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Title: Evolutionary paths along the BPT diagram for luminous and ultraluminous infrared galaxies

The evolutionary connection between nuclear starbursts and active galactic nuclei (AGNs) in luminous infrared galaxies (LIRGs) and ultraluminous infrared galaxies (ULIRGs), which result from galaxy interactions and mergers and produce the bulk of their radiation as infrared (IR) emission, is not well understood. To this effort, we present and examine new spectrophotometric data for five U/LIRGs (10{sup 11} < L {sub IR} < 10{sup 13} L {sub ☉}) within the IRAS 2 Jy Redshift Survey with 0.05 ≲ z ≲ 0.07. We show that our sample consists almost entirely of composite objects—thus hosting both a nuclear starburst and an AGN—using the BPT diagrams. We then show that for our sample of U/LIRGs the properties that describe their nuclear starbursts and AGNs (e.g., star formation rate, L[O III], optical D parameter, D4000, and EW(Hδ)) are independent of one another, ensuring that no biases affect correlations between these parameters and the object locations on the BPT diagrams. Finally, we derive evolutionary paths on the BPT diagram involving [N II]/Hα that are based on how these parameters vary between two U/LIRGs positioned at the end-points of these paths. The U/LIRGs at the end-points of a given path represent the beginning and end statesmore » of a U/LIRG evolving along that path. These paths may be able to specifically explain how all local U/LIRGs evolve along the BPT diagram, and serve as a starting point for future quantitative analysis on the evolution of U/LIRGs.« less
Authors:
 [1] ; ;  [2] ;  [3]
  1. Physics Department, CUNY Graduate Center, New York, NY 10016 (United States)
  2. Division of Particle and Astrophysical Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602 (Japan)
  3. Astrophysical Observatory, Department of Engineering Science and Physics, College of Staten Island, City University of New York, Staten Island, NY 10314 (United States)
Publication Date:
OSTI Identifier:
22357261
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 784; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CORRELATIONS; EMISSION; EVOLUTION; GALAXIES; GALAXY NUCLEI; INFRARED RADIATION; INTERACTIONS; LUMINOSITY; RED SHIFT; SPECTROPHOTOMETRY; STARS