Detection of a Supervirial Hot Component in the Milky Way Circumgalactic Medium Along Multiple Sight Lines by Using the Stacking Technique

Lara-DI, Armando; Mathur, S.; Krongold, Y.; Das, Sanskriti; Gupta, Anjali

doi:10.3847/1538-4357/acbf40

Cited by 6 publications

(2 citation statements)

References 26 publications

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“…Based on the oxygen-only analysis, we cannot test the possibility of deviation from a single phase. However, by simultaneously studying multiple metal ions (e.g., N, Ne, and Si) in addition to oxygen, a supervirial ≈10 7 K hot phase coexisting with the ≈10 6 K warm-hot CGM has been identified toward several individual high S/N sightlines (Das et al 2019b(Das et al , 2021McClain et al 2024; highlighted in Figure 2) and stacking of many low S/N sightlines (Lara-DI et al 2023). In those scenarios, O VII comes predominantly from the warm-hot phase, but O VIII comes from both the hot and warm-hot phases in a comparable amount.…”

Section: Multiple Temperature Componentsmentioning

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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Section: Multiple Temperature Componentsmentioning

confidence: 99%

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

Das

2024

ApJL

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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

Chiang

Mathur

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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Supervirial hot phase in Milky Way circumgalactic medium: further evidences

McClain,

Mathur,

Das

et al. 2023

Monthly Notices of the Royal Astronomical Society

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Recent discoveries of a super-virial hot phase of the Milky Way circumgalactic medium (CGM) has launched new questions regarding the multi-phase structure of the CGM around the Galaxy. We use 1.05 Ms of archival Chandra/HETG observations to characterize highly ionized metal absorption at z=0 along the line of sight of the quasar NGC 3783. We detect two distinct temperature phases with T$_1 = 5.83^{+0.15}_{-0.07}$ K, warm-hot virial temperature, and T$_2=6.61^{+0.12}_{-0.06}$ K, hot super-virial temperature. The super-virial hot phase coexisting with the warm-hot virial phase has been detected in absorption along only two other sightlines and in one stacking analysis. There is scatter in temperature of the hot as well as warm-hot gas. Similar to previous observations, we detect super-solar abundance ratios of metals in the hot phase, with a Ne/O ratio 2σ above solar mixtures. These new detections continue the mystery of the mechanism behind the super-virial hot phase, but provide evidence that this is a true property of the CGM rather than an isolated observation. The super-virial CGM could hold the key to understanding the physical and chemical history of the Milky Way.

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Detection of a Supervirial Hot Component in the Milky Way Circumgalactic Medium Along Multiple Sight Lines by Using the Stacking Technique

Cited by 6 publications

References 26 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

Supervirial hot phase in Milky Way circumgalactic medium: further evidences

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