THE REST-FRAME ULTRAVIOLET SPECTRA OF UV-SELECTED ACTIVE GALACTIC NUCLEI AT z {approx} 2-3
- Department of Astronomy, University of California, Los Angeles, 430 Portola Plaza, Los Angeles, CA 90024 (United States)
- Department of Astronomy, University of Texas, Austin, TX 78712 (United States)
- California Institute of Technology, MS 105-24, Pasadena, CA 91125 (United States)
We present new results for a sample of 33 narrow-lined UV-selected active galactic nuclei (AGNs), identified in the course of a spectroscopic survey for star-forming galaxies at z {approx} 2-3. The rest-frame UV composite spectrum for our AGN sample shows several emission lines characteristic of AGNs, as well as interstellar absorption features detected in star-forming Lyman break galaxies (LBGs). We report a detection of N IV] {lambda}1486, which has been observed in high-redshift radio galaxies, as well as in rare optically selected quasars. The UV continuum slope of the composite spectrum is significantly redder than that of a sample of non-AGN UV-selected star-forming galaxies. Blueshifted Si IV absorption provides evidence for outflowing highly ionized gas in these objects at speeds of {approx}10{sup 3} km s{sup -1}, quantitatively different from what is seen in the outflows of non-AGN LBGs. Grouping the individual AGNs by parameters such as the Ly{alpha} equivalent width, redshift, and UV continuum magnitude allows for an analysis of the major spectroscopic trends within the sample. Stronger Ly{alpha} emission is coupled with weaker low-ionization absorption, which is similar to what is seen in the non-AGN LBGs, and highlights the role that cool interstellar gas plays in the escape of Ly{alpha} photons. However, the AGN composite does not show the same trends between Ly{alpha} strength and extinction seen in the non-AGN LBGs. These results represent the first such comparison at high redshift between star-forming galaxies and similar galaxies that host AGN activity.
- OSTI ID:
- 21576812
- Journal Information:
- Astrophysical Journal, Vol. 733, Issue 1; Other Information: DOI: 10.1088/0004-637X/733/1/31; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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