JWST reveals widespread CO ice and gas absorption in the Galactic Center cloud G0.253+0.016

Abstract

We report JWST NIRCam observations of G0.253+0.016, the molecular cloud in the Central Molecular Zone known as The Brick, with the F182M, F187N, F212N, F410M, F405N, and F466N filters. We catalog 56,146 stars detected in all 6 filters using the crowdsource package. Stars within and behind The Brick exhibit prodigious absorption in the F466N filter that is produced by a combination of CO ice and gas. In support of this conclusion, and as a general resource, we present models of CO gas and ice and CO${}_2$ ice in the F466N, F470N, and F410M filters. Both CO gas and ice may contribute to the observed stellar colors. We show, however, that CO gas does not absorb the Pf$\beta$ and Hu$\epsilon$ lines in F466N, but that these lines show excess absorption, indicating that CO ice is also present and contributes to observed F466N absorption. The most strongly absorbed stars in F466N are extincted by $\sim$ 2 magnitudes, corresponding to $>$ 80\% flux loss. This high observed absorption requires very high column densities of CO, requiring total CO column that is in tension with standard CO abundance and/or gas-to-dust ratios. There is therefore likely to be a greater CO/H${}_2$ ratio (X${}_{CO}>10^{-4}$) and more dust per H${}_2$ molecule ($>0.01$) in the Galactic Center than the Galactic disk. Ice and/or gas absorption is observed even in the cloud outskirts, implying that additional caution is needed when interpreting stellar photometry in filters that overlap with ice bands throughout our Galactic Center. The widespread CO absorption in our Galactic Center hints that significant ice absorption is likely present in other galactic centers.

Accepted to ApJ. 16 pages, 11 figures. Visualization of star removal at https://www.adamgginsburg.com/brick/slider.html and https://cosmicds.github.io/minids/jwst-brick/ . Figures & table 1 updated to correct magnitude zero-point error in original posting

References in corpus (30)

• Formation of methyl formate and other organic species in the warm-up phase of hot molecular cores
• astroquery: An Astronomical Web-Querying Package in Python
• The dynamical evolution of molecular clouds near the Galactic Centre - I. Orbital structure and evolutionary timeline
• Magnetic Fields in High-Mass Infrared Dark Clouds
• The link between turbulence, magnetic fields, filaments, and star formation in the Central Molecular Zone cloud G0.253+0.016
• A cluster in the making: ALMA reveals the initial conditions for high-mass cluster formation
• Turbulence sets the initial conditions for star formation in high-pressure environments
• 'The Brick' is not a brick: A comprehensive study of the structure and dynamics of the Central Molecular Zone cloud G0.253+0.016
• Milky Way Mid-Infrared Spitzer Spectroscopic Extinction Curves: Continuum and Silicate Features
• The Survey of Water and Ammonia in the Galactic Center (SWAG): Molecular Cloud Evolution in the Central Molecular Zone
• pyspeckit: A spectroscopic analysis and plotting package
• Galactocentric variation of the gas-to-dust ratio and its relation with metallicity
• G0.253+0.016: A centrally condensed, high-mass protocluster
• Seeding the Galactic Centre gas stream: gravitational instabilities set the initial conditions for the formation of protocluster clouds
• Ubiquitous velocity fluctuations throughout the molecular interstellar medium
• The dynamics and star-forming potential of the massive Galactic centre cloud G0.253+0.016
• A multi-wavelength view of the Galactic center dust ridge reveals little star formation
• Abundant Methanol Masers but no New Evidence for Star Formation in GCM0.253+0.016
• Survey of Ices toward Massive Young Stellar Objects: I. OCS, CO, OCN${}^{-}$, and CH${}_3$OH
• CHIMPS2: Survey description and ${}^{12}$CO emission in the Galactic Centre
• Star formation in 'the Brick': ALMA reveals an active proto-cluster in the Galactic centre cloud G0.253+0.016
• M-Band Spectra of Dust Embedded Sources at the Galactic Center
• Distance to three molecular clouds in the central molecular zone
• Absorption Filaments Towards the Massive Clump G0.253+0.016
• A wind-blown bubble in the Central Molecular Zone cloud G0.253+0.016
• AzTEC Survey of the Central Molecular Zone: Increasing Spectral Index of Dust with Density
• Massive Young Stellar Objects in the Galactic Center. II. Seeing Through the Ice-rich Envelopes
• A method for mapping the aliphatic hydrocarbon content of interstellar dust towards the Galactic Centre
• Mapping the aliphatic hydrocarbon content of interstellar dust in the Galactic plane
• The complex multi-scale structure in simulated and observed emission maps of the proto-cluster cloud G0.253+0.016 (`the Brick')

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