ИI ЯN ИR

Dark Matter searches with Spectrum-Roentgen-Gamma (SRG) space observatory

Dmitry Gorbunov

Institute for Nuclear Research of RAS, Moscow

New Frontiers in Physics, ICNFP 2020 Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 1 / 32 ИI ЯN ИR eROSITA (0.2-10 keV), ART-XC (4-30 keV)

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 2 / 32 ИI ЯN ИR

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 3 / 32 ИI ЯN ИR

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 4 / 32 ИI ЯN ИR

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 5 / 32 ИI ЯN ИR

Launch on 13 July 2019 from Baikonur

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 6 / 32 ИI ЯN ИR

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 7 / 32 ИI ЯN ИR

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 8 / 32 ИI ЯN ИR

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 9 / 32 ИI ЯN ИR

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 10 / 32 ИI ЯN ИR

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 11 / 32 ИI ЯN ИR

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 12 / 32 ИI ЯN ИR eROSITA observation of Shapley Supercluster

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 13 / 32 ИI ЯN ИR MW stars, LMC and clusters with eROSITA

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 14 / 32 ИI ЯN ИR Variable sources and clusters with ART-XC

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 15 / 32 ИI ЯN ИR ART-XC: 3 months in the survey mode

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 16 / 32 ИI ЯN ИR Full-sky observation by ART-XC

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 17 / 32 ИI ЯN ИR Main goal of the SRG mission

To build a map of the brightest X-ray sources on the sky

Find all the galaxy clusters emitting X-rays (M > 3 1014M ) find filaments, galaxy groups emitting X-rays × — study the structure formation and probe Dark Energy Active Galactic Nuclei — one more population to investigate BAO — millions of supermassive BH in AGN centers Galactic sources of X-rays — accretion of White Dwarfs, Neutron stars, BH in binary system Transient sources Search for new sources of X-rays, e.g. Dark Matter

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 18 / 32 ИI ЯN ИR Searches for DM with SRG

Specific DM candidates with signatures in X-rays WIMPs with bremstruhlung

¯ + X + X e + e− + γ −→ excess of a certain form in the spectrum annihilation into photons, e.g. DM models with hidden photons

X + X¯ γ + γ (0) −→ 4 3 a line of 10− -10− width in galactic spectra DM radiative decay, e.g. axions, sterile neutrinos, etc

a γ + γ , νs ν + γ −→ −→

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 19 / 32 ИI ЯN ИR

Three Generations of Matter (Fermions) spin ½ I II III

mass→ 2.4 MeV 1.27 GeV 171.2 GeV 0 charge→ ⅔ u ⅔ c ⅔ t 0 g name→ up charm top gluon Left Right Left Right Left Right

4.8 MeV 104 MeV 4.2 GeV 0 -⅓ d -⅓ s -⅓ b 0 γ down strange bottom photon Left Right Left Right Left Right Quarks 0 eV 0 eV 0 eV 91.2 GeV 0 >114 GeV 0 e 0νμ 0 ντ 0 0 ν Z 0 H electron muon tau weak Higgs neutrino force boson neutrinoLeft Left neutrinoLeft

0.511 MeV 105.7 MeV 1.777 GeV 80.4 GeV spin 0 ± -1 -1 -1 ± 1 m 125 GeV e μ τ W H ≈ weak electron muon tau force Left Right Left Right Left Right Leptons Bosons (Forces) spin 1

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 20 / 32 ИI ЯN Sterile neutrinos ИR

Three Generations of Matter (Fermions) spin ½ I II III

mass→ 2.4 MeV 1.27 GeV 171.2 GeV 0 charge→ ⅔ ⅔ ⅔ 0 t t t h h h t t t g f f f g g g i i i e u e c e t name→ L up R L charm R L top R gluon

4.8 MeV 104 MeV 4.2 GeV 0 s

k - - 0 r -⅓ ⅓ ⅓ t t t a h h h t t t f f f

u γ g g g i i i e d e s e b Q L down R L strange R L bottom R photon 1 <0.0001 eV ~10 keV ~0.01 eV ~GeV ~0.04 eV ~GeV 91.2 GeV >114 GeV n i 0 0 0 0 p 0 0 s

μ τ ) t νe t ν t ν

f f f 0 N N N s Z e e e H 1 muon 2 tau sterile3 e electronL L L weak Higgs sterile sterile neutrino c neutrino neutrino neutrino neutrino neutrino r force boson o F

105.7 MeV 1.777 GeV ( 80.4 GeV 0.511 MeV spin 0 s

s ± n -1 -1 -1 n ± 1 o t t t o t m 125 GeV

h h h H s t t t p f f f g g g ≈ o i i i e e e e μ e τ W L R L R L R L

B weak electron muon tau force

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 21 / 32 ИI ЯN Sterile neutrinos ИR Seesaw mechanism: M 1 eV N 

With mactive . 1 eV we work in the seesaw (type I) regime:

c M c L = Ni∂/N f L HN˜ N N N + h.c. N − e − 2 Higgs gains H = v/√2 and then h i f !  1  c 0 v ν V = ν , N √2 e + h.c. N 2 e v f M N √2 N

For a hierarchy M MD = v f we have N  √2 flavor state νe = U ν + θ N with U 1 and 1 ≈ MD v f active-sterile mixing: θ = = 1 MN 2MN  and mass eigenvalues

M and m = θ 2 M M ≈ N − active N ≪ N

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 22 / 32 ИI ЯN Sterile neutrino as Dark Matter ИR Sterile neutrino: well-motivated keV-mass Dark Matter

massive fermions giving mass to active neutrino through mixing (seesaw)

f 2v 2 m M 2M a 2 N θ N ∼ MN ∼

unstable, N ννν is always open → but exceeding the age of the Universe if

(applicable for MN < MW )  5  2 5 2  2 7 50keV τN 3ν 1/ GF MN θαN = θ < 1.5 10− → ∼ ⇒ × MN

2 with seesaw constraint ma θ M ∼ N  2 4  11 4 τN 3ν 1/ GF MN mν 10 yr (10keV/MN ) → ∼ ∼

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 23 / 32 ИI ЯN Sterile neutrino as Dark Matter ИR Sterile neutrino: indirect searches

f 2v 2 m M 2M a 2 N θ N ∼ MN ∼

unstable, but exceeding the age of the Universe if

θ 2  10keV 5 < 3 3 10 MN × − DM sterile neutrinos can be searched at X-ray telescopes because of two-body radiative decay give limits in absence of the feature

3 a narrow line (δEγ /Eγ v 10 ) ∼ ∼ − at photon frequency Eγ = MN /2

θ 2  10 keV 4 11 . 10− MN

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 24 / 32 ИI ЯN Sterile neutrino as Dark Matter ИR . . . 6 years ago: Dark Matter decay observed in X-ray?

10-7

) DM overproduction θ

α Excluded by X-ray observations (2 -8 2 10

0.36 10-9 0.34 M31 ON-center No line at 3.5 keV 10-10 0.32

0.30 10-11 0.28 10-12 Not enough DM

[cts/sec/keV] 0.26 Tremaine-Gunn / Lyman- 0.24 Interaction strength Sin 10-13 Normalized count rate 0.22 1 2 5 10 50 1⋅10-2 No line at 3.5 keV Dark matter mass MDM [keV] 8⋅10-3 Line at 3.5 keV 6⋅10-3 4⋅10-3 Astro-H SXS -3 Perseus, 1 Msec 2⋅10 −3 0 [cts/sec/keV] 0⋅10 kT = 6.5 keV, 0.6 solar Data - model -3 -2⋅10 1.5×10 z=0.0178 -3 v(baryons) = 300 km/s -4⋅10 3.0 3.2 3.4 3.6 3.8 4.0 v(line) = 1300 km/s Energy [keV] Stacking signals from many 3.62 keV −3 Ar XVII DR Ca XIX 10 galaxies, especially Perseus (ph cm  s  keV ) Flux Ar XVII cluster, then Andromeda Ar XVIII

1402.2301, 1402.4119 3.55 keV Line −4

5×10 3 3.2 3.4 3.6 3.8 Energy (keV) Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 25 / 32 ИI ЯN Sterile neutrino as Dark Matter ИR Production in oscillations

∂ ∂ fs(t,p) Hp fs(t,p) =Γ α P (να νs) fα (t,p). ∂t − ∂p → 2 4 Γα ∝ GF T E is the weak interaction rate in plasma  t  P ( ) = sin2 2 mat sin2 , να νs θα mat → · 2tα vac mat tα tα = q , 2 vac 2 sin 2θα + (cos2θα Vαα t ) − · α tmat 2E sin2θmat = α sin2θ , tvac = α tvac α α 2 α · MN sign of the effective plasma potential matters:

Vαα < 0 = mixing gets suppressed ⇒ Vαα > 0 = amplification via resonance ⇒

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 26 / 32 ИI ЯN Sterile neutrino as Dark Matter ИR DM from oscillations: (DW& ShF) case 1 10-4 LMC MW M31 vac
2 -6 106 n / s cos2θα Vαα t 10 ν MW − · α e 0.0 SPI non-resonant: 10-8

2 4 θ Vαα #G T E 2 F 2 -10 ∼− 10 2

sin 4 resonant production in 25 16 12 8 -12 70 the lepton asymmetric 10 250 700 plasma 2500 -14 2 10 Vαα +#G T µ ∼ F Lα 10-16 1601.07553 100 101 102 M / keV 1

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 27 / 32 ИI ЯN Sterile neutrino as Dark Matter ИR

. . . present searches 1609.00667, 1706.03118

Chandra M31 NR production upper limits on -10 10 mixing: from X-ray NuSTAR Fermi-GBM MW searches

-11 Bullet Cluster lower limits on mass: 10 from structure MW Satellite formation with pN T , Counts DM free streaming ∼ INTEGRAL MW

θ -12 2 10 too fast at T = 1 eV 2 νM SM n i s

10-13 BBN

10-14

NuSTAR GC (2016) 10-15 101 mχ [ keV ] Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 28 / 32 ИI ЯN Sterile neutrino as Dark Matter ИR

1908.09037, 2007.07969

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 29 / 32 ИI ЯN Sterile neutrino as Dark Matter ИR

Huge advantage thanks to the survey mode 2007.07969

Drop the regions with visible matter take mostly dark halo (e.g. Galactic center, disc)

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 30 / 32 ИI ЯN Sterile neutrino as Dark Matter ИR

SRG observation of MW 2007.07969

time needed to reach the BBN limit

4.0 100 ART-XC ART-XC 2 Constraints from BBN eROSITA 2 Constraints from BBN eROSITA 3.5 GC (Radius = 1.5 ) GC (Radius = 60 ) 80 3.0

2.5 60

2.0

40 1.5 Observation time [Ms] Observation time [Ms]

1.0 20 0.5

0.0 0 5.0 7.5 10.0 12.5 15.0 17.5 20.0 22.5 25.0 5.0 7.5 10.0 12.5 15.0 17.5 20.0 22.5 25.0 Energy [keV] Energy [keV] 24 days. . . 1 year

one can amplify the DM production with more ingredients, e.g. scalars 1705.02184, 1809.09123 it can be just one of the DM components. . .

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 31 / 32 ИI ЯN Sterile neutrino as Dark Matter ИR Summary and Outlook

SRG operates perfectly for 0.5 year in the survey mode, 3.5 years are ahead, and then 2.5 years for a particular sources There are many discoveries in astrophysics (distant quasars, etc) and we are waiting for cosmological data SRG can also start hunting for the DM Excellent sensitivity to the sterile neutrino 25 ks for Galactic Center and 0.4 Ms for large angle are enough for 5 σ discovery of 3.5 keV line.

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 32 / 32 ИI ЯN ИR

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 33 / 32 ИI ЯN ИR

Backup slides

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 34 / 32 ИI ЯN ИR Limits form SN

Energy transfer 102 Η=0

10-2 L Energy loss 10-3

-4 keV 10 H s 10-5 m

10 θ 10-6 2 2

10-7 2 sin Wsh =0.1 10-8 1% 10% 10-9 100% 1 10-10 -12 -10 -8 -6 -4 -2 10 10 10 10 10 10 1 10-11 1 10 sin2 H2 ΘL Sterile Neutrino Mass (keV)

1102.5124

1603.05503

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 35 / 32 ИI ЯN ИR

Results for details see 1705.02184

ΩN /ΩDM Tc, MeV 1 0 1 10− 10 10− 500 2 2 10− 10− 2 1 10 3 10− 3 10− 10−

4 4 10− 2 10− 10−

) 10 ) 5

5 θ θ 10− 10− (2 (2 2 2 6 3 6 10− 10− 10− sin sin 7 7 1 10− 10− 4 10− 8 8 10− 10−

9 9 1 10 5 10− 10− − 10− 10 10 10 10 − 100 101 − 100 101 M, keV M, keV

2 Important: ma θ M ∼ N 1 seesaw light sterile neutrino (dashed lines: ma 0.008 0.2 eV) ∼ − 2 can be directly tested !! (between green and white lines)

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 36 / 32 ИI ЯN ИR Sterile neutrino spectra from resonant production

2 12 2 12 2 12 sin (2θ) =1.0 10− 5 sin (2θ) =1.0 10− sin (2θ) =1.0 10− 6 msn=7.1 keV × msn=10.0 keV × × 2 11 2 11 3 msn=15.0 keV 2 12 sin (2θ) =1.0 10− sin (2θ) =1.0 10− sin (2θ) =2.5 10− × × × 2 11 2 11 2 12 sin (2θ) =2.5 10− sin (2θ) =2.5 10− sin (2θ) =5.0 10− × × × 2 10 2 11 2 11 5 sin (2θ) =1.0 10− sin (2θ) =5.0 10− sin (2θ) =1.0 10− × 4 × × 2 10 2 10 2 11 sin (2θ) =2.5 10− sin (2θ) =1.0 10− sin (2θ) =2.5 10− × × × 2 10 2 10 2 11 sin (2θ) =5.0 10− sin (2θ) =2.5 10− sin (2θ) =5.0 10−

] × ] × ] ×

3 4 2 9 3 2 10 3 2 10 sin (2θ) =1.0 10− sin (2θ) =5.0 10− sin (2θ) =1.0 10−

0 0 0 2 × × × 1 2 9 1 3 2 10 1 2 10

× sin (2θ) =1.8 10− × sin (2θ) =9.9 10− × sin (2θ) =4.8 10−

[ × [ × [ ×

) 3 ) ) x x x ( ( ( f f f

2 2 2 2 x x x 2 1

1 1

0 0 0 10-1 100 10-1 100 10-1 100 x [p/T] x [p/T] x [p/T]

1000 1601.07553

100 P(k) 3 = k 2 ∆ 10

CDM 2 θ −10 L6 = 8, sin (2 ) = 2.1x10 L = 10, sin2(2θ) = 3.7x10−11 6 2 θ −11 L6 = 12, sin (2 ) = 1.6x10 1 0.1 1.0 10.0 100.0 1/3 k [h/Mpc] p T  g ,0  1611.00005 v = hmi = 3.15 m g∗ ∗ Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 37 / 32 ИI ЯN ИR Sterile neutrino: a vast region of mass

Within the seesaw paradigm, as far as

2 2 f v 2 ma 2 MN θ MN ∼ MN ∼

Any set (mass scale MN , Yukawa coupling f ) is viable

And with special tunning or symmetry larger (but not smaller) mixing is viable

1 mˆ ˆf T ˆf v 2 a ˆ ∼ MN

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 38 / 32 ИI ЯN ИR Sterile neutrino lagrangian

Most general renormalizable with2(3. . . ) right-handed neutrinos NI

M c ˜ NI L = N i∂/N f Lα HN N N + h.c. N I I − αI I − 2 I I

Parameters to be determined from experiments

9(7): active neutrino sector 11: N = 2 sterile neutrinos 18: N = 3 sterile neutrinos: 2 ( works if mν = 0 !!!) 2 ∆mij : oscillation 3: Majorana masses M experiments NI 2: Majorana masses MNI 15: New Yukawa couplings fαI 3 θij : oscillation experiments 9: New Yukawa couplings f αI which form 1 CP-phase: oscillation which form 3: Dirac masses MD = f H experiments 2: Dirac masses MD = f H 3+3: mixing anglesh i 2(1) Majorana phases:0 νee, 3+1: mixing anglesh i 3+3: CP-violating phases 0νµµ 2+1: CP-violating phases 3 3 1(0) mν : H He + e + ν¯e, 9 new parameters in total →cosmology, . . . 4 new parameters in total

Profit: can suggest why neutrinos are so light, mν 0.1 0.01 eV ∼ − Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 39 / 32 ИI ЯN ИR Direct searches are deep inside the forbidden region

1 0 0 G a l e a z z i 2 0 0 1

1 0 - 1 M a i n z 2 0 1 3 H i d d e m a n n 1 9 9 5 x 2 e U

1 0 - 2 T r o i t s k 2 0 1 3

T h i s w o r k 1 0 - 3 0 . 0 1 0 . 1 1 1 0 m ( k e V ) x 1703.10779 (Troitsk)Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 40 / 32 ИI ЯN ИR

Sterile neutrinos: a part of dark matter 1701.03128

105 0.0 165 104 150 ]

3 3 1.5 135 10 − h)

/ 120 2 N 10 ncdm sat f 3.0 105 1 10 − 10 90 log 100 75 ΛCDM 4.5 P(k)[(Mpc − fncdm = 0.05 mncdm = 1.5 eV 60 1 3 10− fncdm = 0.25 mncdm = 10 eV SDSSDR11 45 2 6.0 10− 4 3 2 1 0 1 2 − 4 2 0 2 4 10− 10− 10− 10− 10 10 10 − − k[h/Mpc] log10 mncdm/eV 100 Fermions 102 1 Bosons 10− Nsat 160 2 1 ' 10− 10 M

3 ln 10− ncdm

/d 0 Nsat 60 f 10 ' 4 sat 10−

dN 1 5 10− 10−

10 6 − 5 4 3 2 1 0 1 2 3 4 5 10 2 10− 10− 10− 10− 10− 10 10 10 10 10 10 −108 109 1010 1011 1012 mncdm [eV] M[M /h]

Dmitry Gorbunov (INR) Dark matter searches with Spektr-RG 11.09.2020, OAC Crete 41 / 32