1. The cooling-flow problem
Bremsstrahlung emission ) L / n2 ) center parts cool faster.
Pressure equilibrium ) mass in-flow ) density increases.
Abel 1835
RGS Spectra
Sersic
EPIC Radial Profiles
Mariano Mendez - SRON

2. The cooling-flow problem
Heating mechanism: Magnetic reconnection? Central AGN? Turbulence?
Spatially-resolved, high-resolution spectra to map out the temperature distribution and the dynamics of the gas in the center.
500£500 2-eV resolution spectrum of the nucleus of a cluster of galaxies with XEUS.
Instrument requirements:
- FoV = As large as possible (goal 10 £ 10). Mosaic observations.
- DE = 2 eV (v ¼ few 100 km/s)
- E range = 0.3 – 12 keV (0.3 keV to reach up to z ¼ 0.05)
Mariano Mendez - SRON

3. Warm-hot intergalactic medium (WHIM)
Missing baryons at z ¼ 0
Wbaryon; WMAP =
Wbarion; observed =
Mass
Temperature
OVII
Simulations of structure formation
Mariano Mendez - SRON

4. Warm-hot intergalactic medium (WHIM)
XMM-Newton: Soft excess
emission in Cl. of Galaxies.
Possible infalling groups.
XEUS: Simulated observation
for A 2052.
Other lines: CVI, NVII, OVIII and the Fe-L complex. Abundance up to z ¼ 0.5 (after that, problems with background lines)
Properties of the emitting gas:
kT ¼ 0.2 keV
[O] ¼ 0.1 [O¯]
Mass ¼ MassCl. of Galaxies
Mariano Mendez - SRON

5. Warm-hot intergalactic medium (WHIM)
WHIM can also be detected in absorption to higher redshifts, provided enough bright background sources exist.
Instrument requirements:
- FoV = Not a driver. Snapshots of outskirts of Clusters or bright
background sources.
- DE = 2 eV (weak narrow lines)
- E range = 0.1 – 2 keV (0.1 keV ! N up to z ¼ 0.5 and O up to z ¼ 2)
Mariano Mendez - SRON

6. Active Galactic Nuclei
Mildly-ionized material in the vicinity of an AGN (warm absorber)
- Broadened lines ! vturbulent & 600 km/sec
- Outflow velocity = 200 km/sec
- Two photo-ionisation components
Mariano Mendez - SRON

7. Active Galactic Nuclei
Time-resolved spectroscopy of Seyfert 1 galaxies with sufficient spectral resolution to determine outflow velocities down to a few 100 km/s.
NGC s with XEUS
Instrument requirements:
- Effective area (»100-s time-scale variability)
- DE = 2 eV (v ¼ few 100 km/s)
- E range = 0.3 – 12 keV (constrain continuum / Fe line at ¼ 6.5 keV)
Changes in the plasma parameters related to changes in the X-ray luminosity provide information about the location of the absorbing plasma.
Mariano Mendez - SRON

8. Extreme gravity and NS equation of state
Close to NS or black holes, gravitational energy is comparable to rest-mass energy. This regime has so far not been tested.
Inside NS, r & 10 £ rnuclear. Possible exotic particles, like strangeness-bearing
baryons, pions and kaon condensates, or deconfined quarks.
Only possibility, since the Big Bang, to find those particles in nature.
Mariano Mendez - SRON

9. Neutron star equation of state
Composition of NS from Mass-Radius measurements – Possible Quark stars – Physics of nuclear interactions
OVII xy
OVII Edge
OVII Kg
OVII Kb
OVIII Lya
Ne IX w
NVII Lyb
OVII w
NVI Kg
NVII Lya
NVI Kb
CVI Lyd
CVI Lyg
CVI Lyb
NVI w
FeXXV 2-3
(z = 0.35)
FeXXVI Ha
z = 0.35
Mariano Mendez - SRON

10. Neutron star equation of state
Composition of NS from Mass-Radius measurements – Possible Quark stars – Physics of nuclear interactions
30-second exposures of the early part of a single X-ray burst, for 3 different spin frequencies of the neutron star.
Instrument requirements:
- Effective area!!!
- DE = 2 eV (to measure line width)
- E range = 0.3 – 2 keV (»10 keV ! redshifted Fe XXVI Lya)
Redshift ! M/R
Line width ! M/R2
Mariano Mendez - SRON

11. Life cycle of the elements
SNe and SNR. Explosive nucleosynthesis.
Cas A – 1 Ms with Chandra
Doppler maps
Mariano Mendez - SRON

12. Life cycle of the elements
Rare elements – ISM enrichment
XMM-Newton
XEUS
Instrument requirements:
- Detector uniformity/stability. FoV less important
- DE = 2 eV (shock dynamics)
- E range = 0.3 (to include C-K edge) to »10 keV (Fe-K edge)
Mariano Mendez - SRON