active galactic nuclei x-ray broad--band study a. de rosa, l. piro 1987 - 2000 ginga/rosat/asca...
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ACTIVE GALACTIC NUCLEIX-ray broad--band studyA. De Rosa, L. Piro
1987 - 2000 Ginga/ROSAT/ASCAIASF-RomaUniversita' di Roma La SapienzaInstitute of Physical and Chemical Research Japan
1996-2002 BeppoSAX: Broad band spectral variability. T
obs~ 1.5 Ms on bright Sy 1 galaxies
IASF-Roma, BolognaUniverista' di Roma Roma treOsservatorio Astronomico di RomaOsservatorio Astronomico di Brera
1999 - now XMM-Newton/BeppoSAX & ChandraIASF-RomaUniverista' di Roma Roma treInstitute 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 BeppoSAXobservation NGC 3783. 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. 1986
MCG-6-30-15Vaughan & Edelson 2001
Thermal Comptonization: two-phases model
Probing the close and distant environment in AGN: The reflection component and the iron line
MCG -6-30-15 ASCA. Tanaka et al. 1995
BeppoSAX Guainazzi et al 1999
Wilms et al 2001
... and the narrow iron line
Mkn 509, XMM. Pounds et al 2001
NGC 5548. 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. 1998)
NGC 5548. 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 105-107 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 assumingthat 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: Lbol
~1040- 44erg s-1
AGN: Lbol
~1040-48 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) F2-10 keV
> 2x10-11 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, Ec.
● Photon Index vs Luminosity correlation● Photon Index vs E
c correlation
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