THE 3.5 KEV CANDIDATE DARK MATTER DECAY SIGNAL - CURRENT STATUS AND NEAR-FUTURE PROSPECTS

Transcription

1 THE 3.5 KEV CANDIDATE DARK MATTER DECAY SIGNAL - CURRENT STATUS AND NEAR-FUTURE PROSPECTS Jeroen Franse Instituut Lorentz & Leiden Observatory Garching, 8 December 2015 With Alexey Boyarsky, Oleg Ruchayskiy, Dmytro Iakubovskyi, Esra Bulbul JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

2 INTRODUCTION DECAYING DM IN X-RAYS For a kev-scale DM particle Fermionic DM γ + ν resulting in a monochromatic line with E γ = 1 2 m DMc2 and velocity width E E γ v vir c JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

3 INTRODUCTION DECAYING DM IN X-RAYS Boyarsky; Ruchayskiy; Riemer-Sorenson; Abazajian; Watson; and more ( ) JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

4 INTRODUCTION STERILE NEUTRINOS IN X-RAYS JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

5 INTRODUCTION TARGET SOURCES Decay is not as sensitive to density as annihilation, giving more freedom in source selection simulation from B. Moore JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

6 I NTRODUCTION TARGET S OURCES Good targets are dark matter dominated. Specifically, sources with high expected decay signal strength signal DM mass in FoV / distance2 J EROEN F RANSE I NSTITUUT L ORENTZ & L EIDEN O BSERVATORY G ARCHING, 8 D ECEMBER / 33

7 INTRODUCTION TARGET SOURCES Boyarsky et al. 2006, 2009 JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

8 DETECTIONS DETECTIONS OF THE UNIDENTIFIED 3.5 KEV LINE ApJ (2014) [ ] PRL (2014) [ ] JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

9 DETECTIONS DETECTION AT 3.55 KEV IN ANDROMEDA (M31) Boyarsky et al. 2014a [ ] JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

10 DETECTIONS DETECTION AT 3.55 KEV IN ANDROMEDA (M31) Boyarsky et al. 2014a [ ] JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

11 DETECTIONS DETECTION IN CLUSTER STACK (BULBUL ET AL.) Bulbul et al JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

12 DETECTIONS DETECTIONS OF THE UNIDENTIFIED 3.5 KEV LINE BOYARSKY ET AL. 2014A [ ] M31 galaxy XMM-Newton, center & outskirts Perseus cluster XMM-Newton, outskirts only 4.4σ BULBUL ET AL [ ] 73 clusters XMM-Newton (MOS & PN), centers only, up to z = 0.4 5σ & 4σ Perseus cluster Chandra, center only 3.5σ Perseus cluster Estimated global significance 6.6σ JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

13 INTERMEZZO X-RAY ASTRONOMY SOME NOTES ON X-RAY ASTRONOMY Complicated instrumental (particle-induced) spectral and spatial features Non-trivial telescope response Lumb et al JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

14 INTERMEZZO X-RAY ASTRONOMY ATOMIC LINES IN HOT PLASMA Typical cluster spectrum Werner et al JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

15 INTERMEZZO X-RAY ASTRONOMY ATOMIC LINES IN HOT PLASMA Atoms are excited in high temperature plasmas and emit characteristic lines. Intensity depends on Plasma temperature Element abundance Various elements are synthesized in stars and expelled during supernovae or stellar winds. Abundances vary with environment Abundances have large theoretical and observational uncertainties JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

16 LINE ORIGIN INSTRUMENTAL ORIGIN? Instrumental origin unlikely 1. Detected in 5 different detectors XMM-Newton MOS and PN detectors Chandra ACIS-S, ACIS-I Suzaku XIS 2. Line redshifts correctly with sources Clusters stacked in object restframe (Bulbul et al. 2014) Line in Perseus redshifted correctly at 2σ 3. Not detected in blank sky dataset 16 Msec with XMM 8 Msec with Suzaku (Sekiya et al [ ]) JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

17 LINE ORIGIN BLANK-SKY SPECTRUM Boyarsky et al. 2014a [ ] JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

18 LINE ORIGIN ATOMIC LINE? Unlikely: can not explain consistently all observations Bulbul et al M31 line is stronger than other atomic emission CLUSTERS need anomalous line ratios of a factor JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

19 LINE ORIGIN DARK MATTER DECAY? The line flux should be proportional to mass / distance 2 JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

20 LINE ORIGIN DARK MATTER DECAY? The line flux should be proportional to mass / distance 2 JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

21 LINE ORIGIN DARK MATTER DECAY? The line flux should be proportional to mass / distance 2 JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

22 DECAYING DM INTERPRETATION GALACTIC CENTER GALACTIC CENTER Expect large signal from GC easy cross-check JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

23 DECAYING DM INTERPRETATION GALACTIC CENTER GALACTIC CENTER VS. M31 SIMULATIONS Lovell et al [ ] JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

24 DECAYING DM INTERPRETATION GALACTIC CENTER GALACTIC CENTER Boyarsky et al. 2014b [ ] JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

25 DECAYING DM INTERPRETATION GALACTIC CENTER GALACTIC CENTER JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

26 DECAYING DM INTERPRETATION GALACTIC CENTER GALACTIC CENTER CAVEAT GC is an extremely complicated environment Line in GC might be Potassium (Riemer-Sorensen [ ]; Jeltema & Profumo [ ]) but not necessarily (Boyarsky et al. 2014b,c [ , ]) The important thing is the GC is not inconsistent and potassium cannot explain all observations JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

27 DECAYING DM INTERPRETATION DWARF GALAXIES DWARF GALAXIES Nearby, dark matter dominated object Well-known DM content (Geringer-Sameth+ 2014) Very gas-poor (do not expect any atomic lines) Line flux, 10-6 photons cm -2 s τ DM = 2.1 x sec Blank-sky Bulbul et al. (2014) GC Perseus Stacked dsph bound M31 τ DM = 15.6 x sec MALYSHEV, NERONOV & ECKERT [ ] Stacked analysis of all XMM archival dwarf data. τ > Projected DM mass density, M Sun /pc 2 JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

28 DECAYING DM INTERPRETATION MORE STUDIES PERSEUS WITH SUZAKU Two papers using the same data URBAN ET AL. [ ] The 3.55 kev line is detected in the center, but seems too strong compared to non-detections in other Suzaku clusters. TAMURA ET AL. [ ] No detection of the 3.55 kev line reported; does not comment on Urban et al. JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

29 NEW & FUTURE WORK MORE PERSEUS WITH SUZAKU (SOON) Preliminary 1 Ms with Suzaku, 5σ detection in the center Franse, Bulbul et al. (in prep) JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

30 NEW & FUTURE WORK MORE PERSEUS WITH SUZAKU (SOON) Preliminary No detection in outskirts with Suzaku Franse, Bulbul et al. (in prep) JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

31 NEW & FUTURE WORK POSSIBLE ALTERNATIVE: CHARGE-EXCHANGE GU, KAASTRA, ET AL [ ] Colliding cold gas and hot gas can emit lines through charge-exchange. At 3.48 kev, possible S XVI CX-line. Depends on amount of cold gas and velocity. JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

32 NEW & FUTURE WORK POSSIBLE ALTERNATIVE: CHARGE-EXCHANGE GU, KAASTRA, ET AL [ ] Difficult to predict, but may be plausible in Perseus. Not expected in dsph s. Astro-H will be able to resolve line broadening. JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

33 NEW & FUTURE WORK IMMINENT: LOTS OF DRACO We have been awarded 1.4 Ms of XMM observations of the Draco dwarf galaxy this year Highest expected signal of all dwarf galaxies (Geringer-Sameth+ 2014, Lovell+ 2014) Very gas-poor (do not expect any atomic lines) We will be able to confirm or deny the DM origin of the 3.5 kev line in early See talk by Tesla Jeltema JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

34 NEW & FUTURE WORK DRACO DSPH OBSERVATION PROJECTIONS Line flux, 10-6 photons cm -2 s τ DM = 2.1 x sec Blank-sky Bulbul et al. (2014) GC Perseus Stacked dsph bound M31 τ DM = 15.6 x sec Projected DM mass density, M Sun /pc 2 JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

35 NEW & FUTURE WORK FUTURE: CORRELATION TECHNIQUES Advantage: no spectral modeling Zandanel et al [ ] Angular cross-correlation measureable with erosita Correlations in spectral, spatial and redshift space Franse (in prep.) JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

36 NEW & FUTURE WORK FUTURE: ASTRO-H & MICRO CALORIMETERS (see talks by Enectali Figueroa-Feliciano and Daniel Maier) Bulbul et al.(2014) JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

37 NEW & FUTURE WORK MIGHT BE STERILE ν, MIGHT BE... JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

38 NEW & FUTURE WORK SUMMARY Line flux, 10-6 photons cm -2 s τ DM = 2.1 x sec Blank-sky Bulbul et al. (2014) GC Perseus Stacked dsph bound M31 τ DM = 15.6 x sec Projected DM mass density, M Sun /pc 2 JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

39 PARAMETER SPACE JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33

40 Line flux, 10-6 photons cm -2 s τ DM = 2 x s Blank-sky τ DM = 6 x s GC Perseus M31 τ DM = 8 x s τ DM = 1.8 x s Projected mass density, M Sun /pc 2 JEROEN FRANSE INSTITUUT LORENTZ & LEIDEN OBSERVATORY GARCHING, 8 DECEMBER / 33