Evidence has mounted in recent decades that outflows of matter and energy from the central few parsecs of our Galaxy have shaped the observed structure of the Milky Way on a variety of larger scales1. On scales of 15 parsecs, the Galactic Centre has bipolar lobes that can be seen in both the X-ray and radio parts of the spectrum2,3, indicating broadly collimated outflows from the centre, directed perpendicular to the Galactic plane. On larger scales, approaching the size of the Galaxy itself, γ-ray observations have revealed the so-called ‘Fermi bubble’ features4, implying that our Galactic Centre has had a period of active energy release leading to the production of relativistic particles that now populate huge cavities on both sides of the Galactic plane. The X-ray maps from the ROSAT all-sky survey show that the edges of these cavities close to the Galactic plane are bright in X-rays4,5,6. At intermediate scales (about 150 parsecs), radio astronomers have observed the Galactic Centre lobe, an apparent bubble of emission seen only at positive Galactic latitudes7,8, but again indicative of energy injection from near the Galactic Centre. Here we report prominent X-ray structures on these intermediate scales (hundreds of parsecs) above and below the plane, which appear to connect the Galactic Centre region to the Fermi bubbles. We propose that these structures, which we term the Galactic Centre ‘chimneys’, constitute exhaust channels through which energy and mass, injected by a quasi-continuous train of episodic events at the Galactic Centre, are transported from the central few parsecs to the base of the Fermi bubbles4.
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Data and code availability
The datasets analysed during the current study and the software to perform the analysis are available in the XMM-Newton, Chandra and ROSAT repository: http://nxsa.esac.esa.int, https://www.cosmos.esa.int, http://cxc.harvard.edu and http://www.xray.mpe.mpg.de/rosat/archive.
Ponti, G., Morris, M. R., Terrier, R. & Goldwurm, A. in Cosmic Rays in Star-Forming Environments (eds Torres, D. & Reimer, O.) 331–369 (Astrophysics and Space Science Proceedings Vol. 34, Springer, Berlin, 2013).
Morris, M. et al. Deep X-ray imaging of the central 20 parsecs of the Galaxy with Chandra. Astron. Notes Suppl. 324, 167–172 (2003).
Zhao, J.-H., Morris, M. R. & Goss, W. M. A new perspective of the radio bright zone at the Galactic Center: feedback from nuclear activities. Astrophys. J. 817, 171–187 (2016).
Su, M., Slatyer, T. R. & Finkbeiner, D. P. Giant gamma-ray bubbles from Fermi-LAT: active galactic nucleus activity or bipolar galactic wind? Astrophys. J. 724, 1044–1082 (2010).
Snowden, S. L. et al. ROSAT Survey diffuse X-ray background maps. II. Astrophys. J. 485, 125–135 (1997).
Bland-Hawthorn, J. & Cohen, M. The large-scale bipolar wind in the Galactic Center. Astrophys. J. 582, 246–256 (2003).
Sofue, Y. & Handa, T. A radio lobe over the Galactic Centre. Nature 310, 568–569 (1984).
Law, C. J. A multiwavelength view of a mass outflow from the Galactic Center. Astrophys. J. 708, 474–484 (2010).
Ponti, G. et al. The XMM-Newton view of the central degrees of the Milky Way. Mon. Not. R. Astron. Soc. 453, 172–213 (2015).
Genzel, R., Eisenhauer, F. & Gillessen, S. The Galactic Centre massive black hole and nuclear star cluster. Rev. Mod. Phys. 82, 3121–3195 (2010).
Kataoka, J. et al. Suzaku observations of the diffuse X-ray emission across the Fermi bubbles’ edges. Astrophys. J. 779, 57–73 (2013).
Heard, V. & Warwick, R. S. XMM-Newton observations of the Galactic Centre Region—II. The soft-thermal emission. Mon. Not. R. Astron. Soc. 434, 1339–1354 (2013).
Chevalier, R. A. & Clegg, A. W. Wind from a starburst galaxy nucleus. Nature 317, 44–45 (1985).
Heckman, T. M., Armus, L. & Miley, G. K. On the nature and implications of starburst-driven galactic superwinds. Astrophys. J. Suppl. 74, 833–868 (1990).
Suchkov, A. A., Balsara, D. S., Heckman, T. M. & Leitherer, C. Dynamics and X-ray emission of a galactic superwind interacting with disk and halo gas. Astrophys. J. 430, 511–532 (1994).
Krumholz, M. R., Kruijssen, J. M. D. & Crocker, R. M. A dynamical model for gas flows, star formation and nuclear winds in galactic centres. Mon. Not. R. Astron. Soc. 466, 1213–1233 (2017).
Rees, M. J. Tidal disruption of stars by black holes of 106 to 108 solar masses in nearby galaxies. Nature 333, 523–528 (1988).
Generozov, A., Stone, N. C. & Metzger, B. D. Circumnuclear media of quiescent supermassive black holes. Mon. Not. R. Astron. Soc. 453, 775–796 (2015).
Lu, J. R. et al. Stellar populations in the central 0.5 pc of the Galaxy. II. The initial mass function. Astrophys. J. 764, 155–172 (2013).
Morris, M. The Galactic Center magnetosphere. J. Phys. Conf. Ser. 54, 1–9 (2006).
Crocker, R. M., Jones, D. I., Melia, F., Ott, J. & Protheroe, R. J. A lower limit of 50 microgauss for the magnetic field near the Galactic Centre. Nature 463, 65–67 (2010).
Eatough, R. P. et al. A strong magnetic field around the supermassive black hole at the centre of the Galaxy. Nature 501, 391–394 (2013).
Mauerhan, J. C., Muno, M. P., Morris, M. R., Stolovy, S. R. & Cotera, A. Near-infrared counterparts to Chandra X-ray sources toward the Galactic Center. II. Discovery of Wolf-Rayet stars and O supergiants. Astrophys. J. 710, 706–728 (2010).
Dong, H., Wang, Q. D. & Morris, M. R. A multiwavelength study of evolved massive stars in the Galactic Centre. Mon. Not. R. Astron. Soc. 425, 884–906 (2012).
Strickland, D. K. & Stevens, I. R. Starburst-driven galactic winds—I. Energetics and intrinsic X-ray emission. Mon. Not. R. Astron. Soc. 314, 511–545 (2000).
Crocker, R. M. & Aharonian, F. Fermi bubbles: giant, multibillion-year-old reservoirs of Galactic Center cosmic rays. Phys. Rev. Lett. 106, 101102 (2011).
Kataoka, J. et al. X-ray and gamma-ray observations of the Fermi bubbles and NPS/loop I structures. Galaxies 6, 27 (2018).
Lacki, B. C. The Fermi bubbles as starburst wind termination shocks. Mon. Not. R. Astron. Soc. 444, L39–L43 (2014).
Bland-Hawthorn, J., Maloney, P. R., Sutherland, R. S. & Madsen, G. J. Fossil imprint of a powerful flare at the Galactic Center along the Magellanic stream. Astrophys. J. 778, 58–74 (2013).
Roberts, S. R., Jiang, Y.-F., Wang, Q. D. & Ostriker, J. P. Towards self-consistent modelling of the Sgr A* accretion flow: linking theory and observation. Mon. Not. R. Astron. Soc. 466, 1477–1490 (2017).
Spitzer, L. Jr Theories of the hot interstellar gas. Annu. Rev. Astron. Astrophys. 28, 71–101 (1990).
Jenkins, E. B. Coronal gas in the Galaxy. I—A new survey of interstellar O vi. Astrophys. J. 219, 845–860 (1978).
Savage, B. D. & de Boer, K. S. Observational evidence for a hot gaseous Galactic corona. Astrophys. J. 230, L77–L82 (1979).
Ferrière, K. M. The interstellar environment of our galaxy. Rev. Mod. Phys. 73, 1031–1066 (2001).
Cox, D. P. The three-phase interstellar medium revisited. Annu. Rev. Astron. Astrophys. 43, 337–385 (2005).
Strüder, L. et al. The European Photon Imaging Camera on XMM-Newton: the pn-CCD camera. Astron. Astrophys. 365, L18–L26 (2001).
Turner, M. J. L. et al. The European Photon Imaging Camera on XMM-Newton: the MOS cameras. Astron. Astrophys. 365, L27–L35 (2001)
Haberl, F. et al. The XMM-Newton survey of the Small Magellanic Cloud. Astron. Astrophys. 545, A128 (2012).
Garmire, G. P., Bautz, M. W., Ford, P. G., Nousek, J. A. & Ricker, G. R. Jr. Advanced CCD imaging spectrometer (ACIS) instrument on the Chandra X-ray Observatory. Proc. SPIE 4851, 28–44 (2003).
Fruscione, A. et al. CIAO: Chandra’s data analysis system. Proc. SPIE 6270, 62701V (2006).
Hofmann, F., Sanders, J. S., Nandra, K., Clerc, N. & Gaspari, M. Thermodynamic perturbations in the X-ray halo of 33 clusters of galaxies observed with Chandra ACIS. Astron. Astrophys. 585, A130 (2016).
Markevitch, M. et al. Chandra spectra of the soft X-ray diffuse background. Astrophys. J. 583, 70–84 (2003).
Sanders, J. S. Contour binning: a new technique for spatially resolved X-ray spectroscopy applied to Cassiopeia A. Mon. Not. R. Astron. Soc. 371, 829–842 (2006).
Arnaud, K. A. XSPEC: The first ten years. In Astronomical Data Analysis Software and Systems V Vol. 101, 17 (Astronomical Society of the Pacific Conference Series, 1996).
Foster, A. R., Ji, L., Smith, R. K. & Brickhouse, N. S. Updated atomic data and calculations for X-ray spectroscopy. Astrophys. J. 756, 128–139 (2012).
Anders, E. & Grevesse, N. Abundances of the elements—meteoritic and solar. Geochim. Cosmochim. Acta 53, 197–214 (1989).
Eisenhauer, F. et al. A geometric determination of the distance to the Galactic Center. Astrophys. J. 597, L121–L124 (2003).
Uchida, K. I., Morris, M. R., Serabyn, E. & Bally, J. AFGL 5376: a strong, large-scale shock near the Galactic Center. Astrophys. J. 421, 505–516 (1994).
Blanton, M. C. The Galactic Center lobe: new 14 GHz GBT observations. PhD thesis, Univ. North Carolina at Chapel Hill (2008).
Churazov, E., Forman, W., Jones, C. & Böhringer, H. Asymmetric, arc minute scale structures around NGC 1275. Astron. Astrophys. 356, 788–794 (2000).
Fabian, A. C. Observational evidence of active galactic nuclei feedback. Annu. Rev. Astron. Astrophys. 50, 455–489 (2012).
Baganoff, F. K. et al. Chandra X-ray spectroscopic imaging of Sagittarius A* and the central parsec of the Galaxy. Astrophys. J. 591, 891–915 (2003).
Wang, Q. D. et al. Dissecting X-ray-emitting gas around the center of our Galaxy. Science 341, 981–983 (2013).
Yuan, F. & Narayan, R. Hot accretion flows around black holes. Annu. Rev. Astron. Astrophys. 52, 529–588 (2014).
Koyama, K. Diffuse X-ray sky in the Galactic center. Publ. Astron. Soc. Jpn 70, R1, https://doi.org/10.1093/pasj/psx084 (2018).
Sofue, Y. The Galactic Center lobe. Publ. Astron. Soc. Jpn 37, 697–713 (1985).
This work is dedicated to the memory of A. M. Ponti, who contributed to its realization by focusing the energy and motivation of G.P. G.P. thanks A. Merloni for discussions and the Max-Planck-Institut für Astronomie Heidelberg for hospitality. This research has made use of data obtained both with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA, and with the Chandra Data Archive and software provided by the Chandra X-ray Center. G.P. and F. Hofmann acknowledge financial support from the Bundesministerium für Wirtschaft und Technologie/Deutsches Zentrum für Luft- und Raumfahrt (BMWI/DLR; grants FKZ 50 OR 1604, FKZ 50 OR 1715 and FKZ 50 OR 1812) and the Max Planck Society. A.G. and R.T. acknowledge support from CNES and ANR (grant ANR-17-CE31-0014) and M.R.M. acknowledges support from NASA.
Nature thanks Masha Chernyakova and the other anonymous reviewer(s) for their contribution to the peer review of this work.
The authors declare no competing interests.
Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Extended data figures and tables
Extended Data Fig. 1 Diffuse Galactic Centre X-ray emission at different scales.
a, ROSAT (0.9–2-keV energy band) large-scale map of the Galactic Centre. The X-ray counterparts of the Fermi bubbles are strong X-ray emitters. The edges (white ellipses) are clearly detected on scales of several degrees, whereas they become confused (because of the short exposure of 200–300 s and soft X-ray energy band) close to the plane. The red dashed line indicates the XMM-Newton area covered by our survey. b, XMM-Newton map zooming into the central degrees of the Milky Way. The magenta dashed line intersects both chimneys, passing through Sgr A*. The map shows the X-ray emissivity within the 1.5–2.6-keV energy band (see Extended Data Fig. 2). c, Schematic view of the main diffuse X-ray-emitting features within the central 500 pc or so from Sgr A*. The red star and the yellow ellipses indicate the position of Sgr A* and of Sgr A’s ±15-pc bipolar lobes. The large violet ellipses indicate the location and extension of the X-ray counterpart of the Galactic Centre lobe with shell-like morphology (the northern chimney), of its eastern protrusion and of its roughly symmetric southern counterpart (the southern chimney). The orange filled ellipse, the two red circles and the red ellipse indicate the location of the Arc super-bubble (SB), the Quintuplet and Arches clusters and the super-bubble candidate G359.77–0.09 (ref. 8). The pink regions indicate the location of the edges to the Fermi bubbles. The dotted circles and solid ellipses indicate the position of bright X-ray sources with intense dust-scattering halos (DSH) and known supernova remnants (SNR). d, Chandra RGB map zooming into the central tens of parsecs of the Galaxy. The ±15-pc lobes are clearly visible (orange). The dashed circles have radii of 1 pc, 5 pc and 15 pc.
Extended Data Fig. 2 X-ray emission from the central degrees of the Milky Way.
Bright X-ray emission traces the coherent edge brightened shell-like feature, dubbed the northern chimney, located north of Sgr A* and characterized by a diameter of about 160 pc. On the opposite side, the southern chimney appears as a bright linear feature. Bright X-ray emission is observed at high latitude (\(\left|b\right|\) ≳ 1°), corresponding to the X-ray counterparts of the Fermi bubble. The magenta dashed line intersects both chimneys, passing through Sgr A*. The map shows the X-ray emissivity within the 1.5–2.6-keV energy band. The contours indicate the location of the radio Galactic Centre lobe as it appears in the background-filtered surface brightness map at 10.55 GHz (see ref. 56). Point sources have been removed. Larger circles have been excised to remove the dust-scattering haloes around bright sources.
Extended Data Fig. 3 Continuum-subtracted S xv line emission.
The map highlights sources characterized by bright soft X-ray emission lines, such as diffuse thermally emitting plasma. On the other hand, point sources and dust-scattering halos are efficiently removed. The white dashed tilted line indicates a linear ridge, about 450 pc long, that appears to run west of the chimneys.
Extended Data Fig. 4 Chandra 1–2 keV map of the Galactic Centre.
The same structures seen in the XMM-Newton 1.5–2.6-keV image (Extended Data Fig. 2, footprint indicated by red dashed box) are observed also in the shallower Chandra image. Although the 1–2-keV band map is more affected by neutral absorption towards the plane compared with the 1.5–2.6-keV band (Extended Data Fig. 2), we display it here in order to emphasize the residual high-latitude emission (for example, inside the Fermi bubbles). GX 3+1 is an accreting X-ray binary.
Extended Data Fig. 5 Chandra spectra (with relative extraction regions) used to derive the physical properties of the chimneys.
a, b, Chandra spectra used to derive the latitudinal profiles at l = 0° and shown in Fig. 2 for the southern (a) and northern (b) sides, respectively. c, XMM-Newton 1.5–2.6 keV emission map in greyscale, showing the extraction areas of the Chandra spectra used to derive the latitudinal profiles at l = 0°, with colours corresponding to those of the spectra. The areas at l ≈ −0.7° indicate the extraction regions of the spectra used to derive the grey constraints in Fig. 2. d, e, XMM-Newton spectra used to derive the latitudinal profiles of the diffuse emission in Fig. 2. The error bars represent 1σ.
Extended Data Fig. 6 XMM-Newton spectra (with relative extraction regions) used to derive the physical properties of the chimneys.
b, c, XMM-Newton spectra used to measure the longitudinal profiles shown in Extended Data Fig. 7. a, XMM-Newton 1.5–2.6-keV map displaying the regions used to extract the spectra corresponding to a longitudinal cut through the northern shell (at b ≈ 0.7°) and through the jet-like feature (at b ≈ −1.2°). The error bars represent 1σ.
Extended Data Fig. 7 Longitudinal profiles of the physical properties of the chimneys.
From top to bottom, temperature, density and pressure profiles are shown as a function of longitude cutting through the northern and southern chimneys at latitudes b ≈ 0.7° and b ≈ −1.2° (see Extended Data Fig. 6). Positive values indicate Galactic west (‘west’ is ‘right’ as in an image in Galactic coordinates b and l). Black squares and red circles indicate the longitudinal cut through the northern and southern chimneys, respectively. The densities have been estimated assuming a volume V = (PA)3/2, where PA is the projected area. Vertical error bars represent 1σ uncertainties; horizontal error bars show the radial range of the extraction regions.
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Ponti, G., Hofmann, F., Churazov, E. et al. An X-ray chimney extending hundreds of parsecs above and below the Galactic Centre. Nature 567, 347–350 (2019). https://doi.org/10.1038/s41586-019-1009-6
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