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Title: A pilot study using deep infrared imaging to constrain the star formation history of the XUV stellar populations in NGC 4625

In a ΛCDM universe, disk galaxies' outer regions are the last to form. Characterizing their contents is critical for understanding the ongoing process of disk formation, but observing outer disk stellar populations is challenging due to their low surface brightness. We present extremely deep 3.6 μm observations (Spitzer/Infrared Array Camera) of NGC 4625, a galaxy known for its radially extended ultraviolet-emitting stellar population. We combine the new imaging with archival UV imaging from the GALEX mission to derive multi-wavelength radial profiles for NGC 4625 and compare them to stellar populations models. The colors can be explained by the young stellar population that is responsible for the UV emission and indicate that the current star formation rates in the outermost disk are recent. Extended star formation in NGC 4625 may have been initiated by an interaction with neighboring galaxies NGC 4618 and NGC 4625a, supporting speculation that minor interactions are a common trigger for outer disk star formation and late stage disk growth.
Authors:
; ;  [1] ; ;  [2] ;  [3]
  1. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02143 (United States)
  2. Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)
  3. Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)
Publication Date:
OSTI Identifier:
22364999
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 793; 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; BRIGHTNESS; COLOR; COMPARATIVE EVALUATIONS; EMISSION; EVOLUTION; EXTREME ULTRAVIOLET RADIATION; GALAXIES; INTERACTIONS; STARS; UNIVERSE; WAVELENGTHS