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Seyfert galaxies have been observed by many authors in the past twenty years, and spectrophotometric results were published some years ago for NGC 1068 by Parker and myself [21], fo NGC 4151 by Oke and Sargent [22], and for those two plus several other bright Seyferts by Anderson [23], Wampler [24], and others. Lower resolution spectrophotometry of several more Seyfert galaxies, extending to the near infrared has more recently been published by Neugebauer, Becklin, Oke and Searle [25]. Nevertheless, it seemed worthwhile for us to measure spectra of a large number of Seyfert galaxies on a homogeneous spectral system for interpretation and comparison with the radio-galaxy spectra. One objective of the program is to see just how similar the spectra of Seyfert galaxies, first identified on the basis of their optical spectra and appearance, are to the spectra of radio galaxies, first identified on the basis of their radio luminosity. To date we have obtained spectra at lick Observatory of most of the NGC, Zwicky, and Markarian galaxies that have been identified as Seyfert galaxies in the published literature, together with several Arakelian galaxies described as possible Seyfert galaxies by Arakelian, Dibai and Yesipov [26] and Doroskenko and Terebizh [27].

The spectra of Seyfert galaxies can be classified into two types, Seyfert I and Seyfert 2 [28, 29] and these two types are defined by essentially the same emission-line profiles as the broad-line radio galaxies and narrow-line radio galaxies respectively. More details are given in two excellent reviews of recent research on Seyfert galaxies by Weedman [30, 31]. Of the known Seyfert galaxies, approximately one-third belong to the Seyfert 2 group, with narrow (full width at half maximum of order 500 km/s) forbidden and recombination lines. Our spectra of these galaxies have been reduced, analyzed and discussed by Koski [14]. He finds that they are essentially identical in optical spectra with narrow-line radio galaxies, having similar line widths, relative intensities of the emission lines, and continuous spectra. An example is shown in Fig. 1, where the spectrum of the Seyfert 2 galaxy Mrk 348 is seen to be very similar to the spectrum of the radio galaxy 3C 33. Although there is some range of properties within the radio-galaxy group, there is a corresponding range within the Seyfert 2 group, and there appears to be no object in either group whose spectrum cannot be matched by a similar spectrum from the other group.

Figure 4

Figure 4. Measured spectrum of Seyfert 1 galaxy III Zw 2 in relative energy units per unit frequency interval versus wavelength.

About two-thirds of the known Seyfert galaxies belong to the Seyfert 1 group, having broad recombination lines in their spectra as well as narrow forbidden lines. Spectra in the blue region of four typical examples, III Zw 2, Mrk 79, Mrk 509 and Mrk 335 are shown in Figs 4 through 7, exhibiting a wide range in the widths of the H II lines. Note also that in different Seyfert 1 galaxies the relative intensities of the He II lambda4686 broad emission varies greatly, although the He I lambda5876 line (not shown) is much more nearly constant in relative intensity with respect to Hbeta. Quantitative spectrophotometric data on 36 Seyfert 1 galaxies measured on our scans are in press [32]. The widths of the H I lines cover a wide range, with full widths at half maximum ranging from about 1000 kin/s to about 5000 km/s, and full widths at 0 intensity ranging from about 7000 km/s to about 19000 km/s. The H I lines are often asymmetric, which is particularly noticeable at Hbeta, with the peak falling to the violet (short wavelength) side of the midpoint of the wings. The H I lines often exhibit real structure which could be described as being due to "currents", "clouds", or any other kind of structure in velocity space.

Figure 5

Figure 5. Measured spectrum of Seyfert 1 galaxy Mrk 79 in relative energy units per unit frequency interval versus wavelength.

Figure 6

Figure 6. Measured spectrum of Seyfert 1 galaxy Mrk 509 in relative energy units per unit frequency interval versus wavelength.

These spectral scans clearly show that almost all Seyfert 1 galaxies have in their spectra the broad Fe II features near lambda4570, lambda5190, and lambda5320, first identified in the quasar 3C 273 by Wampler and Oke [33] and confirmed in the Seyfert 1 galaxy I Zw 1 by Sargent [34]. Although these features have been reported as present in a few other Seyfert 1 galaxies previously, the Lick scans show that they are present in greater or lesser strength in nearly every Seyfert 1 galaxy [35].

Figure 7

Figure 7. Measured spectrum of Seyfert 1 galaxy Mrk 335 in relative energy units per unit frequency interval versus wavelength.

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