testing general relativity theories with athena€¦ · testing general relativity theories with...
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Testing General Relativity Theories with Athena
Thomas Boller MPE Garching
Andreas MüllerTU Munich, Excellence Cluster Universe, Garching
Walter Greiner Institute of Advanced Studies, Frankfurt a.M.
Peter HessInstituto
de Ciencias
Nucleares, UNAM, Mexico
1. AGN observations and Athena perspectives
2. The Pseudo‐Complex Theory
3. Tests of GR theories with Athena and GRAVITY
4. ISCO predictions from different theories and BH spin determination
Outline
1. AGN observations and Athena perspectives
the accretion flows around black holes emit significant amounts of X‐rays within only a few RG
= GM/c2
spectroscopically
resolved timing observations with Athena detectors will allow to perform
‐
spectral analysis to derive basic disc and BH parameters‐ time resolved X‐ray spectroscopy‐ fully energy‐resolved time correlation analyses
Athena provides an instrument to test different gravity theories
Example spectral fitting results on 1H0707Boller11
Rin
index Fe/solar[RG
]
[ erg cm s‐1]
RGS 1.21+‐0.35 1036+‐51 5.56+‐0.67 3.86+‐0.24
emission from matter very close to the central black hole
strong gravity and strong Compton broadening are relevant
2. The Pseudo‐Complex Theory Hess et al. 07‐11
1with 2 IXIXX IRX: pseudo‐complex number
2
2
0121
821
I
Tc
RgR new Einstein equationenergy represents repulsion
222
222
00 cos2
cos2
arr
Bamrrg
g00
: metric tensorB: new pseudo‐complex variable a: spin parameter
no coordinate singularityat r = 2m for a = 0
reversal point = ISCO = 5.3
2. Effective potential in Pseudo‐complex theory Hess et al. 07‐11effective Po
tential V
RG
repulsion at 4/3 RGsimilar to Yukawa potential in nuclear physics
for a = 0
Standard ART
Pseudo‐ComplexHess et al. 07‐11
Reversal point = ISCO = 6
minima: stable Kepler orbitsmaxima: infall into BH
Reversal point = ISCO = 5.3
Repulsion at 4/3 RG
2. The Pseudo‐Complex Theory vs. General Relativityeffective Po
tential V
Standard GRplot by A. Müller
RGRG
3. Testing GR theories with Athena and GRAVITY
3.1. Gravitational redshift zG
as a function of BH distance RG
‐
X‐ray spectroscopy (Athena)‐
sub‐mm shadowing at the GC and M87 (GRAVITY)
3.2 Keplerian frequencies as a function of RG
3.3 Time‐resolved X‐ray spectroscopy
3.4 Reverberation mapping
Riobs
significant z difference at inner radius:
Pseudo‐Complex Standard GRzPC
= 0.7 zGR
= 6.0gpc
= 0.60 gGR
= 0.14
Iobs
= g3
Irest
PC BHs are “brighter”
than standard GR BHs
tem
tobs
em
obs
pp
zg
ˆˆ
11
generalized
Doppler factor
70~)()(
GRIPCI
obs
obs
a/m = 0.998
3.1. Gravitational redshift zG
as a function of RG3.1.1 X‐ray spectroscopy with Athena
RG
zG
z in Standard ART
z in Pseudo‐Complex theorytest particle in prograde rotation
Kerr BHview from pole
a = 0.998 m
PC BH are bright
3.1. Gravitational redshift zG
as a function of RG3.1.1 X‐ray spectroscopy with Athena
significant differences in zG
between standard and PC theory
zG
RG
Schwarzschild/Kerr BHview to equator
PC BH are bright
RG
Δx = 7.5 µas= 1RS
the first image of a black hole
Fish09
image different for PC and standard GR due to different zG
3.1.2 sub‐mm shadowing at the GC (GRAVITY)
3.1. Gravitational redshift zG
as a function of RG
3.1. Gravitational redshift zG
as a function of RG3.1.2 sub‐mm shadowing in M87 (GRAVITY)
M = 6.6 x 109 Msun
RS
= 1.8 x 1015
cm
Δx = 8 µas = 1RSobserving:‐
sub mm shadowing
‐
disk tomography
8 as
image different for PC and standard GR due to different zG
A. Müller
3.2 Keplerian frequencies as a function of RG
RG
c / m]
Kerr BHa = 0.995 m
maximum at11 minutes fora = 0.995 m
GR
PC theory
QPO time scale ~ 17 min = 265 mas =34 RS
GC: X‐ray and sub‐mm flares
a > 0.5
test:
compare QPO frequencies from theories with AthenaAthena
observations
AGN hot spots Iwasawa04
The trajectory of the infall The dynamical spectrum in the energy‐time plane. The spectrum for time bins
3.3 Tracing the infall of matter into black holes with Athena Athena time‐resolved X‐ray spectroscopy
T. Boller, A. Müller, C. Räth, M. Dovciak, J. Svoboda
matter is falling on a Schwarzschild BH, disappearing at event horizon at 2 RG
3.3.1 The theoretical model in the standard theory
3.3.2 Feasibility studies for AthenaAthena
(Time‐resolved spectra)
First infall segment: The relativistic line isclearly visible
Coun
ts s‐1 keV
‐1
Third infall segment: the infalling matter is receding from the observer.
Coun
ts s‐1 keV
‐1Fourth infall segment: the relativistic line
profile becomes visible again at around
4.5 keV
Coun
ts s‐1 keV
‐1
Energy [keV]
Significant differences are expected for
‐ the Fe Kline profiles‐ the infall frequencies
for the Standard theory and the Pseudo‐Complex Theory which can be measured and tested with AthenaAthena.
3.3 Tracing the infall of matter into black holes with time‐resolved X‐ray spectroscopy
3.3.2 Feasibility studies for AthenaAthena
3.4 Reverberation mapping 3.4.1 fully energy‐resolved timing observations with AthenaAthena
The scalar „time lag“
can be extended with
AthenaAthena
observations to a
two‐dimensional
function
depending
on
the
pair
of
wavelengths
for which the time series are compared with each other.
This will reveal which parts of the spectra are connected with each other and how these relations persist or change during the rotation
of matter and its infall into the black hole.
4. ISCO predictions from Pseudo‐Complex theory and standard GR using effective potential approach: BH spins becomes different
Standard GR
ISCO at 6 RG
for Schwarzschild BH
ISCO as a function of BH spin:solved in Standard GR
Pseudo‐Complex Theory
ISCO at 5.3 RG
for PC Schwarzschild BH
ISCO as a function of BH spin:in prep. for PC theory
Summary
several
tests
have
been
proposed
to
work
out
the theoretical
and
observational prospects
in
testing
the
Pseudo‐Complex theory and the Standard GR theory
with
spectroscopically
resolved
timing
observations
made possible
with
the
AthenaAthena
detectors, Athena
observationsAthena
observations
allow
to
test
and
to
discriminate
between
different
GR theories