Checking the potassium origin of the new emission line at 3.5 keV using the K xix line complex at 3.7 keV

Abstract

Whether the new line at ∼3.5 keV, recently detected in different samples of galaxy clusters, Andromeda galaxy and central part of our Galaxy, is due to Potassium emission lines, is now unclear. By using the latest astrophysical atomic emission line database AtomDB v. 3.0.2, we show that the most prospective method to directly check its Potassium origin will be the study of K XIX emission line complex at ∼3.7 keV with future X-ray imaging spectrometers such as Soft X-ray spectometer on-board Astro-H mission or microcalorimeter on-board Micro-X sounding rocket experiment. To further reduce the remaining (factor ∼ 3 − 5) uncertainty of the 3.7/3.5 keV ratio one should perform more precise modeling including removal of significant spatial inhomogeneities, detailed treatment of background components, and further extension of the modeled energy range.

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

“…However, because at the moment there is no established mechanism that could effectively provide such an enhancement, the results of [102] only indicate the potential level of uncertainty, similar to the measurements in [101]. at 3.51 keV found largely sub-dominant in Galactic Centre region [79] and in galaxy clusters [99]), K XVIII line complex does not have stronger counterparts at other energies and can hardly be excluded by measurements of other lines, the strongest of them is the K XIX line complex at 3.71 keV of comparable strength [103]. The same is true about the charge exchange of S XVI ions recently suggested by [104].…”

Towards Robust Detection of a Faint Narrow Line in X-Rays – the Role of Continuum-Induced Systematics

“…6.5 of [30] for details. As a result, to decrease Δ line,est , one needs to: 1. increase the energy resolution (scales as Δ line ); 2. increase the effective area (scales as −1 eff ); 3. increase the observation exposure time (scales as The first two options can be reached by new better instruments, for example, Micro-X sounding rocket experiment [31], Soft X-ray spectrometer (SXS) [32] [37,38], the eROSITA instrument on-board planned Spektrum-Röntgen-Gamma mission [39], and the Large Area Detector (LAD) onboard proposed LOFT mission [40], see also [41][42][43][44][45][46][47][48][49] for more details. The next two possibilities can be addressed by prolonged observations (with larger exp ) of fainter objects (with both smaller cont and cont ).…”

Identification of the ~3.55 keV emission line candidate objects across the sky

“…The new narrow emission line at ∼3.55 keV reported in February 2014 from different stacks of galaxy clusters [1], the Andromeda galaxy and the Perseus galaxy cluster [2], still remains unexplained, see reviews [3,4] for details. Although the standard astrophysical explanation due to enhanced K XVIII emission lines at ∼3.51 keV proposed in [5] remains possible [6], subsequent measurements of the new line strength in the Galactic Centre [7,8] and in the nearby dark matter-dominated galaxy clusters [9] argue for physics beyond the Standard Model, presumably in a form of radiatively decaying dark matter. Further studies with future high-resolution imaging spectrometers, such as Soft X-ray Spectrometer (SXS) on-board forthcoming Astro-H mission [10] and Micro-X sounding rocket experiment [11] will be able to determine the line origin [1,12,6] in the nearest future.…”