Some like it hot: Linking diffuse X-ray luminosity, baryonic mass, and star formation rate in compact groups of galaxies

Journal Article · Fri Aug 01 04:00:00 EDT 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/790/2/132· OSTI ID:22365477

Desjardins, Tyler D.; Gallagher, Sarah C. ^[1]; Hornschemeier, Ann E.; Tzanavaris, Panayiotis ^[2]; Mulchaey, John S. ^[3]; Walker, Lisa May; Johnson, Kelsey E. ^[4]; Brandt, William N.; Charlton, Jane C. ^[5]

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1. Department of Physics and Astronomy, University of Western Ontario, London, ON N6A 3K7 (Canada)
2. Laboratory for X-ray Astrophysics, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
3. Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)
4. Department of Astronomy, University of Virginia, Charlottesville, VA 22904 (United States)
5. Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States)

We present an analysis of the diffuse X-ray emission in 19 compact groups (CGs) of galaxies observed with Chandra. The hottest, most X-ray luminous CGs agree well with the galaxy cluster X-ray scaling relations in L{sub X} -T and L{sub X} -σ, even in CGs where the hot gas is associated with only the brightest galaxy. Using Spitzer photometry, we compute stellar masses and classify Hickson CGs 19, 22, 40, and 42, and RSCGs 32, 44, and 86 as fossil groups using a new definition for fossil systems that includes a broader range of masses. We find that CGs with total stellar and H I masses ≳ 10{sup 11.3} M{sub ☉} are often X-ray luminous, while lower-mass CGs only sometimes exhibit faint, localized X-ray emission. Additionally, we compare the diffuse X-ray luminosity against both the total UV and 24 μm star formation rates of each CG and optical colors of the most massive galaxy in each of the CGs. The most X-ray luminous CGs have the lowest star formation rates, likely because there is no cold gas available for star formation, either because the majority of the baryons in these CGs are in stars or the X-ray halo, or due to gas stripping from the galaxies in CGs with hot halos. Finally, the optical colors that trace recent star formation histories of the most massive group galaxies do not correlate with the X-ray luminosities of the CGs, indicating that perhaps the current state of the X-ray halos is independent of the recent history of stellar mass assembly in the most massive galaxies.

• OSTI ID: 22365477
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 790; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
COLOR
COMPARATIVE EVALUATIONS
EMISSION
GALAXY CLUSTERS
LUMINOSITY
MASS
PHOTOMETRY
STARS
X RADIATION
X-RAY GALAXIES