Simbol-X Science

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• Mission Summary
• Simbol-X is a broad-band focusing hard-X-ray
  telescope that operates from 0.5 to 80 keV. The
  mission is sponsored jointly by CNES (French
  Space Agency) and ASI (Italian Space Agency). Its
  single optics module contains a set of nested
  nickel shells coated with special multilayers to
  boost high-energy response and field of view. Its
  focal plane detectors are a novel hybrid
  configuration, with thick-depletion silicon
  providing the low energy range and Cadmium
  Telluride the high. To achieve a long focal
  length, for large collecting area at high
  energies, the optics and detectors are on
  separate high-earth-orbit formation-flying
  spacecrafts, 20 m apart. Simbol-X will be three
  orders of magnitude more sensitive than current
  non-focusing hard-X-ray missions. Key features of
  the mission include
• Soft and hard X-ray response from novel
  detectors and multilayer coatings.
• Good angular resolution with nickel electroform
  replication mirrors like those on XMM-Newton and
  Swift XRT.
• Formation-flying to provide the long focal
  length necessary for good high-energy response.
• High-earth-orbit to provide high-efficiency
  viewing and long, uninterrupted observing.

A novel detector design provides energy response
with good energy resolution from 0.5-80 keV.
Multilayer coatings provide large effective area
out to 80 keV. The electroformed nickel mirrors
offer exceptional angular resolution above 10 keV.
Formation-flying provides the long focal length
needed for good high-energy efficiency.
Simbol-X will use a highly elliptical orbit for
increased viewing efficiency.
Simbol-X Science The wide Simbol-X discovery
space is particularly significant for advancing
the critical areas of high energy astrophysics
and cosmology black hole accretion, shock
physics, and particle acceleration. These broad
topics define the core scientific objectives of
Simbol-X and drive the mission requirements. Here
we describe several Simbol-X key projects.

• US Participation in Simbol-X
• SAO, with partners from NASA/MSFC and NASA/GSFC,
  is proposing participation by the US in the
  Simbol-X mission by providing
• Collaboration on multilayer coating development
• - SAO will use existing software to help
• design and optimize coatings for high-
• energy response. Test coatings will
• be fabricated/tested at SAO and OAB
• Thermal filter development
• - SAO will oversee fabrication of the
• thermal and optical blocking filter used

Black Hole Physics and Census The cosmic X-ray
background (CXB) is dominated by the integrated
output of all the accretion onto supermassive
black holes (SMBHs) that has taken place over all
of cosmic history. These SMBHs, which we observe
as quasars and AGNs, appear to play a key role in
galaxy formation. However, the CXB spectral
density peaks at 30 keV, well above the 10 keV
predicted from AGN currently observed to make up
the soft CXB. A population of Compton-thick AGNs
twice as large as the unobscured population
appears to be exist. Deep surveys with Simbol-X
will reveal this long-sought population,
providing crucial constraints on accretion
efficiency and feedback effects on galaxy
formation and evolution. The good image
quality and relatively large field-of-view for
Simbol-X are crucial for this census of SMBHs.
Energetic Particles in Galaxy Clusters The main
baryonic mass component in clusters is hot (kT
5-10 keV) intergalactic gas emitting in thermal
X-rays. However, radio observations reveal a
significant component of synchrotron-emitting
relativistic electrons (E 1-10 GeV) in some
clusters. The radio-emitting clusters show
evidence of recent mergers, suggesting that these
events provide the energy source of the energetic
electrons. However, the process by which the
particles are accelerated is unclear. Simbol-X
will map the inverse-Compton emission produced by
these same energetic electrons, decoupling the
degenerate contributions of particle density and
magnetic field strength that determine the radio
intensity, thereby constraining the origin of the
electrons.
Simulated Simbol-X observation of 5x5 arcmin
region of A2256 illustrating thermal and
inverse-Compton emission components, based on
ROSAT, Chandra, SAX, and RXTE observations.
Simulated 1 Msec deep survey of the Chandra Deep
Field South (blue) with Simbol-X. (red). Red
circles are Spitzer-discovered Compton-thick AGN
candidates
Black Hole Binaries Accreting BHs are observed
to have three distinct spectral states thought to
correspond to different flow configurations and
accretion rates. Thermal emission from the disk
is observed, as is a power law component whose
origin is controversial. It may arise from
Comptonization of the disk photons or from
relativistic electrons produced in jets.
Simultaneous determination of the soft and hard
spectra with Simbol-X will constrain the nature
of the hard emission, providing crucial
information on the geometry and dynamics of
accretion flows onto BHs.
Acceleration Mechanisma in Supernova
Remnants Supernova remnants are prime sources
for particle acceleration to energies approaching
the knee of the cosmic-ray spectrum. A cut-off
energy is expected in the X-ray synchrotron
spectrum that depends on the maximum electron
energy and the magnetic field strength.
High-sensitivity measurements with Simbol-X will
probe this cut-off region and help differentiate
between inverse-Compton and pion-decay models for
the energetic gamma-ray emission. The combined
soft and hard X-ray response will allow the
separation of thermal and nonthermal emission,
each of which constrain the above emission
mechanisms. The large field-of-view will permit
mapping of the emission over extended SNRs.
Cyg X-1 spectra. The peak flux shifts from soft
to hard in different states. Simbol-X will
measure both soft and hard emission components
simultaneously.