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X線天文からのコメント

鶴 剛（京都大学・物理・宇宙線研究室）
2020.09.08(tsuru@cr.scphys.kyoto-u.ac.jp 075-753-3868)

20200908̲Axion̲XrayAstro̲v0

rse if mA & 20 eV.

The interaction with fermions f has derivative form and is 2inv

X線衛星観測による制限

Figure 91.1: Exclusion plot for ALPs as described in the text.

X線衛星観測による制限

3

B
Figure 4. Some example photon survival probability curves using one representative realization of Model-B for the magnetic ﬁeld structure, pγ(E). Left panel: curves
for ﬁxed mass (log10 (ma eV) = -12.7) and magnetic ﬁeld conﬁguration, but various values of the coupling constant log10 (gag GeV-1) = -11.9 (black), −12.1(blue), −12.3 (green), −12.5 (magenta), −12.7 (red). Right panel: curves for ﬁxed coupling constant log10 (gag GeV-1) = -12.1 and magnetic ﬁeld conﬁguration, butvarious ALP masses log10 (ma eV) = -12.3 (black), −12.5 (blue), −12.7 (green), −12.9 (red).

aChandra X-ray Observatory

グレーティングによる精密分光
The Astrophysical Journal, 890:59 (9pp), 2020 February 10Counts

4. Constraints on ALP Parameters

Equipped with the library of photon survival probability
curves, we can now use our HETG spectra of NGC1275 todetermine the allowed regions of the (ma, gag )-plane.
In order to determine the probability of the parameters given
this data, appropriately marginalized over the unknown cluster
magnetic ﬁeld conﬁguration, we follow the Bayesian procedureof Marsh et al. (2017). We assume ﬂat priors on lnma and lngag
intherange
andlog10 (ma eV) Î [-30, -11.1]
1
log10 (gag GeV ) Î [- 19, - 10.7]. We will ﬁnd that ourresults are insensitive to the minimum allowed mass, and theparticular choice considered here corresponds to cosmologically large Compton wavelengths of the ALPs. The minimum
allowed coupling constant corresponds to the inverse Planck
mass, below which quantum gravitational corrections areexpected to become important. We also assume ﬂat priors on
the randomly generated magnetic ﬁeld conﬁgurations, labeled
by iA/B. Motivated by the initial ﬁtting presented in Section 2,
our baseline spectral model for NGC1275 consists of a powerlaw continuum modiﬁed by the effects of Galactic absorption(NH = 1.32 ´ 10 21 cm-2 ; Kalberla et al. 2005).
For a given magnetic ﬁeld model (Model-A and Model-B),
we takeour photonprobabilitycurves
Figure 5. Example photon survival probability curves for one choice of ALP
Figure3. Lefteachpanel: ofbest-ﬁtting
power-lawsurvival
model to the
combined HEG(blue) aparameters (ma = 10-12eV, gag = 10-12 GeV−1) and two representativeig,
andthemagnetic
ﬁeldrealization(indexedmodel.
by mThebest-ﬁtting
datahavebeen
heavilybinnedfor
thepurposesofplotting,A B ),aag
magnetic ﬁeld realizations from each of Model-A (black) and Model-B (red).
ratiosof
thedatato
thebest-ﬁtting
modelfor
theHEG(blue)
andMEG(red). Th
multiply by the power-law spectrum (modiﬁed by Galactic
absorption), and then ﬁt to the unbinned HEG/MEG spectra,
minimizing
the C-statistic
the HEG/MEG
photon indicescluster.
However,the simpleover
analytic
model of Churazov
et al.
andHEG/MEG
normalizations.
Thelowest
massesin(2003) does not apply to small radii, r<10 kpc, where ourit)where
yieldtheﬁts
that aremodel library the(log) = -13.6
are actually realized in nature, but are simple models that
10 (ma eV
underestimateselectrondensity,andspherically
https://www.chandra.si.edu/photo/2019/coma/
https://chandra.harvard.edu/press/cxcfact.html
indistinguishable from the massless case, and hence thesecapture some aspects of the underlying physicalmagnetic ﬁeld.

X-ray Energy

Reynolds+20 ApJ Lett., 890(1), 59. http://doi.org/10.3847/1538-4357/ab6a0c

X線衛星の観測技術

4

X-ray op!cs

IAXO

LSolaraxionflux

できるだけ小さい面積

MAGNET COILA

B field

Movable pla"orm

MAGNET COIL
X-ray detectors
ShieldingMultiSuperMirroroffor
Hard X-rays(> 10keV)
Figure Layer
15. Conceptualarrangement
an enhanced
axion helioscopewith X-ray focalization. Solaraxions are converted into photons by the transverse magnetic field inside the bore of a powerful
The resulting quasi-parallel beam of photons of cross sectional area A is concentrated by
NuSTARmagnet.
an appropriate X-ray optics onto a small spot area a in a low background detector. The envisaged
design for IAXO, shown in figure 16, includes eight such magnet bores, with their respective optics
and detectors.

field of the cluster [322]. Depending on the dark matter lifetime, the line signal can be
reproduced for axion-photon couplings of order 10 15 GeV 1 . ga . 10 10 GeV 1 for
ALP masses ma < 10 12 eV. Interestingly, IAXO will be able to test a relatively large
region of this parameter space.

JCAP06(2019)047

できるだけ大きな面積γThe morphology of the 3.5 keV signal can be explained by ALP-photon conversion.
The stronger signal in clusters would then arise from the larger and more extended
magnetic fields present in clusters compared to galaxies. As Perseus is a close cool-corecluster, observations of Perseus only cover the central region with a large magnetic field
1(as B / ne (r) 2 , the magnetic field is significantly enhanced in the central high-ne coolArmengaud, E., Avignone, F. T., Betz, M., Brax, P., Brun, P., Cantatore, G., et al. (2014, January 14). Conceptual Design of the International Axion Observatory (IAXO).
core). http://doi.org/10.1088/1748-0221/9/05/T05002
The extremely strong signal in the centre of Perseus would then be a consequence
Journal of Instrumentation.

一人のX線天文屋から…
• X線天文は，実際の実験でも，技術の面でも，AXION / ALP の観測に寄与をしています．
• ただ，日本のX線コミュニティはそれをあまり知りません．
残念ですし，もったいない．．．
• ぜひ，研究交流をさせていただけると，うれしく思います5

我々の武器6

Xrism 衛星（2021年度打ち上げ予定）

FORCE衛星（2020年代後半の実現を目指す）

マイクロカロリメータによる精密分光

低バックグラウンド広帯域X線精密撮像

第24期学術の大型×7銀河団等の背景のAGNのスペクトル観測

BGD (ph/s/keV/arcmin2/cm2)

研究計画マスター
プランに採択済み1010-4 41010-5 5

チャンドラXMM

すざく混入CXBNuSTAR

1010-6 61010-7 7
混入CXB
8-81010112220%

FORCE2055
101020
EnergyX-rayX-ray
Energy(keV)

NuSTARの数倍の角度分解能

50508080

点源感度 10倍

20191024 default
星間磁場で変換されたX線（kT>10keV）
SOI 500um 単層 + CdTe (27keV使
それぞれの検出器の地上実験応用もありですね

銀河団磁場でX線 → Axionの変換

20191024 default
赤色巨星コアの黒体放射AxionがGiannotti+17