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 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 DM → a → γ 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
Outline 1. Summary of 3.5 keV observations 2. The model: DM → a → γ 3. vs morphology DM → a → γ DM → γ 4. A Cosmic Axion Background A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel 3 / 50
Timeline of observational evidence 2014 • Bulbul et al.: Det. in stacked cluster (XMM, Chandra) Feb • Boyarsky et al.: Det. in Perseus & M31 (XMM) • Riemer-Sørensen: No Det. in MW (Chandra) May • Jeltema et al.: Det. in GC, no det. in M31 (XMM) Aug • 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) A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel 4 / 50
Timeline of observational evidence 2014 • Urban et al.: Det. in Perseus (Suzaku) Nov • Carlson, Jeltema, Profumo: Morphology of signal in Perseus and GC (XMM) • Jeltema Profumo: Reply to comments of Bulbul et al. and Boyarsky et al. • ... A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel 5 / 50
The stacked cluster analysis [Bulbul, Markevitch, Foster, Smith, Loewenstein, Randall ’14(Feb)] • 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) A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel 6 / 50
The observed line [Bulbul, Markevitch, Foster, Smith, Loewenstein, Randall ’14(Feb)] -1 ) -1 keV XMM-MOS 0.8 3.57 ± 0.02 (0.03) Full Sample Flux (cnts s 0.7 6 Ms 0.6 0.02 0.01 Residuals 0 -0.01 -0.02 315 2 ) Eff. Area (cm 310 305 300 3 3.2 3.4 3.6 3.8 4 Energy (keV) A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel 7 / 50
The observed line [Bulbul, Markevitch, Foster, Smith, Loewenstein, Randall ’14(Feb)] -1 ) 5.5 keV Chandra 5 3.56 ± 0.02 (0.03) keV ACIS-S 1 - Flux (cnts s 4.5 Perseus 4 883 ks 3.5 3 0.06 0.04 Residuals 0.02 0 -0.02 -0.04 -0.06 Eff. Area (cm 2 ) 425 420 415 410 405 400 3 3.2 3.4 3.6 3.8 Energy (keV) A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel 8 / 50
The Boyarsky et al. analysis [Boyarsky, Ruchayskiy, Iakubovskyi, Franse ’14(Feb)] 10.00 0.36 M31 ON-center Normalized count rate Normalized count rate M31 ON-center 0.34 No line at 3.5 keV 0.32 [cts/sec/keV] [cts/sec/keV] 1.00 0.30 0.28 0.10 0.26 0.24 0.22 0.01 1 ⋅ 10 -2 1 ⋅ 10 -2 No line at 3.5 keV No line at 3.5 keV 8 ⋅ 10 -3 8 ⋅ 10 -3 Line at 3.5 keV Data - model Data - model 6 ⋅ 10 -3 6 ⋅ 10 -3 [cts/sec/keV] [cts/sec/keV] 4 ⋅ 10 -3 4 ⋅ 10 -3 2 ⋅ 10 -3 2 ⋅ 10 -3 0 ⋅ 10 0 0 ⋅ 10 0 -2 ⋅ 10 -3 -2 ⋅ 10 -3 -4 ⋅ 10 -3 -6 ⋅ 10 -3 -4 ⋅ 10 -3 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 3.0 3.2 3.4 3.6 3.8 4.0 Energy [keV] Energy [keV] Detected in Perseus Cluster (0.7 Ms) and Andromeda (M31) galaxy (2.5 Ms) with XMM-Newton MOS data A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel 9 / 50
The galactic center No detection with Chandra (750 ks): [Riemer-Sørensen ’14 (Aug)] Strength per arcmin 2 Element Energy Strength (ph arcmin � 2 cm � 2 s � 1 ) (ph cm � 2 s � 1 ) (keV) . 5 × 10 � 6 . 2 . 1 × 10 � 8 95 % Upper bound 3.55 keV 2 . 2 × 10 � 6 9 . 2 × 10 � 9 K XVIII 3.48 4 . 2 × 10 � 6 1 . 8 × 10 � 8 K XVIII 3.52 4 . 2 × 10 � 6 1 . 8 × 10 � 8 Ar XVII 3.62 But detection with XMM (~2 Ms): Strength per arcmin 2 Detector Energy Strength (ph arcmin � 2 cm � 2 s � 1 ) (ph cm � 2 s � 1 ) (keV) 4 . 1 × 10 � 5 7 . 7 × 10 � 8 XMM MOS [4] 3.5 2 . 8 × 10 � 5 5 . 3 × 10 � 8 XMM PN [4] 3.5 (2 . 9 ± 0 . 5) × 10 � 5 (5 . 5 ± 0 . 9) × 10 � 8 XMM [5] 3.53 [4] Jeltema, Profumo ’14 (Aug), [5] Boyarsky, Ruchayskiy, Iakubovskyi, Franse ’14 (Aug) A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel 10 / 50
The galactic center [Boyarsky, Ruchayskiy, Iakubovskyi, Franse ’14(Aug)] 1.40 GC ON, MOS1 Normalized count rate Normalized count rate GC ON, MOS2 1.30 GC ON, MOS1 1.00 GC ON, MOS2 1.20 [cts/sec/keV] [cts/sec/keV] 1.10 1.00 0.90 0.80 0.70 MOS1 3 ⋅ 10 -2 3.0 ⋅ 10 -2 MOS2 Data - model Data - model [cts/sec/keV] [cts/sec/keV] 2 ⋅ 10 -2 2.0 ⋅ 10 -2 1 ⋅ 10 -2 1.0 ⋅ 10 -2 0 ⋅ 10 0 0.0 ⋅ 10 0 -1 ⋅ 10 -2 -1.0 ⋅ 10 -2 3.0 3.5 4.0 4.5 5.0 5.5 6.0 3.0 3.2 3.4 3.6 3.8 4.0 Energy [keV] Energy [keV] • Atomic composition of GC more complicated (multi-phase and multi temperature) • Potassium line cannot be excluded A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel 11 / 50
Dwarf spheroidal galaxies [Malyshev, Neronov, Eckert ’14(Aug)] • Stacked XMM data of 8 dwarfs analyzed (~ 0.6 Ms) • high mass to light ratio • not a source of thermal X-ray emission No detection: Exclusion of Dark matter origin of ⇒ 3.5 keV line at only ~ 2 sigma A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel 12 / 50
Stacked galaxy spectra [Anderson, Churazov, Bregman ’14(Aug)] • 89 galaxies (XMM, 14.6 Ms) and 81 galaxies (Chandra, 15 Ms) with kT � 1 keV • dark matter masses via virial radius • instrumental background is not modeled and substracted but fitted with smoothing spline No detection : Exclusion of dark matter origin ⇒ at 4.4 sigma (Chandra), 11.8 (!) sigma (XMM) A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel 13 / 50
Suzaku: Perseus and nearby cluster [Urban, Werner, Allen, Simionescu, Kaastra, Strigari ’14(Nov)] • 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) A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel 14 / 50
Morphology in Perseus and GC 0 . 2 0 . 2 0 . 2 25 × 1 / 2 20 0 . 1 0 . 1 0 . 1 15 Residual Counts Latitude [deg] 10 0 . 0 0 . 0 0 . 0 5 GC 0 − 0 . 1 − 0 . 1 − 0 . 1 − 5 − 10 − 15 − 0 . 2 − 0 . 2 − 0 . 2 − 20 Neighboring 2 Sidebands High Energy Sidebands All Sidebands − 25 − 0 . 3 − 0 . 3 − 0 . 3 0 . 2 0 . 1 0 . 0 − 0 . 1 − 0 . 2 − 0 . 3 0 . 2 0 . 1 0 . 0 − 0 . 1 − 0 . 2 − 0 . 3 0 . 2 0 . 1 0 . 0 − 0 . 1 − 0 . 2 − 0 . 3 Longitude [deg] Longitude [deg] Longitude [deg] 25 × 1 / 3 O ff set Eq. North [deg] 0 . 2 0 . 2 0 . 2 20 15 Residual Counts 0 . 1 0 . 1 0 . 1 10 5 Perseus 0 0 . 0 0 . 0 0 . 0 − 5 − 10 − 0 . 1 − 0 . 1 − 0 . 1 − 15 − 20 − 0 . 2 − 0 . 2 − 0 . 2 Neighboring Sidebands High Energy Sidebands All Sidebands − 25 0 . 2 0 . 1 0 . 0 − 0 . 1 − 0 . 2 0 . 2 0 . 1 0 . 0 − 0 . 1 − 0 . 2 0 . 2 0 . 1 0 . 0 − 0 . 1 − 0 . 2 O ff set Eq. East [deg] O ff set Eq. East [deg] O ff set Eq. East [deg] • Both morphologies seem inconsistent with dark matter decay to photons • Caution: low count rates [Carlson, Jeltema, Profumo ’14(Nov)] A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel 15 / 50
Possible origins of the line Instrumental effect? • 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) A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel 16 / 50
Possible origins of the line Instrumental effect? • 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) 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!) A 3.5 keV Photon Line from a 3.5 keV ALP Line Markus Rummel 16 / 50
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