Intense 6.7-keV iron line emission from the Galactic Centre

Koyama, K.; Awaki, Hisamitsu; Kunieda, H.; Takano, Shiro; Tawara, Yuzuru; Yamauchi, Shigeo; Hatsukade, Isamu; Nagase, F.

doi:10.1038/339603a0

Cited by 197 publications

(164 citation statements)

References 4 publications

Supporting

Mentioning

156

Contrasting

Unclassified

Order By: Relevance

“…As reported in Koyama et al (1989Koyama et al ( , 1996, a large amount of hot plasma was found in our Galactic center, emitting K-shell lines from various highly-ionized ions, including S xvi.…”

Section: Charge Exchange In Galaxy Clusters and Galaxiessupporting

confidence: 73%

A novel scenario for the possible X-ray line feature at ~3.5 keV

Kaastra

Raassen

et al. 2015

A&A

View full text Add to dashboard Cite

Motivated by recent claims of a compelling ∼3.5 keV emission line from nearby galaxies and galaxy clusters, we investigate a novel plasma model incorporating a charge exchange component obtained from theoretical scattering calculations. Fitting this kind 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 be populated by the charge exchange process. In this scenario, the observed 3.5 keV line flux in clusters can be naturally explained by an interaction in an effective volume of ∼1 kpc 3 between a ∼3 keV temperature plasma and cold dense clouds moving at a few hundred keV −1 . The S xvi lines at ∼3.5 keV also provide a unique diagnostic of the charge exchange phenomenon in hot cosmic plasmas.

show abstract

Section: Charge Exchange In Galaxy Clusters and Galaxiessupporting

confidence: 73%

A novel scenario for the possible X-ray line feature at ~3.5 keV

Kaastra

Raassen

et al. 2015

A&A

View full text Add to dashboard Cite

show abstract

“…Another potential candidate for the ambient material is the '' diffuse X-ray plasma,'' which extends across the inner few hundred parsecs of the Galactic center (Koyama et al 1989). The temperature of the diffuse X-ray plasma is as high as 10 keV, so the Mach number is probably less than unity and the SNR will expand without interaction.…”

Section: Dynamical Evolution I: Forward Shock and Ambient Environmentmentioning

confidence: 99%

AChandraStudy of Sagittarius A East: A Supernova Remnant Regulating the Activity of Our Galactic Center?

Maeda

Baganoff

Feigelson

et al. 2002

ApJ

191

222

View full text Add to dashboard Cite

We report on the X-ray emission from the shell-like, nonthermal radio source Sgr A East (SNR 000.0+00.0), located in the inner few parsecs of the Galaxy based on observations made with the ACIS detector on board the Chandra X-Ray Observatory. This is the first time Sgr A East has been clearly resolved from other complex structures in the region. The X-ray-emitting region is concentrated within the central '2 pc of the larger radio shell. The spectrum shows strong K lines from highly ionized ions of S, Ar, Ca, and Fe. A simple isothermal plasma model gives electron temperature $2 keV, absorption column $1 Â 10 23 H cm À2 , luminosity $8 Â 10 34 ergs s À1 in the 2-10 keV band, and gas mass $2 1=2 M with a filling factor . The plasma appears to be rich in heavy elements, overabundant by roughly a factor of 4 with respect to solar abundances, and shows a spatial gradient of elemental abundance; the spatial distribution of iron is more compact than that of the lighter elements. The gas mass and elemental abundance of the X-ray emission support the long-standing hypothesis that Sgr A East is a supernova remnant (SNR), perhaps produced by the Type II supernova explosion of a massive star with a main-sequence mass of 13-20 M . The combination of the radio and X-ray morphologies classifies Sgr A East as a new metal-rich '' mixed morphology '' (MM) SNR. The size of the Sgr A East radio shell is the smallest of the known MM SNRs, which strongly suggests that the ejecta have expanded into a very dense interstellar medium. The ejecta-dominated chemical compositions of the plasma indicate that the ambient materials should be highly homogeneous. We thus evaluate a simplified dynamical evolution model where an SNR was formed about 10,000 yr ago and expanded into an ambient medium with a homogeneous density of 10 3 cm À3 . The model roughly reproduces most of the observed properties in the X-ray and radio wavelengths. A comparison with the radio observations requires the dense ambient medium to be ionized, but a luminous X-ray irradiator with an expected X-ray luminosity of $10 40 ergs s À1 is not currently present. The presence of the ionized gas may be explained if the massive black hole (MBH) associated with the compact, nonthermal radio source Sgr A* was bright in X-rays about 300 yr ago but is presently dim. It is possible that the dust/molecular ridge compressed by the forward shock of Sgr A East hit Sgr A* in the past, and the passage of the ridge may have supplied material to accrete onto the black hole in the past and may have removed material from the black hole vicinity, leading to its present quiescent state. This may be a specific example of the intimate relationship between an SNR and MBH accretion activity in galactic nuclei.

show abstract

“…The Galactic Center (GC) region has been extensively studied by the XMM and several mega-seconds of raw exposure exist. On the other hand, the GC region has strong X-ray emission as many complicated processes occur there [96][97][98][99][100][101][102][103][104]. In particular, the X-ray emitting gas may contain several thermal components with different temperatures; it may be more difficult to constrain the abundances of potassium and argon reliably than in the case of intercluster medium.…”

mentioning

confidence: 99%

Checking the Dark Matter Origin of a 3.53 keV Line with the Milky Way Center

et al. 2015

View full text Add to dashboard Cite

We detect a line at 3.539 ± 0.011 keV in the deep exposure dataset of the Galactic Center region, observed with the XMM-Newton. The dark matter interpretation of the signal observed in the Perseus galaxy cluster, the Andromeda galaxy [1] and in the stacked spectra of galaxy clusters [2], together with non-observation of the line in blank sky data, put both lower and upper limits on the possible intensity of the line in the Galactic Center data. Our result is consistent with these constraints for a class of Milky Way mass models, presented previously by observers, and would correspond to radiative decay dark matter lifetime τDM ∼ 6 − 8 × 10 27 sec. Although it is hard to exclude an astrophysical origin of this line based the Galactic Center data alone, this is an important consistency check of the hypothesis that encourages to check it with more observational data that are expected by the end of 2015.Recently, two independent groups [1, 2] reported a detection of an unidentified X-ray line at energy 3.53 keV in the long-exposure X-ray observations of a number of dark matterdominated objects. The authors of [2] have observed this line in a stacked XMM spectrum of 73 galaxy clusters spanning a redshift range 0.01 − 0.35 and separately in subsamples of nearby and remote clusters. Ref. [1] have found this line in the outskirts of the Perseus cluster and in the central 14 ′ of the Andromeda galaxy. The global significance of detection of the same line in the datasets of Ref.[1] is 4.3σ (taking into account the trial factors); the signal in [2] has significance above 4σ based on completely independent data.The position of the line is correctly redshifted between galaxy clusters [2] and between the Perseus cluster and the Andromeda galaxy [1]. In a very long exposure blank sky observation (15.7 Msec of cleaned data) the feature is absent [1]. This makes it unlikely that an instrumental effect is at the origin of this feature (e.g. an unmodeled wiggle in the effective area).To identify this spectral feature with an atomic line in galaxy clusters, one should assume a strongly super-solar abundance of potassium or some anomalous argon transition [2]. Moreover, according to the results of [1] this should be true not only in the center of the Perseus cluster considered in [2], but also (i) in its outer parts up to at least 1/2 of its virial radius and (ii) in the Andromeda galaxy.This result triggered significant interest as it seems consistent with a long-sought-for signal from dark matter decay , annihilation [11, 35, 48], de-excitation [11, 49-58] or conversion in the magnetic field [59][60][61]. Many particle physics models that predict such properties for the dark matter particle, have been put forward, including sterile neutrino, axion, axino, gravitino and many others, see for reviews e.g. [37,62] and references therein. If the interaction of dark matter particles is weak enough (e.g. much weaker than that of the Standard Model neutrino), they need not to be stable as their lifetime can exceed the age of the Universe...

show abstract

Intense 6.7-keV iron line emission from the Galactic Centre

Cited by 197 publications

References 4 publications

A novel scenario for the possible X-ray line feature at ~3.5 keV

A novel scenario for the possible X-ray line feature at ~3.5 keV

AChandraStudy of Sagittarius A East: A Supernova Remnant Regulating the Activity of Our Galactic Center?

Checking the Dark Matter Origin of a 3.53 keV Line with the Milky Way Center

Contact Info

Product

Resources

About