An extremely low gas-to-dust ratio in the dust-lane lenticular galaxy NGC 5485?

Baes, Maarten, Allaert, Flor, Sarzi, Marc, De Looze, Ilse, Fritz, Jacopo, Gentile, Gianfranco, Hughes, Thomas M., Puerari, Ivânio, Smith, Matthew ORCID: https://orcid.org/0000-0002-3532-6970 and Viaene, Sébastien 2014. An extremely low gas-to-dust ratio in the dust-lane lenticular galaxy NGC 5485? Monthly Notices of the Royal Astronomical Society: Letters 444 (1) , L90-L94. 10.1093/mnrasl/slu121

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Abstract

Evidence is mounting that a significant fraction of the early-type galaxy population contains substantial reservoirs of cold interstellar gas and dust. We investigate the gas and dust in NGC 5485, an early-type galaxy with a prominent minor-axis dust lane. Using new Herschel PACS and SPIRE imaging data, we detect 3.8 × 106 M⊙ of cool interstellar dust in NGC 5485, which is in stark contrast with the non-detection of the galaxy in sensitive H I and CO observations from the ATLAS3D consortium. The resulting gas-to-dust ratio upper limit is Mgas/Md < 14.5, almost an order of magnitude lower than the canonical value for the Milky Way. We scrutinize the reliability of the dust, atomic gas and molecular gas mass estimates, but these do not show systematic uncertainties that can explain the extreme gas-to-dust ratio. Also a warm or hot ionized gas medium does not offer an explanation. A possible scenario could be that NGC 5485 merged with an SMC-type metal-poor galaxy with a substantial CO-dark molecular gas component and that the bulk of atomic gas was lost during the interaction, but it remains to be investigated whether such a scenario is possible.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Subjects:	Q Science > QB Astronomy
Publisher:	Oxford University Press
ISSN:	1745-3933
Date of First Compliant Deposit:	6 December 2017
Date of Acceptance:	21 July 2014
Last Modified:	05 May 2023 07:36
URI:	https://orca.cardiff.ac.uk/id/eprint/107367

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