VARIATIONS OF MID- AND FAR-INFRARED LUMINOSITIES AMONG EARLY-TYPE GALAXIES: RELATION TO STELLAR METALLICITY AND COLD DUST

Journal Article · Wed May 01 04:00:00 EDT 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/768/1/28· OSTI ID:22126841

Mathews, William G.; Brighenti, Fabrizio ^[1]; Temi, Pasquale; Amblard, Alexandre ^[2]

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1. University of California Observatories/Lick Observatory, Board of Studies in Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)
2. Astrophysics Branch, NASA/Ames Research Center, MS 245-6, Moffett Field, CA 94035 (United States)

The Hubble morphological sequence from early to late galaxies corresponds to an increasing rate of specific star formation. The Hubble sequence also follows a banana-shaped correlation between 24 and 70 {mu}m luminosities, both normalized with the K-band luminosity. We show that this correlation is significantly tightened if galaxies with central active galactic nucleus (AGN) emission are removed, but the cosmic scatter of elliptical galaxies in both 24 and 70 {mu}m luminosities remains significant along the correlation. We find that the 24 {mu}m variation among ellipticals correlates with stellar metallicity, reflecting emission from hot dust in winds from asymptotic giant branch stars of varying metallicity. Infrared surface brightness variations in elliptical galaxies indicate that the K - 24 color profile is U-shaped for reasons that are unclear. In some elliptical galaxies, cold interstellar dust emitting at 70 and 160 {mu}m may arise from recent gas-rich mergers. However, we argue that most of the large range of 70 {mu}m luminosity in elliptical galaxies is due to dust transported from galactic cores by feedback events in (currently IR-quiet) AGNs. Cooler dusty gas naturally accumulates in the cores of elliptical galaxies due to dust-cooled local stellar mass loss and may accrete onto the central black hole, releasing energy. AGN-heated gas can transport dust in cores 5-10 kpc out into the hot gas atmospheres where it radiates extended 70 {mu}m emission but is eventually destroyed by sputtering. This, and some modest star formation, defines a cycle of dust creation and destruction. Elliptical galaxies evidently undergo large transient excursions in the banana plot in times comparable to the sputtering time or AGN duty cycle, 10 Myr. Normally regarded as passive, elliptical galaxies are the most active galaxies in the IR color-color correlation.

• OSTI ID: 22126841
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 768; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BANANAS
BLACK HOLES
BRIGHTNESS
COLOR
CORRELATIONS
DUSTS
EMISSION
EXCURSIONS
GALAXIES
LUMINOSITY
MASS TRANSFER
SPUTTERING
STARS
STELLAR WINDS