Detection of Another Molecular Bubble in the Galactic Center

Tsujimoto, Shiho; Oka, Tomoharu; Takekawa, Shunya; Yamada, Masaya; Tokuyama, Sekito; Iwata, Yuhei; Roll, Justin A.

doi:10.3847/1538-4357/aab36b

Cited by 11 publications

(12 citation statements)

References 27 publications

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“…21 of Bally et al (2010), and Fig. 4 of Tsujimoto et al (2018), is a chimera. Nevertheless the elliptical x 1 orbit has become popular and the notions of an EMR and the face-on view of the CMZ being circular seem to have taken a back seat.…”

Section: Barred Potential and Elliptical Orbit With High Eccentricitymentioning

confidence: 91%

Central 300 Pc of the Galaxy Probed by the Infrared Spectra of H3+ and Co Part Ii. Morphology and Dynamics of the Gas

Oka¹,

Indriolo²,

McCall³

et al. 2018

Proceedings of the 73rd International Symposium on Molecular Spectroscopy

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Velocity profiles of a line of H + 3 at 3.7 µm produced in warm diffuse gas have been observed toward 18 stars in the Central Molecular Zone (CMZ) of the Galaxy. Their longitude-velocity diagram indicates that the gas is radially expanding within the CMZ at speeds up to a maximum of ∼150 km s −1. The current momentum and energy in the gas are ∼ 5 × 10 8 M km s −1 and ∼ 5 × 10 53 erg. The motion is similar to that of the Expanding Molecular Ring (EMR) discovered in 1972 by Kaifu et al. and by Scoville. We propose that the expanding gas seen in H + 3 is part of the same phenomenon, in spite of differences in estimates of density, morphology, and degree of rotation. The outward motion suggests that one or more ejection events occurred near the center of the CMZ (0.5-1) × 10 6 years ago, which may be related to creation of the recently observed microwave bubble. These observations revive the circular face-on view of the CMZ proposed in 1972, which fell out of favor after 1991 when Binney et al. proposed that a face-on view of the CMZ would show it to have an elliptical shape, with high eccentricity. While that model may apply on kiloparsec scales, we argue that it is incorrect to apply it to the much smaller CMZ. We discuss the fate of the expanding gas, which appears to be eventual infall into the center, leading to episodes of star formation and violent events associated with accretion onto Sgr A * .

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Section: Barred Potential and Elliptical Orbit With High Eccentricitymentioning

confidence: 91%

Central 300 Pc of the Galaxy Probed by the Infrared Spectra of H3+ and Co Part Ii. Morphology and Dynamics of the Gas

Oka¹,

Indriolo²,

McCall³

et al. 2018

Proceedings of the 73rd International Symposium on Molecular Spectroscopy

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“…In the Galactic Centre, a number of molecular shell candidates have been identified (Martín-Pintado et al 1999;Oka et al 2001;Butterfield et al 2018;Tsujimoto et al 2018Tsujimoto et al , 2021. The kinetic energy estimated for many of these shells has led to speculation that they are the result of (potentially multiple) supernova explosions (e.g.…”

Section: Is a Wind-blown Bubble The Most Likely Scenario?mentioning

confidence: 99%

“…The kinetic energy estimated for many of these shells has led to speculation that they are the result of (potentially multiple) supernova explosions (e.g. Tsujimoto et al 2018). However, those identified in Sgr B2 by Martín-Pintado et al (1999) share many of the properties displayed by the arc in G0.253+0.016.…”

Section: Is a Wind-blown Bubble The Most Likely Scenario?mentioning

confidence: 99%

A wind-blown bubble in the Central Molecular Zone cloud G0.253+0.016

Henshaw,

Krumholz,

Butterfield

et al. 2021

Preprint

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G0.253+0.016, commonly referred to as "the Brick" and located within the Central Molecular Zone, is one of the densest (≈ 10 3−4 cm −3 ) molecular clouds in the Galaxy to lack signatures of widespread star formation. We set out to constrain the origins of an arc-shaped molecular line emission feature located within the cloud. We determine that the arc, centred on {l 0 , b 0 } = {0. • 248, 0. • 018}, has a radius of 1.3 pc and kinematics indicative of the presence of a shell expanding at 5.2 +2.7 −1.9 km s −1 . Extended radio continuum emission fills the arc cavity and recombination line emission peaks at a similar velocity to the arc, implying that the molecular and ionised gas are physically related. The inferred Lyman continuum photon rate is N LyC = 10 46.0 -10 47.9 photons s −1 , consistent with a star of spectral type B1-O8.5, corresponding to a mass of ≈ 12-20 M . We explore two scenarios for the origin of the arc: i) a partial shell swept up by the wind of an interloper high-mass star; ii) a partial shell swept up by stellar feedback resulting from in-situ star formation. We favour the latter scenario, finding reasonable (factor of a few) agreement between its morphology, dynamics, and energetics and those predicted for an expanding bubble driven by the wind from a high-mass star. The immediate implication is that G0.253+0.016 may not be as quiescent as is commonly accepted. We speculate that the cloud may have produced a 10 3 M star cluster 0.4 Myr ago, and demonstrate that the high-extinction and stellar crowding observed towards G0.253+0.016 may help to obscure such a star cluster from detection.

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“…These shells typically have huge kinetic energies of E kin ∼ 10 52 erg, which corresponds to 10 1-2 SNe. The follow-up observations of dense and shocked gas tracers in these regions have exhibited shell/arc-dominated morphology and expanding kinematics (Tanaka et al 2007;Tsujimoto et al 2018). Moreover, SiO clumps were detected at the high-velocity ends of the shells.…”

Section: Introductionmentioning

confidence: 98%

“…In addition, dozens of high-velocity compact clouds (HVCCs) with large kinetic energy were detected in our recent studies on the CMZ (Oka et al 1998b(Oka et al , 1999(Oka et al , 2001(Oka et al , 2007(Oka et al , 2012Tanaka et al 2014;Takekawa et al 2017Takekawa et al , 2019b. Some of the HVCCs exhibit one or more shell-like structures that may have been accelerated by a series of SN explosions that occurred in massive star clusters 10-30 Myr ago (Tanaka et al 2007;Tsujimoto et al 2018). The presence of these shells suggests that numerous micro-starbursts have occurred in the CMZ 10-30 Myr ago.…”

Section: Introductionmentioning

confidence: 99%

New Look at the Molecular Superbubble Candidate in the Galactic Center

Tsujimoto,

Oka,

Takekawa

et al. 2021

Preprint

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The l = +1. • 3 region in the Galactic center is characterized by multiple shell-like structures and their extremely broad velocity widths. We revisit the molecular superbubble hypothesis for this region, based on high resolution maps of CO J=1-0, 13 CO J=1-0, H 13 CN J=1-0, H 13 CO + J=1-0, SiO J=2-1, and CS J=2-1 lines obtained from the Nobeyama radio observatory 45-m telescope, as well as CO J=3-2 maps obtained from the James Clerk Maxwell telescope. We identified eleven expanding shells with total kinetic energy and typical expansion time E kin ∼ 10 51.9 erg and t exp ∼ 10 4.9 yr, respectively. In addition, the l = +1. • 3 region exhibited high SiO J=2-1/H 13 CN J=1-0 and SiO J=2-1/H 13 CO + J=1-0 intensity ratios, indicating that the region has experienced dissociative shocks in the past. These new findings confirm the molecular superbubble hypothesis for the l = +1. • 3 region. The nature of the embedded star cluster, which may have supplied 20-70 supernova explosions within 10 5 yr, is discussed. This work also show the importance of compact broad-velocity-width features in searching for localized energy sources hidden behind severe interstellar extinction and stellar contamination.

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Detection of Another Molecular Bubble in the Galactic Center

Cited by 11 publications

References 27 publications

Central 300 Pc of the Galaxy Probed by the Infrared Spectra of H3+ and Co Part Ii. Morphology and Dynamics of the Gas

Central 300 Pc of the Galaxy Probed by the Infrared Spectra of H3+ and Co Part Ii. Morphology and Dynamics of the Gas

A wind-blown bubble in the Central Molecular Zone cloud G0.253+0.016

New Look at the Molecular Superbubble Candidate in the Galactic Center

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