Galaxies and the Universe - Active Galactic Nuclei

Galaxies and the Universe - Active Galactic Nuclei -...

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Unformatted text preview: 1/15/12 Gala ie and he Uni e e - Ac i e Galac ic N clei I d ci g Ac i e Ga ac ic N c ei Ac i e ga ac ic c ei (AGN) a be defi ed e a he ce a e e g e ea e be d ha ca be a ib ed a ce e i c de Se fe ga a ie , adi ga a ie , a a , QSO , BL Lac di a ga a ie . The a a e c a N- ga a ie a d X- a ece a i a e c i e, bei g ba ed di a a e c i e ia. egi f ga a ie hich h b a ia f a , ISM, a d hei i e ac i . Thi bjec , a d ib he c LINER i b igh ga a ie . The e c a ifica i a e Rec g i i ha ga ac ic c ei ca be i e f e e e ge ic a d c ac he e a a ge bega i h he ide ifica i f g adi ce i h ga a ie e i e ec ia i f , f e e i h he adi e i i a i i g i he f f a ai f ce e ica ca ed ab he ga a ("d b e- bed adi ce"). Ea i e fe e e i i f he be a e ei ed i a h g a h f C g A i Fig. 15 f Ma he , M ga , a d Sch id 1964 A J 140, 35 (c e f he AAS): i a i g he ge e a a e f a che f e i i . The ce a ga a ( e ecifica he c e ) i i ica ed i e i g he e i i . M e de ai ed adi a h i ica e c e i he e i i , i c di g je i ig f a b i ia c ec d c e (ge e a h be e ha a a ec i i e, ei e ch e ). S ch c ei e h i he VLA a f C g A b Pe e e a . (1984 A JLe 284, L35) h he e i a ga i h ic di a f hei da a f he NRAO Radio Uni erse CD- ROM i h a e ii he ica fie d f c ai . .a . a.ed /keel/gala ie /agnin o.h ml 1/4 1/15/12 Gala ie and he Uni e e - Ac i e Galac ic N clei Dis cove r and Ta onom of AGNs T AGN ( , ,S , BL L ) . Radio gala ie s M , S , Quas ars ( 1964 (A J 140, 35). T , , . - Q SO ) ( 197, 1037). I , .T .a . a.ed /keel/gala ie /agnin o.h ml 3C 273, H 13 - S M 1 , , ; 2. T - ,M S S 1963 N , (1963 N 197, 2/4 1/15/12 Gala ie and he Uni e e - Ac i e Galac ic N clei 1040) G T PASP 73, 392) S (1963, A J 140, 1) 500 B 1046 / = 0.158. H (1963 - .S , .T 1011 , BLR UV 105 1 . Se fe rt gala ie s S 1943 (A J 97, 28). T , /. B H II K ). T W B , 1974 A J 192, 581). T .T 2 1 ( B Q SO - BLRG = .T - 2 (BLR) 1 , . BL Lac obje cts , , (. . M Q SO D X- (BL L .I 219, L85) ,F , H , , AP L ). T 1978 A JL .T , .T - , , .T (OVV) BL L A , bla ars. AGN , .T , mc2 /2, , Script a 17, 193, 255) B ,B , R .M R (1978 Ph sica R . M . P . 56, : M AGN , .T ( AGN )- AGN. A , : Quas ar - ( ' ?). S QSO - ( Q SO . Radio gala ie s S 2 (NLRG) Se fe rt nucle i .a ), , QSRS ( ). ) S . a.ed /keel/gala ie /agnin o.h ml ( .B , 1 (BLRG). .U - , 90% .E ( 5% , 3/4 1/15/12 Gala ie and he Uni e e - Ac i e Galac ic N clei limited sample), but some are also known as BLRGs (like 3C 120). Intermediate objects (like Seyfert 1.5,1.8,...) exist, with distinct narrow and broad components in Balmer lines. LINER (Low- Ionization Nuclear Emission- Line Region) - defined by Heckman 1980 (A&A 87, 152). These are possibly related objects with peculiar emission- line ratios not easy to make with stars. They are extremely common in nearby galaxies (80% of Sab galaxies, Keel 1982 ApJSuppl 52, 229) and frequently associated with weak BLRs (Filippenko and Sargent 1985 ApJSuppl 57, 503). N-gala - purely a morphological class, dominated by the light of an unresolved nucleus (with what seeing?). These were originally part of the Yerkes classification; Morgan and Dreiser (1983 ApJ 269, 438) discuss aspects of classification of these galaxies. There are further grab- bag classes selected in single wavelength bands that may, for example, effectively find heavily obscured examples (such as X- ray galaxies, of which some are Sy 2, and luminous far- IR sources, some of which are dust- obscured broad- line objects). The sequence from Seyfert to QSO (at least radio- quiet ones) is largely one of luminosity, but a bright enough AGN may alter its surroundings by ionizing all the ISM, sweeping the area clean via a wind, or triggering star formation. The host galaxies of QSOs might not be remotely normal by present- day standards even if there is real physical continuity all along this sequence. There has been discussion of the distinction between radio- quiet and radio- loud AGN being between spiral and elliptical host galaxies, as in nearby objects. It is not clear what this might mean at early cosmic times, and in fact HST imagery of QSO hosts at ~ 0.4 shows that life is more complicated. « The intergalactic medium | Extragalactic radio sources Course Home | Bill Keel's Home Page | Image Usage and Copyright Info | UA Astronomy k [email protected] r.ua.edu Ls cags 1/00 at hne: 020 .a . a.ed /keel/gala ie /agnin o.h ml 20 00 4/4 ...
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This note was uploaded on 01/15/2012 for the course AY 620 taught by Professor Williamkeel during the Fall '09 term at Alabama.

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