| 1. |
- Tamura, Yoichi, et al.
(författare)
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The 300 pc Resolution Imaging of a z=8.31 Galaxy : Turbulent Ionized Gas and Potential Stellar Feedback 600 Million Years after the Big Bang
- 2023
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Ingår i: Astrophysical Journal. - : Institute of Physics (IOP). - 0004-637X .- 1538-4357. ; 952:1
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Tidskriftsartikel (refereegranskat)abstract
- We present the results of 300 pc resolution Atacama Large Millimeter/submillimeter Array imaging of the [O iii] 88 & mu;m line and dust continuum emission from a z = 8.312 Lyman-break galaxy MACS0416_Y1. The velocity-integrated [O iii] emission has three peaks that are likely associated with three young stellar clumps of MACS0416_Y1, while the channel map shows a complicated velocity structure with little indication of a global velocity gradient unlike what was found in [C ii] 158 & mu;m at a larger scale, suggesting random bulk motion of ionized gas clouds inside the galaxy. In contrast, dust emission appears as two individual clumps apparently separating or bridging the [O iii]/stellar clumps. The cross-correlation coefficient between dust and ultraviolet-related emission (i.e., [O iii] and ultraviolet continuum) is unity on a galactic scale, while it drops at <1 kpc, suggesting well-mixed geometry of multiphase interstellar media on subkiloparsec scales. If the cutoff scale characterizes different stages of star formation, the cutoff scale can be explained by gravitational instability of turbulent gas. We also report on a kiloparsec-scale off-center cavity embedded in the dust continuum image. This could be a superbubble producing galactic-scale outflows, since the energy injection from the 4 Myr starburst suggested by a spectral energy distribution analysis is large enough to push the surrounding media creating a kiloparsec-scale cavity.
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| 2. |
- Tokuoka, Tsuyoshi, et al.
(författare)
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Possible Systematic Rotation in the Mature Stellar Population of a z=9.1 Galaxy
- 2022
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Ingår i: Astrophysical Journal Letters. - : Institute of Physics Publishing (IOPP). - 2041-8205 .- 2041-8213. ; 933:1
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Tidskriftsartikel (refereegranskat)abstract
- We present new observations with the Atacama Large Millimeter/submillimeter Array for a gravitationally lensed galaxy at z = 9.1, MACS1149-JD1. [O III] 88 mu m emission is detected at 10 sigma with a spatial resolution of similar to 0.3 kpc in the source plane, enabling the most distant morphokinematic study of a galaxy. The [O iii] emission is distributed smoothly without any resolved clumps and shows a clear velocity gradient with Delta V-obs/2 sigma(tot) = 0.84 +/- 0.23, where Delta V-obs is the observed maximum velocity difference and sigma(tot) is the velocity dispersion measured in the spatially integrated line profile, suggesting a rotating system. Assuming a geometrically thin self-gravitating rotation disk model, we obtain V-rot/sigma(V)=0.67-0.26+0.73, where V-rot and sigma (V) are the rotation velocity and velocity dispersion, respectively, still consistent with rotation. The resulting disk mass of 0.65-0.40+1.37x10(9) M-circle dot is consistent with being associated with the stellar mass identified with a 300 Myr old stellar population independently indicated by a Balmer break in the spectral energy distribution. We conclude that the most of the dynamical mass is associated with the previously identified mature stellar population that formed at z similar to 15.
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