POLYCYCLIC AROMATIC HYDROCARBONS, IONIZED GAS, AND MOLECULAR HYDROGEN IN BRIGHTEST CLUSTER GALAXIES OF COOL-CORE CLUSTERS OF GALAXIES

Journal Article · Sun May 01 00:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/732/1/40· OSTI ID:21574639

Donahue, Megan; Mark Voit, G; Hoffer, Aaron ^[1]; De Messieres, Genevieve E; O'Connell, Robert W ^[2]; McNamara, Brian R ^[3]; Nulsen, Paul E. J., ^[4]

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1. Physics and Astronomy Department, Michigan State University, East Lansing, MI 48824 (United States)
2. Astronomy Department, University of Virginia, Charlottesville, VA (United States)
3. Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1 (Canada)
4. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

We present measurements of 5-25 {mu}m emission features of brightest cluster galaxies (BCGs) with strong optical emission lines in a sample of nine cool-core clusters of galaxies observed with the Infrared Spectrograph on board the Spitzer Space Telescope. These systems provide a view of dusty molecular gas and star formation, surrounded by dense, X-ray-emitting intracluster gas. Past work has shown that BCGs in cool-core clusters may host powerful radio sources, luminous optical emission-line systems, and excess UV, while BCGs in other clusters never show this activity. In this sample, we detect polycyclic aromatic hydrocarbons (PAHs), extremely luminous, rotationally excited molecular hydrogen line emission, forbidden line emission from ionized gas ([Ne II] and [Ne III]), and infrared continuum emission from warm dust and cool stars. We show here that these BCGs exhibit more luminous forbidden neon and H{sub 2} rotational line emission than star-forming galaxies with similar total infrared luminosities, as well as somewhat higher ratios of 70 {mu}m/24 {mu}m luminosities. Our analysis suggests that while star formation processes dominate the heating of the dust and PAHs, a heating process consistent with suprathermal electron heating from the hot gas, distinct from star formation, is heating the molecular gas and contributing to the heating of the ionized gas in the galaxies. The survival of PAHs and dust suggests that dusty gas is somehow shielded from significant interaction with the X-ray gas.

• OSTI ID: 21574639
• Journal Information: Astrophysical Journal, Vol. 732, Issue 1; Other Information: DOI: 10.1088/0004-637X/732/1/40; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
DUSTS
EMISSION
GALAXY CLUSTERS
HEATING
HYDROGEN
INFRARED RADIATION
LUMINOSITY
NEON
POLYCYCLIC AROMATIC HYDROCARBONS
STARS
AROMATICS
ELECTROMAGNETIC RADIATION
ELEMENTS
FLUIDS
GASES
HYDROCARBONS
NONMETALS
OPTICAL PROPERTIES
ORGANIC COMPOUNDS
PHYSICAL PROPERTIES
RADIATIONS
RARE GASES