1. NHXM: scientific goals Galactic sources presented by Giorgio Matt presented by Giorgio Matt (Dipartimento di Fisica, Università Roma Tre, Italy)

2. NHXM in a context NuStar (NASA SMEX). First hard X-ray (6-79 keV) mission with focusing telescopes (HPD@30 keV: 60”). Energy resolution ΔE~1 keV. Launch in 2011. ASTRO-H (JAXA). Broad-band (0.3-80 keV) focusing telescopes (HPD@30 keV: 100”). Non focusing soft γ-ray detector in the 10-600 keV band. High energy resolution (calorimeter) in the 0.3-12 keV range. Launch in 2013. GEMS (NASA SMEX). Non imaging X-ray (2-10 keV) polarimeter. Launch in 2014.

3. NHXM in a context

6. NHXM and IXO IXO will have a much larger area, much better energy and angular resolution, but:  it will fly (hopefully!!) in the twenties  its soft and hard X-ray response will be very much mismatched; the effective area above 10 keV is less than the NHXM one  its polarimeter will have a much narrower energy range and will not work simultaneously with the spectroscopic instruments To draw an analogy, NHXM : IXO = BeppoSAX : XMM

7. Key science (in Galactic Astronomy)  Acceleration phenomena SNR (Shell, PWN); Active stars; jets  Matter under extreme conditions (fundamental physics) Strong gravity; extreme B  Accretion physics Accretion on WD, NS, BH; the GC

8. Particle acceleration in SNRs HESS/ASCA view of RXJ1713.7-3946 Regions with similar TeV and X-ray morphology are probably sites of e - acceleration. Strong GeV-TeV emission in regions with little hard X-ray emission are probably site of hadron acceleration. Contours: X-ray (ASCA) Aharonian et al. (2006)

9. Non thermal emission in shell SNRs Synchrotron emission: ( spatially resolved !! ) Cutoff energy  max energy of electrons Polarization  direction and level of order of the magnetic field 5 keV 50 keV Bykov et al. 2009 MDP~5% in 100 ks on the NT emission of Cas A

10. Vela (Chandra) From Weisskopf et al. (2000) The Crab Nebula is the only source in which polarization has been measured so far in X-rays ( P=19% Weisskopf et al. 1978), confirming the synchrotron nature of the X-ray emission. The nebula is highly structured, as shown by Chandra observations, with a jet and a torus. Imaging spectroscopy and polarimetry would be extremely important to map the magnetic field, and to understand the acceleration and emission mechanisms in this (and other) Nebula. PWN: the Crab

11. INTEGRAL ( SPI: 0.1-1 MeV : Dean et al. 2008, IBIS: >200 keV: Forot et al. 2008) measured a high γ-ray polarization in the off-pulse, aligned with the optical one (and with the NS spin axis). 0.1-1 MeV

12. GRS 1915+105 Is the jet contributing to the X-ray emission? Hard X-ray spectroscopy and polarimetry may tell us (as a function of state) Mirabel & Rodriguez (1994) Fender, Belloni & Gallo (2004) Jets in accreting black holes

13. Matter under extreme conditions Black Holes  Black Holes: Probing strong gravity, measuring the BH spin Neutron stars  Neutron stars: Confirming vacuum birefringence in extreme magnetic fields; constraining the equation of state of superdense matter; and even searching for axions

14. Dovciak et al. (2008) Strong gravity and black hole spin a=0 Fabian et al. (2000) Li et al. (2005) a=1 a=0.,0.5, 0.9, 0.999 Different, independent methods (line profile, continuum shape, rotation of the polarization angle) can be applied simultaneously to estimate the black hole spin (“concordance model”) The broad band is required !!! a within 20-30% for extreme Kerr

15. NS EoS (M-R relationship) Crucial measurements: R or M/R (assuming M known). Several X-ray techniques:  Pulse profiles  Redshift of lines  Thermal emission  QPO  Iron line profiles  Polarization Lattimer & Prakash (2007) 4U1705-44, di Salvo et al. (2009)

16. Vacuum birefringence in strong B van Adelsberg & Lai 2006 Soft Gamma Repeaters and Anomalous X-ray Pulsars are interpreted in the frame of the Magnetar theory (Thompson & Duncan 1993): neutron stars with extreme magnetic fields. a test of the magnetar paradigm and a probe of strong- field QED For high B, a yet-to-be-confirmed QED effect (vacuum birefringence, Heisenberg & Euler 1936) becomes important, significantly changing the dependence on the phase and the energy of the polarization, providing a test of the magnetar paradigm and a probe of strong- field QED

17. Vacuum birefringence in strong B van Adelsberg & Lai 2006 Soft Gamma Repeaters and Anomalous X-ray Pulsars are interpreted in the frame of the Magnetar theory (Thompson & Duncan 1993): neutron stars with extreme magnetic fields. a test of the magnetar paradigm and a probe of strong- field QED For high B, a yet-to-be-confirmed QED effect (vacuum birefringence, Heisenberg & Euler 1936) becomes important, significantly changing the dependence on the phase and the energy of the polarization, providing a test of the magnetar paradigm and a probe of strong- field QED

18. Vacuum birefringence in strong B van Adelsberg & Lai 2006 Soft Gamma Repeaters and Anomalous X-ray Pulsars are interpreted in the frame of the Magnetar theory (Thompson & Duncan 1993): neutron stars with extreme magnetic fields. a test of the magnetar paradigm and a probe of strong- field QED For high B, a yet-to-be-confirmed QED effect (vacuum birefringence, Heisenberg & Euler 1936) becomes important, significantly changing the dependence on the phase and the energy of the polarization, providing a test of the magnetar paradigm and a probe of strong- field QED

19. Vacuum birefringence in strong B Proton cyclotron E=0.63B 14 keV Lai et al. 2009 Soft Gamma Repeaters and Anomalous X-ray Pulsars are interpreted in the frame of the Magnetar theory (Thompson & Duncan 1993): neutron stars with extreme magnetic fields. a test of the magnetar paradigm and a probe of strong- field QED For high B, a yet-to-be-confirmed QED effect (vacuum birefringence, Heisenberg & Euler 1936) becomes important, significantly changing the dependence on the phase and the energy of the polarization, providing a test of the magnetar paradigm and a probe of strong- field QED

20. Accretion physics: magnetic WD Magnetic CVs (in particular IPs) are hard X-ray emitters. They may provide the bulk of the (now resolved by Chandra and INTEGRAL) diffuse Galactic Ridge emission. NHXM can confirm or disproof this hypothesis Moreover, broad band spectroscopy and polarimetry will be crucial in understanding the accretion processes in magnetic CVs Lebrun et al. 2004 Feasible in the half dozen of brightest objects!

21. Accretion physics: magnetic NS Meszaros et al. (1988) Spectropolarimetry may constraint the accretion geometry. Electron (in strong B) or proton (in extreme B) cyclotron lines may be searched for and studied in detail

22. Accretion physics: black holes Esin et al. (1997) Broad band spectroscopy and polarimetry can help answering several important questions:  is the disc really truncated in the low state?  is the hard X-ray emission in the different states due to a hot corona, or a jet?  is the broad line really relativistic (vs. Comptonization)  is the hard emission thermal or not thermal?  is the accretion an ADAF in the quiescent state?

23. The Galactic Centre XMM Decourchelle et al. 2002 I NTEGRAL, Belanger et al. 2006 Accretion physics and GR test in the closest SMBH: spectrum and variability of Sgr A* flares in hard X-rays Particle acceleration from SMBH: identify and reveal the nature of the central INTEGRAL and HESS source The nature of the hot diffuse X-ray emission

24. The Galactic Centre Transient at ~ 2.5 ” from Sgr A* in 2004 (Chandra) With XMM-Newton it was possible to localize the flare of 31 st August 04 with 1 ” accuracy and identify it with Sgr A* (Belanger et al. 2005) The same will be possible with NHXM in hard X-rays, thanks to its sharp PSF

25. Our own SMBH in a context Sgr A* as a (very) low luminosity accreting BH:  What is the accretion mode?  Does it experience episodes of much larger activity?  ~2x10 33 erg/s

26. The strange case of Sgr B2 SgrB2 is a giant molecular cloud at ~100pc projected distance from the SgrA*, with a radius of 7 pc (3’.5) The spectrum of SgrB2 is a pure reflection spectrum Reflection of what? No bright enough source is there !!! INTEGRAL Image of GC (Revnivtsev 2004) The emission from SgrB2 is extended and brighter in the direction of the BH (Murakami 2001). Is SgrB2 echoing past emission from the BH, which was then active in the past (e.g. Koyama et al. 1996) ??? Sunyaev et al. 1993

27. Was the GC an AGN a few hundreds years ago? SgrB2 should be highly polarized with the electric vector perpendicular to the line connecting the two sources. X-ray polarimetry can definitively proof or reject this hypothesis. SgrB2 should be highly polarized with the electric vector perpendicular to the line connecting the two sources. Reid et al. (2009) Measurable with NHXM!

28. What is the accretion mode? Narayan et al. (1997) Is the ADAF the actual accretion mode? is there a difference in the accretion mode during quiescence and flares? Is ADAF the accretion mode in low luminosity AGN? Sensitive spectroscopy in hard X-rays is needed!!

29. Summary NHXM NHXM, with its unique combination of high sensitivity, high angular resolution broad band spectroscopy and imaging polarimetry, will help us understanding acceleration and accretion phenomena on a variety of classes of Galactic X-ray sources, as well as probing matter behaviour under extreme conditions, in so doing testing fundamental physical processes.