DUST EMISSION AND STAR FORMATION IN STEPHAN'S QUINTET

Journal Article · Fri Dec 10 00:00:00 EST 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/725/1/955· OSTI ID:21474395

Natale, G; Tuffs, R J ^[1]; Xu, C K; Lu, N ^[2]; Popescu, C C ^[3]; Fischera, J ^[4]; Lisenfeld, U ^[5]; Appleton, P ^[6]; Dopita, M ^[7]; Duc, P -A ^[8]; Gao, Y ^[9]; Reach, W ^[10]; Sulentic, J ^[11]; Yun, M ^[12]

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1. Max Planck Institute fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany)
2. Infrared Processing and Analysis Center, California Institute of Technology 100-22, Pasadena, CA 91125 (United States)
3. University of Central Lancashire, Preston, PR1 2HE (United Kingdom)
4. Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 Saint George Street, Toronto, ON, M5S 3H8 (Canada)
5. Department de Fisica Teorica y del Cosmos, Universidad de Granada, Granada (Spain)
6. NASA Herschel Science Center, IPAC, California Institute of Technology, Pasadena, CA 91125 (United States)
7. Research School of Astronomy and Astrophysics, The Australian National University, Cotter Road, Weston Creek, ACT 2611 (Australia)
8. Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, Dapnia/Service d'Astrophysique, CEA-Saclay, 91191 Gif-sur-Yvette Cedex (France)
9. Purple Mountain Observatory, Chinese Academy of Sciences, 2 West Beijing Road, Nanjing 210008 (China)
10. Spitzer Science Center, IPAC, California Institute of Technology, Pasadena, CA 91125 (United States)
11. Instituto de Astrofisica de AndalucIa, CSIC, Apdo. 3004, 18080, Granada (Spain)
12. Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States)

We analyze a comprehensive set of MIR/FIR observations of Stephan's Quintet (SQ), taken with the Spitzer Space Telescope. Our study reveals the presence of a luminous (L{sub IR} {approx} 4.6 x 10{sup 43} erg s{sup -1}) and extended component of infrared dust emission, not connected with the main bodies of the galaxies, but roughly coincident with the X-ray halo of the group. We fitted the inferred dust emission spectral energy distribution of this extended source and the other main infrared emission components of SQ, including the intergalactic shock, to elucidate the mechanisms powering the dust and polycyclic aromatic hydrocarbon emission, taking into account collisional heating by the plasma and heating through UV and optical photons. Combining the inferred direct and dust-processed UV emission to estimate the star formation rate (SFR) for each source we obtain a total SFR for SQ of 7.5 M{sub sun} yr{sup -1}, similar to that expected for non-interacting galaxies with stellar mass comparable to the SQ galaxies. Although star formation in SQ is mainly occurring at, or external to the periphery of the galaxies, the relation of SFR per unit physical area to gas column density for the brightest sources is similar to that seen for star formation regions in galactic disks. We also show that available sources of dust in the group halo can provide enough dust to produce up to L{sub IR} {approx} 10{sup 42} erg s{sup -1} powered by collisional heating. Though a minority of the total infrared emission (which we infer to trace distributed star-formation), this is several times higher than the X-ray luminosity of the halo, so could indicate an important cooling mechanism for the hot intergalactic medium (IGM) and account for the overall correspondence between FIR and X-ray emission. We investigate two potential modes of star formation in SQ consistent with the data, fueled either by gas from a virialized hot IGM continuously accreting onto the group, whose cooling is enhanced by grains injected from an in situ population of intermediate mass stars, or by interstellar gas stripped from the galaxies. The former mode offers a natural explanation for the observed baryon deficiency in the IGM of SQ as well as for the steep L{sub X}-T{sub X} relation of groups such as SQ with lower velocity dispersions.

• OSTI ID: 21474395
• Journal Information: Astrophysical Journal, Vol. 725, Issue 1; Other Information: DOI: 10.1088/0004-637X/725/1/955; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
BARYONS
COLLISIONAL HEATING
DUSTS
EMISSION
ENERGY SPECTRA
GALACTIC EVOLUTION
GALAXIES
LUMINOSITY
PHOTONS
PLASMA
POLYCYCLIC AROMATIC HYDROCARBONS
STAR EVOLUTION
STARS
TELESCOPES
X RADIATION
AROMATICS
BOSONS
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
EVOLUTION
FERMIONS
HADRONS
HEATING
HIGH-FREQUENCY HEATING
HYDROCARBONS
IONIZING RADIATIONS
MAGNETIC-PUMPING HEATING
MASSLESS PARTICLES
OPTICAL PROPERTIES
ORGANIC COMPOUNDS
PHYSICAL PROPERTIES
PLASMA HEATING
RADIATIONS
SPECTRA