Recent Updates on the 3.5 keV Line - MIT Esra Bulbul - CERN Indico
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Recent Updates on the 3.5 keV Line Esra Bulbul MIT
Fourth Type of Neutrino as Dark Matter
Diffuse X-ray Background
• Decay of DM particles Cluster X-ray
M31 Forbidden
Decay
Unresolved CXB
rate
(keV)
Massm(keV)
Milky Way
#%& * Allowed BMW
"# = '(") + (1+z)
s
,
Pulsar
Kicks
100-300 kpc
Fornax Core
Mixing angle: Γ ∝ 2 76
Tremaine-Gunn Bound
2
sin 2θ
Mixing Angle à Abazajian 2009
Galaxy Clusters: Good Targets for Dark Matter Search • Galaxy clusters are the largest reservoirs of DM FeFeKK Flux 2 keV 10 keV Energy (keV)
Galaxy Clusters 15% of their total mass is in baryons
Galaxy Clusters: Good Targets for Dark Matter Search • Galaxy clusters are the largest reservoirs of DM FeFeKK • Thermal Bremsstrahlung Flux +atomic emission lines • Very weak emission lines from dark matter decay 2 keV 10 keV Energy (keV)
The Deepest Search in Galaxy Clusters The Astrophysical Journal, 789:13 (23pp), 2014 July 1 doi:10.1088/0004-637X/789/1/13 C 2014. ⃝ The American Astronomical Society. All rights reserved. Printed in the U.S.A. DETECTION OF AN UNIDENTIFIED EMISSION LINE IN THE STACKED X-RAY SPECTRUM OF GALAXY CLUSTERS • Stacked clusters at their Esra Bulbul1,2 , Maxim Markevitch3 , Adam Foster1 , Randall K. Smith1 , 1 Michael Loewenstein2,4 , and Scott W. Randall1 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA; ebulbul@cfa.harvard.edu 2 CRESST and X-ray Astrophysics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA 3 NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA rest frame 4 Department of Astronomy, University of Maryland, College Park, MD 20742, USA • Smeared non-source Received 2014 February 10; accepted 2014 April 28; published 2014 June 10 ABSTRACT We detect a weak unidentified emission line at E = (3.55–3.57) ± 0.03 keV in a stacked XMM-Newton spectrum of 73 galaxy clusters spanning a redshift range 0.01–0.35. When the full sample is divided into three subsamples (Perseus, Centaurus+Ophiuchus+Coma, and all others), the line is seen at >3σ statistical significance in all three independent MOS spectra and the PN “all others” spectrum. It is also detected in the Chandra spectra of the Perseus Cluster. However, it is very weak and located within 50–110 eV of several known lines. The detection is signal at the limit of the current instrument capabilities. We argue that there should be no atomic transitions in thermal plasma at this energy. An intriguing possibility is the decay of sterile neutrino, a long-sought dark matter particle candidate. Assuming that all dark matter is in sterile neutrinos with ms = 2E = 7.1 keV, our detection corresponds to a neutrino decay rate consistent with previous upper limits. However, based on the cluster masses and distances, the line in Perseus is much brighter than expected in this model, significantly deviating from other subsamples. • Analysis is sensitive to This appears to be because of an anomalously bright line at E = 3.62 keV in Perseus, which could be an Ar xvii dielectronic recombination line, although its emissivity would have to be 30 times the expected value and physically difficult to understand. Another alternative is the above anomaly in the Ar line combined with the nearby 3.51 keV K line also exceeding expectation by a factor of 10–20. Confirmation with Astro-H will be critical to determine the nature of this new line. weak lines Key words: dark matter – elementary particles – line: identification – neutrinos – X-rays: galaxies: clusters Online-only material: color figures 1. INTRODUCTION motivated our present work is the hypothetical sterile neutrino that is included in some extensions to the standard model of particle physics (Dodelson & Widrow 1994 and later works; for
An Unidentified Emission Line is Discovered Flux (cnts s keV ) -1 0.8 6 Ms- MOS XMM MOS 3.57 ± 0.02 (0.03) Observations -1 Full Sample 0.7 64.5σ Ms 0.6 0.015 Residuals 0.01 0.005 0 -0.005 3 3.2 3.4 3.6 3.8 4 No Line Added Energy (keV) Bulbul+2014
Comparison of Perseus with Others 7.16 7.14 7.12 B08 Perseus is (keV) 7.1 Full Sample (MOS) ms (keV) H14 Full Sample (PN) 7.08 Coma + Centaurus + Ophiuchus (MOS) anomalously bright! Mass Coma + Centaurus + 7.06 Ophiuchus (PN) Other Clusters (MOS) Other Clusters (PN) 7.04 Perseus (Core-Cut) (MOS) Perseus (Core-Cut) (PN) Perseus (ACIS-I) 7.02 Perseus (ACIS-S) Virgo (ACIS-I) 7 1 10 100 -11 Mixing angle à 10 sin 2 (2θ)
Testing for Decaying Dark Matter Detections ( ≥3σ ) Non- Detections (≥ 3σ ) 1- Perseus Cluster – too bright 1- Virgo Cluster (Bulbul+2014a, Urban+2015, Franse+2016) (Bulbul+2014a) consistent ✓ 2- Stacked clusters (Bulbul+2014a)✓ 2- Coma, Ophiuchus (Suzaku) 3- Galactic Center ✓ (Urban+2015) consistent ✓ (Boyarsky+2015, Jeltema & Profumo 2015) 3- Stacked galaxies 4- Coma, A2199, and A2319 ✓ (Anderson+2015) inconsistent! (Iakubovskyi & Bulbul+15) 4- Perseus Cluster 5- M31 (Boyarsky+2014) ✓ (Hitomi Collaboration) ✓ 6- NuSTAR Galactic Halo (Neronov+2016) ✓ 7- NuSTAR Bullet Cluster (Wik+2014) ✓ 8- Chandra Galactic Halo Observations (Cappelluti +2017) ✓
Detection in the 10Ms Chandra Fields 8 HDFN COSMOS CDFS Cappelluti+2017
Hitomi Observations of the Perseus Cluster (200ks) N E 7% of the time required for the ral 3 arcmin detection of cent r oute the 3.5 keV line 1’ 20 kpc km/s -50
Hitomi 3-4 keV Band • Broad instrumental dip near 3.5 keV • Potassium is sub- solar Hitomi Collaboration, 2017
Hitomi Constraints on the 3.5 keV Line Hitomi Collaboration, 2017 XMM- Newton Detection in the Hitomi FOV Best-fit DM line
Dividing the Hitomi Observations HITOMI COLLABORATION Obs 2 Obs 3+4 are a week apart Hitomi Collaboration, 2017
SXS Not in Thermal Equilibrium (PROBLEM 2) Cal pixel gain drift ! Detector common-mode gain Broad• Instrumental Dip 55-Fe SXS cal pixel has a dedicated in Observation source. 2 • Sole method of gain tracking until MXS or FW 55-Fe source • Cal pixel gain is strongly affected by He tank (shown) and IVCS Temp Obs 2 Obs 3+4 are a week apart Launch 2/17/16 Hitomi 15th SWG May 19, 2016 9
Hitomi Constraints are Consistent! 3.5 keV line flux from a sample excluding Perseus Hitomi Collaboration, 2017
What is Next for Warm Dark Matter Searches in the X-ray Band? Perseus Perseus Cluster Athena XIFU 150 ks • XARM/Athena XIFU 1Ms XARM kT = 6.5 keV Observations to test the 3.5 Flux (cnts s keV ) -1 10 v(baryons) = 300 km/s 150ks Athena v(line) = 1300 km/s keV line in clusters -1 Ar XVII • See Ranjan Laha’s talk for Ar XVII DR Ca XIX Ar XVIII testing the Galactic Center 5 3.55 keV Line signal with Micro-X 3 3.2 3.4 3.6 3.8 4 Energy (keV)
Summary • Most of the astrophysical including potassium has been eliminated • Upper limits provided by the Hitomi observations are consistent with decaying dark matter model Abazajian 2017
Hitomi (Launched 2/17/2016) Spectrometer (calorimeter) has 20 times better resolution!
DM candidate production is resonantly enhanced in Origin the presence of a claimed detection! ( arXiv-mediated hep-phino production )! • No known plausible atomic lines at this energy! • Astrophysical Origin (K XVIII, DM candidates Shower of new shower o Ar XVII DR, charge VP*! new mod exchange) and DM ! candidate • Simple decaying Dark Matter • Others ALPs, fluorescent > 300 .org! Citation since published VP=virtual pre DM, XDM quantumdiaries
Hitomi Constraints are Consistent! Stacked Clusters 3σ Constraints M31 Mixing Angle From Hitomi Perseus XMM Chandra Deep Fields Abazajian 2017 DM Mass (keV)
Comparison with Upper Limits in the Literature Diffuse X-ray Background Cluster X-ray M31 Forbidden Unresolved CXB (keV) (keV) Milky Way BMW Allowed Mass ms Pulsar Kicks 100-300 kpc Fornax Core Tremaine-Gunn Bound Mixing angle à 2 Abazajian 2009 sin 2θ
Dark matter searches going bananas: the contribution of Potassium (and Chlorine) to the 3.5 keV line 1⋆ 1 Tesla 1 Jeltema and Stefano Profumo † Department of Physics and Santa Cruz Institute for Particle Physics University of California, Santa Cruz, CA 95064, USA [astro-ph.HE] 7 Aug 2014 11 August 2014 Claims: ABSTRACT • Various line ratios We indicate examine thewide claimedand excessinconsistent X-ray line emissionplasma temperatures near 3.5 keV with a new analysis of XMM-Newton observations of the Milky Way center and with a re-analysis of the data on M 31 • can’t restrict the temperature and clusters. In no caserange and do we find use evidence conclusive other for lines to predict an excess. the We show that K known plasma lines, including in particular K XVIII lines at 3.48 and 3.52 keV, provide a satisfactory XVIII flux fit to the XMM data from the Galactic center. We assess the expected flux for the K XVIII lines and find that the measured line flux falls squarely within the predicted range based on the brightness of other well-measured lines in the energy range of interest. We then re-evaluate • there may be a very coolforcomponent the evidence excess emission from which clusters ofwill produce galaxies, including aa muchunaccounted previously for Cl XVII line at 3.51 keV, and allowing for systematic uncertainty in the expected flux from brighter K line known plasma lines and for additional uncertainty due to potential variation in the abundances of different elements. We find that no conclusive excess line emission is present within the • Possible contribution of Cl systematic XVII atin3.51 uncertainties PerseuskeV notclusters. or in other included Finally, we re-analyze XMM data for M 31 and find no statistically significant line emission near 3.5 keV to a level greater than one sigma.
COMMENT ON “DARK MATTER SEARCHES GOING BANANAS: THE CONTRIBUTION OF POTASSIUM (AND CHLORINE) TO THE 3.5 KEV LINE” Esra Bulbul (1), Maxim Markevitch (2), Adam R. Foster (1), Randall K. Smith (1), Michael Loewenstein (2), Scott W. Randall (1) (1) Harvard-Smithsonian Center for Astrophysics, (2) NASA/GSFC Draft version September 16, 2014 ABSTRACT The recent paper by Jeltema & Profumo (2014) claims that contributions from K XVIII and Cl XVII [astro-ph.HE] 15 Sep 2014 lines can explain the unidentified emission line found by Bulbul et al. (2014) and also by Boyarsky • The line ratio temperatures in JP et al. (2014a,b). We show that their analysis relies upon incorrect atomic data and inconsistent spectroscopic modeling. We address these points and summarize in the appendix the correct values for the relevant atomic data from AtomDB. 1. INTRODUCTION are inconsistent because JP used AtomDB v2.0.2. In theory, these should be the fluxes In a recent preprint “Dark matter searches going ba- from their Table 2, multiplied by the ratio of predicted nanas: the contribution of Potassium (and Chlorine) to incorrect atomic data — in fact, K XVIII emissivities to that of the line in question. We can, however, recreate their Table 3 if we use the the 3.5 keV line,” Jeltema & Profumo (2014, hereafter JP) claim that the unidentified E ⇡ 3.55 3.57 keV emis- approximate values available in the “strong lines” option sion line that we detected in the stacked galaxy cluster spectra (Bulbul et al. 2014, hereafter B14) and Boyarsky different ratios are in agreement. at http://www.atomdb.org/WebGUIDE/webguide.php. As described on that page, this option uses an approxi- et al. (2014a) detected in Perseus and M31 (as well as mation kT = 3.5 keV their more recent detection of the same line in the Galac- ✏(T ) = ✏(Tpeak )N (T )/N (Tpeak ) (1) tic Center, (Boyarsky et al. 2014b)) can be accounted for where ✏ is the emissivity, T is the requested temperature, by an additional Cl XVII Ly line and by broadening Tpeak is the temperature for which the transition’s emis- the model uncertainty for the flux of the K XVIII He-like sivity is its maximum, and N is the abundance of the triplet. These transitions occur at E ⇡ 3.51 keV, close to ion. This approximation is intended for quick identifica- our unidentified line. In B14, we considered the K line tion of possible strong lines, as it disregards the change among other possibilities and concluded that it cannot in line emissivity with temperature, instead accounting explain the new line. Here we respond to JP’s concerns, only for the relative change in ion abundance.1
COMMENT ON “DARK MATTER SEARCHES GOING BANANAS: THE CONTRIBUTION OF POTASSIUM (AND CHLORINE) TO THE 3.5 KEV LINE” Esra Bulbul (1), Maxim Markevitch (2), Adam R. Foster (1), Randall K. Smith (1), Michael Loewenstein (2), Scott W. Randall (1) (1) Harvard-Smithsonian Center for Astrophysics, (2) NASA/GSFC Draft version September 16, 2014 ABSTRACT The recent paper by Jeltema & Profumo (2014) claims that contributions from K XVIII and Cl XVII S XV • found peaks at(2014) T ~and1 keV. astro-ph.HE] 15 Sep 2014 lines can explain the unidentified emission line by Bulbul et al. also by Boyarsky et al. (2014a,b). We show that their analysis relies upon incorrect atomic data and inconsistent for the relevant atomic data from AtomDB. • The S line ratio indicates absence of spectroscopic modeling. We address these points and summarize in the appendix the correct values 1. INTRODUCTION significant quantities AtomDB v2.0.2. ofshould In theory, these such gas be the even fluxes In a recent preprint “Dark matter searches going ba- from their Table 2, multiplied by the ratio of predicted nanas: the contribution of Potassium (and Chlorine) to in Kthe XVIIIPerseus cool emissivities to that ofcore the line (as well as in question. in the 3.5 keV line,” Jeltema & Profumo (2014, hereafter We can, however, recreate their Table 3 if we use the approximate values available in the “strong lines” option JP) claim that the unidentified E ⇡ 3.55 3.57 keV emis- sion line that we detected in the stacked galaxy cluster other subsamples). at http://www.atomdb.org/WebGUIDE/webguide.php. spectra (Bulbul et al. 2014, hereafter B14) and Boyarsky As described on that page, this option uses an approxi- et al. (2014a) detected in Perseus and M31 (as well as mation their more recent detection of the same line in the Galac- ✏(T ) = ✏(Tpeak )N (T )/N (Tpeak ) (1) tic Center, (Boyarsky et al. 2014b)) can be accounted for where ✏ is the emissivity, T is the requested temperature, by an additional Cl XVII Ly line and by broadening Tpeak is the temperature for which the transition’s emis- the model uncertainty for the flux of the K XVIII He-like sivity is its maximum, and N is the abundance of the triplet. These transitions occur at E ⇡ 3.51 keV, close to ion. This approximation is intended for quick identifica- our unidentified line. In B14, we considered the K line tion of possible strong lines, as it disregards the change
COMMENT ON “DARK MATTER SEARCHES GOING BANANAS: THE CONTRIBUTION OF POTASSIUM (AND CHLORINE) TO THE 3.5 KEV LINE” Esra Bulbul (1), Maxim Markevitch (2), Adam R. Foster (1), Randall K. Smith (1), Michael Loewenstein (2), Scott W. Randall (1) (1) Harvard-Smithsonian Center for Astrophysics, (2) NASA/GSFC Draft version September 16, 2014 ABSTRACT The recent paper by Jeltema & Profumo (2014) claims that contributions from K XVIII and Cl XVII S XV • found peaks at(2014) T ~and1 keV. astro-ph.HE] 15 Sep 2014 lines can explain the unidentified emission line by Bulbul et al. also by Boyarsky et al. (2014a,b). We show that their analysis relies upon incorrect atomic data and inconsistent for the relevant atomic data from AtomDB. • The S line ratio indicates absence of spectroscopic modeling. We address these points and summarize in the appendix the correct values 1. INTRODUCTION significant quantities AtomDB v2.0.2. ofshould In theory, these such gas be the even fluxes In a recent preprint “Dark matter searches going ba- from their Table 2, multiplied by the ratio of predicted nanas: the contribution of Potassium (and Chlorine) to in Kthe XVIIIPerseus cool emissivities to that ofcore the line (as well as in in question. We can, however, recreate their Table 3 if we use the the 3.5 keV line,” Jeltema & Profumo (2014, hereafter approximate values available in the “strong lines” option JP) claim that the unidentified E ⇡ 3.55 3.57 keV emis- sion line that we detected in the stacked galaxy cluster other subsamples). at http://www.atomdb.org/WebGUIDE/webguide.php. spectra (Bulbul et al. 2014, hereafter B14) and Boyarsky As described on that page, this option uses an approxi- et al. (2014a) detected in Perseus and M31 (as well as • Sixmation times brighter ✏(T ) = ✏(TpeakCl )N (TXVII )/N (TLy-σ peak ) at 2.96 (1) their more recent detection of the same line in the Galac- tic Center, (Boyarsky et al. 2014b)) can be accounted for by an additional Cl XVII Ly line and by broadening keV Tpeakwas not detected where ✏ is the emissivity, T is the requested temperature, is the temperature for which the transition’s emis- the model uncertainty for the flux of the K XVIII He-like sivity is its maximum, and N is the abundance of the triplet. These transitions occur at E ⇡ 3.51 keV, close to ion. This approximation is intended for quick identifica- our unidentified line. In B14, we considered the K line tion of possible strong lines, as it disregards the change
Discovery of a 3.5 keV line in the Galactic Center and a Critical 99v2 [astro-ph.HE] 8 Apr 2015 Look at the Origin of the Line Across Astronomical Targets Tesla Jeltema1⋆ and Stefano Profumo1† 1 Department of Physics and Santa Cruz Institute for Particle Physics University of California, Santa Cruz, CA 95064, USA −4 10 April 2015 10 from Ca from 6 ABSTRACT Allowed in B14 • Claim: Ca Line ratios We examine the claimed excess X-ray line emission near 3.5 keV including Full both a new anal- Distant −5 −1 10 ysis of XMM-Newton observations of the Milky Sampl Way center and a reanalysis of the data on indicate ~1 keV plasma? V Clustersevidence for an excess. M 31 and clusters. In no case do we find conclusive e In the case of 2 flux Sh cm the Galactic center we show that known plasma lines, including in particular K XVIII lines at 3.48 and 3.52 keV, provide a satisfactory fit to the XMM data.Perseus We estimate the expected flux of the K XVIII lines10 −6 and findBright Cluster that the measured line flux falls squarely within the predicted range based on the brightness of other well-measured lines in the energy range of interest and on detailed multi-temperature Clusters plasma models. We then re-assess the evidence for excess emis- • A further mistake in the sionCafrom clusters of galaxies, allowing for systematic uncertainty in the expected flux from line ratio to temperature known plasma lines and−7additional uncertainty due to potential variation in the abundances of different elements. We10 find that no conclusive excess line emission can be advocated when k7 3.7keV k7 3.1keV k7 3.8keV k7 3.7keV k7 3.5keV k7 4.2keV k7 3.8keV k7 3.2keV fullVamSle fullVamSle conversion in v2 of the J&P systematic uncertainties in Perseus or in other clusters. We also re-analyze the SerVeuV SerVeuV considering moV moV moV moV excl excl cco cco Sn Sn Sn Sn XMM data for M 31 and find no statistically significant line emission near 3.5 keV to a level paper ... greater than one sigma. Finally, we analyze the Tycho supernova remnant, which shows sim- ilar plasma features to the sources above, but does not host any significant dark matter. We detect a 3.55 keV line from Tycho, which points to possible systematic effects in the flux de-
Discovery of a 3.5 keV line in the Galactic Center and a Critical 99v2 [astro-ph.HE] 8 Apr 2015 Look at the Origin of the Line Across Astronomical Targets Tesla Jeltema1⋆ and Stefano Profumo1† 1 Department of Physics and Santa Cruz Institute for Particle Physics University of California, Santa Cruz, CA 95064, USA −4 10 April 2015 10 from Ca from 6 ABSTRACT Allowed in B14 • Claim: Ca Line ratios We examine the claimed excess X-ray line emission near 3.5 keV including Full both a new anal- Distant −5 −1 10 ysis of XMM-Newton observations of the Milky Sampl Way center and a reanalysis of the data on indicate ~1 keV plasma? V Clustersevidence for an excess. M 31 and clusters. In no case do we find conclusive e In the case of 2 flux Sh cm the Galactic center we show that known plasma lines, including in particular K XVIII lines at 3.48 and 3.52 keV, provide a satisfactory fit to the XMM data.Perseus We estimate the expected flux of the K XVIII lines10 −6 and findBright Cluster that the measured line flux falls squarely within the predicted range based on the brightness of other well-measured lines in the energy range of interest and on detailed multi-temperature Clusters plasma models. We then re-assess the evidence for excess emis- • A further mistake in the sionCafrom clusters of galaxies, allowing for systematic uncertainty in the expected flux from line ratio to temperature known plasma lines and−7additional uncertainty due to potential variation in the abundances of different elements. We10 find that no conclusive excess line emission can be advocated when k7 3.7keV k7 3.1keV k7 3.8keV k7 3.7keV k7 3.5keV k7 4.2keV k7 3.8keV k7 3.2keV fullVamSle fullVamSle conversion in v2 of the J&P systematic uncertainties in Perseus or in other clusters. We also re-analyze the SerVeuV SerVeuV considering moV moV moV moV excl excl cco cco Sn Sn Sn Sn XMM data for M 31 and find no statistically significant line emission near 3.5 keV to a level paper ... greater than one sigma. Finally, we analyze the Tycho supernova remnant, which shows sim- ilar plasma features to the sources above, but does not host any significant dark matter. We detect a 3.55 keV line from Tycho, which points to possible systematic effects in the flux de-
Where do the 3.5 keV photons come from? A morphological study of the Galactic Center and of Perseus arXiv:1411.1758v3 [astro-ph.HE] 15 Jan 2015 Carlson, Jeltema & Profumo (cont.) a,b Eric Carlson, Tesla Jeltema,a,b Stefano Profumoa,b a Department of Physics, University of California, Santa Cruz profile Radial of the residual 3.5 keV emission: 1156 High St, Santa Cruz, CA 95064 b Santa Cruz Institute for Particle Physics, R=3’ • 3.55 keV line is ∼ 1% of continuum, so any 1156 High St, Santa Cruz, CA 95064 120 E-mail: erccarls@ucsc.edu, tesla@ucsc.edu, profumo@ucsc.edu errors of continuum Abstract. > fewWe % will result in 100 test the origin of the 3.5 keV line photons by analyzing the morphology Perseus Cluster Averaging: −180◦ < φ < 180◦ Counts [ph µsr−1 ] of the emission at that energy from the Galactic Center and from 80the Perseus cluster of mapping the astrophysical continuum galaxies. We employ a variety of di↵erent templates to model the continuum emission and analyze the resulting radial and azimuthal distribution of the 60 residual emission. We then perform a pixel-by-pixel binned likelihood analysis including line emission tem- ALP Photo-conversion (Ref. [34]) • The line from the whole Perseus cluster is plates and dark matter templates and assess the correlation of 40 the 3.5 keV emission with these templates. We conclude that the radial and azimuthal distribution of the NFW DM residual emission is incompatible with a dark matter origin for both 20 the Galactic center detected at 3σ significance and Perseus; the Galactic center 3.5 keV line photons trace the morphology of lines at comparable energy, while the Perseus 3.5 keV photons are highly0correlated with the cluster’s cool core, and exhibit a morphology incompatible with dark matter decay. The • small error bars on the profile cannot template analysis additionally allows us to set the most stringent−20 constraints to date on lines in the 3.5 keV range from dark matter decay. 0.00 0.05 0.10 0.15 0.20 0.25 represent the line signal 100 Radius [deg]
Charge Exchange
A novel scenario for the possible X-ray line feature at ∼3.5 keV: Charge exchange with bare sulfur ions Liyi Gu1 , Jelle Kaastra1, 2 , A. J. J. Raassen1, 3 , P. D. Mullen4 , R. S. Cumbee4 , D. Lyons4 , and P. C. Stancil4 L. Gu et al.: S xvi Charge Exchange 1 SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands 0.04 (a) BU14 XMM-PN • charge exchange (CX) e-mail: L.Gu@sron.nl tro-ph.HE] 20 Nov 2015 2 Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands 3 Astronomical Institute “Anton Pannekoek”, Science Park 904, 1098 XH 0Amsterdam, University of Amsterdam, The Netherlands between 4 bare sulfur and Department of Physics and Astronomy and the Center for Simulational Physics, University of Georgia, Athens, GA 30602, USA (Data - Model) / Model November 23, 2015 0.04 (b) BO14 XMM-MOS ( neutral hydrogen interacting 0.01 ABSTRACT 0 with a relative velocity of ∼ 200 Motivated by recent claims of a compelling ∼3.5 keV emission line from nearby galaxies and galaxy clusters, we investigate a 0 novel plasma model incorporating a charge exchange component obtained from (c)theoretical U15 scattering calculations. Fitting this kind km/s. 0.01 of component with a standard thermal model yields positive residuals around 3.5 keV, produced mostly by S xvi transitions from principal quantum numbers n ≥ 9 to the ground. Such high-n states can only 0 be populated by the charge exchange process. In this -0.01 • S XVI CX Line is located at 3.44 scenario, the observed 3.5 keV line flux in clusters can be naturally explained by an interaction in an effective volume of ∼1 kpc3 between a ∼3 keV temperature plasma and cold dense clouds moving at a few hundred km s−1 . The S xvi lines at ∼3.5 keV also Suzaku provide a unique diagnostic of the charge exchange phenomenon in hot cosmic plasmas.3.2 3.6 4.0 keV Key words. Atomic processes – Line: identification – X-rays: galaxies: clusters Energy (keV) Fig. 2. (a, b, and c) The spectral fitting residuals reported in BU14 (top right panel Line panel of their Fig. 2), in the together with thestacked MOS observations expected residuals, shown as red curves, fr model in (c) is half of those in (a) and (b). As described in §3.2, the data-to-mode 1. Introduction panded to various types of objects, from neighboring planets to emission lines. (d) Fitting residual from a 1 Ms simulation of the XMM-Newton
Future: Observations with Hitomi re-flight Astro-H SXS 1Ms Perseus Perseus, 1 Msec 1.5×10−3 Observations kT = 6.5 keV, 0.6 solar z=0.0178 v(baryons) = 300 km/s Flux (ph cm-2s-1keV-1) v(line) = 1300 km/s Hitomi re-flight launch 2021 3.62 keV 10−3 Ar XVII DR Ca XIX Ar XVII Ar XVIII 3.55 keV Line 5×10−4 3 3.2 3.4 3.6 3.8 Energy (keV)
EBIT Experiments to Test the Astrophysical Origin • LLNL EBIT/ECS experiment for measuring Ar XVII an K XVIII transitions 70 60 Ar XVII Number of Photons n = 2 →1 50 K-alpha Ar XVII 40 K beta 30 20 10 2900 3000 3100 3200 3300 3400 3500 3600 3700 Energy (keV) Energy (keV)
EBIT Argon Helium-like Experiment Argon XVII Kβ emission Ar XVII400 Kβ: EBIT, FAC, APEC 2.0.2 Ar XVII Kβ: tokamak at 400 EBIT Ar16+ Kβ 3 to 1 kTe = 2.0 ± 0.2 KeV EBIT 350 Kβ Beiersdorfer et al 1995 intensity (arb. units) DR onto Ar16+ APEC 2.0.2 DR onto Ar16+ 300 DE of Ar15+ DE of Ar15+ DE of Ar14+ 200 300 intensity (arb. units) APEC 100 Kβ satellites = 0.8 250 Kβ EBIT 0 3580 3600 3620 3640 3660 3680 3700 200 energy (eV) Greg Brown, Natalie Hell, and -3 intensity (arb. units)x10 4.0 FAC 150 Kβ satellites Peter Beiersdorfer 3.0 3.36 3.40 3.44 3.48 2.0 Wavelength (Å) 100 1.0 0.0 50 • Lines identified using Beiersdorfer 1995 3580 3600 3620 3640 3660 3680 3700 energy (eV) 0 -18 1.0 • DR feature at 3.62 keV also includes (arb. units)x10 APEC 2.0.2 3580 3600 3620 3640direct3660 Bulbul & Smith+2017, in excitation3680 lines from3700 0.8 0.6 Li-likeprep Ar15+ energy (eV) 0.4
EBIT Argon Helium-like Experiment Argon XVII Kβ emission Ar XVII400 Kβ: EBIT, FAC, APEC 2.0.2 Ar XVII Kβ: tokamak at 400 EBIT Ar16+ Kβ 3 to 1 kTe = 2.0 ± 0.2 KeV EBIT 350 Kβ Beiersdorfer et al 1995 intensity (arb. units) DR onto Ar16+ APEC 2.0.2 DR onto Ar16+ 300 DE of Ar15+ DE of Ar15+ DE of Ar14+ 200 300 intensity (arb. units) APEC 100 Kβ satellites = 0.8 250 Kβ EBIT 0 3580 3600 200 3620 APEC is not off by factor of 30! 3640 energy (eV) 3660 3680 3700 -3 intensity (arb. units)x10 4.0 FAC 150 Kβ satellites 3.0 3.36 3.40 3.44 3.48 2.0 Wavelength (Å) 100 1.0 0.0 50 • Lines identified using Beiersdorfer 1995 3580 3600 3620 3640 3660 3680 3700 energy (eV) 0 -18 1.0 • DR feature at 3.62 keV also includes (arb. units)x10 APEC 2.0.2 0.8 3580 3600 3620 3640direct3660 excitation3680 lines from3700 Li-like Bulbul+2017, Ar15+ in prep 0.6 energy (eV) 0.4
Stacked Suzaku Observations 0.01 < z < 0.45 Particle Mass ➔ Mixing Angle ➔ Bulbul+2016b
E 2 Figure 3: Left panel: MOS1 spectrum and residuals. Right panel: = 1, 4, 9 Deep XMM Observations of Draco rule out at the 99% Confidence 2 camera (thick lines). The PN camera contours with = 1, 4, 9 are shown as Level a Dark Matter Decay Origin for the 3.5 keV Line to the contours in Fig. 2). Tesla Jeltema1⋆ and Stefano Profumo1† 1 Department of Physics and Santa Cruz Institute for Particle Physics University of California, Santa Cruz, CA 95064, USA ? K Kα Ca Kα TiMOS2 Kα65 eV Cr Kα Mn Kα Fe Kα s-1 keV2016 10 March 2016 • Band is very 1.0x10-8 -1) 0.08 ABSTRACT crowded with normalized counts s−1 keV−1 9 Mar We searched for an X-ray line at energies around 3.5 keV in deep, ∼ 1.6 Msec XMM-Newton 0.06 observations of the dwarf spheroidal galaxy Draco. No line instrumental was found in either linesthe MOS 8.0x10-9 or the PN detectors. The data in this energy range are completely consistent with a single, Anydominates • which inaccuracies Flux (cnts Flux [cts/sec/cm /arcmin ] 2 unfolded power law modeling the particle background, at these energies, 0.04 plus instrumental lines; the addition of a ∼ 3.5 keV line feature gives no improvement to the fit. The corresponding upper limit on the line flux rules outin the modeling [astro-ph.HE] a dark matter decay origin for the 6.0x10-9 2 3.5 keV line found in observations of clusters of galaxies and in the Galactic Center at greater would produce 0.02 than 99% C.L.. 0 (cosmology:) dark matter artificially high Key words: X-rays: galaxies; X-rays: galaxies: clusters; X-rays: ISM; line: identification; 4.0x10-9 normalized counts s−1 keV−1 2×10 −3 continuum 239v2Residuals 10−3 2.0x10-9 0 1 INTRODUCTION • Instrumental lines As a result, the case for K XVIII as the culprit for the 3.5 keV line −10−3 The detection of a line with an energy between 3.50 – 3.57 are not included in appears at present quite plausible. 0.0x100 −2×10−3 keV (hereafter indicated as “the 3.5 keV line” for brevity) Additional circumstantial evidence against a dark matter de- 3 3.5 4 4.5 in the X-ray data from individual and stacked observations Energy (keV) 5 5.5 6 thehas J&P 6.5 cay origin for the 3.5 keV line 2016 also emerged. Malyshev et al. 3.45 3.5 Energy (keV) of clusters of galaxies (Bulbul et al. 2014), from the Galac- (2014) searched for the line in stacked, archival XMM observa- Ruchayskiy+2016 tic center (Jeltema & Profumo 2015) and, tentatively, from M31 tions of dwarf spheroidal galaxies, reporting a null result that highly constrained a dark matter decay origin for the line. Anderson et al. (Boyarsky et al. 2014) (see however Jeltema & Profumo 2015;
Dwarf Spheroidal Draco 4.5x10-6 cm-2) Distant clusters 4.0x10-6 Distant clusters (MOS) 3.5x10-6 ] -1 All clusters s-1 keV 3.0x10-6 (MOS) 2 Flux [cts/sec/cm 2 ∆χ = 9 M31 2.5x10-6 2 Distant clusters ∆χ = 4 2.0x10-6 (PN) Flux (cnts 2 ∆χ = 1 Best-fit Draco PN 1.5x10-6 GC 1.0x10-6 aco MOS1+MOS2+PN 5.0x10-7 Energy (keV) 0.0x100 3.6 3.62 3.64 3.48 3.5 3.52 3.54 3.56 3.58 3.6 Energy (keV) Line position [keV] Decay OS1, MOS2, •and PN rate is consistent cameras with clusters, (see text M31, and for details). TheGalactic normal-Center Ruchayskiy,..& Bulbul+2016
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