The newly launched X-ray satellite, eROSITA, has recently revealed two gigantic bubbles extending to ~80° above and below the Galactic Centre. The morphology of these ‘eROSITA bubbles’ bears a remarkable resemblance to the Fermi bubbles previously discovered by the Fermi Gamma-ray Space Telescope and its counterpart, the microwave haze. The physical origin of these striking structures has been intensely debated; however, because of their symmetry about the Galactic Centre, they probably originate from some energetic outbursts from the Galactic Centre in the past. Here we propose a theoretical model in which the eROSITA bubbles, Fermi bubbles and the microwave haze could be simultaneously explained by a single event of jet activity from the central supermassive black hole a few million years ago. Using numerical simulations, we show that this model could successfully reproduce the morphology and multi-wavelength spectra of the observed bubbles and haze, which allows us to derive critical constraints on the energetics and timescales of the outburst. This study serves as an important step forward in our understanding of the past Galactic Centre activity of our own Galaxy and may bring valuable insights into the broader picture of supermassive-black-hole–galaxy co-evolution in the context of galaxy formation.
This is a preview of subscription content
Subscribe to Nature+
Get immediate online access to the entire Nature family of 50+ journals
Subscribe to Journal
Get full journal access for 1 year
only $8.25 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Get time limited or full article access on ReadCube.
All prices are NET prices.
Source data are provided with this paper. Source data associated with Figs. 1 and 2 are available from the corresponding author upon reasonable request.
Predehl, P. et al. Detection of large-scale X-ray bubbles in the Milky Way halo. Nature 588, 227–231 (2020).
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).
Finkbeiner, D. P. Microwave interstellar medium emission observed by the Wilkinson Microwave Anisotropy Probe. Astrophys. J. 614, 186–193 (2004).
Planck Collaboration. Planck intermediate results. IX. Detection of the Galactic haze with Planck. Astron. Astrophys. 554, A139 (2013).
Carretti, E. et al. Giant magnetized outflows from the centre of the Milky Way. Nature 493, 66–69 (2013).
Bland-Hawthorn, J. & Cohen, M. The large-scale bipolar wind in the Galactic Center. Astrophys. J. 582, 246–256 (2003).
Bland-Hawthorn, J. et al. The large-scale ionization cones in the Galaxy. Astrophys. J. 886, 45 (2019).
Yang, H. Y., Ruszkowski, M. & Zweibel, E. Unveiling the origin of the Fermi bubbles. Galaxies 6, 29 (2018).
Ackermann, M. et al. The spectrum and morphology of the Fermi bubbles. Astrophys. J. 793, 64 (2014).
Crocker, R. M., Bicknell, G. V., Taylor, A. M. & Carretti, E. A unified model of the Fermi bubbles, microwave haze, and polarized radio lobes: reverse shocks in the Galactic Center’s giant outflows. Astrophys. J. 808, 107 (2015).
Mou, G., Yuan, F., Bu, D., Sun, M. & Su, M. Fermi bubbles inflated by winds launched from the hot accretion flow in Sgr A*. Astrophys. J. 790, 109 (2014).
Guo, F. & Mathews, W. G. The Fermi bubbles. I. Possible evidence for recent AGN jet activity in the galaxy. Astrophys. J. 756, 181 (2012).
Yang, H.-Y. K., Ruszkowski, M., Ricker, P. M., Zweibel, E. & Lee, D. The Fermi bubbles: supersonic active galactic nucleus jets with anisotropic cosmic-ray diffusion. Astrophys. J. 761, 185 (2012).
Yang, H.-Y. K., Ruszkowski, M. & Zweibel, E. The Fermi bubbles: gamma-ray, microwave and polarization signatures of leptonic AGN jets. Mon. Not. R. Astron. Soc. 436, 2734–2746 (2013).
Yang, H.-Y. K. & Ruszkowski, M. The spatially uniform spectrum of the Fermi bubbles: the leptonic active galactic nucleus jet scenario. Astrophys. J. 850, 2 (2017).
Cheng, K.-S., Chernyshov, D. O., Dogiel, V. A., Ko, C.-M. & Ip, W.-H. Origin of the Fermi bubble. Astrophys. J. Lett. 731, L17 (2011).
Sarkar, K. C., Nath, B. B. & Sharma, P. Clues to the origin of Fermi bubbles from O viii/O vii line ratio. Mon. Not. R. Astron. Soc. 467, 3544–3555 (2017).
Mertsch, P. & Petrosian, V. Fermi bubbles from stochastic acceleration of electrons in a Galactic outflow. Astron. Astrophys. 622, A203 (2019).
Abeysekara, A. U. et al. Search for very high-energy gamma rays from the northern Fermi bubble region with HAWC. Astrophys. J. 842, 85 (2017).
Guo, F., Mathews, W. G., Dobler, G. & Oh, S. P. The Fermi bubbles. II. The potential roles of viscosity and cosmic-ray diffusion in jet models. Astrophys. J. 756, 182 (2012).
Berkhuijsen, E. M., Haslam, C. G. T. & Salter, C. J. Are the Galactic loops supernova remnants? Astron. Astrophys. 14, 252–262 (1971).
Das, K. K. et al. Constraining the distance to the North Polar Spur with Gaia DR2. Mon. Not. R. Astron. Soc. 498, 5863–5872 (2020).
Sofue, Y. Bipolar hypershell Galactic Center starburst model: further evidence from ROSAT data and new radio and X-ray simulations. Astrophys. J. 540, 224–235 (2000).
Kataoka, J. et al. X-ray and gamma-ray observations of the Fermi bubbles and NPS/Loop I structures. Galaxies 6, 27 (2018).
LaRocca, D. M. et al. An analysis of the North Polar Spur using HaloSat. Astrophys. J. 904, 54 (2020).
Panopoulou, G. V., Dickinson, C., Readhead, A. C. S., Pearson, T. J. & Peel, M. W. Revisiting the distance to radio Loops I and IV using Gaia and radio/optical polarization data. Astrophys. J. 922, 210 (2021).
Ezoe, Y., Ohashi, T. & Mitsuda, K. High-resolution X-ray spectroscopy of astrophysical plasmas with X-ray microcalorimeters. Rev. Mod. Plasma Phys. 5, 4 (2021).
Barret, D. et al. The Athena space X-ray observatory and the astrophysics of hot plasma. Astron. Nachr. 341, 224–235 (2020).
Barret, D. et al. The Athena X-ray Integral Field Unit (X-IFU). In Society of Photo-Optical Instrumentation Engineers Conference Series Vol. 10699 (eds den Herder, J.-W. A. et al.) 106991G (SPIE (Society of Photo-Optical Instrumentation Engineers), 2018).
Zhang, R. & Guo, F. Simulating the Fermi bubbles as forward shocks driven by AGN jets. Astrophys. J. 894, 117 (2020).
Totani, T. A RIAF interpretation for the past higher activity of the Galactic Center black hole and the 511 keV annihilation emission. Publ. Astron. Soc. Jpn 58, 965–977 (2006).
Fox, A. J. et al. Probing the Fermi bubbles in ultraviolet absorption: a spectroscopic signature of the Milky Way’s biconical nuclear outflow. Astrophys. J. Lett. 799, L7 (2015).
Miller, M. J. & Bregman, J. N. The interaction of the Fermi bubbles with the Milky Way’s hot gas halo. Astrophys. J. 829, 9 (2016).
Bordoloi, R. et al. Mapping the nuclear outflow of the Milky Way: studying the kinematics and spatial extent of the northern Fermi bubble. Astrophys. J. 834, 191 (2017).
Ponti, G. et al. An X-ray chimney extending hundreds of parsecs above and below the Galactic Centre. Nature 567, 347–350 (2019).
Heywood, I. et al. Inflation of 430-parsec bipolar radio bubbles in the Galactic Centre by an energetic event. Nature 573, 235–237 (2019).
Paumard, T. et al. The two young star disks in the central parsec of the galaxy: properties, dynamics, and formation. Astrophys. J. 643, 1011–1035 (2006).
Heckman, T. M. & Best, P. N. The coevolution of galaxies and supermassive black holes: insights from surveys of the contemporary universe. Annu. Rev. Astron. Astrophys. 52, 589–660 (2014).
Ashley, T. et al. Mapping outflowing gas in the Fermi bubbles: a UV absorption survey of the Galactic nuclear wind. Astrophys. J. 898, 128 (2020).
Fryxell, B. et al. FLASH: an adaptive mesh hydrodynamics code for modeling astrophysical thermonuclear flashes. Astrophys. J. Suppl. Ser. 131, 273–334 (2000).
Lee, D. & Deane, A. E. An unsplit staggered mesh scheme for multidimensional magnetohydrodynamics. J. Comput. Phys. 228, 952–975 (2009).
Strong, A. W. & Moskalenko, I. V. Propagation of cosmic-ray nucleons in the galaxy. Astrophys. J. 509, 212–228 (1998).
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).
Arnaud, K. A. XSPEC: the first ten years. In ASP Conference Series Vol. 101 (eds Jacoby, G. H. & Barnes, J.) 17 (Astronomical Society of the Pacific, 1996).
Miller, M. J. & Bregman, J. N. The structure of the Milky Way’s hot gas halo. Astrophys. J. 770, 118 (2013).
Teodoro, E. M. D. et al. Blowing in the Milky Way wind: neutral hydrogen clouds tracing the Galactic nuclear outflow. Astrophys. J. 855, 33 (2018).
Fox, A. J. et al. Kinematics of the Magellanic Stream and implications for its ionization. Astrophys. J. 897, 23 (2020).
Turk, M. J. et al. yt: a multi-code analysis toolkit for astrophysical simulation data. Astrophys. J. Suppl. Ser. 192, 9 (2011).
Su, M. & Finkbeiner, D. P. Evidence for gamma-ray jets in the Milky Way. Astrophys. J. 753, 61 (2012).
Kataoka, J. et al. Suzaku observations of the diffuse X-ray emission across the Fermi bubbles’ edges. Astrophys. J. 779, 57 (2013).
Fang, T. & Jiang, X. High resolution X-ray spectroscopy of the local hot gas along the 3C 273 sightline. Astrophys. J. Lett. 785, L24 (2014).
Sutherland, R. S. & Dopita, M. A. Cooling functions for low-density astrophysical plasmas. Astrophys. J. 88, 253 (1993).
Kataoka, J. et al. Global structure of isothermal diffuse X-ray emission along the Fermi bubbles. Astrophys. J. 807, 77 (2015).
Rosswog, S. & Brüggen, M. Introduction to High-Energy Astrophysics (Cambridge University Press, 2011).
Blandford, R., Meier, D. & Readhead, A. Relativistic jets from active galactic nuclei. Annu. Rev. Astron. Astrophys. 57, 467–509 (2019).
Lagage, P. O. & Cesarsky, C. J. The maximum energy of cosmic rays accelerated by supernova shocks. Astron. Astrophys. 125, 249–257 (1983).
Zweibel, E. G. Cosmic-ray history and its implications for galactic magnetic fields. Astrophys. J. 587, 625–637 (2003).
Sironi, L. & Spitkovsky, A. Relativistic reconnection: an efficient source of non-thermal particles. Astrophys. J. Lett. 783, L21 (2014).
Sarkar, K. C. Possible connection between the asymmetry of the North Polar Spur and Loop I and Fermi bubbles. Mon. Not. R. Astron. Soc. 482, 4813–4823 (2019).
Cecil, G., Wagner, A. Y., Bland-Hawthorn, J., Bicknell, G. V. & Mukherjee, D. Tracing the Milky Way’s vestigial nuclear jet. Astrophys. J. 922, 254 (2021).
Fiacconi, D., Sijacki, D. & Pringle, J. E. Galactic nuclei evolution with spinning black holes: method and implementation. Mon. Not. R. Astron. Soc. 477, 3807–3835 (2018).
Bardeen, J. M. & Petterson, J. A. The Lense–Thirring effect and accretion disks around Kerr black holes. Astrophys. J. Lett. 195, L65 (1975).
Dobler, G. & Finkbeiner, D. P. Extended anomalous foreground emission in the WMAP three-year data. Astrophys. J. 680, 1222–1234 (2008).
H.-Y.K.Y. acknowledges support from the Yushan Scholar Program of the Ministry of Education of Taiwan and Ministry of Science and Technology of Taiwan (MOST 109-2112-M-007-037-MY3). M.R. acknowledges support from National Science Foundation Collaborative Research Grants AST-1715140 and AST-2009227 and National Aeronautics and Space Administration grants 80NSSC20K1541 and 80NSSC20K1583. E.G.Z. acknowledges support from National Science Foundation Collaborative Research Grant AST-2009323. The simulations are performed and analysed using computing facilities operated by the National Center for High-performance Computing and the Center for Informatics and Computation in Astronomy at National Tsing Hua University. FLASH was developed largely by the US Department of Energy-supported ASC/Alliances Center for Astrophysical Thermonuclear Flashes at University of Chicago. Data analysis presented in this paper was conducted with the publicly available yt visualization software48.
The authors declare no competing interests.
Peer review information
Nature Astronomy thanks Jun Kataoka and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Yang, HY.K., Ruszkowski, M. & Zweibel, E.G. Fermi and eROSITA bubbles as relics of the past activity of the Galaxy’s central black hole. Nat Astron 6, 584–591 (2022). https://doi.org/10.1038/s41550-022-01618-x