Evolution of Perturbations in Decaying Dark Matter Models
Evolution of perturbations and
cosmological constraints
in decaying dark matter models with
arbitrary decay mass products
Shohei Aoyama
Nagoya University
Collaborators: Toyokazu Sekiguchi, Kiyotomo Ichiki & Naoshi Sugiyama
JCAP07(2014)021, arXiv:
1402.2972
KIAS workshop (2014)
3
rd
November, 2014
CDM and its problem
•
The ΛCDM model can predict
numerous cosmological observations
on large scales about
temperature anisotropy of the CMB
C
l
TT
and the large scale structure.
•
However the nature of dark matter
(eg. the mass or interactions )
is still unknown.
•
In addition, observations on
the small scale, the discrepancies
between the observations and
the theoretical predictions.
(eg. missing satellite problem)
Moore et al. (1999) [astro-ph/9907411]
http://cdn.arstechnica.net/wp-
content/uploads/2013/03/Planck_cosmic_recipe.png
Planck anomaly
Planck
collaborations pointed out that σ8 which is estimated from
C
l
TT
is larger than that from the number counts of cluster by SZ effect on
CMB by more than 2σ CL.
Planck Collaboration(2013,XX)[1303.5080]
A prescription of these problems
Some mechanisms that suppress small scale structure formation may rescue
these problems. (Ostriker & Steinhardt (2003) [astro-ph/0306402]).
Decaying dark matter (DDM) is a candidate of these problems because
product particles are generated with large momentum and smear out of the
gravitational potential which was originated by progenitor particles.
Planck Collaboration(XX)[1303.5080]
Moore+ (1999) [astro-ph/9907411]
•
We consider the DDM which decays into two product dark
matter particles. In this case, the decaying process and the
time evolutions of distribution functions of dark matter
particles can be characterized by 4 parameters.
•
In our calculation, by solving Boltzmann equations for these
product particles directly, one can take
the mass of one of
daughter particles
arbitrary
and obtain the time evolutions
of density perturbations,
C
l
TT
and σ
8
.
•
•
•
Our model of DDM
The effect on
C
l
TT
peak shift
integrated
SW
•
We consider the DDM which decays into two product dark
matter particles. In this case, the decaying process and the
time evolutions of distribution functions of dark matter
particles can be characterized by 4 parameters.
•
In this work, we set the constraint on the lifetime of DDM
from σ8 estimated from BOSS III data.
σ
8
=0.80±0.02
S
á
nchez et al.(2012)[arXiv: 1203.6616]
)
Our model of DDM
The constraint on the lifetime of DDM
The lifetime of the DDM should be longer than 200Gyr
in the case relativistic decay. This constraint is consistent with
previous works (Ichiki et al. (2004), [astro-ph:astro-ph/0403164]).
2σ anomaly
This SDSS data excluded σ
8
< 0.76 on 2 σ CL.
Planck anomaly
Favored region
The DDM whose lifetime of DDM is around 200 Gyr and
which decays into two relativistic particles can explain
observational
C
l
TT
and the number of clusters.
The power spectrum of CMB lens potential
C
l
φφ
―
m
D1
/
m
M
=0.3
―
―
m
m
D1
D1
/
/
m
m
M
M
=0.9
=0.9
―
Λ
CDM
The DDM which decays into two relativistic particles
is not
ruled out from the current CMB lensing observation.
Conclusion
•
We consider the decaying dark matter which decays two
particles and its effect on the cosmological observables.
•
Even in the case that the finite mass of one of product
particles, the lifetime should be larger than 200 Gyr.
•
DDM may reconcile the tension between the observed
σ
8
estimated from ClTT and that from number counts of
cluster from
SZ effect.
The study discusses the evolution of perturbations and cosmological constraints in decaying dark matter models, focusing on the impact on ClTT, large-scale structure, and small-scale discrepancies. Mechanisms to address these issues, such as decaying dark matter, are explored in detail. The model considered involves dark matter decay into two product particles, with parameters characterized to analyze density perturbations and other cosmological effects.
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Presentation Transcript
KIAS workshop (2014) 3rdNovember, 2014 Evolution of perturbations and cosmological constraints in decaying dark matter models with arbitrary decay mass products Shohei Aoyama Nagoya University Collaborators: Toyokazu Sekiguchi, Kiyotomo Ichiki & Naoshi Sugiyama JCAP07(2014)021, arXiv: 1402.2972
CDM and its problem The CDM model can predict numerous cosmological observations on large scales about temperature anisotropy of the CMB ClTT and the large scale structure. http://cdn.arstechnica.net/wp- content/uploads/2013/03/Planck_cosmic_recipe.png However the nature of dark matter (eg. the mass or interactions ) is still unknown. In addition, observations on the small scale, the discrepancies between the observations and the theoretical predictions. (eg. missing satellite problem) Moore et al. (1999) [astro-ph/9907411]
Planck anomaly Planck collaborations pointed out that 8 which is estimated from ClTT is larger than that from the number counts of cluster by SZ effect on CMB by more than 2 CL. Planck Collaboration(2013,XX)[1303.5080]
A prescription of these problems Some mechanisms that suppress small scale structure formation may rescue these problems. (Ostriker & Steinhardt (2003) [astro-ph/0306402]). Decaying dark matter (DDM) is a candidate of these problems because product particles are generated with large momentum and smear out of the gravitational potential which was originated by progenitor particles. Moore+ (1999) [astro-ph/9907411] Planck Collaboration(XX)[1303.5080]
Our model of DDM We consider the DDM which decays into two product dark matter particles. In this case, the decaying process and the time evolutions of distribution functions of dark matter particles can be characterized by 4 parameters. In our calculation, by solving Boltzmann equations for these product particles directly, one can take the mass of one of daughter particles arbitrary and obtain the time evolutions of density perturbations, ClTTand 8.
The effect on ClTT peak shift integrated SW
Our model of DDM We consider the DDM which decays into two product dark matter particles. In this case, the decaying process and the time evolutions of distribution functions of dark matter particles can be characterized by 4 parameters. In this work, we set the constraint on the lifetime of DDM from 8 estimated from BOSS III data. 8=0.80 0.02 S nchez et al.(2012)[arXiv: 1203.6616])
The constraint on the lifetime of DDM This SDSS data excluded 8< 0.76 on 2 CL. 2 anomaly The lifetime of the DDM should be longer than 200Gyr in the case relativistic decay. This constraint is consistent with previous works (Ichiki et al. (2004), [astro-ph:astro-ph/0403164]).
Planck anomaly Favored region The DDM whose lifetime of DDM is around 200 Gyr and which decays into two relativistic particles can explain observational ClTTand the number of clusters.
The power spectrum of CMB lens potential Cl mD1/mM=0.3 mD1/mM=0.9 CDM The DDM which decays into two relativistic particles is not ruled out from the current CMB lensing observation.
Conclusion We consider the decaying dark matter which decays two particles and its effect on the cosmological observables. Even in the case that the finite mass of one of product particles, the lifetime should be larger than 200 Gyr. DDM may reconcile the tension between the observed 8estimated from ClTT and that from number counts of cluster from SZ effect.
