STRONG NEBULAR LINE RATIOS IN THE SPECTRA of z ∼ 2-3 STAR FORMING GALAXIES: FIRST RESULTS FROM KBSS-MOSFIRE

We present initial results of a deep near-IR spectroscopic survey covering the 15 fields of the Keck Baryonic Structure Survey using the recently commissioned MOSFIRE spectrometer on the Keck 1 telescope. We focus on a sample of 251 galaxies with redshifts 2.0 < z < 2.6, star formation rates (SFRs) 2 ≾ SFR ≾ 200 M_☉ yr^(–1), and stellar masses 8.6 < log (M_*/M_☉) < 11.4, with high-quality spectra in both H- and K-band atmospheric windows. We show unambiguously that the locus of z ~ 2.3 galaxies in the "BPT" nebular diagnostic diagram exhibits an almost entirely disjointed, yet similarly tight, relationship between the line ratios [N II] λ6585/Hα and [O III]/Hβ as compared to local galaxies. Using…

• NS
  National Science Foundation

  Awards: 0908805, 1313472
• NA
  National Aeronautics and Space Administration
• AP
  Alfred P. Sloan Foundation
• WM
  W. M. Keck Foundation
• CI
  California Institute of Technology
• SA
  Science and Technology Facilities Council

  Awards: ST/H00243X/1, ST/L001381/1, ST/K000985/1