Extragalactic Astronomy ASTR 5630
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This 13 page Class Notes was uploaded by Willie Cummings on Monday September 21, 2015. The Class Notes belongs to ASTR 5630 at University of Virginia taught by D. Whittle in Fall. Since its upload, it has received 63 views. For similar materials see /class/209713/astr-5630-university-of-virginia in Astronomy at University of Virginia.
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Date Created: 09/21/15
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Emigxlmlz Aman mums H mm Bll e rnela pool lo slpeuum slas nlgn slella denslnes wlh sleep pmule vllolw N 1 long lved lal llnea alslumllon ol slas asoaalea dus1 lanes and 13 lounalon asoaalea ungs and spllal palleln Ml lens oenlla lt lnpc leglon ol vely nlgn denslly Nln5 mm dense lsM amp0 S13bu 51 ampols13 auslel masslve blew nole Sella Halo vely low 53 ewe lola llgnl pool slas ch awals lowrderlslly nol g on a Dam Halo domlnales mass and polenlla oulsde Nln Kpc mlldly lallenea ampol mama name unknown Next Prev Top 2 3D Shapes a Disks Ds1llbunorl ollpmleclea ba lunagesl Nual ovel wde lawge uom us lo ma land use uom 2610 al ba laud lal uom lnlelplelallon a lanaornly ollenled llun wells as glve Mme oonsl lved Mme oonslslenl wlh mos1ly lal wells as 0 amp alloWba due lo e nole rnuan sowel use lo ms blggel bulges rnuan l lel use lol so smalel bulge e mlrllmum lo bulgeless 91m ba Nuna 7 ul gt as can be nlgnlyl l e Nullornaxalbawa maxalbENDEloaboulEl Bib31 L as allel polenllas slgnlly wilemama 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dwscoveved guve Fveemaw Law 5 new mougm to be away ase ecnon e ect guve iii Bulge lo Di Hmio megvanng me R awa exponerma aws gwes ux vanes 0 ED 357 ReRd Md 0L equwaermy 0 ET Ra ma a n2a Ham meve we me my me mge oomponem omy meve d ma my me max oomponem omy aong me Hubme sequence ED deae es monomch tevms m quot13ng m quota me data ae pvesemed heve m o m u m lUsersdmwmXnesxsvaSZmdex mm Wm Ammo mimlmk Asimmy l2272nns H mm Note mele ls oorlsldelaole seailel some ls lrllilrlsc oul mudl depends on lllrlg memod b Vertical Disk Struaure Sludy edge on dl ltS eg lgule ol 9d Two lolms have been used 1z 1051P zo 53a 1z 10 mach2 7 zlZzo a so Yecal secmz 2 expz exprz a Zn ls me scale helgluollhe dlS le lza1Ie lm see Adm oelowlol lumel dlseusslorl ol yellca dlslt siluclule Nexi Prev 4 Disk Velacily Field lrl genela Sellrglavllanrlg sysiems ae D9lts ae cold low dlspelsorl so vm Nole VD amp geomelly yelld Mlt F0 unmlugu l Hdlsx lolallorl ls a yely lmpollawl piooe ol M a 2D Velocin Fields Spider Diagrams el dlcula lolallorl v l lrl aplawa dlcula dlslt e dlslt llled oy mgle l lo los 04 pole on me malol an ol me plolecled elllpse ls me Illle 01 nodes Top ppolled by both ioianoii 31d dspaslon N ycy ynele vE ldea dlcula yeloclly lrl plolecled 9w dale s oz dlsialce lo nuc mgle llom malol an lrl unplolecled gaaxy dale dulyaenl locailorl Fol menled Dopplel yeloclly leld massed we have 105 a vows 11 tan2 a 5 AB BiD tODE t VTl0 Wm lawylawalooslawdls1 srl20na12l A Convelsely ll We wall lo piolecl veg onlo me sky We have 739 003031111 54b ll lUsersldmwmKneslxsvaSZlndex ml 7195 m u Whittle ASTR 5534 Extragalactic Astronomy 12272006 1126 AM with tan or tan 539 cos i and s r cos25I sin25I cos2i V2 Contours of VloS on the projected disk give a quotspider diagramquot images Kinematic Major Axis KMA line through nucleus perpendicular to velocity contours Kinematic Minor Axis KMI VloS contour at VSys through the nucleus There are various forms for VlossQ 0 Circular velocity in inclined plane MA aligned with photometric major axis PMA KMI aligned with photometric minor axis PMI it Vr is approximately flat ie indep of r beyond initial rise VloS contours approx radial at large R VloS contours close in loop it Vr declines past Vmax solid body nuclear rise in Vcr equally spaced contours across nuclear KMA spacing oc 1slope it disk is warped twisted VloS contours in outer parts 0 O 0 Bars evidence of radial motion over bar region oval disk eg defined by nonaxisymmetric halo KMI and KMA not perpendicular KMA not aligned with PMA KMI not aligned with PMI spiral arms small perturbations to VloS contours near arm positions viewgraph 0 Full datasets can be analysed as a set of independent rings each with different Vc PA i images Eg here is an analysis of the circinus galaxy Jones et al 2001 Hl intensity velocity and dispersion maps interred run of Vr PAr ir 3D model of warped disk b VmaX and the TullyFisher Relation Vmax maximum rotation velocity inclination corrected derived from 0 Major axis optical otten HOE rotation curves tigurequot o Hi 21 cm integrated single dish protile width W20 figure 2Vmax W20 39 Wdisp Sin i where Wdisp 36 0 and 0 10 kms random component and cos i ba2 u2 1 u2 where u is ba tor edgeon system detines i Tully amp Fisher 1977 recognised that Vmax correlates with galaxy luminosity o L xvmaxa or34 As for the FaberJackson relation the TF relation stems from virial equilibrium vc2 x MR and L x l0 R2 L o ML392 l0391 v64 fileUsersdmw8fSitesastr553indexhtm Page 6 of 14 Wm Ammo Eungmmz Asuarmmv 12272nns H mm m 17 F ve anon News w my2 mquot N oonst vougnw uue Usuaw dnoose ongev wave engms eg 1 amp H bands valhev man a amp v a sma ev seanev on me 17F ve anon a sngnuys1eepevgvad1en1margev Tn1s1s because al172 m s ess sensmve to s1a Vovmanon and 11151 L uadlts o dev popwanon men dommales mass 0 W popwanon nm amove homogeneous ML vano gm e Tne 17F ve anon 1 one 039 me Key memods 0V d1s1ance detevmmanon a wstcamale on gaanes Mn cepnem d1s1ances guve 1m nexds me VoHowmg ve anons Mg 7711 log 139 7 725 7 2001 mum I 7809 109117f 725 7 9105 tom 55 7855 102147i 7 25 7 2151 i 001 My 71039 10g 117 7 25 7 29 92 i008 a nen vmax a M a mrM a d1s1ance a these d1s1ances can men he used Mn vedshms to denve Ha eg 11115 guve we d Hg 7 an xmsM c heve s asrnde cat0ch musuanng me TF ve anon c Flotation Curve Shapes and Systematics Tydca Manon wvve oompnses a nse nom zen at me nudeus a vmax peak a ax a extended veg1on dose to at Many Manon wvves nave now been memned guve some sys1ernanc uends ae noucame i Al Large Radius a VW memes m L memes 17F ve anonn Wages a Rm memes m L deaemes sowev nsng wvves m e pes 0 RM meme 0 omev sope memes m L deaemes mewgvaph VON19 R we nd in me vmge 712 0 12 n llUsersldmwmKnesxsvaSKmdex mm m 7 m u Whittle ASTR 5534 Extragalactic Astronomy 12272006 1126 AM specifically 10V2 6 232 0096MB 215 2056 011MB 215 flat I5 0 occurs for MB N 225 a drop in massive early types caused in part by high Vmax from bulge o Galaxies in dense environments have falling Vr consistent with removingdisturbing some of the halo c Galaxies in dense environments have high fraction of anomalies in Vr asymmetries across nucleus dips in disk region and inner peculiarities consistent with tidal disturbance ii At Small Radius o For luminous early type spirals Vr rises very rapidly often unresolved dense bulge core amp black hole cf Milky Way rotation curve figure for low luminosity later type spirals Vr rises more slowly slow rise often Vr ocr quotsolid bodyquot careful however sometimes when Vr drops 0r increases so Vr is not VC ie rotation and dispersion both provide support in general Vr lt Vcr this is called asymmetric drift 0 d Stellar Velocities in the Disk Disks are faint stellar LOSVD difficult to measure Also brighter central regions are confused by bulge component Nevertheless some results are emerging i Rotation For disk stars VloS gtgt 0105 so stars are cold and have N circular orbits Usually Vstars follows Vgas which is close to VC sometimes star rotation can be slower than gas this is called asymmetric drift and indicates a higher stellar dispersion support beginning to be shared with dispersion stars at r likely to be at apogee so have V lt VC ln SOs 30 have counterrotating gas disks images lt 10 spirals may even have two counterrotating stellar disks figure both indicate external origin postdating galaxy formation ii Dispersion Faceon galaxies yield 039Z the vertical stellar dispersion o measurements indicate OZ decreases exponentially with scale length 2Rd this agrees with simple theory L stellar dynamics for isothermal disk gives 022 2 7 G 20 2 where 392 is the surface mass density and Z0 is the scale height henceO Z x 212 cc lr 2 x expFl2Flda as found 1 o combining major and minor axis observations of 0108 yields OZ 4quot 039r fileUsersdmw8fSitesastr553indexhtml Page 8 of 14 Wm Ammo bungame Ammy x2272nns H 2W 390 NGCAEE We ndvanoso39 01 17 n7 DE 1n men s SmHaI to me ve ocuy ewpsmd n me 90 s newghbomood a oonswdev now me mevdependenoe our and me vevnca densuy dwswbuuon by an Isolhamal d9lt 0 nst s1eua dynamo gwes 2 222 H volume densny 92 Pm seen a men moew us me obsevved ugn dwswbuuon m Eq 63b We so nd 3901 me scale hewgm 2a 01 m T 3 so We can use menved value our and 2a to cacu ale Pm gt dak manev doesn l dommale n me MW dw9lt nea me sun a wrung newts oonswdev me emonamal vemca aw Eq 635 an n Vast Ms edge on gaaxwes benev a1 2w by Pa m exp z ma s1eua dynamo gwes 2 V2 exbpman vev an somevmal dwswbuuon a oonst bane u we nave 01m No39zmwgh man gt dw9lt bane y cools man above by a actov SqHQ Remnng to compare wan obsevvanons 039 me M Ky Way a meve ae seyeva components 039 dmevem Zn and a g awddust zDN an boy gamma young mm dwsa za 2nu boy 7 25 xrns za15 Kpc U39IN5EIKmB a we may mew an x ennev subevbosmon 0V seyeva somevmal components ooo ev neaev me eduaxona bane a me myophyswca onger 039 an s mougm to be o39anae es W a e 51a Dom com worn mo ew al douds dwsswpanon ensuves a Nmund speed and za 5 oonespondwng y sman 51a gvaduany heated by soanenng on DMOS and spa am 01 neanng 039 me dw9lt ovev me by Salem s pa age andov mmov mevgevs a Heve y a MW dw9lt mode ved young 51a uueg gveenaoxd 51a bamma Next Prev Top 5 Mass Estimates and Dark Miner Hala vcn gwes mpona and unmuguous aboess b mass dw vwwuons a Deriving Mr from Vcir n geneva n HummmwmmesamSSZmdu my m s m u Wm ASYRSSzo mwm Aswaan 12272nns H mm meve ws ageomeuy Vactov n7 lt I lt12 Spneve I m Hanenea I N n7 Fov an exponerma mm use one can snow ma 1 3 39 I l 4RRd RltV1Rd 57 R 1 l235RRd2 3 V30 391 0767 Tmsh pealt vmax a1 RWN22 Rd vc 393 N R Keuenan Tm guve snows mm V01 exp om pom mass and spheve ax Mn smwe MltRd b Results from Optical Holmion Curves 196D Bumdge s galheved Hthanon we and assumea Kep euaw whoquot beyond new data a quote weH oenneo gaaxy m ses 197m amp an mom et a wem deepev ilal om to N2 7 a n we ooncmoe dak manev cale ll exponerma max 51m mat neve Kent 1986 Wage same gaaxwes and oenves Manon mes dwecny worn ugn pvome mey malch me obsevved Manon woes w a manev no leqnlleu mge max Mn nonna ML sumoes c Results from HI mapping Fonunalew H extends wqu beyond me opuca max We HQ goes to 273 Rd a 75 R25 H o en goes to gt 5 Rd 15 RH vm mew dedmes 51m at 0 nsmg WeH oe nd m sometimes om to rm kpc yo e 9lt Ms 0 VM mun nave dak manev es aaw n omev vegwons eg beyond 1 9w Typ caw mge max mom s V01 nnev Manon wvve see above Mn ve onab e MILE Na 7 a a K manev halo needed gwmg o a MILE Nan n geneva a me move Dak Manev man mass n 51a g 51m onw alowa llmllsnce vMNoons vnpues MltR o R a wnen y Dak Manev Haos nave meme masses Moe exmwp e worn van Nbada et a 1985 Wage 0V NGC 3198 Mn H omnouuon Manon wvve 0V NGC 3198 Mn max nao m aoavam 0V papev surnrnamng vesuHs d Dark Mamer Halo Slruaure oomousy g a r2 allalge vadu ance vmws at umonunalew mme to oonsuan me quotme pats uma m e ampd9lt ae made to m nnev vM me m nnurn max m an 51m my new amodest ML N 375 SJggeswvg DM not mpona neve dea y me nao oonmbunon amps a ma Vadu om mncnona Vovm not Known smue mode 3 umes somevma spheve Mn aoove VD n lUsersdmwmXnelunSSZmdex nwnw V19 m m u Wm mum Eungmm Asuarmmv 12272nns H mm M a 8 Po 0 r2 men m me oonect ympmc behavwouv my 1 gtgt a megvalmg me mass pmme gwes avmanon wvve men m VD quqA 39Gpm a2 3901 a ma VB 7 qu Mi 39Gpm a2 x Us 3901 1 ltlt 3 Heve y amode nae wm some vamus m 1 Kpc gme e DiskHalo Conspiracy openy m mese Manon wvves quot1051 VO EMOH wvves ae 4 51 a all ladll Theve y aw nmgumg p a a ev av a use y detevmmed bydw9lt m a39 n m cum have me same Manon mumae 77 a m y not wnenuy undev ood my ndwcales somemmg mpona about gaaxy Vovmanon a name may ave aled puzz e also unaemes me Ttu shev ve anon vmax y se by e 0 me M y set by me ummous manev Nextl m Tov 6 Spiral and Bar Slruclures a Spirals i S ral Clases vecay mo types extlemes m swal s1mctuve nmage a emu Deswgn A012 mo 51mg am1 a Hoocu em A01 move wanna 8EI a Numue Ann Umevmedwa e 51mg nnev ams omev vany ii Arm Prominence Ann Hmevram oormas1 y useM a yo oormas1 6m magnuuaes typcaw 172 w my aenne A dexE 4 6m 0 note am peony Mame m azzmmnany avevaged yams acme A depends on oo ov a emu Deswgn A5 N Ay N alge 1573 a Hoocu em A5 gtgt Ay N m m HUsersmmwmxnesxsvaSZmdex mm m n m u Whittle ASTR 5534 Extragalactic Astronomy 12272006 1126 AM a plot of AB A vs Al separates the classes well Clearly o spiral arms are bluer than the underlying red disk 0 sprial arms are younger than the disk 0 the old disk in flocculents is uniform o the old disk in Grand design has spiral pattern Interpretation a Grand design is a density wave it involves a spiral in the underlying mass distribution global coherence implies global process generates structure 0 Flocculent spirals are not density waves lack of coherence implies local process generates structure iii Leading or Trailing I consider direction of rotation 0 arm ends point forward leading spiral 0 arm ends point backwards trailing spiral to decide need to know which side is nearest o difficult but try to identify the least obscured by dust near side arms are almost always trailing 0 many arms have dust lanes amp Hll regions on inside concave edge gas runs into arms on concave side compressed star formation HI and CO distribution is narrow and focussed on inner edge image 0 trailing arms exert a torque on the disk matter inwards AM outwards rotation energy transferred into random motions disk heats this would halt arm formation see below but new stars form from quotcoldquot gas so disk kept unstable to arm formation note SO galaxies have no arms no gas to keep disk quotcoolquot gas is necessary to the formation of spiral arms iv Pitch Angle 39lll39quot defined as the angle between the tangents of arm and circle eg tight spiral has small ll clearly tan Tilquot dr r d39quot where quot339 is azimuth Most spirals have quotilk const throughout disk 1 y Y logarithmic spiral r39quot r0 exp39l 3 0 tan39lquot 39 With r r0 at 10 this is in fact predicted by density wave theory v The Winding Problem if arms were quotfixedquot wrt the disk eg like leaves on water I for typical VC const so A x Fl391 and we predict very tight spiral 39lll39quot N 2 eg two points at R and RdR are separated azimuthally after time dt by thdrR so tan lquot Rth and taking V 200 kms R 8 kpc dt 1Gyr we have tan itquot 1quot 8200 2 w for 8Gyr I in reality for Sa lt 39lr39quot39gt N 5 for Sc lt 39ll39quot39gt 10 30 fileUsersdmw8fSitesastr553indexhtml Page 12 of 14 Whittle ASTR 5534 Extragalactic Astronomy 12272006 1126 AM This suggests we might have two types of condition Long lived spiral arms are not material features in the disk they are a pattern through which stars and gas move these might be the grand design spirals Short lived spiral arms can arise from temporary patches pulled out by differential rotation the patches might arise from local disk instabilities leading to star formation these might be the flocculent spirals b Bars fileUsersdmw8fSitesastr553indexhtml barred galaxies are common 50 NGC 1300 is a nice example figure axis ratio up to 15 they can be strong up to 30 of the galaxy light not fit by elliptical isophotes more rectangular probably flat in disk plane K 22Im images can show bars within bars inner bar independent light profile IR along bar Early Hubble types and Grand design IR const strong bar helps drive spiral pattern Later Hubble types and Flocculant IR exponential Rdbar Rddisk weaker bar Bars are straight rigid rotation of pattern with well defined 42b stars stay in the bar bars are not density waves closed orbits in frame rotating at M stars move along the bar in the rotating frame such orbits only occur for M lt wgars Vcr r bars dont extend beyond corotation CR typically they extend out to 80 of CR simulations suggest bars form too easily see Topic 8 they are long lived they slow with age amp lengthen CR moves out as cub drops angular momentum is transferred to disk and halo stars bars may be important in long term AM redistribution in galaxies bars can drive density wave in disk gas motions important and interesting observationally star formation occurs at bar ends dust lanes seen down leading edge of bar velocity fields suggest strong noncircular motion simulations orbits mildly selfintersecting gtgt weak shocks gtgt compression where dust lanes seen inner gas loses AM and goes inwards this gas may go to the nucleus feed AGN or collect in disk near ILR outer gas in bar stored in ring near bar ends CR gas beyond this is stored in ring at OLR may explain inner and outer rings seen in many barred galaxies Page 13 of 14