Galaxy Merger Research Paper

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Major mergers, however, are not the only “flavor” of galaxy collisions. Nowadays, ma- jor mergers are considered to be mergers of galaxies with mass ratios of ∼ (1 − 4.5) : 1.
Galaxy mergers with mass ratios of ∼ (1 − 2) : 1 can directly produce slowly rotating el- liptical galaxies, i.e. systems which are mostly random motion pressure supported, while mergers with mass ratios of ∼ (3 − 4.5) : 1 will, likely, result in disky, rapidly rotating ellipti- cal galaxies (e.g. Naab and Burkert, 2003; Bournaud et al., 2005). These are not disk galax- ies, but rather elliptical galaxies with a disky isophotal shape, i.e. systems which are, to some considerable extent, still rotationally supported. Galaxy mergers with mass ratios of
∼ (4.5 − 10) : 1
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The main difference between them is that a typical Seyfert AGN releases as much energy in the visual bands as all the stars of its (∼ 1011 L ) host galaxy, while a typical QSO is by a factor of
∼ 100 times brighter than the stars of its host galaxy. Seyferts and QSOs, however, are not the only sub-classes of the AGN family. Below, I briefly summarize the most important characteristics of the basic AGN sub-classes: i Seyfert type-1/Seyfert type-2: Likely, they are intrinsically the same type of source.
Seyfert type-1s show broad line emission in their spectra, while Seyfert type-2s do not (except in polarized light). Presently, it is generally accepted that this distinction is a function of our line-of-sight angle. If we can see directly towards the nucleus, then we can see the broad line region (BLR) and, therefore, we observe a Seyfert type-1 galaxy, otherwise, we observe a Seyfert type-2. ii QSOs: They have similar spectra with Seyfert galaxies but with weaker stellar ab- sorption features and weaker narrow lines relative to their broad lines. About 5−10% of QSOs are strong radio emitters. The number of QSOs per unit volume reaches a maximum at a redshift of ∼
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