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Title: EVIDENCE FOR NON-STELLAR REST-FRAME NEAR-IR EMISSION ASSOCIATED WITH INCREASED STAR FORMATION IN GALAXIES AT z ∼ 1

We explore the presence of non-stellar rest-frame near-IR (2–5 μm) emission in galaxies at z ∼ 1. Previous studies identified this excess in relatively small samples and suggested that such non-stellar emission, which could be linked to the 3.3 μm polycyclic aromatic hydrocarbons feature or hot dust emission, is associated with an increased star formation rate (SFR). In this Letter, we confirm and quantify the presence of an IR excess in a significant fraction of galaxies in the 3D-HST GOODS catalogs. By constructing a matched sample of galaxies with and without strong non-stellar near-IR emission, we find that galaxies with such emission are predominantly star-forming galaxies. Moreover, star-forming galaxies with an excess show increased mid- and far-IR and Hα emission compared to other star-forming galaxies without. While galaxies with a near-IR excess show a larger fraction of individually detected X-ray active galactic nuclei (AGNs), an X-ray stacking analysis, together with the IR-colors and Hα profiles, shows that AGNs are unlikely to be the dominant source of excess in the majority of galaxies. Our results suggest that non-stellar near-IR emission is linked to increased SFRs and is ubiquitous among star-forming galaxies. As such, the near-IR emission might be a powerful tool to measuremore » SFRs in the era of the James Webb Space Telescope.« less
Authors:
; ; ; ;  [1] ;  [2] ;  [3] ;  [4]
  1. Department of Astronomy, Yale University, New Haven, CT 06520 (United States)
  2. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
  3. Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States)
  4. Leiden Observatory, Leiden University, Leiden (Netherlands)
Publication Date:
OSTI Identifier:
22518605
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 819; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CATALOGS; COLOR; COMPARATIVE EVALUATIONS; COSMIC DUST; EMISSION SPECTRA; GALAXIES; GALAXY NUCLEI; NEAR INFRARED RADIATION; POLYCYCLIC AROMATIC HYDROCARBONS; RED SHIFT; SPACE; STAR EVOLUTION; STARS; TELESCOPES; X RADIATION