scholarly journals The dark matter interpretation of the 3.5-keV line is inconsistent with blank-sky observations

Science ◽  
2020 ◽  
Vol 367 (6485) ◽  
pp. 1465-1467 ◽  
Author(s):  
Christopher Dessert ◽  
Nicholas L. Rodd ◽  
Benjamin R. Safdi
Keyword(s):  
Dark Matter ◽  
Emission Line ◽  
Decay Rate ◽  
Milky Way ◽  
Line Emission ◽  
Mass Range ◽  
Sterile Neutrinos ◽  
X Ray ◽  
Upper Limit ◽  
Nearby Galaxies

Observations of nearby galaxies and galaxy clusters have reported an unexpected x-ray emission line around 3.5 kilo–electron volts (keV). Proposals to explain this line include decaying dark matter—in particular, that the decay of sterile neutrinos with a mass around 7 keV could match the available data. If this interpretation is correct, the 3.5-keV line should also be emitted by dark matter in the halo of the Milky Way. We used more than 30 megaseconds of XMM-Newton (X-ray Multi-Mirror Mission) blank-sky observations to test this hypothesis, finding no evidence of the 3.5-keV line emission from the Milky Way halo. We set an upper limit on the decay rate of dark matter in this mass range, which is inconsistent with the possibility that the 3.5-keV line originates from dark matter decay.

scholarly journals The XMM Cluster Survey: new evidence for the 3.5-keV feature in clusters is inconsistent with a dark matter origin

2020 ◽  
Vol 497 (1) ◽  
pp. 656-671 ◽  
Author(s):  
S Bhargava ◽  
P A Giles ◽  
A K Romer ◽  
T Jeltema ◽  
J Mayers ◽  
...  
Keyword(s):  
Dark Matter ◽  
Emission Line ◽  
Galaxy Clusters ◽  
Sterile Neutrino ◽  
Significant Excess ◽  
Mixing Angle ◽  
X Ray ◽  
Cluster Survey ◽  
Upper Limit ◽  
New Evidence

ABSTRACT There have been several reports of a detection of an unexplained excess of X-ray emission at $\simeq$3.5 keV in astrophysical systems. One interpretation of this excess is the decay of sterile neutrino dark matter. The most influential study to date analysed 73 clusters observed by the XMM–Newton satellite. We explore evidence for a ≃3.5-keV excess in the XMM-PN spectra of 117 redMaPPer galaxy clusters (0.1 < z < 0.6). In our analysis of individual spectra, we identify three systems with an excess of flux at $\simeq$3.5 keV. In one case (XCS J0003.3+0204), this excess may result from a discrete emission line. None of these systems are the most dark matter dominated in our sample. We group the remaining 114 clusters into four temperature (TX) bins to search for an increase in ≃3.5-keV flux excess with TX – a reliable tracer of halo mass. However, we do not find evidence of a significant excess in flux at ≃3.5 keV in any TX bins. To maximize sensitivity to a potentially weak dark matter decay feature at ≃3.5 keV, we jointly fit 114 clusters. Again, no significant excess is found at ≃3.5 keV. We estimate the upper limit of an undetected emission line at ≃3.5 keV to be 2.41 × 10−6 photons cm−2 s−1, corresponding to a mixing angle of sin 2(2θ) = 4.4 × 10−11, lower than previous estimates from cluster studies. We conclude that a flux excess at ≃3.5 keV is not a ubiquitous feature in clusters and therefore unlikely to originate from sterile neutrino dark matter decay.

scholarly journals Observation of the new emission line at ~3.5 keV in X-ray spectra of galaxies and galaxy clusters

2016 ◽  
Vol 6 (1) ◽  
pp. 3-15 ◽  
Author(s):  
D. Iakubovskyi
Keyword(s):  
Dark Matter ◽  
Emission Line ◽  
Galaxy Clusters ◽  
Particle Physics ◽  
Emission Lines ◽  
Beyond The Standard Model ◽  
Future Directions ◽  
X Ray ◽  
The Standard Model ◽  
Nearby Galaxies

The detection of an unidentified emission line in the X-ray spectra of cosmic objects would be a `smoking gun' signature for the particle physics beyond the Standard Model. More than a decade of its extensive searches results in several narrow faint emission lines reported at 3.5, 8.7, 9.4 and 10.1 keV. The most promising of them is the emission line at ~3.5 keV reported in spectra of several nearby galaxies and galaxy clusters. Here I summarize its up-to-date status, overview its possible interpretations, including an intriguing connection with the radiatively decaying dark matter, and outline future directions for its studies.

scholarly journals Double X/Peanut Structures in Barred Galaxies – Insights from an N–body Simulation

2020 ◽  
Author(s):  
Bogdan C Ciambur ◽  
Francesca Fragkoudi ◽  
Sergey Khoperskov ◽  
Paola Di Matteo ◽  
Françoise Combes
Keyword(s):  
Dark Matter ◽  
Milky Way ◽  
Large Fraction ◽  
Formation Time ◽  
Dark Matter Halo ◽  
Barred Galaxies ◽  
Pattern Speed ◽  
Nearby Galaxies ◽  
Dynamical Instabilities ◽  
Bow Tie

Abstract Boxy, peanut– or X–shaped “bulges” are observed in a large fraction of barred galaxies viewed in, or close to, edge-on projection, as well as in the Milky Way. They are the product of dynamical instabilities occurring in stellar bars, which cause the latter to buckle and thicken vertically. Recent studies have found nearby galaxies that harbour two such features arising at different radial scales, in a nested configuration. In this paper we explore the formation of such double peanuts, using a collisionless N–body simulation of a pure disc evolving in isolation within a live dark matter halo, which we analyse in a completely analogous way to observations of real galaxies. In the simulation we find a stable double configuration consisting of two X/peanut structures associated to the same galactic bar – rotating with the same pattern speed – but with different morphology, formation time, and evolution. The inner, conventional peanut-shaped structure forms early via the buckling of the bar, and experiences little evolution once it stabilises. This feature is consistent in terms of size, strength and morphology, with peanut structures observed in nearby galaxies. The outer structure, however, displays a strong X, or “bow-tie”, morphology. It forms just after the inner peanut, and gradually extends in time (within 1 to 1.5 Gyr) to almost the end of the bar, a radial scale where ansae occur. We conclude that, although both structures form, and are dynamically coupled to, the same bar, they are supported by inherently different mechanisms.

scholarly journals Quantifying tidal stream disruption in a simulated Milky Way

2017 ◽  
Vol 470 (1) ◽  
pp. 522-538 ◽  
Author(s):  
Emily Sandford ◽  
Andreas H. W. Küpper ◽  
Kathryn V. Johnston ◽  
Jürg Diemand
Keyword(s):  
Dark Matter ◽  
Milky Way ◽  
Galactic Halo ◽  
Mass Range ◽  
Galactic Centre ◽  
High Dimensions ◽  
Density Profiles ◽  
Upper Limits ◽  
Tidal Stream ◽  
Tidal Streams

Abstract Simulations of tidal streams show that close encounters with dark matter subhaloes induce density gaps and distortions in on-sky path along the streams. Accordingly, observing disrupted streams in the Galactic halo would substantiate the hypothesis that dark matter substructure exists there, while in contrast, observing collimated streams with smoothly varying density profiles would place strong upper limits on the number density and mass spectrum of subhaloes. Here, we examine several measures of stellar stream ‘disruption' and their power to distinguish between halo potentials with and without substructure and with different global shapes. We create and evolve a population of 1280 streams on a range of orbits in the Via Lactea II simulation of a Milky Way-like halo, replete with a full mass range of Λcold dark matter subhaloes, and compare it to two control stream populations evolved in smooth spherical and smooth triaxial potentials, respectively. We find that the number of gaps observed in a stellar stream is a poor indicator of the halo potential, but that (i) the thinness of the stream on-sky, (ii) the symmetry of the leading and trailing tails and (iii) the deviation of the tails from a low-order polynomial path on-sky (‘path regularity') distinguish between the three potentials more effectively. We furthermore find that globular cluster streams on low-eccentricity orbits far from the galactic centre (apocentric radius ∼30–80 kpc) are most powerful in distinguishing between the three potentials. If they exist, such streams will shortly be discoverable and mapped in high dimensions with near-future photometric and spectroscopic surveys.

scholarly journals Multiwavelength Milky Way: An Educational Poster

1998 ◽  
Vol 179 ◽  
pp. 237-237 ◽  
Author(s):  
D. Leisawitz ◽  
S.W. Digel ◽  
S. Geitz
Keyword(s):  
Milky Way ◽  
Gamma Ray ◽  
Line Emission ◽  
Electromagnetic Spectrum ◽  
Data Sets ◽  
X Ray ◽  
Nasa Goddard Space ◽  
Broadband Emission ◽  
The Galaxy ◽  
Effective Use

The Astrophysics Data Facility at NASA Goddard Space Flight Center supports the processing, management, and dissemination of data obtained by past, current, and future NASA and international astrophysics missions, and promotes the effective use of those data by the astrophysics community, educators, and the public. Our Multiwavelength Milky Way poster was printed for broad distribution. It depicts the Galaxy at radio, infrared, optical, X-ray, and gamma-ray wavelengths. In particular, the poster contains images of the Galactic 21-cm and CO (J = 1 → 0) line emission, and IRAS 12, 60, and 100 μm, COBE/DIRBE 1.25, 2.2, and 3.5 μm, Digitized Sky Survey optical wavelength, ROSAT/PSPC 0.25, 0.75, and 1.5 keV X-ray, and CGRO/EGRET E > 100 MeV gamma ray broadband emission. All of the data sets are publicly available. Captions describe the Milky Way and what can be learned about the Galaxy from measurements made in each segment of the electromagnetic spectrum. The poster is intended to be an educational tool, one that will stimulate heightened awareness by laypersons of NASA's contribution to modern astronomy.Through an interface available on the World Wide Web at http://adf.gsfc.nasa.gov/adf/adf.html one may view the images that appear on the poster, read the poster captions, and locate the archived data and references.

scholarly journals Structure and Emission Line Spectrum of an X-ray Heated Accretion Disk in AGN

1994 ◽  
Vol 159 ◽  
pp. 484-484
Author(s):  
Yuan-Kuen Ko ◽  
Timothy R. Kallman
Keyword(s):  
Emission Line ◽  
Active Galactic Nuclei ◽  
Accretion Disk ◽  
Line Emission ◽  
Galactic Nuclei ◽  
X Ray ◽  
Disk Size ◽  
Emission Line Spectrum ◽  
Self Gravity ◽  
A Site

We investigate the structure of an X-ray heated accretion disk in active galactic nuclei. It is found that X-ray heating can prevent the disk to be disrupted by its self-gravity under sufficient X-ray heating. The disk size can be two orders of magnitute larger than that limited by self-gravity of the disk without X-ray heating. An accretion disk corona will be formed by X-ray heating and can be a site for line emission. We present such emission line spectra which range from optical to hard X-ray energies and compare with the observational data.

scholarly journals Upper limit on the central density of dark matter in the Eddington-inspired Born–Infeld (EiBI) gravity

2015 ◽  
Vol 30 (11) ◽  
pp. 1550056 ◽  
Author(s):  
Ramil Izmailov ◽  
Alexander A. Potapov ◽  
Alexander I. Filippov ◽  
Mithun Ghosh ◽  
Kamal K. Nandi
Keyword(s):  
Dark Matter ◽  
Alternative Model ◽  
Milky Way ◽  
Viable Alternative ◽  
Central Density ◽  
Density Profiles ◽  
Milky Way Galaxy ◽  
Upper Limit ◽  
The Stability ◽  
Individual Galaxy

We investigate the stability of circular material orbits in the analytic galactic metric recently derived by Harko et al., Mod. Phys. Lett. A29, 1450049 (2014). It turns out that stability depends more strongly on the dark matter central density ρ0 than on other parameters of the solution. This property then yields an upper limit on ρ0 for each individual galaxy, which we call here [Formula: see text], such that stable circular orbits are possible only when the constraint [Formula: see text] is satisfied. This is our new result. To approximately quantify the upper limit, we consider as a familiar example our Milky Way galaxy that has a projected dark matter radius R DM ~180 kpc and find that [Formula: see text]. This limit turns out to be about four orders of magnitude larger than the latest data on central density ρ0 arising from the fit to the Navarro–Frenk–White (NFW) and Burkert density profiles. Such consistency indicates that the Eddington-inspired Born–Infeld (EiBI) solution could qualify as yet another viable alternative model for dark matter.

SIGNALS FOR LIGHT DARK MATTER AXINO

2007 ◽  
Vol 22 (25n28) ◽  
pp. 2113-2120
Author(s):  
HANG BAE KIM
Keyword(s):  
Dark Matter ◽  
Parity Violation ◽  
Particle Physics ◽  
Cold Dark Matter ◽  
Line Emission ◽  
Dark Matter Particle ◽  
Mass Range ◽  
Γ Rays ◽  
Γ Ray ◽  
The Continuum

Light dark matter aims at explaining the 511 keV γ-ray line emission from the galactic bulge as well as cold dark matter in our universe. The former is achieved via the annihilations or decays of light dark matter particles, which implies interesting observational consequences in addition to 511 keV γ-rays. We consider the axino in the 1 ~ 10 MeV mass range as the light dark matter particle and discuss the particle physics models for it, its cosmological production, and its decay arising from R-parity violation. For additional observational signals, we consider the connection to the neutrino data made by bilinear R-parity violations and the continuum γ-ray emission from light dark matter particles.

scholarly journals High-Resolution X-Ray Spectroscopy of Galactic Supernova Remnants

2014 ◽  
Vol 1 (1) ◽  
pp. 200-204
Author(s):  
Satoru Katsuda ◽  
Hiroshi Tsunemi
Keyword(s):  
High Resolution ◽  
Supernova Remnants ◽  
Line Emission ◽  
Collisionless Shock ◽  
Reverse Shock ◽  
X Ray ◽  
Upper Limit ◽  
Hot Plasma ◽  
Forward Shock ◽  
Intensity Ratios

High-resolution X-ray spectroscopy of Galactic supernova remnants (SNRs), based on grating spectrometers onboard XMM-Newton and Chandra, has been revealing a variety of new astrophysical phenomena. Broadened oxygen lines for a northwestern compact knot in SN 1006 clearly show a high oxygen temperature of ~300 keV. The high temperature together with a lower electron temperature (<em>kT<sub>e</sub></em> ~ 1 keV) can be reasonably interpreted as temperature non-equilibration between electrons and oxygen behind a collisionless shock. An ejecta knot in the Puppis A SNR shows blueshifted line emission by ~ 1500kms<sup>-1</sup>. The line widths are fairly narrow in contrast to the SN 1006's knot; an upper limit of 0.9 eV is obtained for O VIII Lyα, which translates to an oxygen temperature of <em>kT<sub>O</sub></em> &lt; 30 keV. The low temperature suggests that the knot was heated by a reverse shock whose velocity is 4 times slower than that of a forward shock. Anomalous intensity ratios in O VII Heα lines, i.e., a stronger forbidden line than a resonance line, is found in a cloud-shock interaction region in Puppis A. The line ratio can be best explained by the charge-exchange emission that should arise at interfaces between the cold/warm clouds and the hot plasma. There are several other targets for which we plan to analyze high-quality grating data prior to the operation of the soft X-ray spectrometer onboard Astro-H.

scholarly journals 7.1 keV sterile neutrino dark matter constraints from a deep Chandra X-ray observation of the Galactic bulge Limiting Window

2019 ◽  
Vol 625 ◽  
pp. L7 ◽  
Author(s):  
F. Hofmann ◽  
C. Wegg
Keyword(s):  
Dark Matter ◽  
Sterile Neutrino ◽  
Line Strength ◽  
Galactic Bulge ◽  
Sterile Neutrinos ◽  
Additional Line ◽  
Mixing Angle ◽  
X Ray ◽  
Systematic Uncertainties ◽  
Good Target

Context. An unidentified emission line at 3.55 keV was recently detected in X-ray spectra of clusters of galaxies. The line has been discussed as a possible decay signature of 7.1 keV sterile neutrinos, which have been proposed as a dark matter (DM) candidate. Aims. We aim to further constrain the line strength and its implied mixing angle under the assumption that all DM is made of sterile neutrinos. Methods. The X-ray observations of the Limiting Window (LW) towards the Galactic bulge (GB) offer a unique dataset for exploring DM lines. We characterise the systematic uncertainties of the observation and the fitted models with simulated X-ray spectra. In addition, we discuss uncertainties of indirect DM column density constraints towards the GB to understand systematic uncertainties in the assumed DM mass in the field of view of the observation. Results. We find tight constraints on the allowed flux for an additional line at 3.55 keV with a positive (∼1.5σ) best fit value FX3.55 keV ≈ (4.5 ± 3.5) × 10−7 cts cm−2 s−1. This would translate into a mixing angle of sin2(2Θ) ≈ (2.3 ± 1.8) × 10−11 which, while consistent with some recent results, is in tension with earlier detections. Conclusions. We used a very deep dataset with well understood systematic uncertainties to derive tight constraints on the mixing angle of a 7.1 keV sterile neutrino DM candidate. The results highlight that the inner Milky Way will be a good target for DM searches with upcoming missions like eROSITA, XRISM, and ATHENA.

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