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Table A.2.

Line components along the main sequence.

Line component Definition
Low-ionization lines (LILs): HI Hβ

HβVBC Gaussian FWHM ∼ 10 000 km s−1, redshifted by 1−2000 km s−1 (defining property of Pop. B; absent in Pop. A)
HβBC Lorentzian, FWHM ∼ 1−4000 km s−1 (Pop. A); Gaussian FWHM(Hβ) ≳ 4000 km s−1 (Pop. B)
Hβ BLUE Asymmetric Gaussian which models an excess of emission on the blue side of Hβ; usually weak save in ST A3 and A4
Hβ Sum of HβBC, HβVBC, and BLUE (when applicable); full broad Hβ profile
HβNC Hβ narrow component

High-ionization lines (HILs): C IVλ1549

C IVλ1549VBC Gaussian FWHM ∼ 10 000 km s−1, redshifted by 1−2000 km s−1
C IVλ1549BC Lorentzian, if FWHM(Hβ) ≲ 4000 km s−1 (Pop. A); Gaussian FWHM ≳ 4000 km s−1 (Pop. B)
C IVλ1549 BLUE Asymmetric Gaussian which models an excess of emission on the blue side of C IVλ1549; detected in most quasar and most prominent in spectral types A3 and A4
C IVλ1549 Sum of C IVλ1549BC, C IVλ1549VBC, and C IVλ1549 BLUE; full broad C IVλ1549 profile
C IVλ1549NC C IVλ1549 narrow component, prominent in Pop. B at low-z; almost absent in most Pop. A sources

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