ACTIVE GALACTIC NUCLEI X-ray broad--band study A. De Rosa, L. Piro Ginga/ROSAT/ASCA IASF-Roma Universita' di Roma La Sapienza Institute of Physical and Chemical Research Japan BeppoSAX: Broad band spectral variability. T obs ~ 1.5 Ms on bright Sy 1 galaxies IASF-Roma, Bologna Univerista' di Roma Roma tre Osservatorio Astronomico di Roma Osservatorio Astronomico di Brera now XMM-Newton/BeppoSAX & Chandra IASF-Roma Univerista' di Roma Roma tre Institute of Astronomy Cambridge (UK)

Why study AGN in X-ray? – They emit about 5-10 % their power in X-ray – Rapid time scale variations (on timescales as small as 1000 s) X-ray observations probe deep inside the AGN's core

The complex X-ray spectra Intrinsic continuum Warm absorber(s) Soft excess emission Compton reflection features Broad-band BeppoSAX observation NGC De Rosa et. al 2002

Broad band spectral variability of bright Sy 1 galaxies with BeppoSAX: Main results I First detection of the high energy cut-off in a single source and intrinsic spectral variability. NGC 4151, Perola et al MCG Vaughan & Edelson 2001 Thermal Comptonization: two-phases model

Probing the close and distant environment in AGN: The reflection component and the iron line MCG ASCA. Tanaka et al BeppoSAX Guainazzi et al 1999 Wilms et al 2001

... and the narrow iron line Mkn 509, XMM. Pounds et al 2001 NGC Chandra. Yaqoob et al 2001 Regions: molecular torus, BLR, NLR. Do they contribute to the Compton reflection hump? (NGC5506, Matt et. Al 2001, NGC 4051, Guainazzi et al ) NGC Nicastro et al. 2000

Future prospects Sample of 20 Seyfert 1s in the BeppoSAX archive Compton reflection features. Iron line(s). Extend the ionization model to a larger sample of sources to investigate as the ionization changes with the source's parameters (accretion rate, black hole mass) IASF Roma-Bologna, Univ di Roma Roma Tre, Oss. astronomico di Roma, Institute of Astronomy, Cambridge-UK) Intrinsic continuum. Detailed Comptonization code (Petrucci et al. 2000, 2001). Physical parameters of the hot corona, Electron temperature T e and optical depth IASF Roma-Bologna, Univ di Roma Roma Tre, Oss. astronomico di Roma, Oss. astronomico di Brera) BeppoSAX & XMM-Newton simultaneous observations!!!!

Warm-Hot Intergalactic Medium: the missing baryons at z<2 At z~0 the baryon in stellar systems, neutral Hydrogen, X- ray emitting gas in cluster of galaxies is one order of magnitude less than the predictions. Chen & Ostriker 1999 propose that the gas is shock-heated at T K by the gravitational pull of Dark Matter and is in the form of sheets/filaments (Warm-Hot Intergalactic Medium:WHIM). Supported by recent observations of EUV and X-ray absorption lines (Nicastro et.al 2002)

Current searches are concentrated towards two approaches: narrow absorption features (OVII) produced by the WHIM in the spectrum of bright background source or detection of the emission. As for the latter method, the relevant parameter is the product of eff area * solid angle. Simulated spectra observed by a microcalorimeter (IMBOSS), assuming a FOV of 10°, an integration time of 30 ksec and assuming that all the WHIM is located at z=0.1. The quest for WHIM in soft X-rays

Gamma-ray observations: Integral and SuperAGILE 3C273. Courvoisier et al. 2003

Normal galaxies and AGN Luminosity Normal galaxies: L bol ~ erg s -1 AGN: L bol ~ erg s -1 Variations large amplitude: I/I~1 rapid: T < 1 day or shorter ==> ACCRETING BLACK HOLE Why study AGN in X-ray? They emit about 5-10 % their power in X-ray Rapid time scale variations (on timescales as small as 1000 s) The observed radiation comes from the innermost region

1) F 2-10 keV > 2x erg cm -2 s -1 2) Variations of a factor of two on timescales of days 3) Long exposure time (about a week) Continuum shape with a very good accuracy Good S/N up to 100 keV High energy cut-off and reflection hump Spectral variability study Spectral behaviour in different flux level states Broad band BeppoSAX observations. Target selection and observational strategy

Questions Compton reflection components – Is the (ionized?) accretion disc the reprocessing gas? Broad ionized iron line – There is a contribute from a far away medium? Intrinsic continuum & spectral variablity – Is a thermal Comptonization scenario a good model? High energy cut-off, E c. Photon Index vs Luminosity correlation Photon Index vs E c correlation