arXiv subjects

W. Becker

Publications and source records attributed to W. Becker.

At least 19 recordsLinked to original sources

arXiv2026

The SRG/eROSITA All-Sky Survey DR2: Cumulative X-ray catalogues from the first three surveys and multi-wavelength counterparts in the western Galactic hemisphere

The eROSITA telescope array on board the Spektrum-Roentgen-Gamma (SRG) mission began its all-sky survey program in December 2019, scanning the sky at an approximately six-month cadence. Here, we present new catalogues of point-like and extended X-ray sources derived from the first three completed eROSITA all-sky surveys (eRASS:3), covering the western Galactic hemisphere, which Germany's eROSITA consortium holds proprietary rights for. We describe the observational strategy, data processing, and analysis pipelines. We also characterise the resulting X-ray source populations. The eRASS:3 main catalogue contains nearly two million sources, including 1,911,744 point-like and 63,796 extended sources, detected in the 0.2-2.3 keV energy band, eROSITA's most sensitive energy window. This volume has doubled the X-ray source content of eRASS1 and provides a comprehensive census of X-ray-emitting objects across diverse astrophysical classes. We also released a secondary hard catalogue of nearly 15,000 sources detected in the harder 2.3-5.0 keV energy band. In addition, we released six catalogues, three for the main sample and three for the hard sample, in which we identify and classify the optical and infrared counterparts of eRASS:3 point-like sources. This approach delivers a homogeneous, high-quality identification of mostly extragalactic X-ray emitters; for example, we estimate that approximately 88% of the 1.4 million counterparts identified within the footprints of the Legacy Survey Imaging for DESI are extragalactic sources. This work has enabled the generation of samples optimised for completeness and purity, while expanding the discovery space for rare populations. The second data release (DR2) of the SRG/eROSITA all-sky survey is a catalogue-only release, comprising the catalogues presented in this work together with an updated version of the eROSITA upper flux limit server.

astro-ph.HE↗

arXiv2026

Multiwavelength study of supernova remnants in the Circinus constellation with SRG/eROSITA

Supernova remnants (SNRs) are key tracers of stellar feedback and the chemical and dynamical evolution of the interstellar medium. However, identifying SNRs in complex regions remains challenging, particularly when only archival multi-wavelength data are available. We aim to search for previously unrecognized SNR candidates in the Circinus constellation by combining optical imaging, radio continuum data, and available SRG/eROSITA all-sky survey X-ray observations, to provide a prioritized list of targets for future confirmation. Candidate remnants were classified according to the strength of the combined diagnostics. This joint analysis yields improved constraints on the morphology and spectral properties of known remnants in the region, including MSH 15-52 and G320.6- 1.6. In addition, we identify a new promising SNR candidate, G320.2-3.6. Our study provides a first multi-wavelength search of SNR candidates in the Circinus region. In addition to G320.2-3.6, three objects (G319.8-2.0, G321.8-1.1, and G320.5-1.8) emerge as promising targets for follow-up radio, spectroscopic optical, and deeper, spatially resolved X-ray observations to confirm their nature.

astro-ph.HE↗

arXiv2026

The Salamander: A case study of the magnetic field and peculiar morphology of G309.8-2.6 through radio polarimetry

Studying the interaction between core-collapse supernova remnants (SNRs) and their surrounding environments is essential to understanding the mechanism for energy transfer to the interstellar medium (ISM) and the intrinsic physical properties of these remnants. In this paper, we focus on G309.8-2.6. Our new observations reveal that this object includes an SNR shell with a relic pulsar wind nebula (PWN) that extends well beyond the emission that has been previously observed in X-rays. We present new radio continuum and polarization images of G309.8-2.6 from the Evolutionary Map of the Universe (EMU) and Polarization Sky Survey of the Universe's Magnetism (POSSUM) surveys with the Australian Square Kilometre Array Pathfinder (ASKAP). The images reveal the complex and peculiar morphology of G309.8-2.6. The linear polarization displays an atypical S-shaped morphology and a highly ordered magnetic field. The rotation measure (RM) map shows a large-scale gradient or possible sign reversal, depending on the foreground RM. We reprocessed archival X-ray observations from Chandra and eROSITA, and retrieved archival H$\alpha$ and infrared observations. We performed a joint analysis of the multiwavelength data and proposed scenarios to explain the unusual shape. Our results place new constraints on the magnetic field of G309.8-2.6, including its environment, and demonstrate the power of polarization observations in probing the properties of SNRs.

astro-ph.GA↗

arXiv2026

Low-mass stars dominate the hot (0.7 keV) Galactic X-ray emission

The circumgalactic medium (CGM) of the Milky Way is composed of a tenuous atmosphere filled with multi-phase plasma, including a warm-hot virialised component. Recent studies suggest a much hotter (~0.7 keV) super-virial component detected in both absorption and emission. We want to shed light on the nature of this putative super-virial component. We analysed the X-ray background as observed by SRG/eROSITA over the entire western Galactic hemisphere. We show that low-mass stars provide a large fraction of the 0.7 keV emission. Indeed, a tight correlation is found between the surface brightness of the 0.7 keV emission and the mass distribution of the Milky Way across a large portion of the western Galactic hemisphere. The correlation coefficient implies an X-ray luminosity per unit of stellar mass comparable to that of the average low-mass stars within 10 pc of the Sun, suggesting that unresolved M dwarfs and F, G, and K type stars dominate the 0.7 keV emission. This emission is asymmetric with respect to the Galactic plane, influenced by the asymmetric distribution of nearby star-forming regions, and broadly consistent with the known offset of the Sun above the Galactic midplane. The remaining signal might be produced by the cumulative emission of stars of different types or ages, in addition to other sources (e.g. hot interstellar medium, Galactic corona, etc.). Assuming that the putative residual hot super-virial atmosphere is homogeneous and has a spherical beta profile with slope $\beta=0.4$, we constrain its density at 10 kpc to be $n_e<4\times10^{-4}$~cm$^{-3}$. Our findings may help refine models of the circumgalactic medium around external galaxies, advancing our understanding of hot baryon flows and galaxy evolution.

astro-ph.GA↗

arXiv2025

A Catalog of Galactic Supernova Remnants and Supernova Remnant Candidates from the EMU/POSSUM Radio Sky Surveys. I

We use data from the EMU (Evolutionary Map of the Universe) and POSSUM (Polarization Sky Survey of the Universe's Magnetism) radio southern sky surveys, conducted with the Australian Square Kilometre Array Pathfinder (ASKAP), to compile a catalogue of Galactic supernova remnants (SNRs) and candidate SNRs within the region of $277.5^\circ \leq \ell \leq 311.7^\circ$ Galactic longitude, $|b| \leq 5.4^\circ$ Galactic latitude, as well as an additional field along the Galactic plane, approximately $315.5^\circ \leq \ell \leq 323.0^\circ$ Galactic longitude, $-4.5^\circ \leq b \leq 1.5^\circ$ Galactic latitude. In the areas studied, there are 44 known SNRs and 46 SNR candidates that have been previously identified in the radio. We confirm eight of these candidates as SNRs based on evidence of linear polarization or through the calculation of nonthermal spectral indices. Additionally, we identify possible radio counterparts for seven SNR candidates that were previously only identified in X-rays (four) or optical (three). We also present six new SNRs and 37 new SNR candidates. The results of this study demonstrate the utility of ASKAP for discovering new and potential SNRs and refining the classification of previously identified candidates. In particular, we find that the EMU and POSSUM surveys are particularly well suited for observing high-latitude SNRs and confirming SNR candidates with polarization. The region studied in this work represents approximately one-quarter of the Galactic plane, by longitude, that will eventually be surveyed by EMU/POSSUM and we expect that the ongoing surveys will continue to uncover new SNRs and SNR candidates.

astro-ph.GA↗

arXiv2025

ASKAP EMU Radio Detection of the Reflection Nebula VdB-80 in the Monoceros Crossbones Filamentary Structure

We present a new radio detection from the Australian Square Kilometre Array Pathfinder (ASKAP) Evolutionary Map of the Universe (EMU) survey associated with the reflection nebula (RN) VdB-80. The radio detection is determined to be a previously unidentified HII region, now named Lagotis. The RN is located towards Monoceros, centred in the molecular cloud feature known as the `Crossbones'. The 944 MHz EMU image shows a roughly semicircular HII region with an integrated flux density of 30.2$\pm$0.3 mJy. The HII region is also seen at 1.4 GHz by NVSS, yielding an estimated spectral index of 0.65$\pm$0.51, consistent with thermal radio emission. Gaia DR3 and 2MASS data give a distance to the stars associated with the HII region of $\sim$960 pc. This implies a size of 0.76$\times$0.68($\pm$0.09) pc for the HII region. We derive an HII region electron density of the bright radio feature to be 26 cm$^{-3}$, requiring a Lyman-alpha photon flux of $10^{45.6}$ s$^{-1}$, which is consistent with the expected Lyman flux of HD 46060, the B2II type star which is the likely ionising star of the region. The derived distance to this region implies that the Crossbones feature is a superposition of two filamentary clouds, with Lagotis embedded in the far cloud.

astro-ph.GA↗

arXiv2024

The TRAPUM Small Magellanic Cloud pulsar survey with MeerKAT -- II. Nine new radio timing solutions and glitches from young pulsars

We report new radio timing solutions from a three-year observing campaign conducted with the MeerKAT and Murriyang telescopes for nine Small Magellanic Cloud pulsars, increasing the number of characterised rotation-powered extragalactic pulsars by 40 per cent. We can infer from our determined parameters that the pulsars are seemingly all isolated, that six are ordinary pulsars, and that three of the recent MeerKAT discoveries have a young characteristic age of under 100 kyr and have undergone a spin-up glitch. Two of the sources, PSRs J0040$-$7337 and J0048$-$7317, are energetic young pulsars with spin-down luminosities of the order of 10$^{36}$ erg s$^{-1}$. They both experienced a large glitch, with a change in frequency of about 30 $\mu$Hz, and a frequency derivative change of order $-10^{-14}$ Hz s$^{-1}$. These glitches, the inferred glitch rate, and the properties of these pulsars (including potentially high inter-glitch braking indices) suggest these neutron stars might be Vela-like repeating glitchers and should be closely monitored in the future. The position and energetics of PSR J0048$-$7317 confirm it is powering a new Pulsar Wind Nebula (PWN) detected as a radio continuum source; and similarly the association of PSR J0040$-$7337 with the PWN of Supernova Remnant (SNR) DEM S5 (for which we present a new Chandra image) is strengthened. Finally, PSR J0040$-$7335 is also contained within the same SNR but is a chance superposition. It has also been seen to glitch with a change of frequency of $10^{-2}$ $\mu$Hz. This work more than doubles the characterised population of SMC radio pulsars.

astro-ph.HE↗

arXiv2024

TRAPUM search for pulsars in supernova remnants and pulsar wind nebulae -- I. Survey description and initial discoveries

We present the description and initial results of the TRAPUM (TRAnsients And PUlsars with MeerKAT) search for pulsars associated with supernova remnants (SNRs), pulsar wind nebulae and unidentified TeV emission. The list of sources to be targeted includes a large number of well-known candidate pulsar locations but also new candidate SNRs identified using a range of criteria. Using the 64-dish MeerKAT radio telescope, we use an interferometric beamforming technique to tile the potential pulsar locations with coherent beams which we search for radio pulsations, above a signal-to-noise of 9, down to an average flux density upper limit of 30 $\mu$Jy. This limit is target-dependent due to the contribution of the sky and nebula to the system temperature. Coherent beams are arranged to overlap at their 50 per cent power radius, so the sensitivity to pulsars is not degraded by more than this amount, though realistically averages around 65 per cent if every location in the beam is considered. We report the discovery of two new pulsars; PSR J1831$-$0941 is an adolescent pulsar likely to be the plerionic engine of the candidate PWN G20.0+0.0, and PSR J1818$-$1502 appears to be an old and faint pulsar that we serendipitously discovered near the centre of a SNR already hosting a compact central object. The survey holds importance for better understanding of neutron star birth rates and the energetics of young pulsars.

astro-ph.HE↗

arXiv2024

The TRAPUM Small Magellanic Cloud pulsar survey with MeerKAT: I. Discovery of seven new pulsars and two Pulsar Wind Nebula associations

The sensitivity of the MeerKAT radio interferometer is an opportunity to probe deeper into the population of rare and faint extragalactic pulsars. The TRAPUM (TRAnsients and PUlsars with MeerKAT) collaboration has conducted a radio-domain search for accelerated pulsars and transients in the Small Magellanic Cloud (SMC). This partially targeted survey, performed at L-band (856-1712 MHz) with the core array of the MeerKAT telescope in 2-h integrations, is twice as sensitive as the latest SMC radio pulsar survey. We report the discovery of seven new SMC pulsars, doubling this galaxy's radio pulsar population and increasing the total extragalactic population by nearly a quarter. We also carried out a search for accelerated millisecond pulsars in the SMC Globular Cluster NGC 121 using the full array of MeerKAT. This improved the previous upper limit on pulsed radio emission from this cluster by a factor of six. Our discoveries reveal the first radio pulsar-PWN systems in the SMC, with only one such system previously known outside our galaxy (the "Crab pulsar twin" in the Large Magellanic Cloud, PSR J0540$-$6919). We associate the 59 ms pulsar discovery PSR J0040$-$7337, now the fastest spinning radio pulsar in the SMC, with the bow-shock Pulsar Wind Nebula (PWN) of Supernova Remnant DEM S5. We also present a new young pulsar with a 79 ms period, PSR J0048$-$7317, in a PWN recently discovered in a MeerKAT radio continuum image. Using the multi-beam capability of MeerKAT, we localised our pulsar discoveries, and two previous Murriyang discoveries, to a positional uncertainty of a few arcseconds.

astro-ph.HE↗

arXiv2024

The SRG/eROSITA all-sky survey: First X-ray catalogues and data release of the western Galactic hemisphere

The eROSITA telescope array aboard the Spektrum Roentgen Gamma (SRG) satellite began surveying the sky in December 2019, with the aim of producing all-sky X-ray source lists and sky maps of an unprecedented depth. Here we present catalogues of both point-like and extended sources using the data acquired in the first six months of survey operations (eRASS1; completed June 2020) over the half sky whose proprietary data rights lie with the German eROSITA Consortium. We describe the observation process, the data analysis pipelines, and the characteristics of the X-ray sources. With nearly 930000 entries detected in the most sensitive 0.2-2.3 keV energy range, the eRASS1 main catalogue presented here increases the number of known X-ray sources in the published literature by more than 60%, and provides a comprehensive inventory of all classes of X-ray celestial objects, covering a wide range of physical processes. A smaller catalogue of 5466 sources detected in the less sensitive but harder 2.3-5 keV band is the result of the first true imaging survey of the entire sky above 2 keV. We show that the number counts of X-ray sources in eRASS1 are consistent with those derived over narrower fields by past X-ray surveys of a similar depth, and we explore the number counts variation as a function of the location in the sky. Adopting a uniform all-sky flux limit (at 50% completeness) of F_{0.5-2 keV} > 5 \times 10^{-14}$ erg\,s$^{-1}$\,cm$^{-2}$, we estimate that the eROSITA all-sky survey resolves into individual sources about 20% of the cosmic X-ray background in the 1-2 keV range. The catalogues presented here form part of the first data release (DR1) of the SRG/eROSITA all-sky survey. Beyond the X-ray catalogues, DR1 contains all detected and calibrated event files, source products (light curves and spectra), and all-sky maps. Illustrative examples of these are provided.

astro-ph.HE↗

arXiv2024

G321.3-3.9: A new supernova remnant observed with multi-band radio data and in the SRG/eROSITA All-Sky Surveys

G321.3-3.9 was first identified as a partial shell at radio frequencies a few decades ago. Although it continued to be observed, no additional studies were undertaken until recently. In this paper we present results from a large selection of radio and X-ray data that cover the position of G321.3-3.9. We confirmed G321.3-3.9 as a new supernova remnant (SNR) using data collected by several radio surveys, spanning a frequency range from 200 to 2300 MHz. Stacked eROSITA data from four consecutive all-sky surveys (eRASS:4) provide spectro-imaging information in the energy band 0.2 - 8.0 keV. G321.3-3.9 has an elliptical shape with major and minor axes of approximately 1.7 deg x 1.1 deg. From CHIPASS and S-PASS data, we calculate a spectral index {\alpha} = -0.8 +- 0.2, consistent with synchrotron emission from an expanding shell in the radiative phase. The eROSITA data show an X-ray diffuse structure filling almost the entire radio shell. Based on our spectral analysis, we found the temperature to be approximately 0.6 keV and the column absorption density about 10^21 cm^-2. Comparing this absorption density to optical extinction maps, we estimated the distance to fall within the range of (1.0 - 1.7) kpc, considering the 1{\sigma} uncertainty range.

astro-ph.HE↗

arXiv2023

Searching for X-Ray Counterparts of Degree Wide TeV Halos Around Middle-Aged Pulsars with SRG/eROSITA

Context. Extended gamma-ray TeV emission (TeV halos) around middle-aged pulsars has been detected. A proposed model to explain these TeV halos is that electrons from a degree-wide Pulsar Wind Nebula (PWN) get up-scattered by cosmic microwave background photons through inverse Compton processes. However, no X-ray degree-wide faint diffuse PWNe have been found around these middle-aged pulsars in previous X-ray observations. Aims. We have performed a search for degree wide PWNe around Geminga, PSR B0656+14, B0540+23, J0633+0632, and J0631+1036, using data from the first four consecutive Spectrum Roentgen Gamma/eROSITA all-sky surveys. In order to better understand the mechanisms underlying the formation of TeV halos, we investigated the magnetic field strength in the degree wide neighbourhood of those pulsars. Results. We did not detect degree-wide diffuse emission around Geminga, PSR B0656+14, B0540+23, J0633+0632, and J0631+1036, which can be attributed to being powered by the rotation-powered pulsars. Indeed, a close inspection of the data shows that the pulsars of interest are all embedded in diffuse emission from supernova remnants like the Monogem Ring or the Rosetta Nebula, while PSR B0540+23 is located ~2.5 degrees away from the bright Crab pulsar, which shines out the eROSITA point-spread function up to the position of PSR B0540+23 and thus reduced the sensitivity to search for degree wide bright diffuse X-ray emission strongly. Conclusions. Despite the non-detection of any degree-wide PWN surrounding the analysed pulsars, we set flux upper limits to provide useful information on magnetic field strength and its spatial distribution around those pulsars, providing additional constraints to the proposed theory for the formation of TeV halos around pulsars.

astro-ph.HE↗

arXiv2023

The warm-hot circumgalactic medium of the Milky Way as seen by eROSITA

The first all-sky maps of the diffuse emission of high ionization lines observed in X-rays by SRG/eROSITA, provide an excellent probe for the study of the warm-hot phase (T~10^6 K) of the circumgalactic medium (CGM) of the Milky Way (MW). In this work we analyse the O VIII line detected in the first eROSITA All-Sky Survey data (eRASS1). We fit a sky map made in a narrow energy bin around this line, with physical emission models embedded in a 3D geometry to constrain the density distribution of the warm-hot gas around our Galaxy, with a focus on mid and high (absolute) Galactic latitudes. By masking out the eROSITA bubbles and other bright extended foreground sources, we find that an oblate geometry of the warm-hot gas (T~0.15-0.17 keV), flattened around the Galactic disk with scale height z_h~1-3 kpc, best describes the eRASS1 O VIII map, with most of the observed emission resulting to be produced within a few kpc from the Sun. The additional presence of a large scale warm-hot spherical halo, while providing a minor contribute to the X-ray emission, accounts for the high O VII absorption column densities detected with XMM-Newton, as well as most of the baryon budget of the CGM of the MW. The eROSITA data carry the largest amount of information and detail of O VIII CGM intensities to date, allowing for a significant reduction of the statistical uncertainties of the inferred physical parameters.

astro-ph.GA↗

arXiv2022

The TRAPUM L-band survey for pulsars in Fermi-LAT gamma-ray sources

More than 100 millisecond pulsars (MSPs) have been discovered in radio observations of gamma-ray sources detected by the Fermi Large Area Telescope (LAT), but hundreds of pulsar-like sources remain unidentified. Here we present the first results from the targeted survey of Fermi-LAT sources being performed by the Transients and Pulsars with MeerKAT (TRAPUM) Large Survey Project. We observed 79 sources identified as possible gamma-ray pulsar candidates by a Random Forest classification of unassociated sources from the 4FGL catalogue. Each source was observed for 10 minutes on two separate epochs using MeerKAT's L-band receiver (856-1712 MHz), with typical pulsed flux density sensitivities of $\sim$100$\,\mu$Jy. Nine new MSPs were discovered, eight of which are in binary systems, including two eclipsing redbacks and one system, PSR J1526$-$2744, that appears to have a white dwarf companion in an unusually compact 5 hr orbit. We obtained phase-connected timing solutions for two of these MSPs, enabling the detection of gamma-ray pulsations in the Fermi-LAT data. A follow-up search for continuous gravitational waves from PSR J1526$-$2744 in Advanced LIGO data using the resulting Fermi-LAT timing ephemeris yielded no detection, but sets an upper limit on the neutron star ellipticity of $2.45\times10^{-8}$. We also detected X-ray emission from the redback PSR J1803$-$6707 in data from the first eROSITA all-sky survey, likely due to emission from an intra-binary shock.

astro-ph.HE↗

arXiv2022

Can we measure the Wigner time delay in a photoionization experiment?

No, we cannot! The concept of Wigner time delay was introduced in scattering theory to quantify the delay or advance of an incoming particle in its interaction with the scattering potential. It was assumed that this concept can be transferred to ionization considering it as a half scattering process. In the present work we show, by analyzing the corresponding wave packets, that this assumption is incorrect since the wave function of the liberated particle has to satisfy the incoming-wave boundary condition. We show that the electron released in photoionization carries no imprint of the scattering phase and thus cannot be used to determine the Wigner time delay. We illustrate our conclusions by comparing the numerical results obtained using two different methods of extracting the photoelectron spectra in an attoclock experiment.

quant-ph↗

arXiv2022

The Curious Case of the "Heartworm" Nebula

The curious Galactic features near G357.2$-$0.2 were observed with the MeerKAT radio interferometer array in the UHF and L bands (0.56--1.68 GHz). There are two possibly related features: a newly identified faint heart-shaped partial shell (the "Heart"), and a series of previously known but now much better imaged narrow, curved features (the "Worm") interior to the heart. Polarized emission suggests that much of the emission is nonthermal and is embedded in a dense plasma. The filaments of the worm appear to be magnetic structures powered by embedded knots that are sites of particle acceleration. The morphology of the worm broadly resembles some known pulsar wind nebulae (PWNe) but there is no known pulsar or PWN which could be powering this structure. We also present eROSITA observations of the field; no part of the nebula is detected in X-rays, but the current limits do not preclude the existence of a pulsar/PWN of intermediate spin-down luminosity.

astro-ph.HE↗

arXiv2021

Hoinga: A supernova remnant discovered in the SRG/eROSITA All-Sky Survey eRASS1

Supernova remnants (SNRs) are observable for about 6-15x10^4 years before they fade into the Galactic interstellar medium. With a Galactic supernova rate of approximately two per century, we can expect to have of the order of 1200 SNRs in our Galaxy. However, only about 300 of them are known to date, with the majority having been discovered in Galactic plane radio surveys. Given that these SNRs represent the brightest tail of the distribution and are mostly located close to the plane, they are not representative of the complete sample. Here we report findings from the search for new SNRs in the eROSITA all-sky survey data which led to the detection of one of the largest SNRs discovered at wavelengths other than the radio: G249.5+24.5. This source is located at a relatively high Galactic latitude, where SNRs are not usually expected to be found. The remnant, 'Hoinga', has a diameter of about 4.4 degrees and shows a circular shaped morphology with diffuse X-ray emission filling almost the entire remnant. Spectral analysis of the remnant emission reveals that an APEC spectrum from collisionally ionised diffuse gas and a plane-parallel shock plasma model with non-equilibrium ionisation are both able to provide an adequate description of the data, suggesting a gas temperature of the order of kT = 0.1 keV and an absorbing column density of N_H=3.6 x 10^20 cm^-2. Subsequent searches for a radio counterpart of the Hoinga remnant identified its radio emission in archival data from the Continuum HI Parkes All-Sky Survey (CHIPASS) and the 408-MHz `Haslam' all-sky survey. The radio spectral index alpha=-0.69 +- 0.08 obtained from these data definitely confirms the SNR nature of Hoinga. From its size and X-ray and radio spectral properties we conclude that Hoinga is a middle-aged Vela-like SNR located at a distance of about twice that of the Vela SNR, i.e. at ~500 pc.

astro-ph.HE↗

arXiv2020

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

The halo of the Milky Way provides a laboratory to study the properties of the shocked hot gas that is predicted by models of galaxy formation. There is observational evidence of energy injection into the halo from past activity in the nucleus of the Milky Way; however, the origin of this energy (star formation or supermassive-black-hole activity) is uncertain, and the causal connection between nuclear structures and large-scale features has not been established unequivocally. Here we report soft-X-ray-emitting bubbles that extend approximately 14 kiloparsecs above and below the Galactic centre and include a structure in the southern sky analogous to the North Polar Spur. The sharp boundaries of these bubbles trace collisionless and non-radiative shocks, and corroborate the idea that the bubbles are not a remnant of a local supernova but part of a vast Galaxy-scale structure closely related to features seen in gamma-rays. Large energy injections from the Galactic centre are the most likely cause of both the {\gamma}-ray and X-ray bubbles. The latter have an estimated energy of around 10$^{56}$ erg, which is sufficient to perturb the structure, energy content and chemical enrichment of the circumgalactic medium of the Milky Way.

astro-ph.GA↗