Indirect Detection of Neutrino Portal Dark Matter · Indirect Detection of Neutrino Portal Dark...

Post on 23-Mar-2020

4 views 0 download

Transcript of Indirect Detection of Neutrino Portal Dark Matter · Indirect Detection of Neutrino Portal Dark...

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