2010/09/03 by Ross Fadely, S. Allam, Sahar S. Allam +14 · 1 citation
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Emission spectrum #Equivalent width #Galaxies: Formation, Evolution, Phenomena #Galaxy #Infrared #Metallicity #Physics #Redshift #Rest frame #Spectral line #Spectroscopy #Star formation #Stellar, planetary, and galactic studies #astro-ph.CO
paper · pdf · doi:10.1088/0004-637x/723/1/729
published as Astrophys.J.723:729-736,2010 · 20 pages, 3 figures, 2 tables. ApJ accepted
arxiv created 2010/09/03 · openalex publication_date 2010/10/13 · arxiv updated 2014/11/21 · openalex created_date 2020/11/23 · openalex updated_date 2026/08/06
We present low-resolution, rest-frame ∼ 5 − 12µm Spitzer/IRS spectra of two lensed z ∼ 2 UV-bright star-forming galaxies, SDSS J120602.09+514229.5 and SDSS J090122.37+181432.3. Using the magnification boost from lensing, we are able to study the physical properties of these objects in greater detail than is possible for unlensed systems. In both targets, we detect strong PAH emission at 6.2, 7.7, and 11.3µm, indicating the presence of vigorous star formation. For J1206, we find a steeply rising continuum and significant [S IV] emission, suggest-ing that a moderately hard radiation field is powering continuum emission from small dust grains. The strength of the [S IV] emission also implies a sub-solar metallicity of ∼ 0.5Z, confirming published rest-frame optical measurements. In J0901, the PAH lines have large rest-frame equivalent widths (> 1µm) and the continuum rises slowly with wavelength, suggesting that any AGN contribu-tion to LIR is insignificant, in contrast to the implications of optical emission-line diagnostics. Using [O III] line flux as a proxy for AGN strength, we estimate