Detection of large-scale X-ray bubbles in the Milky Way halo

Predehl, P.; Sunyaev, R.; Becker, Werner; Brunner, H.; Burenin, R.; Bykov, A. M.; Черепащук, А. М.; Чугай, Н. Н.; Churazov, E.; Doroshenko, V.; Éismont, N. A.; Freyberg, M. J.; Gilfanov, M.; Haberl, F.; Khabibullin, Ildar; Krivonos, R.; Maitra, Chandreyee; Медведев, П. С.; Merloni, A.; Nandra, K.; Назаров, В. Н.; Pavlinsky, M.; Ponti, G.; Sanders, J. S.; Sasaki, M.; Sazonov, S.; Strong, A. W.; Wilms, J.

doi:10.1038/s41586-020-2979-0

Cited by 226 publications

(226 citation statements)

References 34 publications

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“…However, not all of the high-latitude X-rays attributed to the NPS need be local. The recent e-ROSITA finding of a symmetric but much fainter X-ray lobe in the south (Predehl et al 2020) leads us to the hypothesis that there is an equally faint northern Galactic center lobe, on top of which there is superimposed local X-ray emission. As argued by several authors (e.g., Borken & Iwan 1977;Iwan 1980), the radio and X-ray emission requires a reheating episode of an old SNR by a more recent event.…”

Section: Loop Imentioning

confidence: 95%

“…From the above discussion, we conclude that there remains no contradiction between the measurements of the distance to Loop I at high latitude and the evidence presented in the literature-the contradiction is in the conclusions that have been drawn. At lower latitude (b  10°), the situation is even more complicated, with many works using X-ray data (Akita et al 2018;Kataoka et al 2021;Predehl et al 2020) and concluding that the NPS is located near the Galactic center, in support of the model proposed by Sofue (1977Sofue ( , 2000. These works assume that Loop I (and similarly the NPS that is associated with it) arises from a single structure.…”

Section: Loop Imentioning

confidence: 95%

“…In partial support of this model, the absorption of X-rays associated with the NPS necessitates a much larger distance than 100 pc (300 pc-4 kpc; Sofue 2015; Lallement et al 2016). Recently, several studies of X-ray data have argued in favor of the NPS being at the Galactic center at 7.8 kpc (Akita et al 2018;Predehl et al 2020;Kataoka et al 2021), possibly related to the Fermi γ-ray bubbles (Dobler et al 2010). The debate has been reviewed several times in the past few years (Planck Collaboration et al 2016b;Dickinson 2018;Kataoka et al 2018).…”

Section: Introductionmentioning

confidence: 98%

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Revisiting the Distance to Radio Loops I and IV Using Gaia and Radio/Optical Polarization Data

Panopoulou

Dickinson

Readhead

et al. 2021

ApJ

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Galactic synchrotron emission exhibits large angular scale features known as radio spurs and loops. Determining the physical size of these structures is important for understanding the local interstellar structure and for modeling the Galactic magnetic field. However, the distance to these structures is either under debate or entirely unknown. We revisit a classical method of finding the location of radio spurs by comparing optical polarization angles with those of synchrotron emission as a function of distance. We consider three tracers of the magnetic field: stellar polarization, polarized synchrotron radio emission, and polarized thermal dust emission. We employ archival measurements of optical starlight polarization and Gaia distances and construct a new map of polarized synchrotron emission from WMAP and Planck data. We confirm that synchrotron, dust emission, and stellar polarization angles all show a statistically significant alignment at high Galactic latitude. We obtain distance limits to three regions toward Loop I of 112 ± 17 pc, 135 ± 20 pc, and <105 pc. Our results strongly suggest that the polarized synchrotron emission toward the North Polar Spur at b > 30° is local. This is consistent with the conclusions of earlier work based on stellar polarization and extinction, but in stark contrast with the Galactic center origin recently revisited on the basis of X-ray data. We also obtain a distance measurement toward part of Loop IV (180 ± 15 pc) and find evidence that its synchrotron emission arises from chance overlap of structures located at different distances. Future optical polarization surveys will allow the expansion of this analysis to other radio spurs.

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Section: Loop Imentioning

confidence: 95%

Section: Loop Imentioning

confidence: 95%

Section: Introductionmentioning

confidence: 98%

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Revisiting the Distance to Radio Loops I and IV Using Gaia and Radio/Optical Polarization Data

Panopoulou

Dickinson

Readhead

et al. 2021

ApJ

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“…Besides these two isotropic background components, we consider the X-ray bubbles, which flux is subdominant with respect to eROSITA's detector background below ∼ 2.3 keV. The X-ray bubbles are observed by eROSITA with an average count rate in the 0.6−1 keV energy band of 0.0038 photons s −1 arcmin −2 and 0.0026 photons s −1 arcmin −2 in the northern and southern bubbles respectively [19], and we consider an uniform template of the Fermi bubbles for its morphology, downloaded from https://fermi.gsfc.nasa.gov/ssc/data/access/. Finally, in order to exclude the extended emission from the Galactic plane, we remove all pixels with | | < 20 • .…”

Section: Backgroundsmentioning

confidence: 99%

Probing sterile neutrinos and axion-like particles from the Galactic halo with eROSITA

Dekker¹,

Peerbooms²,

Zimmer³

et al. 2021

Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021)

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The nature of dark matter remains an open question and could be in the form of warm dark matter. Sterile neutrinos and axion-like particles are well motivated warm dark candidates, and can decay into photons, which are consequently detectable by X-ray telescopes with keV dark matter mass. Both particles could explain the observed unidentified 3.5 keV line and, interestingly, XENON1T observed an excess at a few keV that can originate from axion-like particles. We study the diffuse emission coming from the Galactic halo, and test the sensitivity of all-sky X-ray survey eROSITA to identify a sterile neutrino or axion-like particle. By Monte Carlo method, we set bounds on the mixing angle of the sterile neutrinos and coupling strength of the axion-like particles. With eROSITA, we will be able to set stringent constraints, and in particular, we will be able to firmly probe the best-fit of the unidentified 3.5 keV line, where we reach an order of magnitude better sensitivity. Moreover, eROSITA is able to confirm an axion-like particle origin of the XENON1T excess for an excess greater than 3 keV.

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“…The Galactic Center (GC) region contains a supermassive black hole, Sagittarius A ⋆ , and other types of particle accelerators such as pulsar wind nebulae and supernova remnants. The large-scale bubbles in γ-rays 9 , radio 10 , and X-rays 11 , and the so-called X-ray chimney 12 , may be consequences of the energetic activities of Sagittarius A ⋆ in the past. The GC region was then widely regarded as a very attractive astrophysical laboratory for studying the cosmic ray astrophysics.…”

mentioning

confidence: 99%

A GeV-TeV particle component and the barrier of cosmic-ray sea in the Central Molecular Zone

2021

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Cosmic rays are important probe of a number of fundamental physical problems such as the acceleration of high and very high energy particles in extreme astrophysical environments. The Galactic center is widely anticipated to be an important cosmic-ray source and the observations of some Imaging Atmospheric Cherenkov Telescopes did successfully reveal a component of TeV-PeV cosmic rays in the vicinity of the Galactic center. Here we report the identification of GeV-TeV cosmic rays in the central molecular zone with the γ-ray observations of the Fermi Large Area Telescope, whose spectrum and spatial gradient are consistent with that measured by the Imaging Atmospheric Cherenkov Telescopes but the corresponding cosmic-ray energy density is substantially lower than the so-called cosmic-ray sea component, suggesting the presence of a high energy particle accelerator at the Galactic center and the existence of a barrier that can effectively suppress the penetration of the particles from the cosmic-ray sea to the central molecular zone.

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Detection of large-scale X-ray bubbles in the Milky Way halo

Cited by 226 publications

References 34 publications

Revisiting the Distance to Radio Loops I and IV Using Gaia and Radio/Optical Polarization Data

Revisiting the Distance to Radio Loops I and IV Using Gaia and Radio/Optical Polarization Data

Probing sterile neutrinos and axion-like particles from the Galactic halo with eROSITA

A GeV-TeV particle component and the barrier of cosmic-ray sea in the Central Molecular Zone

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