AKARI NEAR-INFRARED SPECTROSCOPY OF SDSS-SELECTED BLUE EARLY-TYPE GALAXIES

Journal Article · Fri Aug 20 00:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/719/2/1946· OSTI ID:21457046

Lee, Joon Hyeop ^[1]; Hwang, Ho Seong ^[2]; Lee, Myung Gyoon; Lee, Jong Chul ^[3]; Matsuhara, Hideo ^[4]

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1. Korea Astronomy and Space Science Institute, Daejeon 305-348 (Korea, Republic of)
2. CEA Saclay/Service d'Astrophysique, F-91191 Gif-sur-Yvette (France)
3. Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of)
4. Institute for Space and Astronautical Science, Japan Aerospace and Exploration Agency, Sagamihara (Japan)

A near-infrared (NIR; 2.5-4.5 {mu}m) spectroscopic survey of Sloan Digital Sky Survey (SDSS)-selected blue early-type galaxies (BEGs) has been conducted using the AKARI. The NIR spectra of 36 BEGs are secured, which are well balanced in their star formation (SF)/Seyfert/LINER-type composition. For high signal-to-noise ratio, we stack the BEG spectra in its entirety and in bins of several properties: color, specific star formation rate, and optically determined spectral type. We estimate the NIR continuum slope and the equivalent width of 3.29 {mu}m polycyclic aromatic hydrocarbon (PAH) emission. In the comparison between the estimated NIR spectral features of the BEGs and those of model galaxies, the BEGs seem to be old-SSP(simple stellar population)-dominated metal-rich galaxies with moderate dust attenuation. The dust attenuation in the BEGs may originate from recent SF or active galactic nucleus (AGN) activity and the BEGs have a clear feature of PAH emission, evidence of current SF. BEGs show NIR features different from those of ULIRGs from which we do not find any clear relationship between BEGs and ULIRGs. We find that Seyfert BEGs have more active SF than LINER BEGs, in spite of the fact that Seyferts show stronger AGN activity than LINERs. One possible scenario satisfying both our results and the AGN feedback is that SF, Seyfert, and LINER BEGs form an evolutionary sequence: SF {yields} Seyfert {yields} LINER.

• OSTI ID: 21457046
• Journal Information: Astrophysical Journal, Vol. 719, Issue 2; Other Information: DOI: 10.1088/0004-637X/719/2/1946; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ABSORPTION SPECTROSCOPY
COLOR
DUSTS
GALACTIC EVOLUTION
GALAXIES
INFRARED SPECTRA
METALS
POLYCYCLIC AROMATIC HYDROCARBONS
SIGNAL-TO-NOISE RATIO
STARS
AROMATICS
DIMENSIONLESS NUMBERS
ELEMENTS
EVOLUTION
HYDROCARBONS
OPTICAL PROPERTIES
ORGANIC COMPOUNDS
ORGANOLEPTIC PROPERTIES
PHYSICAL PROPERTIES
SPECTRA
SPECTROSCOPY