A surprising number (virgul50%) of field early-type galaxies (E and S0s) contain a cool interstellar medium phase detected through the 21cm hyperfine transition of neutral hydrogen. In some cases, this gas is distributed in extremely extensive outer distributions of up to a few 10^9 solar masses of HI. The origin and relation of such outer gas reservoirs to their host early-type galaxies is currently unknown. The gas may be directly accreted from the IGM, stripped during a tidal interaction, or acquired during a gas-rich merger. Alternatively, such gas may have been long associated with the early-type galaxy, not being exhausted due to a low star formation efficiency. In each of these cases the gas is expected to have a different enrichment history and thus a different present-day metallicity and dust-to-gas ratio. With Herschel PACS and SPIRE photometry, we propose to measure dust masses in the outer HI distributions of 15 nearby early-type galaxies. With interferometric HI data already in hand, we can then calculate dust-to-gas ratios and constrain the origin of such gas. The sample size and variety of HI masses, radial extents and morphologies will let us test if the dust-to-gas ratios vary among the sample in a way described best by a single accretion scenario. Additionally, the temperature derived for the dust in the outer gas will let us constrain the possible heating sources for the dust. In some sample galaxies, coincident UV emission suggests young stars are present. If heating from these young stars is important, we expect a variation of dust temperature in systems with and without UV emission.
Publication
DustPedia: Multiwavelength photometry and imagery of 875 nearby galaxies in 42 ultraviolet-microwave bands . Clark C. J. R. et al. . Astronomy & Astrophysics, Volume 609, id.A37, 30 pp. . 609 . 10.1051\/0004-6361\/201731419 . 2018A&A...609A..37C , Probing the spectral shape of dust emission with the DustPedia galaxy sample . Nersesian Angelos et al. . Monthly Notices of the Royal Astronomical Society . null . null . 2021MNRAS.506.3986N , A nearby galaxy perspective on dust evolution. Scaling relations and constraints on the dust build-up in galaxies with the DustPedia and DGS samples . Galliano Frédéric et al. . Astronomy and Astrophysics . null . null . 2021A&A...649A..18G , Dust emissivity and absorption cross section in DustPedia late-type galaxies . Bianchi S. et al. . Astronomy and Astrophysics . null . null . 2019A&A...631A.102B , Star Formation Bimodality in Early-type Galaxies . Amblard A. et al. . The Astrophysical Journal, Volume 783, Issue 2, article id. 135, 31 pp. (2014). . 783 . 10.1088\/0004-637X\/783\/2\/135 . 2014ApJ...783..135A , DustPedia: the relationships between stars, gas, and dust for galaxies residing in different environments . Davies J. I. et al. . Astronomy and Astrophysics . null . null . 2019A&A...626A..63D , Old and young stellar populations in DustPedia galaxies and their role in dust heating . Nersesian A. et al. . Astronomy and Astrophysics . null . null . 2019A&A...624A..80N , Fraction of bolometric luminosity absorbed by dust in DustPedia galaxies . Bianchi S. et al. . Astronomy & Astrophysics, Volume 620, id.A112, 21 pp. . 620 . 10.1051\/0004-6361\/201833699 . ...6A...620A.112B > 2018A&A...620A.112B , UV to submillimetre luminosity functions of TNG50 galaxies . Trčka Ana et al. . Monthly Notices of the Royal Astronomical Society . null . null . 2022MNRAS.516.3728T , DustPedia: A Definitive Study of Cosmic Dust in the Local Universe . Davies J. I. et al. . Publications of the Astronomical Society of the Pacific, Volume 129, Issue 974, pp. 044102 (2017). . 129 . 10.1088\/1538-3873\/129\/974\/044102 . 2017PASP..129d4102D ,
Instrument
PACS_PacsPhoto_largeScan, SPIRE_SpirePhoto_large
Temporal Coverage
2011-06-20T18:26:22Z/2013-03-01T08:53:14Z
Version
SPG v14.2.0
Mission Description
Herschel was launched on 14 May 2009! It is the fourth 'cornerstone' mission in the ESA science programme. With a 3.5 m Cassegrain telescope it is the largest space telescope ever launched. It is performing photometry and spectroscopy in approximately the 55-671 µm range, bridging the gap between earlier infrared space missions and groundbased facilities.
European Space Agency, 2013, Origin Of Massive Outer Gas Reservoirs In Early-Type Galaxies, SPG v14.2.0, European Space Agency, https://doi.org/10.5270/esa-qqt5bsl
