2. SgrA* X-ray Flares with XMM-Newton P. Goldoni, A. Goldwurm, P. Ferrando, F. Daigne, A. Decourchelle,E. Brion, G. Belanger A. Goldwurm, P. Ferrando, F. Daigne, A. Decourchelle,E. Brion, G. Belanger Service d’Astrophysque / CEA – Saclay, France R.S. Warwick Physics Dept., Leicester University, UK P. Predehl, D. Porquet, B. Aschenbach MPE – Garching, Germany

3. Sgr A* Compact radio source at the dynamical center of our Galaxy Very high column density along the line-of-sight N H ~ 1-2 x 10 23 cm -2 => Only detectable in radio, IR, X-rays, an gamma-rays Motions of stars: => M = 3.5 ± 1.5 x 10 6 solar mass (Schödel et al. 2002) => Supermassive Black Hole Radio: very well known, bright, weakly variable source, 106 day period

4. X-ray observations of SgrA* Only observable above 2 keV Old generation of X-ray satellites (e.g, ASCA, BeppoSAX): spatial confusion with other objects Chandra L (2-10 keV) ~ 2.2 x 10 33 erg/s (Baganoff et al. 2003) => 10 -11 x Eddington Luminosity (~4.5 x 10 44 erg/s), photon index ~ 2.5 roughly compatible with ADAF model

5. Flare detected with Chandra in Sep 2000  Chandra detected a 10 ks flare in October 2000 (Baganoff et al. 2001b)  Sgr A* peak L X (2-10 keV)  10 35 erg s –1 ~50 times stronger than in quiescence ~50 times stronger than in quiescence  Hard spectrum:   1.3  Fast variations, ~600 sec, small emission region ~ 20 Rs for 3 million solar masses BH, argument against ADAF model  Liu & Melia (2001) viscosity decrease in hot circularized accretion flow  Markoff et al. 2001 Sudden shock acceleration

6. XMM-Newton GTO observations-I PI Anne Decourchelle Joint Saclay/Leicester/MPE program PI Anne Decourchelle Joint Saclay/Leicester/MPE program Main scientific goal GC region diffuse emission Main scientific goal GC region diffuse emission Total observing time on Sgr A*: 75 ksec Total observing time on Sgr A*: 75 ksec XMM observations in september 2000 => solar flare XMM observations in september 2000 => solar flare Spring 2001 => solar flare Spring 2001 => solar flare September 2001 initial phases of a Sgr A* flare (Goldwurm et al. 2002 ApJ) September 2001 initial phases of a Sgr A* flare (Goldwurm et al. 2002 ApJ)

7. The XMM-Newton Observation of the GN  Performed on 4 th September 2001  Exposure ~ 26 ks  EPIC in Full Frame Imaging mode : MOS 1, MOS 2, PN, Medium Filter  RGS in spectral+Q mode, OM blocked  MOS 1+2 central CCD: ~ 4.5 cts/s  Some proton flares observed Complex region, diffuse emission + point sources : excess around Sgr A* XMM-NewtonEPIC MOS 1 + 2 EPIC MOS 1+2 Central CCD 2-10 keV Count Rate (20s bin)

8. R= 10 "

9. Search for Variability of Sgr A* Search for Variability of Sgr A* MOS Image (pixels = 1.1"  1.1") with point sources detected by Chandra  Confused region for the XMM PSF (15" HPD)  Optimized selections to search for Sgr A* contribution  Region within 10" from Sgr A* (60 % flux) in the 2-10 keV band  Use of Chandra results to model the contribution of other sources (Baganoff et al. 01)  Search for a variable central source MOS 1+2 0.5 - 7 keV R= 10 "

10. Light Curves from data within 10" from Sgr A* region at 1’ from Sgr A* within 10’’ from Sgr A*MOS 1 + 2 PN Count Rate from within 10’’ from Sgr A* for both MOS and PN (300 s less of data) : zoom around the end of the observation 7  excess Comparison of Count Rate (2-10 keV, 180 s bin) from within 10’’ from Sgr A* and CR from a different region (same CCD) 900 s

11. Images before and during the flare 5'5' The flare is clearly located at the center of the image compatible with a point source close to Sgr A* MOS 1+2 2-10 keV 1000 s before flare1000 s during flare MOS 1+2 2-10 keV Sgr A* position

12. Search & location of other point sources in the total MOS 1+2 0.5-4 keV image (all CCDs)  6 point sources identified with stars  Average and rms offset  RA = –0.03"  Dec = 0.20" rms  RA = 0.29" rms  Dec = 1.5“  Consistent with syst. uncertainties => The flaring source is identified with Sgr A* MOS 1+2 2-10 keV 1000 s during flare Flaring source location 1.5" Offset from Sgr A* PSF fitting of central source on the last 1000 s image  Central source located at (J2000) R.A. = 17 h 45 m 39.99 s Dec. = –29° 00' 26.7" (+/- 0.4" stat. err.)  1.5" from Sgr A* radio position (1.4" in Dec.), compatible with residual systematic errors for XMM

13. Spectra from data within 10" from Sgr A* before the flare  Quiescent spectrum compatible with Chandra measures  Well fitted by Thermal spectrum (Raymond & Smith 77) with kT ~ 1.3 keV + Power law for point sources and background  Sgr A* component (12 % of total emission) not required but consistent MOS 1 + 2PN Spectral fit of MOS and PN data with model used for Chandra data of quiescent state  Best fit (  2 = 1.35, =121) Thermal Component (diffuse) N H = 11.1 ± 0.6 10 22 cm -2 N H = 11.1 ± 0.6 10 22 cm -2 kT = 1.3 ± 0.08 keV kT = 1.3 ± 0.08 keV P–L (point sources + background) P–L (point sources + background)  = 2.1 ± 0.3  = 2.1 ± 0.3 P-L for Sgr A* (fixed to Chandra fit)  = 2.7  = 2.7

14. Spectral Hardening during the Flare MOS before flare MOS during flare H/R = F(4-10 keV) / F(2.5-4 keV) Hardness Ratio Time (s) Spectral fit of MOS + PN data during flare (last 900 s for MOS, last 600 s for PN) with model used for the quiescent state  Thermal and point sources components fixed, Sgr A* Power-Law free  Best fit (  2 = 0.9, =27) for Sgr A* Power-Law (N H = 9.8 10 22 cm -2 fixed to Chandra value) Sgr A* Power-Law (N H = 9.8 10 22 cm -2 fixed to Chandra value)  = 0.9 ± 0.5  = 0.9 ± 0.5 MOS 1 + 2

15. Spectra Parameters during the Flare Spectral fit using the data before flare as background component  Power-Law model (  = 0.98, =20) N H = 9.8 10 22 cm -2 (fixed) N H = 9.8 10 22 cm -2 (fixed)  = 0.7 ± 0.6  = 0.7 ± 0.6  Similar result if dust scattering is included  Luminosity 2–10 keV (8 kpc) : 3.8 ± 0.7 10 34 erg s -1 3.8 ± 0.7 10 34 erg s -1 MOS 1+2 PN  XMM 2001 flare strongly resembles the early phase of the Chandra 2000 flare  Increase of factor 3 in 900 s, implies Sgr A* flux increase of factor 30  Spectrum compatible with hard slope  No indication of lag between soft and hard

16. Correlation with Radio data  106 day radio cycle from VLA data (Zhao et al. 99)  XMM 2001 flare at time phase preceding the main radio peak (d64)  Chandra flare : 6 days after (d70)  Recent radio data show increase in the cycle period (Yuan & Zhao 02)  Flare close to local max in 2001 Radio LC Chandra Flare XMM Flare

17. New Chandra 2002 observations 500 ksec observations with multiwavelength coverage (Keck, VLA,…) 500 ksec observations with multiwavelength coverage (Keck, VLA,…) Results not yet published, ~0.6 +/-0.3 flares/day, mostly weaker (factor ~10) Results not yet published, ~0.6 +/-0.3 flares/day, mostly weaker (factor ~10) No obvious correlation with other wavelengths No obvious correlation with other wavelengths

18. XMM-Newton GTO Observations II 50 ksec pointing on Sgr A* to be performed 50 ksec pointing on Sgr A* to be performed ~30 ksec in February 2002, observation not ~30 ksec in February 2002, observation notcompleted Remaining time in October 2002 Remaining time in October 2002 Brightest flare from Sgr A* !! (Porquet et al. 2003 A&A) Brightest flare from Sgr A* !! (Porquet et al. 2003 A&A)

19. flare duration ~ 2.7 ks, i.e less than one hour Shorter variation ~200 sec, ~7 Rs flux amplication ~ 160 ( peak of the flare/ quiescent) (~ x 3.5 October 2000, Chandra) symmetrical light curve shape Similar light curve shape in the "soft" (2-5 keV) and in the "hard" (5-10 keV) energy bands: no significant spectral evolution between the rise and decay phase October 2002: X-ray flare from Sgr A* (XMM-Newton)

20. XMM/EPIC spectrum photon spectral index :  = 2.5  0.3 XMM, 10/2002 Very soft compared to the previous ones:  ~ 1.3 Chandra, 10/2000  ~ 1.0 XMM, 09/2001

21. Comparisons with flare models The characteristics of this brightest flare in October 2002 (XMM) challenge theoretical Sgr A* flare modelling: Circularized flow (Liu & Melia 2002): when the viscosity increases SSC of mm to sub-mm photons is the dominant process: soft spectrum predicted. A similar increase in the mm and sub-mm, not IR is expected: but not yet reported Jet model (Markoff et al. 2001) when the jet power or accretion rate increase: soft spectrum predicted Simultaneous flaring at all frequencies are expected: but not yet reported Star-disk interaction (Nayakshin et al. 2003): for kT=1 and 70 keV a soft spectrum (  ~ 2.3) is predicted but very fine-tuned. X-rays have become fundamental to solve Sgr A* puzzle

22. INTEGRAL/ISGRI Observations of SgrA*  Spring 2003, 1Msec exposure: Detection of a source at a position compatible with SgrA* in the 20-40 and 40-100 keV band, implied luminosity ~10 35 erg s -1

23. INTEGRAL/ISGRI Observations of SgrA* : variability SgrA* 20-40 keV light Curve: Hints of Variability on a 40 min. timescale But angular resolution 12’ and position error ~0.8’

24.  Rapid / high-amplitude X-ray flaring of Sgr A* is not a rare event  From XMM and Chandra results : ~0.6+/-0.3 flares/day  Hard and soft spectra are observed, non definitive hints on accretion regime and emission mechanisms  Possible hard X-ray source/flaring but source confusion is still a problem  Constraints on models, e.g. in case of change in mass accretion and SSC is the main X-ray radiative mechanism the increase in radio should be comparable (Liu & Melia 02), in all models correlated variability is predicted  Fast IR variability has very recently been observed (Genzel et al. 2003)  No radio variability of such amplitude has been ever observed Present state of Observations Long XMM/INTEGRAL observations with ground based Radio, submm, IR coverage are needed

25. XMM-Newton AO-3 Proposal (Goldwurm et al.) to observe SgrA* for 500 ksec (large program), accepted, 4 orbits granted. Goals Proposal (Goldwurm et al.) to observe SgrA* for 500 ksec (large program), accepted, 4 orbits granted. Goals 1) detect the largest possible number of flares with max. sensitivity 1) detect the largest possible number of flares with max. sensitivity 2) Correlate with Simultaneous hard X-rays (INTEGRAL), radio (VLA) and IR(ESO) 2) Correlate with Simultaneous hard X-rays (INTEGRAL), radio (VLA) and IR(ESO)

26. Perspectives Detection of several flares with different spectra Detection of several flares with different spectra Modelization of X-ray sources in IBIS/ISGRI Modelization of X-ray sources in IBIS/ISGRI error box => hard X-ray spectrum of SgrA* Monitoring of radio,submm and IR flux/variability Monitoring of radio,submm and IR flux/variability Strongest possible constraints on SgrA* emission mechanisms and accretion regime Strongest possible constraints on SgrA* emission mechanisms and accretion regime

27. XMM-Newton October 2002 SgrA* Flare Movie (MPE)