Stephan.s Quintet (SQ) is a compact group of galaxies, where tidal interactions have brought large amounts of gas into the intergalactic medium (IGM). Spitzer IRS observations revealed an unusually bright H2 line emission from a giant (40 kpc long), X-ray emitting shock attributed to a high-speed (1000 km/s) galaxy collision. The extreme H2-to-PAH flux ratio (1000 times more than star-forming galaxies) suggest that H2 is predominantly excited by shocks rather than UV heating from star-forming regions. From our OT1 P2 project, we recently obtained SPIRE images of SQ, revealing for the first time the cold dust associated with the warm H2 gas in the shock. However, the large SPIRE beams do not separate star-forming regions from shocked gas. To confirm what fraction of the dust emission comes from the shock, we propose PACS observations with higher angular resolution. These observations are further motivated by our recent PdBI CO(1-0) observations, which break the SQ shock in large complexes (3-5 kpc in size) with a range of line widths (40-200km/s). Some of them could be sites of star formation. PACS is the only instrument providing the sensitivity and angular resolution to quantify star formation on these scales. With the proposed observations, for the first time for IGM gas, we will be able to (1) calibrate the CO to H2 conversion factor using dust emission and estimate the total cold gas content of the CO complexes, (2) study the impact of turbulence on star-formation efficiency, and (3) constrain the dust size distribution. The results will have important consequences on our understanding of the energetics and the role of dust in cooling the IGM gas in high-redshift mergers, and in the formation of galaxies.
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 | http://adsabs.harvard.edu/abs/2018A%26A...609A..37C
Shock-enhanced C+ Emission and the Detection of H2O from the Stephan.s Quintet Group-wide Shock Using Herschel | Appleton P. N. et al. | The Astrophysical Journal Volume 777 Issue 1 article id. 66 16 pp. (2013). | 777 | 10.1088\\/0004-637X\\/777\\/1\\/66 | 2013ApJ...777...66A | http://adsabs.harvard.edu/abs/2013ApJ...777...66A
Infrared colours and spectral energy distributions of hard X-ray selected obscured and Compton-thick active galactic nuclei | Kilerci Eser Ece et al. | Monthly Notices of the Royal Astronomical Society | null | null | 2020MNRAS.494.5793K |
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 Frederic et al. | Astronomy and Astrophysics | null | null | 2021A&A...649A..18G |
Reproducing the Universe: a comparison between the EAGLE simulations and the nearby DustPedia galaxy sample | Trcka Ana et al. | Monthly Notices of the Royal Astronomical Society | null | null | 2020MNRAS.494.2823T |
Dust emissivity and absorption cross section in DustPedia late-type galaxies | Bianchi S. et al. | Astronomy and Astrophysics | null | null | 2019A&A...631A.102B |
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 |
BAT AGN Spectroscopic Survey. XI. The Covering Factor of Dust and Gas in Swift/BAT Active Galactic Nuclei | Ichikawa Kohei et al. | The Astrophysical Journal Volume 870 Issue 1 article id. 31 16 pp. (2019). | 870 | 10.3847\\/1538-4357\\/aaef8f | 2019ApJ...870...31I | http://adsabs.harvard.edu/abs/2019ApJ...870...31I
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 | 2018A&A...620A.112B | http://adsabs.harvard.edu/abs/2018A%26A...620A.112B
UV to submillimetre luminosity functions of TNG50 galaxies | Trcka Ana et al. | Monthly Notices of the Royal Astronomical Society | null | null | 2022MNRAS.516.3728T |
Herschel observations of Hickson compact groups of galaxies: Unveiling the properties of cold dust | Bitsakis T. et al. | Astronomy & Astrophysics Volume 565 id.A25 31 pp. | 565 | 10.1051\\/0004-6361\\/201323349 | 2014A&A...565A..25B | http://adsabs.harvard.edu/abs/2014A%26A...565A..25B
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 | http://adsabs.harvard.edu/abs/2017PASP..129d4102D
Dust emission profiles of DustPedia galaxies | Mosenkov A. V. et al. | Astronomy & Astrophysics Volume 622 id.A132 24 pp. | 622 | 10.1051\\/0004-6361\\/201833932 | 2019A&A...622A.132M | http://adsabs.harvard.edu/abs/2019A%26A...622A.132M
Instrument
PACS_PacsPhoto_largeScan
Temporal Coverage
2012-05-12T22:54:02Z/2012-05-13T11:55:05Z
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, guillard et al., 2012, 'A high-resolution look at dust emission from shocks and star-forming regions in Stephan.s Quintet', SPG v14.2.0, European Space Agency, https://doi.org/10.5270/esa-vcsweu5
