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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel, University of Oxford Seminar, University of Liverpool 19/11/2014 A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel / 50 A 3.55 keV Photon Line and its Morphology

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

A 3.5 keV Photon Line from a 3.5 keV ALP Line

Markus Rummel, University of Oxford

Seminar, University of Liverpool 19/11/2014

slide-2
SLIDE 2
  • “A 3.55 keV Photon Line and its Morphology from a 3.55 keV ALP

Line”, Michele Cicoli, Joseph Conlon and David Marsh, MR arXiv:1403.2370, Phys.Rev. D90 023540

  • “3.55 keV photon lines from axion to photon conversion in the Milky

Way and M31”, Francesca Day and Joseph Conlon, arXiv:1404.7741

  • “A 3.55 keV line from : predictions for cool-core and

non-cool-core clusters”, Andrew Powell and Joseph Conlon, arXiv:1406.5518

  • “Observational consistency and future predictions for a 3.5 keV ALP

to photon line”, Pedro Alvarez, Joseph Conlon, Francesca Day and David Marsh, MR, arXiv:1410.1867

DM → a → γ

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

Outline

  • 1. Summary of 3.5 keV observations
  • 2. The model:
  • 3. vs morphology
  • 4. A Cosmic Axion Background

3

DM → a → γ DM → a → γ DM → γ

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

Timeline of observational evidence

  • Bulbul et al.: Det. in stacked cluster (XMM, Chandra)
  • Boyarsky et al.: Det. in Perseus & M31 (XMM)
  • Riemer-Sørensen: No Det. in MW (Chandra)
  • Jeltema et al.: Det. in GC, no det. in M31 (XMM)
  • Boyarsky et al.: Comment on M31
  • Bulbul et al.: Comment on atomic lines
  • Boyarsky et al.: Det. in GC (XMM)
  • Malyshev et al.: No det. in dwarfs (XMM)
  • Anderson et al.: No det. in spirals (XMM, Chandra)

4

2014 Feb May Aug

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

Timeline of observational evidence

  • Urban et al.: Det. in Perseus (Suzaku)
  • Carlson, Jeltema, Profumo: Morphology of signal

in Perseus and GC (XMM)

  • Jeltema Profumo: Reply to comments of Bulbul et
  • al. and Boyarsky et al.
  • ...

5

2014 Nov

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SLIDE 6

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

The stacked cluster analysis

  • Stacked data of 73 galaxy clusters (0.01 < z < 0.4)

yielding ~ 8 Ms of XMM observation time

  • Blue-shifted to cluster rest frame
  • Detected independently in XMM-Newton PN and

MOS instruments at 4-5 sigma

  • Detected in all three subsamples (Perseus - also with

Chandra, Coma+Ophiuchus+Centaurus, all others)

6

[Bulbul, Markevitch, Foster, Smith, Loewenstein, Randall ’14(Feb)]

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

The observed line

7

0.6 0.7 0.8

Flux (cnts s

  • 1 keV
  • 1)
  • 0.02
  • 0.01

0.01 0.02

Residuals 3 3.2 3.4 3.6 3.8 4

Energy (keV)

300 305 310 315

  • Eff. Area (cm

2)

3.57 ± 0.02 (0.03) XMM-MOS Full Sample 6 Ms

[Bulbul, Markevitch, Foster, Smith, Loewenstein, Randall ’14(Feb)]

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

The observed line

8

[Bulbul, Markevitch, Foster, Smith, Loewenstein, Randall ’14(Feb)]

3 3.5 4 4.5 5 5.5

Flux (cnts s

  • 1

keV

  • 1)
  • 0.06
  • 0.04
  • 0.02

0.02 0.04 0.06

Residuals

3 3.2 3.4 3.6 3.8

Energy (keV)

400 405 410 415 420 425

  • Eff. Area (cm 2)

Chandra ACIS-S Perseus 883 ks 3.56 ± 0.02 (0.03) keV

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

The Boyarsky et al. analysis

9

[Boyarsky, Ruchayskiy, Iakubovskyi, Franse ’14(Feb)]

Detected in Perseus Cluster (0.7 Ms) and Andromeda (M31) galaxy (2.5 Ms) with XMM-Newton MOS data

0.01 0.10 1.00 10.00 Normalized count rate

[cts/sec/keV]

M31 ON-center

  • 6⋅10-3
  • 4⋅10-3
  • 2⋅10-3

0⋅100 2⋅10-3 4⋅10-3 6⋅10-3 8⋅10-3 1⋅10-2 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 Data - model

[cts/sec/keV]

Energy [keV]

No line at 3.5 keV

0.22 0.24 0.26 0.28 0.30 0.32 0.34 0.36 Normalized count rate

[cts/sec/keV]

M31 ON-center

No line at 3.5 keV

  • 4⋅10-3
  • 2⋅10-3

0⋅100 2⋅10-3 4⋅10-3 6⋅10-3 8⋅10-3 1⋅10-2 3.0 3.2 3.4 3.6 3.8 4.0 Data - model

[cts/sec/keV]

Energy [keV]

No line at 3.5 keV Line at 3.5 keV

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

The galactic center

10

Element Energy Strength Strength per arcmin2 (keV) (ph cm2 s1) (ph arcmin2 cm2 s1) 95 % Upper bound 3.55 keV . 5 × 106 . 2.1 × 108 K XVIII 3.48 2.2 × 106 9.2 × 109 K XVIII 3.52 4.2 × 106 1.8 × 108 Ar XVII 3.62 4.2 × 106 1.8 × 108

Detector Energy Strength Strength per arcmin2 (keV) (ph cm2 s1) (ph arcmin2 cm2 s1) XMM MOS [4] 3.5 4.1 × 105 7.7 × 108 XMM PN [4] 3.5 2.8 × 105 5.3 × 108 XMM [5] 3.53 (2.9 ± 0.5) × 105 (5.5 ± 0.9) × 108

[Riemer-Sørensen ’14 (Aug)]

No detection with Chandra (750 ks): But detection with XMM (~2 Ms):

[4] Jeltema, Profumo ’14 (Aug), [5] Boyarsky, Ruchayskiy, Iakubovskyi, Franse ’14 (Aug)

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

The galactic center

  • Atomic composition of GC more complicated

(multi-phase and multi temperature)

  • Potassium line cannot be excluded

11

1.00 Normalized count rate

[cts/sec/keV]

GC ON, MOS1 GC ON, MOS2

  • 1⋅10-2

0⋅100 1⋅10-2 2⋅10-2 3⋅10-2 3.0 3.5 4.0 4.5 5.0 5.5 6.0 Data - model

[cts/sec/keV]

Energy [keV]

MOS1 MOS2

0.70 0.80 0.90 1.00 1.10 1.20 1.30 1.40 Normalized count rate

[cts/sec/keV]

GC ON, MOS1 GC ON, MOS2

  • 1.0⋅10-2

0.0⋅100 1.0⋅10-2 2.0⋅10-2 3.0⋅10-2 3.0 3.2 3.4 3.6 3.8 4.0 Data - model

[cts/sec/keV]

Energy [keV]

[Boyarsky, Ruchayskiy, Iakubovskyi, Franse ’14(Aug)]

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

Dwarf spheroidal galaxies

  • Stacked XMM data of 8 dwarfs analyzed

(~ 0.6 Ms)

  • high mass to light ratio
  • not a source of thermal X-ray emission

12

[Malyshev, Neronov, Eckert ’14(Aug)]

No detection: Exclusion of Dark matter origin of 3.5 keV line at only ~ 2 sigma ⇒

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

Stacked galaxy spectra

  • 89 galaxies (XMM, 14.6 Ms) and 81 galaxies

(Chandra, 15 Ms) with

  • dark matter masses via virial radius
  • instrumental background is not modeled and

substracted but fitted with smoothing spline

13

[Anderson, Churazov, Bregman ’14(Aug)]

kT 1 keV No detection: Exclusion of dark matter origin at 4.4 sigma (Chandra), 11.8(!) sigma (XMM) ⇒

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

Suzaku: Perseus and nearby cluster

14

  • Detected in Perseus (740 ks): Flux & Energy broadly

consistent with Bulbul et al. and Boyarsky et al.

  • Not detected in Coma (164 ks),

Virgo (90 ks) and Ophiuchus (83 ks)

[Urban, Werner, Allen, Simionescu, Kaastra, Strigari ’14(Nov)]

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

−0.3 −0.2 −0.1 0.0 0.1 0.2

Longitude [deg]

−0.3 −0.2 −0.1 0.0 0.1 0.2

Latitude [deg]

Neighboring 2 Sidebands

−0.3 −0.2 −0.1 0.0 0.1 0.2

Longitude [deg]

−0.3 −0.2 −0.1 0.0 0.1 0.2

×1/2 High Energy Sidebands

−0.3 −0.2 −0.1 0.0 0.1 0.2

Longitude [deg]

−0.3 −0.2 −0.1 0.0 0.1 0.2

All Sidebands −25 −20 −15 −10 −5 5 10 15 20 25

Residual Counts

−0.2 −0.1 0.0 0.1 0.2

Offset Eq. East [deg]

−0.2 −0.1 0.0 0.1 0.2

Offset Eq. North [deg]

Neighboring Sidebands

−0.2 −0.1 0.0 0.1 0.2

Offset Eq. East [deg]

−0.2 −0.1 0.0 0.1 0.2

×1/3 High Energy Sidebands

−0.2 −0.1 0.0 0.1 0.2

Offset Eq. East [deg]

−0.2 −0.1 0.0 0.1 0.2

All Sidebands −25 −20 −15 −10 −5 5 10 15 20 25

Residual Counts

Morphology in Perseus and GC

  • Both morphologies seem inconsistent with dark

matter decay to photons

  • Caution: low count rates

15

GC Perseus

[Carlson, Jeltema, Profumo ’14(Nov)]

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

Possible origins of the line

  • Seen by 5 different detectors (2 XMM, 2 Chandra,

Suzaku)

  • De-redshifting of clusters leaves line at 3.55 keV
  • Not seen in blanck sky survey (16 Ms)

16

Instrumental effect?

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

Possible origins of the line

  • Seen by 5 different detectors (2 XMM, 2 Chandra,

Suzaku)

  • De-redshifting of clusters leaves line at 3.55 keV
  • Not seen in blanck sky survey (16 Ms)

16

Instrumental effect? Atomic line?

  • No known atomic line at this energy. Apart from

known lines exceeding expectation by factor ~20

  • Line also detected in Andromeda (no hot gas!)
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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

Possible origins of the line

  • Sterile neutrinos (compatible with previous bounds)
  • ALP (Axion Like Particle) DM, Axinos, excited states
  • f DM, Gravitinos, ...

17

Dark matter decay/annihilation?

[Bulbul, Markevitch, Foster, Smith, Loewenstein, Randall; Czerny, Hamaguchi, Higaki, Ibe, Ishida, Jeong, Nakayama, Takahashi,Yanagida, Yokozaki; Jaeckel,Redondo,Ringwald; El Asiati, Hambye, Scarna; Dudas, Heurtier, Mambrini; Bomark, Roszkowski; Frandsen, Sannino, Shoemaker, Svendsen; Kolda, Unwin; Finkbeiner, Weiler; Kubo, Lim, Lindner; Choi, Seta; Baek, Okada, Toma; Lee, Park, Park; Chen, Liu, Nath; Ishida, Okada; Geng, Huang, Tsai; Chiang, Yamada; Dutta, Gogoladze, Khalid, Shafi; Rodejohann, Zhang; Cline, Frey; Henning, Kehayias, Murayama, Pinner, Yanagida; Boddy, Feng, Kaplinghat, Shadmi, Tait; Falkowski, Hochberg, Ruderman; Schutz, Slatyer; Cheung, Huang, Tsai]

Γγ(ms, θ) = 1.38 × 10−29 s−1 ✓sin2 2θ 10−7 ◆ ⇣ ms 1 keV ⌘5 (

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

Problems of DM to photons

  • 11.8 sigma inconsistency from stacked galaxy

spectra

  • Non-detection in dwarf spheroidals
  • Galactic center: Non-detection with Chandra but

detection with XMM, (morphology does not fit)

18

[Anderson, Churazov, Bregman ’14(Aug)] [Malyshev, Neronov, Eckert ’14(Aug)] [Riemer-Sørensen ’14 (Aug)], [Jeltema, Profumo ’14 (Aug)], [Boyarsky, Ruchayskiy, Iakubovskyi, Franse ’14 (Aug)], [Carlson, Jeltema, Profumo ’14 (Nov)]

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

Problems of DM to photons

19

XMM-Newton MOS:

Full Sample (73 cluster) Coma +Centaurus +Ophiuchus Perseus (without core) Perseus (with core)

[Bulbul, Markevitch, Foster, Smith, Loewenstein, Randall ’14]

sin2(2θ) (10−11) 6.8+1.4

−1.4

18.2+4.4

−3.9

23.3+7.6

−6.9

55.3+25.5

−15.9

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

Problems of DM to photons

19

XMM-Newton MOS:

Full Sample (73 cluster) Coma +Centaurus +Ophiuchus Perseus (without core) Perseus (with core)

[Bulbul, Markevitch, Foster, Smith, Loewenstein, Randall ’14]

Dark matter to photon may not fit the morphology ⇒

  • Signal in Perseus ~8 times stronger than in full sample
  • Half of the Perseus Signal is within the central 20 kpc

but RDM 360 kpc sin2(2θ) (10−11) 6.8+1.4

−1.4

18.2+4.4

−3.9

23.3+7.6

−6.9

55.3+25.5

−15.9

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

Problems of DM to photons

19

XMM-Newton MOS:

Full Sample (73 cluster) Coma +Centaurus +Ophiuchus Perseus (without core) Perseus (with core)

[Bulbul, Markevitch, Foster, Smith, Loewenstein, Randall ’14]

Dark matter to photon may not fit the morphology ⇒

  • Signal in Perseus ~8 times stronger than in full sample
  • Half of the Perseus Signal is within the central 20 kpc

but RDM 360 kpc sin2(2θ) (10−11) 6.8+1.4

−1.4

18.2+4.4

−3.9

23.3+7.6

−6.9

55.3+25.5

−15.9

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

Problems of DM to photons

19

XMM-Newton MOS:

Full Sample (73 cluster) Coma +Centaurus +Ophiuchus Perseus (without core) Perseus (with core)

[Bulbul, Markevitch, Foster, Smith, Loewenstein, Randall ’14]

Dark matter to photon may not fit the morphology ⇒

  • Signal in Perseus ~8 times stronger than in full sample
  • Half of the Perseus Signal is within the central 20 kpc

but RDM 360 kpc sin2(2θ) (10−11) 6.8+1.4

−1.4

18.2+4.4

−3.9

23.3+7.6

−6.9

55.3+25.5

−15.9

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

Problems of DM to photons

19

XMM-Newton MOS:

Full Sample (73 cluster) Coma +Centaurus +Ophiuchus Perseus (without core) Perseus (with core)

[Bulbul, Markevitch, Foster, Smith, Loewenstein, Randall ’14]

Dark matter to photon may not fit the morphology ⇒

  • Signal in Perseus ~8 times stronger than in full sample
  • Half of the Perseus Signal is within the central 20 kpc

but RDM 360 kpc sin2(2θ) (10−11) 6.8+1.4

−1.4

18.2+4.4

−3.9

23.3+7.6

−6.9

55.3+25.5

−15.9

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

Problems of DM to photons

19

XMM-Newton MOS:

Full Sample (73 cluster) Coma +Centaurus +Ophiuchus Perseus (without core) Perseus (with core)

[Bulbul, Markevitch, Foster, Smith, Loewenstein, Randall ’14]

Dark matter to photon may not fit the morphology ⇒

  • Signal in Perseus ~8 times stronger than in full sample
  • Half of the Perseus Signal is within the central 20 kpc

but RDM 360 kpc sin2(2θ) (10−11) 6.8+1.4

−1.4

18.2+4.4

−3.9

23.3+7.6

−6.9

55.3+25.5

−15.9

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

Problems of DM to photons

19

XMM-Newton MOS:

Full Sample (73 cluster) Coma +Centaurus +Ophiuchus Perseus (without core) Perseus (with core)

[Bulbul, Markevitch, Foster, Smith, Loewenstein, Randall ’14]

Dark matter to photon may not fit the morphology ⇒

  • Signal in Perseus ~8 times stronger than in full sample
  • Half of the Perseus Signal is within the central 20 kpc

but RDM 360 kpc sin2(2θ) (10−11) 6.8+1.4

−1.4

18.2+4.4

−3.9

23.3+7.6

−6.9

55.3+25.5

−15.9

Similar with Suzaku: 85% of signal is within central 130 kpc (66% expected from DM to photons)

[Urban, Werner, Allen, Simionescu, Kaastra, Strigari ’14(Nov)]

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

Problems of DM to photons

19

XMM-Newton MOS:

Full Sample (73 cluster) Coma +Centaurus +Ophiuchus Perseus (without core) Perseus (with core)

[Bulbul, Markevitch, Foster, Smith, Loewenstein, Randall ’14]

Dark matter to photon may not fit the morphology ⇒

  • Signal in Perseus ~8 times stronger than in full sample
  • Half of the Perseus Signal is within the central 20 kpc

but RDM 360 kpc sin2(2θ) (10−11) 6.8+1.4

−1.4

18.2+4.4

−3.9

23.3+7.6

−6.9

55.3+25.5

−15.9

Similar with Suzaku: 85% of signal is within central 130 kpc (66% expected from DM to photons)

[Urban, Werner, Allen, Simionescu, Kaastra, Strigari ’14(Nov)]

XMM morphology: Signal is concentrated in cool core

[Carlson, Jeltema, Profumo ’14]

Consistent with ! DM → a → γ

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

  • 1. Summary of 3.5 keV observations
  • 2. The model:
  • 3. vs morphology
  • 4. A Cosmic Axion Background

DM → a → γ DM → γ

Outline

20

DM → a → γ

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

Dark matter to axion to photon

  • Axions transform to photons in cluster/galactic

magnetic fields

  • Theoretically equally well motivated as

(axions are typically associated to a high scale, nothing is known about the particle nature of DM)

  • Signal strength follows DM density and strength
  • f the magnetic field

21

DM → γ ⇒ Signal peaks on scales of the cluster magnetic field! (Perseus) DM → a → γ

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

Dark matter to axion decays

22

DM is a scalar

  • r DM is a fermion

Φ Λ@µa@µa .

Decay via with lifetime

⌧Φ = ✓7.1 keV mΦ ◆3 ✓ Λ 1017 GeV ◆2 1.85 ⇥ 1027 s .

@µa Λ ¯ µ5 .

Decay via with lifetime

⌧ τψ = ✓7.1 keV mψ ◆3 ✓ Λ 1017 GeV ◆2 0.92 ⇥ 1027 s . (cosmological moduli problem, unless [Linde ’96, Takahashi,Yanagida ’11])

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

with (for )

Axion-photon conversion

23

[Raffelt, Stodolsky ’87]

L = 1 2∂µa∂µa − 1 2m2

aa2 + a

M E · B.

P(a → γ) = sin2(2θ) sin2 ✓ ∆ cos 2θ ◆

θ ∼ B⊥Ea

M ne , ∆ ∼ neL Ea

Axion-photon coupling in

~ B

X-r

L

induces ma < 10−11 eV

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

with (for )

Axion-photon conversion

23

P cluster

a→γ

∼ B2 L Rcluster

M 2

[Raffelt, Stodolsky ’87]

L = 1 2∂µa∂µa − 1 2m2

aa2 + a

M E · B.

P(a → γ) = sin2(2θ) sin2 ✓ ∆ cos 2θ ◆

θ ∼ B⊥Ea

M ne , ∆ ∼ neL Ea

Axion-photon coupling in

~ B

X-r

L

induces ma < 10−11 eV

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

Outline

24

  • 1. Summary of 3.5 keV observations
  • 2. The model:
  • 3. vs morphology
  • 4. A Cosmic Axion Background

DM → a → γ DM → γ DM → a → γ

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

Predictions: Cluster morphology

25

FDM→a = ΓDM→a

4πd(z)2 (1 + z)

  • V

ρDM mDM Pa→γ dV

FDM→γ = ΓDM→γ

4πd(z)2 (1 + z)

  • V

ρDM mDM dV

0.0 0.1 0.2 0.3 0.4 0.5 0.1 0.5 1.0 5.0 10.0 50.0 Distance @ Mpc D Integrand HunnormalizedL

DM -> g DM -> a -> g

Perseus Cluster

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

Predictions: Cluster morphology

26

[Conlon, Powell ’14(June)]

Cool-core vs non-cool-core ⇒

eta =0.5 (Coma): [Bonafede, Feretti, Murgia, Govoni, Giovannini, Dallacasa, Dolag, Taylor ’10] eta = 1 (Hydra A): [Kuchar, Enßlin ’11]

fields are strongest i B(r) ∼ B0 ⇣

ne(r) ne(0)

⌘η

(Gaussian random field with Kolmogorov power spectrum)

toy models!

Perseus eta 1 Perseus eta 0.5

200 400 600 800 1000 1 2 3 4 5

ExtractionRadius kpc Relativesignalstrength Coma eta 1 Coma eta 0.5

200 400 600 800 1000 1 2 3 4 5

ExtractionRadius kpc Relativesignalstrength

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

Predictions: Clusters

  • Nearby cluster do not fit in Field of view of XMM

(2-3 sigma excess of nearby clusters over full sample)

27

Field of view O(1) ∼ 0.5 XMM

Full Sample (73 cluster) Coma +Centaurus +Ophiuchus Perseus (without core) Perseus (with core)

sin2(2θ) (10−11) 6.8+1.4

−1.4

18.2+4.4

−3.9

23.3+7.6

−6.9

55.3+25.5

−15.9

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A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel

Predictions: Clusters

28

[Conlon, Powell ’14 (June)]

Perseus eta 1 Perseus eta 0.5

200 400 600 800 1000 1 2 3 4 5

ExtractionRadius kpc Relativesignalstrength Coma eta 1 Coma eta 0.5

200 400 600 800 1000 1 2 3 4 5

ExtractionRadius kpc Relativesignalstrength

Seems to be already in the data! ⇒ Stack cool-core vs non-cool-core!

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Predictions: Milky Way

29

DM → a → γ

[Conlon, Day ’14(April)]

Magnetic field: [Janson, Farrar ’12] (excluding galactic center) Electron density: [Gomez, Benjamin, Cox ’01]

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Predictions: Milky Way

30

DM → a → γ

[Conlon, Day ’14(April)]

DM → γ

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M31

  • In many ways similar to MW but twice as big
  • Regular magnetic field is significantly bigger and

significantly more coherent than in MW

  • between 6 - 14 kpc

vs generally

  • No sign of large scale field reversal as in MW
  • Close to edge on (77.5 degrees inclination)

31

[Conlon, Day ’14(April)]

Breg ∼ Brandom ∼ 5µG Breg ∼ Brandom

3

[Han, Beck, Berkhuijsen ’98], [Flechter, Berkhuijsen, Beck, Shukurov ’03]

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M31

  • In many ways similar to MW but twice as big
  • Regular magnetic field is significantly bigger and

significantly more coherent than in MW

  • between 6 - 14 kpc

vs generally

  • No sign of large scale field reversal as in MW
  • Close to edge on (77.5 degrees inclination)

31

[Conlon, Day ’14(April)]

Breg ∼ Brandom ∼ 5µG Breg ∼ Brandom

3

[Han, Beck, Berkhuijsen ’98], [Flechter, Berkhuijsen, Beck, Shukurov ’03]

For , :

g B⊥ ∼ 5 µG,

⇒

d L ∼ 20 kpc, Pa→γ,M31 ∼ 102 Pa→γ,MW

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Predictions: Galaxies

32

  • Signals from edge on galaxies should be stronger

than from face on

  • Consistent with Anderson et al. non-detection!
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  • Dwarf spheroidals
  • Stacked spirals

[Malyshev, Neronov, Eckert 1408.3531] [Anderson, Churazov, Bregman 1408.4115]

Prediction: No Signal in generic stacked sample

Stacked galaxy spectra

(List of nearby edge-on spiral galaxies in paper)

33

M31 like galaxy

[Alvarez, Conlon, Day, Marsh, MR ’14(Oct)] [Cicoli, Conlon, Marsh, MR 1403.2370]

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Galactic center

  • Electron density
  • Magnetic field in central 100-200 pc highly

unknown:

  • FOV: (XMM), (Chandra)

34

[Cordes, Lazio ’02] [Alvarez, Conlon, Day, Marsh, MR ’14(Oct)]

16.8 × 16.8 r = 15

ne,GC(x, y, z) = 10 cm−3 exp  −x2 + (y − yGC)2 L2

GC

  • exp

 −(z − zGC)2 H2

GC

  • h LGC = 145 pc and HGC = 26 pc.

y yGC = 10 pc

zGC = −20 pc.

and

0.01 − 1 mG [Davidson ’96], [Morris ’07, ‘14], [Ferrière ’09, ‘10]

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Galactic center

35

[Alvarez, Conlon, Day, Marsh, MR ’14(Oct)]

FXMM FChandra = ( 4.6 for αr = 0 4.4 for αr = 45 FXMM = 2.9 × 105 photons s1cm2 , FChandra = 6.7 × 106 photons s1cm2 ,

hPa!γiXMM hPa!γiChandra = (

3.0⇥10−5 1.4⇥10−5 = 2.1 3.0⇥10−5 1.5⇥10−5 = 2.0

for B = 1 mG over 150 pc

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Galactic center

35

[Alvarez, Conlon, Day, Marsh, MR ’14(Oct)]

FXMM FChandra = ( 4.6 for αr = 0 4.4 for αr = 45 FXMM = 2.9 × 105 photons s1cm2 , FChandra = 6.7 × 106 photons s1cm2 ,

Fz>20pc

XMM = 2.1 × 105 photons s1cm2 .

hPa!γiXMM hPa!γiChandra = (

3.0⇥10−5 1.4⇥10−5 = 2.1 3.0⇥10−5 1.5⇥10−5 = 2.0

for B = 1 mG over 150 pc

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Galactic center

35

[Alvarez, Conlon, Day, Marsh, MR ’14(Oct)]

FXMM FChandra = ( 4.6 for αr = 0 4.4 for αr = 45 FXMM = 2.9 × 105 photons s1cm2 , FChandra = 6.7 × 106 photons s1cm2 ,

Fz>20pc

XMM = 2.1 × 105 photons s1cm2 .

hPa!γiXMM hPa!γiChandra = (

3.0⇥10−5 1.4⇥10−5 = 2.1 3.0⇥10−5 1.5⇥10−5 = 2.0

for B = 1 mG over 150 pc

XMM detection and Chandra non-detection reconciled ⇒

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Conclusions

  • For photon signal is convolution
  • f DM density and magnetic field along l.o.s.
  • Different morphology of cluster and galaxy signals

than : (non-)cool core, edge/face on

  • Observable flux effectively depends on one free

parameter (as )

36

DM → a → γ DM → γ DM → γ FDM→a→γ ∝ 1/τDM→aM 2

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Conclusions

  • Signal is produced in galaxy clusters but absent in

dwarf spheroidals and stacked galaxies

  • A signal is observed in M31 but not in other galaxies
  • Perseus signal follows the cool-core feature

37

Observational consistency of : DM → a → γ More observations will follow in the near future (particularly Astro-H), hopefully the line remains a signal of new physics!

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  • 1. Summary of 3.5 keV observations
  • 2. The model:
  • 3. vs morphology
  • 4. A Cosmic Axion Background

DM → a → γ DM → γ

Outline

38

DM → a → γ

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Moduli Cosmology

39

  • String Theory compactifications

come with moduli O(100) φ

[Cicoli,Conlon,Quevedo ’12], [Higaki, Takahashi ’12]

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Moduli Cosmology

39

  • Get displaced from minimum

during inflation

  • String Theory compactifications

come with moduli O(100) φ

[Cicoli,Conlon,Quevedo ’12], [Higaki, Takahashi ’12]

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Moduli Cosmology

39

Inflation φ1

  • Get displaced from minimum

during inflation

  • String Theory compactifications

come with moduli O(100) φ

[Cicoli,Conlon,Quevedo ’12], [Higaki, Takahashi ’12]

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Moduli Cosmology

39

Inflation φ1

  • Get displaced from minimum

during inflation

  • Lightest modulus comes to

dominate energy of the universe since Γφ ∼ m3

φ/M 2 Pl

  • String Theory compactifications

come with moduli O(100) φ

[Cicoli,Conlon,Quevedo ’12], [Higaki, Takahashi ’12]

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Moduli Cosmology

39

Inflation φ1

  • Get displaced from minimum

during inflation

  • Lightest modulus comes to

dominate energy of the universe since Γφ ∼ m3

φ/M 2 Pl

φ1 After inflation

ρmatter ∼ a−3(t) ρradiation ∼ a−4(t)

  • String Theory compactifications

come with moduli O(100) φ

[Cicoli,Conlon,Quevedo ’12], [Higaki, Takahashi ’12]

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Moduli Cosmology

39

Inflation φ1

  • Decay of lightest modulus starts

big bang cosmology

  • Get displaced from minimum

during inflation

  • Lightest modulus comes to

dominate energy of the universe since Γφ ∼ m3

φ/M 2 Pl

φ1 After inflation

ρmatter ∼ a−3(t) ρradiation ∼ a−4(t)

  • String Theory compactifications

come with moduli O(100) φ

[Cicoli,Conlon,Quevedo ’12], [Higaki, Takahashi ’12]

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Moduli Cosmology

39

Inflation φ1

  • Decay of lightest modulus starts

big bang cosmology

  • Get displaced from minimum

during inflation

  • Lightest modulus comes to

dominate energy of the universe since Γφ ∼ m3

φ/M 2 Pl

φ1 After inflation

ρmatter ∼ a−3(t) ρradiation ∼ a−4(t)

Modulus decay/reheating φ1

  • String Theory compactifications

come with moduli O(100) φ

[Cicoli,Conlon,Quevedo ’12], [Higaki, Takahashi ’12]

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A Cosmic Axion Background

  • decides

population of different sectors

  • String compactifications typically come with light

hidden sectors (e.g. hidden gauge groups, ALPs)

  • Hidden light fields contribute as Dark Radiation

(experimental hints: )

  • generally not suppressed (e.g. via kinetic

coupling to volume modulus in type IIB)

40

Br(φ → visibles) vs Br(φ → hidden)

Planck: Neff = 3.30 ± 0.27 Planck + H0: Neff = 3.62 ± 0.25

φ → ALPs

[Conlon, Marsh ’13]

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A Cosmic Axion Background

  • decides

population of different sectors

  • String compactifications typically come with light

hidden sectors (e.g. hidden gauge groups, ALPs)

  • Hidden light fields contribute as Dark Radiation

(experimental hints: )

  • generally not suppressed (e.g. via kinetic

coupling to volume modulus in type IIB)

40

Dark Radiation/a CAB is a rather generic prediction of String Theory Cosmology

⇒

Br(φ → visibles) vs Br(φ → hidden)

Planck: Neff = 3.30 ± 0.27 Planck + H0: Neff = 3.62 ± 0.25

φ → ALPs

[Conlon, Marsh ’13]

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Properties of the CAB

  • Modulus decay produces relativistic non-thermal

ALPs with

  • Energy density:
  • CAB energy:
  • For ( to avoid CMP)
  • Couples to photons via

41

ρCAB = ∆Neff 7 8 ✓ 4 11 ◆4/3 ρCMB

a Ea = mφ/2

200 400 600 800 1 2 2 4 6 8 EeV d dE 103 cm2 s1 eV1 axions 1057 kpc3 eV1

Ea,now Tγ,now ' Ea,init Tγ,init ⇠ ✓MP mΦ ◆1/2

mφ ∼ 106 GeV ECAB 200 eV (X-ray)

L ⊃ 1 M a E · B ,

104 GeV

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Galaxy Clusters and ALPs

  • Galaxy Clusters are the largest gravitationally

bound objects in the universe

  • Typically kpc scale coherent magnetic fields

42

B ∼ O(1)µG

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Galaxy Clusters and ALPs

  • Galaxy Clusters are the largest gravitationally

bound objects in the universe

  • Typically kpc scale coherent magnetic fields

42

B ∼ O(1)µG

a

γ

n

Interesting “Labs” to study the CAB via ALP to photon conversion!

[Conlon, Marsh ’13]

⇒

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Soft X-ray Excess in Coma

  • Clusters are filled by hot gas which

emits in X-rays via thermal bremsstrahlung

  • Soft Excess is observed by EUVE

and ROSAT in ~30% of 38 clusters

43

[Bonamente, Lieu, Joy, Nevalainen’02]

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Soft X-ray Excess in Coma

  • Clusters are filled by hot gas which

emits in X-rays via thermal bremsstrahlung

  • Soft Excess is observed by EUVE

and ROSAT in ~30% of 38 clusters

43

Fractional excess

15 arcmin = 0.4 Mpc

3 = 5.2 Mpc

[Bonamente, Lieu, Bulbulb ’09] [Bonamente, Lieu, Joy, Nevalainen’02]

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Proposed astrophysical explanations

  • Thermal Bremsstrahlung from a ‘colder’ (T ~ 200

eV) gas: But associated emission lines not seen

  • Inverse-Compton scattering of the CMB by

relativistic cosmic ray electrons: But no associated gamma ray bremsstrahlung flux

44

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Proposed astrophysical explanations

  • Thermal Bremsstrahlung from a ‘colder’ (T ~ 200

eV) gas: But associated emission lines not seen

  • Inverse-Compton scattering of the CMB by

relativistic cosmic ray electrons: But no associated gamma ray bremsstrahlung flux

44

⇒ Known astrophysical explanations not compelling ⇒ Explore cosmological CAB explanation of the soft X- ray excess!

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Conversion parameters

  • Electron density via X-ray

brightness profile

  • Magnetic field via Faraday

rotation

45

ne(r) = n0 ✓ 1 + r2 r2

c

◆ 3

2β

04:00.0 02:00.0 13:00:00.0 58:00.0 56:00.0 54:00.0 12:52:00.0 29.00 28.50 28.00 27.50 27.00

Relic Halo

[Bonafede,Vazza,Bruggen,Murgia, Govoni,Feretti,Giovannini,Ogrean’13]

RM = e3 2πm2

e

Z

l.o.s

ne(l)Bk(l)dl ,

B(r) = C · B0 ✓ne(r) n0 ◆η

⇒

(via simulation vs RM)

  • Coherence Length p(L, x) ∼ Ln−6 or ∼ n−1

e Ln−6

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Coma center results

46 0.5 1 1.5 2 3 6 9 12 15 18 Ratio [Lsim/Lobs] Radial distance [arcminutes] 50 100 150 200 250 1 1011 2 1011 5 1011 1 1012 2 1012 5 1012 Mean axion energy eV M GeV

SN γ-burst bound

Model 2 X-ray bound Model 3 X-ray bound Model 1 X-ray bound

a

γ

z

Size: 20003 points = 1 Mpc3.

[Angus, Conlon, Marsh, Powell, Witkowski ‘13]

∆Neff = 0.5

Model A Model B Λmin 2 kpc 2 kpc Λmax 34 kpc 100 kpc n 17/3 4 B0 4.7 µG 5.4 µG η 0.5 0.7

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Coma outskirts results

47

0.10 0.15 0.20 0.25 0.30 0.35 5.0¥1012 1.0¥1013 1.5¥1013 2.0¥1013 2.5¥1013 3.0¥1013 <ECAB> ê keV M ê GeV Model B centre Model A centre Model B Model A

L = Z

V

Z Λmax(x)/2

Λmin(x)/2

Z Emax

Emin

c LP(a ! γ; L, E, x) p(L, x) CCAB E XCAB(E) dE dL dx3 ,

Model A Model B Λmin 2 kpc 2 kpc Λmax 34 kpc 100 kpc n 17/3 4 B0 4.7 µG 5.4 µG η 0.5 0.7

Semi-analytical approach: L ∝ const L ∝ n−1

e

[Conlon, Kraljic, MR ’14]

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Coma outskirts results

47

0.10 0.15 0.20 0.25 0.30 0.35 5.0¥1012 1.0¥1013 1.5¥1013 2.0¥1013 2.5¥1013 3.0¥1013 <ECAB> ê keV M ê GeV Model B centre Model A centre Model B Model A

L = Z

V

Z Λmax(x)/2

Λmin(x)/2

Z Emax

Emin

c LP(a ! γ; L, E, x) p(L, x) CCAB E XCAB(E) dE dL dx3 ,

Model A Model B Λmin 2 kpc 2 kpc Λmax 34 kpc 100 kpc n 17/3 4 B0 4.7 µG 5.4 µG η 0.5 0.7

Semi-analytical approach: L ∝ const L ∝ n−1

e

[Conlon, Kraljic, MR ’14]

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ALP parameter space

48

Axion

Massive Stars

SN1987A g - Ray Burst Quasar Polarization

Soft X - Ray Excess from Com a g - Ray Transparency

IAXO ALPS -II

Axion CDM Haloscop es

PIXIEê PRISM 3.55 keV Line from Decaying ALP DM ALP CDM

  • 40 -38 -36 -34 -32 -30 - 28 - 26 - 24 - 22 - 20 -18 -16 -14 -12 -10 -8
  • 6 - 4 - 2

2 4

  • 20
  • 18
  • 16
  • 14
  • 12
  • 10
  • 8

Log10 m a @eVD Log10 »g ag» @GeV-1D

Soft X - Ray Excess from Coma (Outskirts) (Center) M

40 38 36 34 32 30 28 26 24 22 20 18 16 14 20 18 16 14

@eVD » »

Soft X - Ray Excess from Coma (Center)

M-1

[Dias,Machado,Nishi,Ringwald,Vaudrevange ’14] [Conlon, Kraljic, MR ’14]

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ALP parameter space

48

Axion

Massive Stars

SN1987A g - Ray Burst Quasar Polarization

Soft X - Ray Excess from Com a g - Ray Transparency

IAXO ALPS -II

Axion CDM Haloscop es

PIXIEê PRISM 3.55 keV Line from Decaying ALP DM ALP CDM

  • 40 -38 -36 -34 -32 -30 - 28 - 26 - 24 - 22 - 20 -18 -16 -14 -12 -10 -8
  • 6 - 4 - 2

2 4

  • 20
  • 18
  • 16
  • 14
  • 12
  • 10
  • 8

Log10 m a @eVD Log10 »g ag» @GeV-1D

Soft X - Ray Excess from Coma (Outskirts) (Center) M

40 38 36 34 32 30 28 26 24 22 20 18 16 14 20 18 16 14

@eVD » »

Soft X - Ray Excess from Coma (Center)

M-1

L ∝ ∆Neff/M 2

[Dias,Machado,Nishi,Ringwald,Vaudrevange ’14] [Conlon, Kraljic, MR ’14]

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ALP Conversion and the Soft X-Ray Excess in the Coma Cluster Markus Rummel

Conclusions

49

  • Dark Radiation/a CAB is a generic prediction of

String Cosmology

  • Soft X-ray excess is present in many clusters
  • Cosmological vs astrophysical explanation:

One CAB to fit them all

  • Has to match both morphology and magnitude of

soft excess

  • Coma Center , Coma Outskirts
  • Other clusters: A2199 , A2255 , A665 ( )

CAB

(M, ECAB)

[Powell ’14]

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50

Thank you for your attention!