Finding Black Hole Systems in Nearby Galaxies With Simbol-X Paul Gorenstein Harvard-Smithsonian Center for Astrophysics

Introduction Black hole systems are laboratories where the predictions of general relativity can be tested. The spin of a black hole should always be in the range 0 to 1. The signature of a black hole system is a compound spectrum containing black body & power law components. Spectra are usually more luminous and harder than a neutron star’s. (Barret, McClintock, and Grindlay, 1996) Cyg X-1 is the only proven example of a permanently active black hole system within our galaxy. Three more exist within the local group of galaxies. Transient black hole sources flare at a rate of about one per year in our galaxy and provide a few more subjects for study. However, most of them have low galactic latitude. Their soft X-rays are absorbed in the ISM Simbol-X spectra of sources in external galaxies will indicate which objects are most likely to be black hole binaries. Those are the subjects of optical studies for identifying the counterpart and measuring the mass and spin.

Larger bandwidth is observable because there is less absorption within the ISM of the external galaxy and ours. Most local compact binaries reside along the galactic plane where absorption is high. By observing the entire 0.2 to 80 keV band Simbol-X will be able to discriminate with high confidence between black hole and neutron star binaries on the basis of total luminosity, spectra, and spectral state transitions, detected in repeat exposures. With current and especially future large optical Telescopes with adaptive optics, e.g. 30m Keck ll and the 100m “OWL” of ESO it will be possible to identify and study the optical counterparts of the black hole binary systems and measure their mass and spin Also- these galaxies contain a new class of object, “ultra luminous” X-ray sources,- which may be intermediate mass black holes. Introduction (Continued)

Four Low Inclination Galaxies GalaxyDist.Nh (Interp.) PaperExp. ksec Number Sources M83,4 mpc3.7 x Soria and Wu A&A 410,53 (2003) Chandra M51, x Terashima and Wilson ApJ 601,735 (2004) Chandra M104,153.7 x Di Stefano et al, ApJ 599,1067 (2003) Chandra M x Grimm et al ApJ 161,271 (2005) Haberl and Pietsch A&A 373,438 (2001) Varies 261 Chandra 184 ROSAT

Simulating keV images of point sources in M83, M51, M104, and M33 At most these images are a qualitative indication of what Simbol-X would see in a 10 5 sec exposure. The sources’ spectra are too uncertain to predict their intensities with any accuracy. BeppoSAX and Suzaku have obtained spectral data from some of these galaxies in the hard X-ray band but the sensitivity and resolution of these non-focusing instruments is so poor so that it is not possible to associate the signals with specific sources

Simbol-X Simulations, Spectra of Sources The simulation of keV images are based upon calculating the photon spectral index from the the Chandra counts in two energy bands*, using the Nh within our galaxy but neglecting local absorption. GalaxyLow Band (keV)High Band (keV ) M M51* M M *did not the photon indices of Terashima and Wilson for M51

Simbol-X Simulations, Angular Resolution 100 ksec exposures of the 4 galaxies were simulated for the keV band. The point response functional form had an angular dependence like that of XMM-Newton. Several values for the angular resolution were taken by scaling the radius Fractional Encircled Power Radius, arc seconds

Simbol-X Simulations, Background The particle background in a cadmium telluride detector was based upon the model of Armstrong, Colburn, and Ramsey for L2. According to these authors background in LEO is higher by factor of 5.

M83 Optical. VLT Twin black holes at the center?

M83 Chandra X-Ray Observatory

M83 Simulated Simbol-X keV Image 20 arc seconds resolution (log scale)

M83 Simulated Simbol-X keV Image 10 arc seconds resolution (log scale)

M51 (Whirlpool Galaxy) Optical SN in July 2005

Chandra Image of M51

M51 Simulated Simbol-X keV Image 20 arc seconds resolution (log scale)

M104 (Sombrero Galaxy), “Great Observatories” Multi-Wavelength Chandra HST Spitzer

M104 Simulated Simbol-X keV Image 20 arc seconds resolution (log scale)

M104 Simulated Simbol-X keV Image 10 arc seconds resolution (log scale)

M104 Simulated Simbol-X keV Image 5 arc seconds resolution (log scale)

M104 Simulated Simbol-X keV Image 2 arc seconds resolution (log scale)

M104 Simulated Simbol-X keV Image 1 arc second resolution (log scale)

M33 (Pinwheel Galaxy) Optical

M33 XMM-Newton

M33 Simulated Simbol-X keV Image 10 arc second resolution (log scale) M33 is much closer than the others. Sources are resolved as well in 10” res image of M33 as well as in 2” of M104

Number of sources expected with > 50 and > 100 counts in the keV band for 10 5 sec exposure GalaxyNo. sources with > 50 counts No. sources with > 100 counts M M M M A significant fraction of these sources are background AGNs

Summary & Conclusions Nearby galaxies are an important resource of black hole binaries (BHBs) but currently we do not know which of the several dozen sources seen by Chandra and XMM-Newton are actually BHBs. Broad band spectral measurements by Simbol-X will indicate which sources are most likely to be BHBs and prime candidates for optical study. The next generation of large optical telescopes employing adaptive optics will be able to identify their optical counterparts out to distances of ~15 mpc. Measurements of the binary period and magnitude of doppler broadening of optical lines in conjunction with the measurements of hard and soft components of the X-ray spectrum will allow determining the mass and spin of the black holes and test the predictions of general relativity. Simbol-X measurements of the X-ray spectrum up to 80 keV should resolve the question of whether or not the ultra-luminous X- ray sources seen by Chandra and XMM are indeed intermediate mass black holes.