3 Myr 10-15 Myr i 60 deg 35 deg B 4 kG 200 G SFR Rho Ophiuchi Beta Pic dist. 120 pc 72 pc 200 ks with Chandra/HETGS 360 ks with XMM Costanza Argiroffi The X-ray Universe - Berlin, 27 June 2011

X-RAY MONITORING OF V2129 OPH seg. 1 seg. 2 (Donati et al. 2011, Argiroffi et al. 2011) We have analyzed X-ray spectra integrated over: ~ 100 ks = 1 segment = 0.18 Prot Costanza Argiroffi The X-ray Universe - Berlin, 27 June 2011

VARIATIONS IN THE COOL EMD COMPONENT EMD1 > EMD2 at 3-4 MK Cool lines (long wavelengths) are stronger in seg.1 than in seg. 2 Costanza Argiroffi The X-ray Universe - Berlin, 27 June 2011

VARIATIONS IN PLASMA DENSITY Densities are higher in seg.1 than in seg. 2 Costanza Argiroffi The X-ray Universe - Berlin, 27 June 2011

INTERPRETATION OF THE OBSERVED VARIABILITY Results summary: EM at ~4 MK is higher in seg.1 than seg.2 Ne at 4 MK is higher in seg. 1 than in seg. 2 (Argiroffi et al. 2011) Costanza Argiroffi The X-ray Universe - Berlin, 27 June 2011

The X-ray Universe - Berlin, 27 June 2011 V4046 SAGITTARI (Stempels & Gahm 2004) Costanza Argiroffi The X-ray Universe - Berlin, 27 June 2011

X-RAY MONITORING OF V4046 SGR Each segment is 120 ks The X-ray observation covered 2.2 system rotations We have analyzed X-ray spectra integrated over: ~25 ks = 0.12 Prot Costanza Argiroffi The X-ray Universe - Berlin, 27 June 2011

TIME RESOLVED X-RAY SPECTROSCOPY Lines detected at 1 sigma in all the time intervals Costanza Argiroffi The X-ray Universe - Berlin, 27 June 2011

VARIABILITY: COOL LINES (Argiroffi et al. 2011, ApJ submitted) Best fit period = 1.22 +/- 0.01 days (rot. period = 2.42 days) Costanza Argiroffi The X-ray Universe - Berlin, 27 June 2011

VARIABILITY: HOT vs COOL LINES Hot lines: Costanza Argiroffi The X-ray Universe - Berlin, 27 June 2011

V4046 SGR X-RAY MONITORING: RESULTS High density Cool plasma is compatible with being material heated in the accretion shock Rot. modulation Cool plasma is not symmetrically distributed with respect to the stellar poles Obs. period = half the system period Naturally explained if high-density cool plasma is located on both the stellar components X-ray vs optical results X-rays are likely produced only by a fraction of the accretion shock region Costanza Argiroffi The X-ray Universe - Berlin, 27 June 2011

The X-ray Universe - Berlin, 27 June 2011 CONCLUSIONS CTTS display variability in their soft X-rays This variability can be explained in terms of X-rays emitted in the accretion shock and seen with different viewing angles during stellar rotation. Soft X-rays, like all the other accretion indicators, display rotational modulation Costanza Argiroffi The X-ray Universe - Berlin, 27 June 2011