Post on 23-Mar-2020
Indirect Detection of Neutrino Portal Dark Matter
Barmak Shams Es Haghi U. Pittsburgh
with Brian Batell, Tao Han - arXiv:1704.08708
TeVPA Aug 9, 2017
Non-gravitational Interaction of DM: Renormalizable Portals
•Scalar portal
•Vector portal
•Neutrino portal
Motivations For Neutrino Portal:
•Explains neutrino mass (via seesaw mechanism)
•Baryogengesis through leptogenesis
•Dark Matter
(�1S+�2S2)|H|2
Bµ⌫Vµ⌫
LHN
1
L � �1
2m2
��2 �
1
2mNNN +
1
2m���+ yLHN + �N��+ h.c.
�
Model:
h�vi =
hRe(�)2(m� +mN ) + Im(�)2(m� �mN )
i2
16⇡[m2� +m2
� �m2N ]2
✓1� m2
N
m2�
◆1/2
Parameters: {�,m�,m�,mN} �! {h�vi,m�,mN}
Relic Abundance & Cosmology:
h�vithermal = 2.2⇥ 10�26 cm3 s�1
h�vi ⇠ h�vithermal
Mass range: Unitarity + Thermal WIMP + BBN
Seesaw:y ' 10�6
⇣ mN
246GeV
⌘1/2 Yukawa coupling is small, Direct Detection/Production at Collider are challenging.
1 GeV < mN < m� . 20 TeV
mN < m� < m�
Thermal equilibrium:
m⌫ ⇠p
(�m⌫)atm ⇠ 0.05 eV !2
Z2 symmetry
Indirect Detection: DM can have multiple annihilation channels
Quantity of interest:
Image Credit: Sky & Telescope / Gregg Dinderman
Energy spectrum per DM annihilation in the photon, electron,… channels
Spectrum Simulation
3
Simulation Chain:
SM_HeavyN_NLO Model Files
(SM+ 3 heavy neutrinos)
MadGraph5_aMC@NLO (Generating Events)
Pythia (Hadronize + Shower)
dNa,f
dEa
χχ→��
�χ = ��� ���
�� = �� ����� = �� ����� = ��� ���
� �� �����-�
�
��
���
�� [���]
� ����
�/��
�[���
]
�- ������� �������
χχ→���χ = ��� ���
�� = �� ����� = �� ����� = ��� ���
� �� �����-�
�
��
��_ [���]
� �_� ���_/�� �
_[���
]
� ������� �������
χχ→���χ = ��� ���
�� = �� ����� = �� ����� = ��� ���
��-� � �� �����-�
�
��
���
�γ [���]
� ��
γ/��
γ[���
]
γ ������� �������
Alva, Han, Ruiz 2015 Degrande, Mattelaer, Ruiz , Turner 2016
(Spectrum)
4
CMBe� + p ⌦ H + �Z ~1100
DM annihilation products:
• neutrino: weakly interacting, so they escape
• protons: highly penetrating and poor at transferring energy
• electron/positron & photon: heating and ionization occurs primarily through them
binding energy : 13.6 eV
✓dE
dV dt
◆
injected
= ⇢2DM(z)h�vimDM
= (1 + z)6⇢2crit⌦2DM,0
h�vimDM
✓dE
dV dt
◆
deposited
= f(z)
✓dE
dV dt
◆
injected
Introducing Efficiency factor: (universal: redshift-independent, model-independent)
fe↵(mDM) =
RmDM
0 EdEh2fe+
e↵ (E)(dNdE )e+ + f�e↵(E)(dNdE )�
i
2mDM
fe↵(mDM)h�vimDM
< 4.1⇥ 10�28cm3/s/GeVPlanck limit:Ade et al. ,2016 5
Slatyer, 2016
�����⟨σ�⟩����������⟨σ�⟩�������λ [�ϕ = �χ]
-��-����
-��
-����
-��
-����
���
�
� π
� χ=� �
�� ��� ���
��
���
���
�χ [���]
��
[���
]
������ ��� ��% ���� �����
6
Gamma rays from dwarf spheroidal galaxies (dSphs)
very clean sources for indirect detection:
• Large DM content
• Having few stars and little gas, negligible background
6 years of Fermi Large Area Telescope (LAT) data:
The Fermi analysis is based on a joint maximum likelihood analysis of 15
dSphs for gamma ray energies in the 500 MeV - 500 GeV range.
d�a
dEa=
1
4⇡
h�annvi2m2
DM
X
f
dNa,f
dEaBf ⇥
Z
V⇢
2DM(~x) dV
Flux Particle PhysicsAstrophysics (J - factor) 7
�����⟨σ�⟩����������⟨σ�⟩�������λ [�ϕ = �χ]
-��
-����-��
-����
-��
-����
���
�
� π� χ=� �
�� ��� ���
��
���
���
�χ [���]
��
[���
]
����� ����� ��% ���� �����
8
Antiprotons
Antiproton content of the astrophysical background is rare:
• its production costs us a lot of energy
• energy flux of cosmic rays is very steep peaked around 0.1 GeV
DM annihilation will produce as much antiproton as proton!
Antiprotons deflection by the Galactic magnetic field and their propagation may be seen
as a diffusion process.
The Alpha Magnetic Spectrometer (AMS-02) has provided the most precise measurements of the cosmic ray proton and antiproton flux to date.
9
⇠ 7mP
χχ→���χ = ��� ���
�� = �� ����� = �� ����� = ��� ���
� �� �����-�
�
��
��_ [���]
� �_� ���_/�� �
_[���
]
� ������� �������
Used Einasto profile & the MED propagation scheme
�2(m�, h�vi)� �20 4
is the best fit assuming no primary DM antiproton source
�20
Giesen, et al. 2015
10
�����⟨σ�⟩����������⟨σ�⟩�������λ [�ϕ = �χ]
-�� -�� -�� -��
���
�
� π
� χ=� �
�� ��� ���
��
���
���
�χ [���]
��
[���
]
���-�� ���������� �����
11
Galactic Center Gamma Ray Excess Interpretation
Calore, Cholis, Weniger 2014
� χ=� �
�� �� �� �� ���
��
��
��
��
���
�χ [���]
��
[���
]
●
●●●●
●●●●● ● ● ●
● ● ● ● ●
●●
● ●
●
●
-
- ---
---- - - - -
- - - - -
--
- -
-
-
- -
--
---
- - - - -- - - - -
--
--
-
●●----χχ→ ��
�χ=���� �����=���� ���
�� ��������������
� �� �����-�
��-�
��-�
��-�
�γ [���]
� γ� Φ
γ[���
/(��
� �����)]
��� ����-������ �����-��� ��������
8>>><
>>>:
h�vi = 3.08⇥ 10
�26cm
3s
�1
m� = 41.3 GeV
mN = 22.6 GeV
�2/dof = 14.12/23
12
Goodenough, Hooper 2009 Various analyses of Fermi-LAT data show an excess of gamma rays coming from the central region of the Milky Way
best-fit point
�-�⟨σ�⟩=���⨯��-�����
���-��
����� �����������
� χ=� �
�� ���
��
���
�χ [���]
��
[���
]
Einasto & MAX
Burket & MED
log10(Jk) = log10(¯Jk)� 2�k
log10(Jk) = log10(¯Jk) + 2�k
GC excess
13
Future prospects
Fermi-LAT: The upcoming change: fast discovery of new dSphs
Fermi-LAT 15 years observations: improvement on the cross section by a factor of a few, probing DM with masses larger than 100 GeV in neutrino portal.
Ground-based imaging air Cherenkov telescopes like CTA: will be able to probe heavy TeV-scale DM annihilation
improve cross section sensitivity by an order of magnitude
14
Summary
• Neutrino portal is an economical and predictive model to
explain thermal WIMP DM.
• Type-I seesaw model necessitates exploring indirect detection
methods.
• Astrophysical data constrain the model, and it provides an
interpretation of Galactic Center Gamma Ray Excess.
• Future detectors will be able to further probe heavy TeV-scale
DM annihilation.
15
Thank you!
Backups
Photon Cooling Processes (ordered by increasing photon energy)
• Photoionization
• Compton scattering
• Pair production off nuclei and atoms
• photon-photon scattering
• pair production off CMB photons
tcool
⌘ 1/(d lnE/dt)
tH ⌘ 1/H(z)
Electron cooling process: electrons from the annihilation products, or from Compton scattering and pair
production considered above lose their energy largely by inverse Compton scattering CMB photons.
Slatyer, Padmanabhan, Finkbeiner 2009
The quantity of interest in the likelihood analysis : the energy flux for kth dwarf and jth energy bin
'k,j =
Z Ej,max
Ej,min
E��,k(E)dE
For each dwarf and energy bin, Fermi/LAT provides likelihood, as a function of flux
Lk(mDM , h�vi, Jk) = LN (Jk|Jk,�k)Y
j
Lk,j('k,j(mDM , h�vi, Jk))
LN (Jk|Jk,�k) =1
ln(10)Jkp2⇡�k
e�(log10(Jk)�log10(¯Jk))
2/2�2k
L(mDM , h�vi, {Ji}) =Y
k
Lk(mDM , h�vi, Jk)
� lnL(mDM , h�vi) = lnL(mDM , h�vi, { ˆJi})� lnL(mDM , dh�vi, {Ji})
� lnL(mDM , h�vi) 2.71/2
J-factor, introduced as as a nuisance parameter
DM density profile (in the galaxy) from N-body simulations:
PPPC 4 DM ID
Antiproton diffusion process
@f
@t�K(K).r2f +
@f
@z(sign(z) f V
conv
) = Q� 2h�(z)(�ann
+ �non-ann
)
Model � K0
(kpc
2/Myr) Vconv
(km/s) R(kpc) L(kpc)
MIN 0.85 0.0016 13.5 20 1
MED 0.70 0.0112 12 20 4
MAX 0.46 0.0765 5 20 15
f(t,~r,K) = dNp/dK K = E �mp
di↵usion coe�cient function : K(K) = K0�(p/GeV)
�
source term from DM annihilation:Q =
1
2
✓⇢(~x)
mDM
◆2 X
f
h�vifdN
fp
dK
�p(K,~r�) =vp
4⇡
✓⇢(~x)
mDM
◆2
R(K)X
f
1
2h�vif
dN
fp
dK
PPPC 4 DM ID