Primordial or Secondary? Testing Models of Debris Disk Gas with ALMA*

The origin and evolution of gas in debris disks are still not well understood. Secondary gas production from cometary material or a primordial origin have been proposed. So far, observations have mostly concentrated on CO, with only a few C observations available. We overview the C and CO content of debris disk gas and test state-of-the-art models. We use new and archival Atacama Large Millimeter/submillimeter Array (ALMA) observations of CO and C i emission, complemented by C ii data from Herschel, for a sample of 14 debris disks. This expands the number of disks with ALMA measurements of both CO and C i by 10 disks. We present new detections of C i emission toward three disks: HD 21997, HD 121191, and HD 121617. We use a simple disk model to derive gas masses and column densities. We find that current state-of-the-art models of secondary gas production overpredict the C-0 content of debris disk gas. This does not rule out a secondary origin, but might indicate that the models require an additional C removal process. Alternatively, the gas might be produced in transient events rather than a steady-state collisional cascade. We also test a primordial gas origin by comparing our results to a simplified thermochemical model. This yields promising results, but more detailed work is required before a conclusion can be reached. Our work demonstrates that the combination of C and CO data is a powerful tool to advance our understanding of debris disk gas.

Aikawa, Yuri (author)
Iwasaki, Kazunari (author)
Marino, Sebastian (author)
Brandeker, Alexis,1974-Stockholms universitet,Institutionen för astronomi(Swepub:su)alexis (author)
Hales, Antonio (author)
Henning, Thomas (author)
Higuchi, Aya E. (author)
Hughes, A. Meredith (author)
Janson, Markus,1981-Stockholms universitet,Institutionen för astronomi(Swepub:su)mjanso (author)
Kral, Quentin (author)
Matra, Luca (author)
Moor, Attila (author)
Olofsson, Göran,1944-Stockholms universitet,Institutionen för astronomi,Oskar Klein-centrum för kosmopartikelfysik (OKC)(Swepub:su)olofsson (author)
Redfield, Seth (author)
Roberge, Aki (author)
Stockholms universitetInstitutionen för astronomi (creator_code:org_t)

By the author/editor: Cataldi, Gianni; Aikawa, Yuri; Iwasaki, Kazunar ...; Marino, Sebastia ...; Brandeker, Alexi ...; Hales, Antonio; show more...; Henning, Thomas; Higuchi, Aya E.; Hughes, A. Mered ...; Janson, Markus, ...; Kral, Quentin; Matra, Luca; Moor, Attila; Olofsson, Göran, ...; Redfield, Seth; Roberge, Aki; show less...

About the subject

NATURAL SCIENCES: NATURAL SCIENCES; and Physical Science ...; and Astronomy Astrop ...

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