Thermal and chemical properties of the eROSITA bubbles from Suzaku observations

Gupta, Anjali; Mathur, S.; Kingsbury, Joshua; Das, Sanskriti; Krongold, Y.

doi:10.1038/s41550-023-01963-5

“…In previous studies of the warm-hot CGM in X-rays, the focus has been to detect the warm-hot 10 6 K CGM and identify it as the CGM (i.e., ruling out the sources of confusion), calculate the temperature, column density in absorption (e.g., Nicastro et al 2002;Williams et al 2005;Fang et al 2015;Das et al 2019bDas et al , 2021, emission measure in emission (e.g., Henley et al 2010;Das et al 2019a;Gupta et al 2023), and estimate the baryonic mass (Gupta et al 2012;Nicastro et al 2016). In this Letter, we take a step forward and attempt to constrain the nonthermal line broadening in the warm-hot CGM.…”

Section: Introductionmentioning

confidence: 99%

Detecting the Effect of Nonthermal Sources on the Warm-hot Galactic Halo

Das

2024

ApJL

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We report the first detection of nonthermal broadening of O vii lines in the warm-hot ≈106 K circumgalactic medium of the Milky Way. We use z = 0 absorption of O vii Kα, O vii Kβ, and O viii Kα lines in archival grating data of b > 15° quasar sightlines from Chandra and XMM-Newton. Nonthermal line broadening is evident in two-thirds of the sightlines considered, and on average is constrained at 4.6σ significance. Nonthermal line broadening dominates over thermal broadening. We extensively test whether the appearance of nonthermal line broadening could instead be because of multiple thermally broadened velocity components and robustly rule it out. Nonthermal line broadening is more evident toward sightlines at lower galactic latitude indicating the Galactic disk origin of the nonthermal sources. There is weak/no correlation between nonthermal line broadening and the angular separation of sightlines from the Galactic center, indicating that the nuclear region might not be a major source of nonthermal factors.

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“…The hot CGM of the Milky Way has been extensively observed in X-ray emission (e.g., Snowden et al 2000;Henley et al 2010;Das et al 2019a;Kaaret et al 2020;Gupta et al 2021;Bluem et al 2022;Bhattacharyya et al 2023;Gupta et al 2023) and X-ray absorption (e.g., Williams et al 2005;Gupta et al 2012;Nicastro et al 2016;Gatuzz & Churazov 2018;Das et al 2019cDas et al , 2021aLara-DI et al 2023). It is incredibly challenging to probe the hot CGM of external galaxies in emission due to the spatially and temporally variable foreground dominating the total X-ray emission.…”

Section: Introductionmentioning

confidence: 99%

Detection of Thermal Sunyaev–Zel’dovich Effect in the Circumgalactic Medium of Low-mass Galaxies—A Surprising Pattern in Self-similarity and Baryon Sufficiency

Das

¹

,

Chiang

²

,

Mathur

³

2023

ApJ

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We report on the measurement of the thermal Sunyaev–Zel’dovich (tSZ) effect in the circumgalactic medium (CGM) of 641,923 galaxies with M ⋆ = 109.8–11.3 M ⊙ at z < 0.5, pushing the exploration of the tSZ effect to lower-mass galaxies compared to those in previous studies. We cross-correlate the galaxy catalog of the Wide-field Infrared Survey Explorer and SuperCOSMOS with Compton-y maps derived from the combined data of the Atacama Cosmology Telescope and Planck. We improve on the data analysis methods (correcting for cosmic infrared background and Galactic dust, masking galaxy clusters and radio sources, stacking, and employing aperture photometry), as well as modeling (taking into account beam smearing, the “two-halo” term, and any zero-point offset). We constrain the thermal pressure in the CGM of M ⋆ = 1010.6–11.3 M ⊙ galaxies for a generalized Navarro–Frenk–White profile and provide upper limits for M ⋆ = 109.8–10.6 M ⊙ galaxies. The relation between M 500 (obtained from an empirical M ⋆–M 200 relation and a concentration factor) and Y ˜ R 500 sph (a measure of the thermal energy within R 500) is >2σ steeper than the self-similarity relation and the deviation from the same that has been reported previously in higher-mass halos. We calculate the baryon fraction of the galaxies, f b , assuming the CGM to be at the virial temperature that is derived from M 200. The baryon fraction f b exhibits a nonmonotonic trend with mass, with M ⋆ = 1010.9–11.2 M ⊙ galaxies being baryon-sufficient.

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“…Ho we v er, man y uncertainties remain in both the modelling of these scenarios and the interpretation of the observations (e.g. Miller & Bregman 2016 ;Nogueras-Lara et al 2020 ;Yang et al 2022 ;Gupta et al 2023 ;Sarkar et al 2023 ). As a result, the origin of the eROSITA / Fermi bubbles is still unclear (e.g.…”

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confidence: 99%

Tracing the energetic outflows from galactic nuclei: observational evidence for a large-scale bipolar radio and X-ray-emitting bubble-like structure in M106

Zeng,

Wang,

Fraternali

2023

Monthly Notices of the Royal Astronomical Society

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The role of energetic outflows from galactic nuclei in shaping galaxy formation and evolution is still shrouded in uncertainty. In this study, we shed light on this complex phenomenon by presenting evidence for a large-scale bipolar radio/X-ray-emitting bubble-like structure emanating from the central region of the nearby disc galaxy M106 (NGC 4258). Our findings, based on Low-Frequency Array survey data and Chandra observations, provide a glimpse into the underlying physical processes driving this enigmatic structure. Similar to the eROSITA/Fermi bubbles in our own Galaxy, the M106 bubbles enclose diffuse hot plasma and are partially bounded by prominent radio/X-ray-emitting edges. We constrain the magnetic field and cosmic-ray properties of the structure. The analysis of the X-ray data gives an estimate of the thermal energy of the bubbles as ∼8 × 1056 erg. This energy can be supplied by the jets and perhaps by the wind from the accretion flow of the galaxy’s low-luminosity AGN, which most likely has been much more powerful in the recent past, with an average mechanical energy release rate of ∼4 × 1042 erg s−1 over the last ∼8 × 106 yr – the estimated age of the structure. We also show evidence for diffuse X-ray emission on larger scales, indicating the presence of a hot galactic corona. Our results provide a clear manifestation of galactic nuclear feedback regulating the gas content and energetics of the circumgalactic medium of disc galaxies similar to our own.

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Thermal and chemical properties of the eROSITA bubbles from Suzaku observations

Cited by 11 publications

References 33 publications

Detecting the Effect of Nonthermal Sources on the Warm-hot Galactic Halo

Detecting the Effect of Nonthermal Sources on the Warm-hot Galactic Halo

Detection of Thermal Sunyaev–Zel’dovich Effect in the Circumgalactic Medium of Low-mass Galaxies—A Surprising Pattern in Self-similarity and Baryon Sufficiency

Tracing the energetic outflows from galactic nuclei: observational evidence for a large-scale bipolar radio and X-ray-emitting bubble-like structure in M106

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