Optical emission lines in radio sources of intermediate power

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Optical Emission Lines

in

Radio Sources

of

Intermediate Power

by

Saul Caganoff

MJSTRAl^

, L1BH

A thesis submitted for the degree of

Doctor of Philosophy

of The Australian National University

October 1989

Mount Stromlo and Siding Spring Observatories

The Australian National University

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Afoot and lig h t-h earted I take to th e open road, H ealthy, free, th e world before me,

T he long brow n p a th before me leading w herever I choose. H enceforth I ask not good-fortune, I m yself am good-fortune, H enceforth I w him per no m ore, postp o n e no m ore, need n o th ­

ing,

Done w ith indoor com plaints, libraries, querulous criticism s, Strong and content I trav el th e open road.

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T h e work described in this thesis is th a t of th e can d id ate alone, w ith th e exception of th e long-baseline interfero m etry described in c h ap te r 3 which was carried out in collaboration w ith Drs. O.B. Slee, G.L. W hite, J.E . R eynolds an d E.M . Sadler.

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Acknowledgments.

U ndoubtedly th e best aspect of doing a Ph.D . thesis has been th e o p p o rtu n ity it has given m e to m eet and work w ith m any people. It is a pleasure now to express my g ra titu d e to them .

F irst th a n k s go to my supervisors Drs. Geoff Bicknell, Ron Ekers and D ave C a rte r for th eir help an d guidance during th e last four years.

I also th a n k th e past and p resen t directors of M t. Strom lo and Siding Spring O bservatories, Professor Alex R odgers an d Professor Don M athew son for p resid ­ ing over th e excellent facilities and intellectual environm ent here a t M t. Strom lo, an d for allow ing me to be a p a rt of this O bservatory. Sim ilarly I th a n k th e Di­ recto r of th e N ational R adio A stronom y O bservatory, Dr. P au l vanden B out for m aking th e facilities at th e N R A O available to me. T h an k s also go to Dr. R on Ekers for allow ing me access to th e com puting facilities at th e A u stralia Telescope H ead q u arters in Sydney.

I acknowledge th e receipt of a C om m onw ealth P o stg ra d u a te R easearch A w ard as well as funds from the IAU Com ission 38 w hich allowed me to trav el to th e VLA where m uch of th is work was carried out.

T h an k s to all th e com puter staff at MSO, th e VLA and th e AT for th eir co­ o p eratio n a n d tolerance over th e last few years. I especially th a n k Dr. M ark C a lla b re tta a t th e A u stralia Telescope for his help and cooperation w hen I crash tested his A IPS system .

I also ex ten d w arm th an k s to m y friends and co m p atrio ts am ong th e staff and stu d e n ts a t M SO, th e VLA a n d th e AT. T h an k s to T im for his com panionship on our frequent “stress m an ag em en t” outings. T h an k s to M atth ew , Jo h n and Jo h n for th e relaxed m an n er th a t all good housem ates should have. T h a n k s to G e rh ard t, G len, Nick, Rob, Jim b o , P eter, Greg, C arl, Roger and Vass an d all the o th er stu d e n ts for th eir m an y co n trib u tio n s to th e good tim es I have h a d here at Strom lo.

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T h an k s to Jam ie H artley who told me ab o u t th e constellations all those years ago and first fired m y in terest in A stronom y.

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Abstract.

We have carried out a stu d y of th e nuclear em ission line regions of a sam ple of rad io galaxies w ith p a rtic u la r em phasis on th e relationship betw een th e radio source an d the narrow emission line region.

It h as long been known th a t powerful radio sources exhibit stro n g emission o ptical em ission lines sim ilar to th e em ission lines observed in o th e r active galaxies (e . g. Seyferts). M uch of our knowledge ab o u t radio galaxies an d th e ir associated

line em ission comes from studies of high powered radio sources such as those in th e 3C R catalogue. T he success of recent studies of low level line em ission in “no rm al” early ty p e galactic nuclei has opened th e way to th e possibilities of system atic studies of em ission lines in early-type galaxies over a wide range of th e radio lum inosity function. Since th ere is already significant knowledge of th e em ission line p ro p erties of high pow ered radio sources we have defined a com plete sam ple of rad io sources of “in term ed iate pow er.” T he sources in our sam ple overlap th e Fanaroff-Riley break betw een high power radio sources w ith edge-brightened m orphology and th e low power sources w ith edge-darkened m orphology. Given th e fu n d am en tal n a tu re of this break we feel this is an in terestin g sam ple of galaxies for stu d y of th eir em ission line properties.

We have also placed considerable em phasis on th e relatio n sh ip of th e radio core w ith th e em ission line gas. T he radio em ission from kiloparsec size rad io cores arises from regions which are coincident w ith th e narrow em ission line regions in rad io galaxies. It seems obvious th en th a t a stu d y of th eir in te rre la tio n will shed light on th e n a tu re of b o th th e radio source and of th e em ission line region.

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em ission line lum inosity and to ta l radio power know n in m ore pow erful rad io sources. T h e m ost rem arkable finding of our study, however is th a t th e correla­ tio n does n o t extend into radio sources of lower power. T he em ission lin e /ra d io correlation switches on at the Fanaroff-Riley tra n sitio n region. T h u s em ission line stre n g th is yet an o th er p ro p erty of radio galaxies which is d ep en d an t on th e m orphological class of th e radio source.

From our radio d a ta we have been able to derive sp ectral indices for a large num b er of radio cores in our sam ple. We found th a t the correlation betw een em ission line lum inosity and to ta l radio power ap p ears to be sensitive to th e radio core sp ectral index. R adio sources w ith optically th in cores (steep sp ectral index) show a strong correlation betw een emission line lum inosity an d to ta l rad io power. Sources w ith optically thick cores (flat sp ectral index) show little or no such correlation. So it seems th a t th e existence of th e em ission lin e /ra d io source correlation depends also on th e n a tu re of th e radio core as well as on th e m orphological class of th e source.

In an a tte m p t to u n d e rstan d these results we have stu d ied th e n a tu re of th e radio cores in th e sources w ithin our sam ple. We have com pared our observations w ith cu rren t theories ab o u t radio core emission. An ex am in atio n th e relative prom inence of radio cores and th e size of the overall radio source as a fu n ctio n of radio core sp ectral index, shows th a t the relativistic beam ing m odel for rad io cores (com m only invoked in reference to quasars) is not applicable to th e cores in our rad io sources. T he radio core spectral index is d eterm in ed by physical conditions w ithin the radio core and not by any o rien tatio n al effects.

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cores have to ta l radio powers which are m ore strongly correlated w ith narrow line lum inosity th a n are flat spectrum core sources.

Em ission line ratios show th a t there is a wide range of ex citatio n levels w ithin th e sources in our sam ple. We also found a continuity betw een LlNER-type sp ec tra and th e higher excitation Seyfert-type sp ectra w ithin our sam ple. T his suggests a photoionisation m echanism for th e liner galaxies. We also found th a t th ere is no tre n d of ionisation p aram eter w ith radio power, alth o u g h th e re is possibly a tre n d w ith radio power of th e hardness of th e photoionising sp ectru m . T his is in th e sense th a t higher power radio sources are associated w ith a softer photoionising spectrum . These results suggest th a t th e correlation betw een rad io power and em ission line lum inosity arises as a result of m ore gas w ith in pow erful rad io sources, ra th e r th a n th ro u g h any tre n d w ith th e lum inosity of th e cen tral ionising source.

O ur overall findings show th a t a likely basis for th e correlation betw een em ission line lum inosity and to ta l radio power is due to g a s/je t in teractio n s w ith in th e narrow line region of radio galaxies. O ur observation th a t th e co rrelatio n switches on at the Fanaroff-Riley break, coupled w ith cu rren t ideas th a t class II rad io sources contain supersonic jets, suggests th a t th e presence (or lum inosity) of cool gas w ithin th e nucleus of these sources is enhanced by th e presence of a supersonic jet powering i t ’s way th ro u g h th e in terstellar m edium .

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Contents

1 I n t r o d u c t io n 1-1

1.1 Nuclear emission lines in radio galaxies

1-1

1.1.1 Emission lines and radio power

1-1

1.1.2 Emission line spectra

1-4

1.2 Motivation and aims of the present work

1-6

1.3 Thesis synopsis

1-8

2 T h e S a m p le 2-1

2.1 Introduction

2-1

2.2 Selection Criteria

2-1

2.3 The Sample

2-3

2.4 Optical Identifications

2-7

2.5 Sample Completeness

2-13

2.6 Conclusion

2-18

3 R a d io O b se r v a tio n s 3-1

3.1 Introduction

3-1

3.2 VLA Observations

3-2

3.3 D ata Reduction

3-5

3.3.1 Calibration

3-6

3.3.2 Total Intensity Maps

3-9

3.3.3 Spectral Index Maps

3-12

3.4 Total Flux-densities and Morphological class

3-14

3.4.1 Morphological class

3-17

3.5 Compact emission in the radio sources

3-23

3.5.1 Introduction-radio cores and hotspots

3-23

3.5.2 Filtered VLA data

3-24

3.5.3 Long baseline interferometry

3-32

3.5.4 Comparison of PTI and VLA core flux densities

3-36

3.6 Dimensions

3-36

3.6.1 Practical aspects of the moment analysis

3-39

3.6.2 Results of the moment analysis

3-40

3.6.3 Central brightness parameter and morphology

3-50

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4 D e r iv e d R a d io Q u a n titie s 4-1

4.1 Introduction

4-1

4.2 Plasma aging and lobe velocities

4-2

4.2.1 Theoretical summary

4-3

4.2.2 Velocity determination

4-6

4.2.3 Discussion of individual sources

4-14

4.3 Radio source energy budget

4-68

4.3.1 Total lobe energy

4-69

4.3.2 Work in lobe expansion

4-70

4.3.3 Radiative luminosity

4-72

4.3.4 Energy budgets

4-72

4.4 The core components

4-76

4.4.1 Models of compact cores

4-76

4.4.2 Core prominence and spectral index

4-79

4.5 Radio source lengths

4-81

4.5.1 Discussion of radio source lengths

4-81

4.5.2 Source length and spectral index

4-83

4.6 Conclusions

4-88

5 O p tic a l O b s e r v a tio n s 5-1

5.1 Introduction

5-1

5.1.1 Instrumental requirements

5-2

5.2 Instrum ental parameters

5-3

5.2.1 The RGO spectrograph

5-3

5.2.2 The faint object redspectrograph (FORS)

5-4

5.2.3 Observing strategy

5-5

5.3 D ata reduction

5-7

5.3.1 IPCS data reduction

5-7

5.3.2 FORS data reduction

5-9

5.4 Redshift determination

5-12

5.4.1 Redshift estimates for unobsderved galaxies

5-15

5.5 Emission line fluxes

5-15

5.5.1 Profile fitting

5-21

6 E m is s io n L ine D a ta 6-1

6.1 Introduction

6-1

6.2 Malmquist bias and correlations

6-2

6.2.1 Survival Analysis

6-3

6.2.1.1 Survival Analysis Tests

6-3

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6.3.1 Discussion of Individual correlations 6-10 6.3.2 C om parison w ith oth er work:high power sam ples 6-23 6.3.3 C om parison w ith other workdow power sam ples 6-28 6.3.4 Em ission lines and radio core spectral index 6-31 6.4 R adio cores and em ission lines 6-39

6.5 E m ission line ratios 6-44

6.5.1 C om parison of line ratios w ith o th er agn sp ec tra 6-46 6.5.2 Line ratios and radio power 6-51 6.5.2.1 R adio sources and X -Ray em ission 6-52 6.5.2.2 R adio power and the ionising continuum 6-56

6.6 C onclusions 6-59

7 C o r e -je t m o d e ls 7-1

7.1 In tro d u ctio n s: m odel requirem ents 7-1 7.2 O rie n ta tio n and beam ing models 7-3

7.3 T h e basic m odel (m odel 1) 7-4

7.3.1 T he base of th e jet 7-6

7.3.2 Core-jet lum inosity and sp ectru m 7-7 7.3.2.1 Synchrotron emission and ab so rp tio n 7-7

7.3.2.2 MHD equations 7-8

7.3.2.3 O ptical d ep th 7-9

7.3.2.4 Core-jet lum inosity 7-10

7.3.3 P a ra m e ter rationalisation: jet power an d eq u ip artio n 7-12 7.3.4 E stim ated p aram eter values 7-13 7.3.5 M odel results and discussion 7-16 7.3.6 A pplication of th e m odel to th e sam ple 7-20

7.4 D ecelerating jet m odel 7-21

7.4.1 Core-jet lum inosity m odifications 7-25 7.4.2 Discussion of p a ra m ete r values 7-27 7.4.3 M odel results and discussion 7-29

7.4.3.1 Core-jet lum inosities 7-33

7.4.4 Core-jet sp ectral index 7-37

7.4.5 Sum m ary 7-40

7.4.6 Je t in teractio n w ith the narrow -line region 7-41 7.4.6.1 T he radio/em ission-line correlation 7-43

7.5 C onclusion 7-44

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R e fe r e n c e s R - l

A p p e n d ic e s :

A A m o d ifie d

(V/Vm)

t e s t A - l

B M o m e n ts o f th e b r ig h tn e ss d is tr ib u tio n B - l

C R a d io m a p s C - l

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List of tables.

2.1 R adio sources selected from the Parkes catalogue 2-4

2.2 R eferences to 2.7Ghz survey 2-6

2.3 R eferences to previous work 2-8

2.4 R eferences 2-10

3.1 VLA observing schedule 3-4

3.2 VLA system p aram eters 3-5

3.3 T otal flux density 3-15

3.4 T otal pow er and m orphological class 3-19

3.5 Core fluxes an d sp ectra 3-30

3.6 C o m p act h o tsp o t fluxes in class II souces 3-34

3.7 P T I system p aram eters 3-35

3.8 2.29GHz P T I fluxes 3-35

3.9a M om ent analysis p aram eters (1.4GHz) 3-41 3.9b M om ent analysis sp atial dim ensions 3-44 3.10 Surface brightness an d lobe m inim um energies 3-53 4.1 Age analysis p aram eters and th eir norm alisation 4-5

4.2 Lobe velocities and ages 4-13

4.3 E nergy bud g et analysis 4-74

5.1 AAT observing schedule 5-5

5.2a Velocity sta n d a rd stars 5-6

5.2b Flux s ta n d a rd stars 5-6

5.2c Sm ooth sp ectru m sta n d a rd stars 5-6

5.2d G alaxy sta n d a rd s 5-7

5.3 R edshifts 5-16

5.4 Em ission line fluxes 5-20

5.5 F itte d H a and [NII]A6584 fluxes 5-23 6.1 R egression against to ta l radio em ission 6-21 6.2 M odel vs ASURV significance levels 6-22 6.3 Two sam ple lum inosity regression 6-38 6.4 R adio cores v ’s em ission line lum inosities 6-40

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List of figures.

2.1 Differential radio flux distribution

2-15

2.2

(V/Vm)

as a function of radio and optical flux limits

2-17

2.3 Distribution of

(V/Vm)

for the sample

2-19

2.4

(

V/Vm

)

test for sample with noise added to magnitudes

2-20

3.1 Diagram of VLA map making process

3-10

3.2 Construction of spectral index maps

3-13

3.3 VLA total flux density versus Parkes flux density

3-18

3.4 Histogram of total powers of radio sources

3-20

3.5 Model source & high-pass filter results

3-26

3.6 Measured core flux vs. model core flux

3-28

3.7 VLA core power vs. VLA core spectral index

3-33

3.8 Distribution of VLA core spectral index

3-33

3.9 Comparison of PTI flux densities and VLA flux densities

3-37

3.10 Moment analysis parameters for 1.4 GHz and tapered 5GHz data 3-45

3.11 Moment analysis dimensions for 1.4GHz data and 5GHz data 3-46

3.12 Check of moment analysis dimensions at 1.4GHz

3-47

3.13 Distribution of central brightness parameters

3-49

4.1a Diagram showing slice technique

4-9

4.1b Diagram illustrating spectral aging analysis

4-11

4.2 Contour map of PKS 0344-345

4-14

4.3 Spectral aging in PKS 0344-345:

east jet

4-15

4.4 Spectral aging in PKS 0344-345:

west jet

4-17

4.5 Contour map of PKS 0349-278

4-20

4.6 Spectral aging in PKS 0349-278:

east lobe

4-21

4.7 Spectral aging in PKS 0349-278:

west lobe

4-23

4.8 Contour map of PKS 0600-131

4-26

4.9 Spectral aging in PKS 0600-131:

east lobe

4-27

4.10 Spectral aging in PKS 0600-131:

west lobe

4-29

4.11 Contour map of PKS 1254-300

4-31

4.12 Spectral aging in PKS 1254-300:

north lobe

4-32

4.13 Spectral aging in PKS 1254-300:

south lobe

4-34

4.14 Contour map of PKS 1414-212

4-37

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4.16 Spectral aging in PKS 1414-212: south lobe

4-40

4.17 Contour map of PKS 1423-177

4-43

4.18 Spectral aging in PKS 1423-177:

4-44

4.19 contour map of PKS 1517-283 at 1.4GHz

4-46

4.20 Spectral aging in PKS 1517-283: east jet

4-47

4.21 Spectral aging in PKS 1517-283: west jet

4-49

4.22 Contour map of PKS 1654-137

4-51

4.23 Spectral aging in PKS 1654-137: east lobe

4-52

4.24 Spectral aging in PKS 1654-137: west lobe

4-54

4.25 Contour map of PKS 2053-201

4-57

4.26 Spectral aging in PKS 2053-201: east lobe

4-58

4.27 Spectral aging in PKS 2053-201: west lobe

4-60

4.28 Contour map of PKS 2317-277

4-62

4.29 Spectral aging in PKS 2317-277: north lobe

4-63

4.30 Spectral aging in PKS 2317-277: south lobe

4-65

4.31 Diagram of a class II radio lobe

4-61

4.32 Component model of a flat spectrum synchrotron source

4-78

4.33 Core prominence and power vs. core spectral index

4-80

4.34 Radio source length vs. total power at 1.4GHz

4-84

4.35 Median size vs. median radio power for 5 samples

4-85

4.36 Distribution of projected radio source size

4-86

4.37 Radio source size distribution for steep and flat spectrum cores 4-87

5.1 Example of a night sky spectrum

5-10

5.2 Example of atmospheric absorption template

5-11

5.3 Power spectrum of HD 114762

5-13

5.4 Filter applied to spectrum during cross-correlation

5-13

5.5 Redshift magnitude relation for 288 Parkes radio sources

5-17

6.1 Test data illustrating effects of Malmquist bias

6-6

6.2 Ha+[NII] line emission vs. total radio emission

6-11

6.3 [Oil] AA3727,9 line emission vs. total radio emission

6-13

6.4 [SII] AA6717, 31 line emission vs. total radio emission

6-15

6.5 [OIII] AA4959, 5007 line emission vs. total radio emission

6-16

6.6 H/d line emission vs. total radio emission

6-17

6.7 Ha line emission vs. total radio emission

6-19

6.8 [NII]A6584 line emission vs. total radio emission

6-20

6.9 [OIII]AA4959,5007 vs. total radio power:

our sample plus that of Rawlings (1987)

6-25

6.10 Ha+[NII] vs. total radio power:

our sample plus that of Baum

ei al.

(1988)

6-27

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6.12 Ha-f[NII] vs. total radio power and core spectral index

6-33

6.13 [Oil] AA3727,9 vs. total radio power and core spectral index

6-34

6.14 [SII]AA6717,31 vs. total radio power and core spectral index

6-35

6.15 [OIII] AA4959, 5007 vs. total radio power and core spectral index 6-36

6.16 H/? vs. total radio power and core spectral index

6-37

6.17 Ha-f[NII] luminosity vs. core radio power

6-41

6.18 [Oil] AA3727,9 luminosity vs. core radio power

6-41

6.19 [SII]AA6717,31 luminosity vs. core radio power

6-42

6.20 [OIII] AA4959,5007 luminosity vs. core radio power

6-42

6.21 H/3 luminosity vs. core radio power

6-43

6.22 Line ratios: [NII]/Ha vs. [OII]/[OIII]

6-47

6.23 Line ratios:

[Olll]/Eß

vs. [OII]/[OIII]

6-48

6.24 Line ratios: [OI]/Ha vs. [OII]/[OIII]

6-49

6.25 Line ratios: [OI]/[OIII] vs. [OII]/[OIII]

6-50

6.26 [Oil]/ [OIII] vs. total radio power

6-53

6.27 [Nil]/Ha vs. total radio power

6-53

6.28 [OIII]/H/? vs. total radio power

6-54

6.29 [01]/H a vs. total radio power

6-54

6.30 [01]/[OIII] vs. total radio power

6-55

6.31 [01]/[OIII] vs. total radio power (X-ray properties)

6-55

6.32 Dependance of [01]/[OIII] and [Oil]/ [OIII]

on the ionisation parameter

6-57

6.33 Dependance of [OI]/[OIII] and [Oil]/ [OIII]

on the hardness of the ionising continuum

6-57

7.1 Schematic illustration of our core-jet model

7-5

7.2 Synchrotron spectra from the core-jet model

7-17

7.3 Synchrotron spectra from the basic core-jet model

7-18

7.4 Schematic diagram of the decelerating jet model

7-23

7.5 Superposition of opaque and optically thin spectra

7-24

7.6 Model spectra with decelerating jet

7-30

7.7 Core luminosity vs. distance to deceleration region (zi)

7-34

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Chapter 1:

Introduction.

This thesis describes a stu d y of emission line lum inosities an d em ission line ratio s in a com plete sam ple of radio galaxies and th e relatio n sh ip of th e em ission line p ro p erties w ith th e radio properties. We find evidence for in teractio n betw een rad io jets an d th e in terstellar m edium in the narrow em ission line region of class II rad io sources. We also present a sim ple theoretical m odel describing th e observed p ro p erties of th e radio cores as a result of this interaction.

In th is in tro d u cto ry ch ap ter we first present (in section 1.1) a b rief overview of nuclear em ission lines in radio galaxies. This is not in ten d ed to be a com pre­ hensive survey of th e field, b u t ra th e r a look at th e general ideas a b o u t nuclear em ission line regions and th eir association w ith rad io galaxies which form th e background for th e current study. Section 1.2 discusses th e m otiv atio n for an d aim s of th is thesis. Section 1.3 presents a synopsis of th e thesis an d th e co ntents of each chapter.

1.1:

Nuclear emission lines in radio galaxies.

1.1.1:

Emission lines and radio power.

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A nother im p o rtan t developm ent in the study of radio galaxies was th e o b ser­ vation by Fanaroff and Riley (1974) of th e existence of two classes of e x trag alactic radio source. Basically the two classes were classified on th e basis of th e p o sitio n of th eir peak brightness in th e overall radio source d istrib u tio n . R adio sources w ith th e peak surface brightness at th e centre of th e surface brightness d is trib u ­ tion are referred to as edge-darkened or “class I” radio sources. T h e o th e r class of radio source (referred to as edge-brightened or “class II” ) has a double-lobe stru c tu re w ith ho tsp o ts at the ends of th e double lobed surface b rightness d is tri­ b u tio n . Fanaroff and Riley also found th a t there is a d istin ct tra n sitio n betw een class I m orphology and class II m orphology over a decade aro u n d a rad io pow er of 1024 W H z-1 at 1.4 GHz. Class II sources lie at higher powers while class I sources lie at lower powers. This division of the extrag alactic rad io source p o p u ­ latio n into two classes m ay also be of fu ndam ental im p o rtan ce in u n d e rsta n d in g rad io galaxies. B ut, once again, th ere is considerable difficulty in u n d e rstan d in g th e reason for th e two classes. One likely explanation is th a t class I sources m ay be sources in which th e jets are subsonic or transonic w hereas class II sources have supersonic jets (Bicknell 1985).

Since th e work of H um ason, M ayall an d Sandage (1956) it has generally been recognised th a t early type galaxies exhibit optical em ission lines less frequently th a n do late type galaxies. Schm idt (1965) found th a t rad io galaxies are m ore likely to exhibit emission lines th a n norm al elliptical galaxies. U ntil recent d a ta on th e rm a l X -ray em ission from early type galaxies (see F abbiano 1989 for a review) it was th o u g h t th a t early-type galaxies are gas deficient. It now ap p ea rs th a t m ost of th e gas in th e in terstellar m edium of elliptical galaxies is in th e form of a hot (T ~ 107 K) gas phase. This hot in terstellar m edium is th o u g h t to exert an influence on th e radio sources in m any types of radio galaxies. For exam ple, th e surface brightness evolution an d spreading rates of class II jets a p p ea r to be d eterm in ed by bouyancy effects and by tu rb u len t e n train m en t of th e in te rste llar m edium into th e jet (Bicknell 1984).

R ecent sensitive surveys of early type galaxies using m odern electronic de­ tecto rs an d stellar tem p late su b tractio n techniques have found th a t a low level of optical line em ission is m ore com m on in early-type galaxies th a n previously th o u g h t (H eckm an 1980, Phillips et al. 1986). Phillips et al. (1986) found th a t approxim ately 50% of “n o rm al” early-type galaxies exhibit H a or [NII]A6584 em ission down to an equivalent w idth of 0.5 Ä relative to th e stellar continuum . T hey infer th a t these galaxies typically contain aro u n d 105 Mq of em ission line

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sam ple of high power, 3C radio sources. T hey classified th e optical sp ec tra of 3C R radio galaxies by w hether the forbidden [OII]AA3727, 9 em ission line is stro n g , or w hether it is weak or absent. In general, they found th a t stro n g [Oil] AA3727, 9 em ission is m ore likely to be found in powerful radio galaxies th a n in weaker radio galaxies. They also found th a t th a t galaxies w ith stro n g [Oil] AA3727, 9 are alm ost exclusively Fanaroff-Riley class II radio sources. T hus Hine an d Longair found evidence for a correlation of em ission line stren g th w ith radio pow er a n d /o r m orphological class.

T h e work of Hine and Longair (1979) is p u t on a q u a n tita tiv e footing by this thesis (see also Caganoff et al. 1988) and th e work of R aw lings (1987). Raw lings (1987) exam ined th e lum inosity of th e [OIII]AA4959,5007 lines in essentially the sam e sam ple used by Hine an d Longair (1979). He found a correlation betw een [OIII] AA4959,5007 lum inosity and the to ta l radio power in th e pow erful (p red o m ­ in an tly class II) galaxies in th e 3CR sam ple of Laing, Riley and Longair (1983). T he correlation does, however contain a large am ount of sca tte r in d icatin g th a t th e to ta l radio power is not the only p aram eter, or is not th e fu n d am en tal p a ra m ­ eter involved in th e correlation. T he m ost significant result from th is work is th a t Raw lings (1987) is able to infer th e energy flux down th e rad io jet for m ost of th e sources in his sam ple. He found th a t th ere is a m uch tig h te r correlation betw een [OIII]AA4959,5007 lum inosity and the jet power, in d icatin g th a t jet pow er has a m ore fun d am en tal relationship to th e [OIII] AA4959, 5007 lum inosity th a n does th e to ta l radio power.

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am o u n ts of ex ten d ed emission line gas. T hey do not rule ou t th e possibility th a t th e gas condenses ou t of the hot in terstellar m edium .

All this evidence p ertain s to predom inantly powerful, class II rad io sources. It was not know n how far down th e sp ectru m in radio lum inosity th e co rrelatio n betw een th e em ission line lum inosity and th e radio power continues. T h ere is a h in t in th e work of Phillips et al. (1986). They find th a t th ere is a higher em ission line detection ra te in early-type galaxies which are detected at rad io w avelengths. A lthough, am ong those sources detected, th ere is no evidence for a co rrelatio n betw een em ission line lum inosity and radio power. T his result is seem ingly a t odds w ith th e correlations dicovered in higher powered radio sources an d suggests th a t th e correlation betw een em ission line lum inosity an d to ta l rad io pow er also has some dependence on th e m orphology of th e radio source.

1.1.2:

Em ission line spectra.

A parallel th re a d in the stu d y of optical emission lines in rad io galaxies has been th e work done on em ission line ratios and m odelling of th e dynam ics a n d ionisation m echanism of the em ission line gas. T he first work in this field was perform ed by O sterbrock and co-workers in th e late 1970’s an d is su m m arised by O sterbrock (1977). We also refer to O sterbrock and M athew s (1986) an d O sterbrock (1989) for m ore recent discussions of th e em ission line regions of active galaxies in general. T he early work of O sterbrock an d co-workers is highly significant because it was the first system atic stu d y of em ission line sp e c tra in a large num b er of Seyfert and rad io galaxies and was responsible for th e c u rre n t p ictu re of th e nuclear em ission line regions in active galaxies.

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th a t it is energetically feasible for the power-law continuum to be responsible for p h o to io n isatio n of th e emission line regions in m ost of th e galaxies stu d ied (e.g.

O sterb ro ck an d M iller 1975, Yee and Oke 1979, B aum an d H eckm an 1989a). Em ission line sp ectra of radio galaxies are alm ost indistinguishable from th e em ission line sp e c tra of Seyfert galaxies. In p articu lar, narrow line radio galaxies exhibit em ission line sp ectra sim ilar to those of Seyfert II galaxies (Koski 1978). Seyfert I galaxies have a radio galaxy analogue in th e b ro ad line radio galaxies

(e.g. O sterb ro ck , Koski and Phillips 1975, 1976). T his observation estab lish ed th e idea th a t th e ionisation m echanism s in radio galaxies an d Seyfert galaxies are essentially identical in n atu re. In fact this parallelism betw een rad io galaxies an d Seyfert galaxies has been expanded by Heckm an ( 1980a,b) who showed th a t low level, low -ionisation nuclear emission line activity is detected in a significant fraction of a p p aren tly norm al galaxies— b o th early type (E an d SO) an d la te ty p e (spirals). B ecause of th eir low ionisation level, these em ission line regions are com m only referred to as LINERS (Low -ionisation N uclear Em ission Regions). A p o p u la r p ic tu re of active galaxies is th a t they divide in to radio loud an d rad io quiet p o p u latio n s w ith late-ty p e liners, Seyferts and radio quiet q u asi-stellar o b jects form ing th e radio quiet analogues of early-type liners, rad io galaxies a n d rad io loud quasi-stellar objects (e.g. O sterbrock and M athew s 1986). It ap p ea rs th a t th e only significant difference betw een these objects (a p a rt from th e s tre n g th of th eir ra d io em ission) is th e optical m orphology of th eir host galaxies— rad io loud o b jects being found in early-type galaxies and radio quiet objects being found in spirals.

H eckm an (1980) initially suggested th a t liner galaxies are ionised by shock- wave h eatin g . T his p ictu re has fallen out of favour following th e failure of shock wave m odels to reproduce th e observed [OIII]A4363 line stre n g th in m any cases. F erland a n d N etzer (1983) and H alpern and Steiner (1983) have shown th a t th e general featu res of liner sp ectra can be reproduced by pho to io n isatio n m odels w ith a sm all ionisation p a ra m ete r (ratio of ionising p h o to n density to electron density). T h e cu rren t p ictu re of liner galaxies is th a t they are photoionised by a pow er-law sp ectru m sim ilar to b u t weaker th a n th a t in Seyfert IIs (O sterb ro ck an d M athew s 1986).

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a hot th erm al com ponent either alone or in com bination w ith th e n o n -th erm al continuum is invoked to achieve b e tte r agreem ent betw een observations and the m odel (e.g. R obinson et al. 1987, B innette, R obinson an d C ourvoisier 1987a,b).

T h u s we m ay sum m arise th e cu rren t p arad ig m for em ission line regions in radio galaxies. T hey ap p ear to be photoionised by an ultrav io let to X -ray con­ tin u u m generally assum ed to be associated w ith th e central engine pow ering the radio source. T h e stre n g th of th is continuum varies widely from galaxy to galaxy w ith LINER sp ec tra being th e result of photoionisation by a relatively weak contin­ uum . It is often im plicitly assum ed th a t powerful radio galaxies exhibit em ission line sp ec tra of high excitation. We stress, however, th a t this assu m p tio n is based on studies of pow erful radio galaxies which are a 'priori know n to possess strong em ission lines a n d hence are not necessarily representative of rad io galaxies in general. We n ote in p a rtic u la r th a t two strong em ission line galaxies w hich have l i n e r type sp e c tra are PK S 2322-12 and 3C 178 (C ostero and O sterb ro ck 1977).

1.2:

Motivation and aims of the present work.

M uch of o u r knowledge of emission lines in radio galaxies has been derived from studies of pow erful n o rth ern radio galaxies generally selected from th e 3C R catalogue. Studies of emission lines in radio sources of lower power h a d not been carried o u t, p resu m ab ly because of th e difficulty of detecting em ission lines in these objects. T h e survey of Phillips et al. (1986) showed, however th a t w ith m od ern detecto rs it is possible to study low level activity in galaxy nuclei. F u r­ th erm o re, by showing th a t low level nuclear activity is com m on in early-type galaxies they estab lish ed a reason for exam ining th e m iddle g ro u n d — th e radio galaxies which are in term ed iate betw een th e powerful 3C R sources an d th e weak or “radio q u iet” elliptical galaxies studied by Phillips et al. (1986) an d Heckm an (1980).

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for such a stu d y is th e radio core which is often th o u g h t to be in tim a te ly related to th e nu clear em ission line region by v irtue of th e fact th a t they are co-spatial.

A n o th er p a ra m e te r which m ay shed light on th e relatio n sh ip betw een th e em ission line region and the radio source is th e excitation level of th e emission line sp ectru m . Given th e large range of excitation levels found in active galaxies (from liners to S ey fert/rad io galaxy type spectra) it is im p o rta n t to ask w hether th ere is any tre n d of excitation level w ith radio power. Since th e ex citatio n level of th e em ission line region is closely related to the ionising p ro p erties of th e central engine, a stu d y of excitation level as a function of radio power m ay shed light on th e relatio n betw een th e radio source and the central engine.

W ith th is threefold m otivation in m ind, we define th e aim s of th e cu rren t study:

1. We aim to define a com plete sam ple of so u th ern hem isphere rad io galaxies of in te rm e d ia te power. T he sam ple should be of in term ed iate pow er so as to fill th e gap in our knowledge of emission line p ro p erties of rad io galaxies in te rm e d ia te betw een th e powerful radio galaxies on th e one h a n d a n d weak or rad io quiet E and SO galaxies on the o th er han d . We w ant to see if th e em ission line behaviour observed in powerful radio galaxies really s ta rts at th e tra n sitio n region betw een Fanaroff-Riley class and class II rad io sources. 2. We aim to o b tain radio d a ta and optical sp ectra of at least a rep resen tativ e

su b set of this sam ple (given th e tim e co n strain ts involved for a 3 year Ph.D . p ro ject).

3. We aim to estab lish (or deny) a q u an titativ e correlation betw een em ission line lum inosity and radio power. We aim to determ ine how th e stu d y of em ission lines in “n o rm a l” early-type galaxies by Phillips et al. (1986) relates to th e work on high pow ered radio sources carried out by Hine an d L ongair (1979). We aim to establish q u an titativ e notions ab o u t how em ission line p ro p erties differ betw een Fanaroff-Riley class I and class II rad io galaxies.

4. We aim to exam ine the relationship betw een th e rad io core an d th e em ission line region. Specifically we exam ine th e role of th e radio core as a second p a ra m e te r in th e emission line correlation w ith rad io power.

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1.3:

Thesis synopsis.

C h a p te r 2 p resen ts the selection criteria used in defining our sam ple of radio galaxies. We exam ine the optical identifications of th e radio sources. We show th a t th e sam ple is com plete and representative of radio galaxies w ith rad io power aro u n d th e Fanaroff-Riley tra n sitio n region.

C h a p te r 3 presents a detailed discussion of th e VLA observations an d th e p ro d u ctio n of to ta l intensity m aps at 1.4 GHz an d 5 GHz plus sp ec tra l index m aps for a rep resen tativ e selection of the sources in our sam ple. We discuss th e m easu rem en t of rad io core fluxes and spectral indices using a high pass filtering technique to elim in ate confusion w ith extended radio em ission. We find evidence for a b im o d al d istrib u tio n of radio core spectral index and define a class of steep sp ectru m core sources and a class of flat sp ectru m core sources. C om parison of our VLA d a ta w ith the results from long-baseline in terfero m etry for selected sources in o u r sam ple indicate th a t th e steep sp ectru m cores have steep sp ectra because of a significant am ount of optically th in radio em ission on scales of h u n ­ dreds of parsecs. By co n trast, th e flat spectrum cores a p p ea r to be d o m in ated by optically thick em ission from length scales on th e order of parsecs or less. We also p resen t a m om ent analysis technique to derive large scale rad io source dim ensions, p o sitio n angles and oth er param eters. M inim um energy calculations of th e in te rn a l pressu re in th e radio lobes are also presented.

C h a p te r 4 discusses a m eth o d of spectral index aging analysis an d derive flow velocities a n d ages for 10 selected radio sources in our sam ple. T hese resu lts are th e n used to analyse th e energy budgets for these sources. We find th a t th e radio lum inosity accounts for at m ost, only a few percent of th e energy b u d g et of these class II rad io sources. This finding agrees w ith th e results of Raw lings (1987) for a sam ple of rad io sources which is m ore powerful th a n o u r sam ple by an order of m ag n itu d e or m ore. T here is no evidence for any dependence w ith rad io power of th e ra tio betw een radio lum inosity and jet power in class II sources. We note th a t Bicknell et al. (1989) find a generally m uch larger ra tio of rad io lum inosity to jet pow er in a sam ple of class I radio sources. B ased on th is observation we suggest th a t th e fraction of jet power which goes into ra d ia tio n is p rim arily a function of th e m orphological class of th e radio source.

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beam ing effects are not im p o rtan t in determ ining these relations in o u r sam ple. T h e likely a lte rn ativ e is th a t th e spectral index of th e radio cores in our sam ple is determ ined by processes intrinsic to the radio cores.

C h ap ter 5 presents a description of th e optical observations carried o u t as p a rt of this p ro ject. We describe th e observational setu p an d d a ta red u ctio n process. We p resen t observed redshifts and em ission line fluxes.

C h ap ter 6 presents a discussion of th e em ission line p ro p erties an d th eir relatio n sh ip w ith th e radio properties of th e galaxy. We present correlations of a n u m b er of em ission lines w ith to ta l radio power. We also show th a t correlations of these em ission lines w ith th e core radio power are significantly weaker th a n the correlations w ith to ta l power suggesting th a t to ta l power is m ore fu n d am en tally related to th e nuclear em ission line region. We exam ine th e radio core sp ectral index as a second p aram eter in th e correlation betw een em ission line lum inosity an d to ta l rad io power. We find evidence for an effect w here th ere is a stro n g correlation betw een emission line lum inosity and to ta l radio pow er for th e radio sources w ith steep spectrum core b u t radio sources w ith flat sp ectru m core, show a less significant correlation betw een em ission line lum inosity an d to ta l radio power. We suggest th a t this is evidence for interactions betw een th e rad io jet and the narrow em ission line region in radio sources w ith steep sp ectru m cores.

C om bination of our results w ith th e results of Raw lings (1987) an d B aum

et al. (1988) confirm s our observed correlation betw een em ission line lum inosity an d to ta l radio power for th e [OIII] AA4959, 5007 and H o + [NII] em ission lines. T h e com bined sam ples show th a t these correlations exist over four decades in rad io power for class II radio sources. A com parison of our resu lts w ith th e resu lts of P hillips et al. (1986) shows th a t th e correlation betw een em ission line lum inosity and to ta l radio power does not extend into th e low pow er radio sources. O ne of th e m ost striking and rem arkable results of this stu d y is th e finding th a t th e correlation “switches on” at th e power of the Fanaroff-Riley class I/c la ss II tra n sitio n region. Given the suggestion th a t class I radio sources have subsonic or tran so n ic je ts while class II sources have supersonic jets, we suggest th a t th is finding is fu rth e r evidence for interaction betw een a supersonic jet a n d the em ission line region in class II radio sources.

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radio power shows evidence for only one tren d . We find a suggestion th a t th e ra tio of [01] A6300/[OIII] A5007 decreases w ith increasing radio power. T h e lack of any corresponding tre n d of [Oil] AA3T2T, 9 / [OIII] A500T suggests th a t we are not seeing a tre n d of increasing ionisation p a ra m ete r w ith increasing radio power. In stead , we suggest th a t increasing radio power is accom panied by a tre n d in decreasing hardness of th e photoionising spectrum .

C h ap ter 7 presents a num ber of core-jet m odels which estab lish a th eo retical basis for u n d erstan d in g th e results presented in previous chapters. We reinforce th e notio n th a t th e spectral index of th e radio cores in our sam ple are due to th e in trin sic n a tu re of the core ra th e r th a n due to o rien tatio n an d beam ing effects. We develop a sim ple m odel for th e synchrotron power an d sp ectru m of a supersonic, non-relativistic, jet. We relate th e observed radio power of th e core an d i t ’s sp ectral index to large scale p aram eters of th e radio jet (jet power, velocity, M ach n u m b er) an d show th a t th e sim ple m odel cannot m atch th e observational d a ta. We find th a t a sim ple m odification of th e core-jet m odel involving deceleration of th e jet on scales of tens to hundreds of parsecs from th e central engine, g reatly enhances th e optically th in radio emission from the core providing a b e tte r m atch to th e observations and th e existence of two d istinct radio core p o p u latio n s. We in te rp re t th is deceleration as being due to je t/g a s in teractio n in th e narro w line region associated w ith steep sp ectru m radio sources. We close th e ch ap ter w ith a discussion of this in te rp re ta tio n in th e light of evidence for in teractio n betw een rad io jets and the narrow line region in Seyfert II galaxies and in com pact steep sp ectru m rad io sources. We point out the obvious parallels betw een these o b jects an d th e steep spectrum core sources in our own sam ple of radio galaxies.

Finally, ch ap ter 8 presents our conclusions on a ch ap ter-b y -ch ap ter basis as well as a discussion of our overall conclusions regarding evidence for in te ra ctio n betw een th e radio jets and th e narrow em ission line region of radio galaxies.

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Chapter 2:

The Sample.

2.1:

Introduction.

T he P arkes catalogue of radio sources provides th e m ost extensive radio c a t­ alogue in th e so u th ern hem isphere. This catalogue has been co n stru cted through a n u m b er of system atic surveys of various p a rts of th e sky at various different frequencies. T h e largest p a rt of the catalogue follows from a 2.7 GHz survey covering m ost of th e so u th ern sky to a 95% com pleteness lim it of 0.25 Jy. A sum m ary of this survey is p resen ted in B olton et al. (1979). It is this 2.7 GHz survey which m akes up m ost of th e 1983 version of th e P arkes catalogue from w hich our sam ple is chosen.

Using selection criteria discussed below we have defined an homogeneous sam ple of radio sources from th e P arkes catalogue. This c h ap te r is concerned w ith th e selection of th e sam ple. T he next section outlines th e selection criteria used to isolate the sam ple from the Parkes catalogue. Section 2.3 presents the sam ple, section 2.4 discusses optical identifications for the sam ple w ith a detailed discussion of a num ber of individual sources. Finally, section 2.5 discusses the com pleteness of th e sam ple.

2.2:

Selection criteria.

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sources s a tis fy in g v a rio u s se le ction c rite ria . These sam ples w ere assessed fo r th e ir

s u it a b ility d e p e n d in g u p o n th e t o t a l n u m b e r o f sources in th e sam ple and the

e x p e c te d fr a c tio n o f F a n a ro ff-R ile y class I I ra d io sources. U s in g an a p p ro p ria te

c o m b in a tio n o f ra d io flu x -d e n s ity lim its a nd o p tic a l m a g n itu d e lim its we have

selected a sam ple w h ic h is biased to w a rd m o d e ra te to h ig h p o w e r ra d io sources.

T h e pre sen t sam ple o f ra d io sources is chosen fro m th e 1983 ve rsio n o f the

P arkes ca ta lo g u e , s a tis fy in g th e fo llo w in g se le ction c rite ria :

1. D e c lin a tio n lim its : —10° < 8 < —35°.

These lim its keep th e sam ple to a m anageable size a nd ensure th a t th e e n tire

sam ple is obse rva b le u s in g b o th th e A A T a n d th e V L A .

2 . R a d io flu x -d e n s ity lim it : S2.7GHZ > 0.5 Jy .

A re a s o n a b ly h ig h ra d io flu x -d e n s ity lim it in c o n ju n c tio n w it h o p tic a l m a g n i­

tu d e lim its biases th e sa m p le to w a rd h ig h e r p o w e re d ra d io sources. T h is p a r­

tic u la r c o m b in a tio n o f lim its y ie ld s a sam ple w h ic h lies a ro u n d th e F a n a ro ff-

R ile y tr a n s itio n re g io n (F a n h a ro ff &: R ile y , 1974) a n d c o n ta in s 78 ra d io

sources, a p p ro x im a te ly h a lf o f w h ic h are F a n a ro ff-R ile y class I I ra d io sources.

A n o th e r reason fo r se le c tin g th is flu x -d e n s ity lim it is th a t fo r some p a rts o f

th e c a ta lo g ue , in co m p le te n e ss m a y becom e a p ro b le m a t lo w e r flu x -d e n s ity

levels.

3

.

O p tic a l m a g n itu d e lim its : 14 < ttlb < 18.

M a n y o f th e g alaxie s in th e P arkes c a ta lo g u e have k n o w n re d s h ifts s im p ly

because th e y e x h ib it p ro m in e n t em issio n lines. T h u s , u s in g k n o w n re d s h ifts

in a n y se le ctio n c r ite r io n w il l bias th e sam ple to w a rd e m is s io n -lin e o b je c ts .

In s te a d , we e ffe c tiv e ly use m a g n itu d e as a d ista n ce in d ic a to r. T h e b r ig h t

o p tic a l lim it o f m a g n itu d e 14 excludes n e a rb y sources o f lo w p ow er. T h e fa in t

o p tic a l lim it o f m a g n itu d e 18 is also im p o se d , b o th to g o ve rn th e n u m b e r

o f sources in th e sa m p le a n d to a v o id in co m plete ne ss due to d iffic u ltie s w ith

m a k in g o p tic a l id e n tific a tio n s on sky s u rv e y p la te s a t m a g n itu d e s g re a te r

th a n 18. A s a re s u lt o f these se le ction c r ite r ia the re d s h ifts in th e sam ple

lie ty p ic a lly in th e ra n g e z = 0.05 to 0.3. T h e fa in t m a g n itu d e lim it also has

th e effect o f e x c lu d in g v e ry p o w e rfu l ra d io sources fr o m o u r sam ple.

4

.

Id e n tifie d w it h a g a la x y .

W e p a r tic u la r ly w is h to s tu d y ra d io galaxies w it h th e e x c lu s io n o f quasars.

H ence we have a d o p te d th is as a necessary c rite rio n . M a n y ra d io sources in

th e P arkes ca ta lo g u e are associated w it h quasars o r w it h e m p ty fields. W e

m a ke th e a s s u m p tio n here th a t ra d io sources associated w it h e m p ty fields

re m a in u n id e n tifie d because th e h ost g a la x y is fa in te r th a n m a g n itu d e 18.

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et al. (1985) rep o rt a high identification ra te for 3C radio sources in th e infra-red largely because m any host galaxies are so d ista n t as to be rendered too faint for detectio n in th e visible region of th e spectrum . A llington-S m ith

et al. (1982) detect m any faint radio identifications in CCD observations to a lim iting m ag n itu d e m r ~ 23. Sim ilarly, Riley et al. (1980) (an d references w ithin) find th a t a considerable fraction of previously unidentified 3C radio sources are 1 to 2 m agnitudes fa in ter th a n the lim iting m ag n itu d e of th e sky survey plates.

2.3:

The sample.

T h e application of th e above selection criteria to th e Parkes catalogue resu lts in th e 78 radio sources listed in tab le 2.1. T h e inform ation listed in this tab le ap p ears as in the original Parkes catalogue:

C o lu m n 1: P arkes designation.

C o lu m n 2: A ltern ativ e designations for those sources which a p p e a r in o th e r catalogues. M any of these a p p ear in the Ohio catalogue (e.g.

K raus 1966) a n d /o r th e catalogue of Mills, Slee and Hill (1960).

C o lu m n 3: T h e 1950 coordinates of th e radio source. These co o rd in ates were d eterm in ed from th e p o in tin g of th e Parkes 64m dish w ith corrections using a p o in tin g solution derived from observations of calib rato r sources.

C o lu m n 4: M orphology of th e optical identification as derived from sky su r­ vey plates.

C o lu m n 5: E stim a te d m ag n itu d e of th e optical identification. T hese are th e estim ates listed in th e Parkes catalogue and are generally estim ates from th e original sky survey plates.

C o lu m n 6: F lu x -d en sity a t 2.7 GHz in Janskys.

(31)

Table 2.1:

R adio sources selected from th e P ark es catalogue.

P K S n a m e R .A . D e c .

(1950)

I .D . m a g n itu d e

(estim ated )

S 2 . 7 G H Z (Jan sk y )

0 0 5 7 -1 8 0 OB-196 00 57 42.1 - 1 8 05 01 D 18 0 .7 1

0 1 0 8 -1 4 2 01 08 40.3 - 1 4 13 43 E 1 4 .7 O.SS 0 1 1 4 -2 1 1 01-24 01 14 25.4 - 2 1 07 55 E 1 6 .5 2 .4

0 1 1 5 -2 6 1 OC-227 01 15 52.3 - 2 6 07 29 E 1 6 .7 0 .5 7

0 1 1 6 -1 9 0 01-18 01 16 08.0 - 1 9 05 04 N 18 0 .6 7

0 2 0 7 -2 2 4 f OD-212 02 07 50.6 - 2 2 27 26 E 1 5 .5 0 .8 6

0 2 0 8 -2 4 0 OD-215 02 08 59.8 - 2 4 05 29 G 1 7 .5 0 .5 4

0 2 2 9 -2 0 8 OD-249 02 29 18.0 - 2 0 53 49 E 1 6 .5 0 .7 5

0 2 4 0 -2 1 7 OD-267 02 40 19.3 - 2 1 45 11 N 1 7 .0 0 .9 7

0 2 4 7 -2 0 7 OD-279 02 47 17.4 - 2 0 43 04 E 1 5 .5 0 .5 4

0 3 0 4 -1 2 2 OE-108 03 04 35.0 - 1 2 17 21 SO 16.0 0 .8 2

0 3 0 7 -3 0 5 03 07 56.1 - 3 0 30 53 E 1 6 .5 0 .6 4

0 3 2 6 -2 8 8 OE-2442 03 26 31.5 - 2 8 51 54 E 1 7 .5 0.S3

0 3 4 4 -3 4 5 03-36 03 44 35.2 - 3 4 32 00 E 1 6 .5 2 .0 8

0 3 4 9 -2 7 8 03-212 03 49 31.9 - 2 7 53 30 E 1 6 .8 2 .8 9

0 4 2 4 -2 6 8 OF-241 04 24 38.5 - 2 6 50 31 E 17 0 .6 0

0 4 3 4 -2 2 5 O F-257 04 34 28.0 - 2 2 32 35 E 1 5 .8 0 .6 6

0 4 4 9 -1 7 5 04 49 07.9 - 1 7 35 01 E 1 4 .6 0 .6 4

0 4 5 3 -2 0 6 04-222 04 53 14.1 - 2 0 39 00 E 14 2 .7 9

0 4 5 6 -3 0 1 04 56 30.2 - 3 0 11 54 E3 18 1.58

0 5 0 2 -1 0 3 05-11 05 02 29.9 - 1 0 19 30 DB 15.4 0 .7

0 5 1 1 -3 0 5 05-35 05 11 38.6 - 3 0 31 36 E 1 6 .5 1 .2 7

0 5 2 1 -3 2 9 05-37 05 21 42.2 - 3 2 54 08 E 18 0 .5 8

0 5 2 3 -3 2 7 05-37 05 23 36.1 - 3 2 45 06 D 16 0 .6 8

0 5 3 3 -1 2 0 05-114 05 33 13.1 - 1 2 04 31 N 1 7 .8 0 .8

0 5 4 1 -2 4 3 f 05-27 05 41 04.3 - 2 4 22 14 N 18 0 .6 1

0 5 4 5 -1 9 9 OG-176 05 45 46.0 - 1 9 59 06 E 16.5 0 .5 9

0 5 4 6 -3 2 9 05 46 36.3 - 3 2 58 32 E 14 0 .8 1

0 5 4 8 -3 1 7 05 48 57.7 - 3 1 45 00 E 14.5 0 .6 8

0 6 0 0 -1 3 1 06 00 49.9 - 1 3 09 58 DB 18.0 0 .7 5

0 6 1 1 -2 5 4 OH-219 06 11 31.7 - 2 5 29 43 E 1 8 .0 0 .6 3

0 6 1 4 -3 4 9 06-36 06 14 48.8 - 3 4 55 11 DB 18.0 1.96

0 6 3 4 -2 0 5 06-210 06 34 22.5 - 2 0 34 18 E 16.8 4 .5

0 7 1 8 -3 4 0 07-37 07 18 56.5 - 3 4 01 27 E 15.8 1.36

0 7 1 9 -1 1 9 01-132 07 19 01.7 - 1 1 59 49 E 17.0 1.10

0 7 4 5 -1 9 1 07 45 18.4 - 1 9 10 12 D 18.0 0 .9

0 8 0 6 -1 0 3 3C195 08 06 30.4 - 1 0 18 59 N 18 2 .4 9

0 9 1 5 -1 1 8 Hydra A 09 15 41.2 - 1 1 53 04 D 14.8 2 3 .5

0 9 2 1 -2 1 3 09 21 21.8 - 2 1 22 47 G 16.5 0 .5 3

1 0 5 3 -2 8 2 OL-288 10 53 09.7 - 2 8 15 28 E 16.5 1.28

1 1 0 3 -2 4 4 11-21 11 03 45.7 - 2 4 28 31 D 17.5 0 .6 2

(32)

Table 2.1 (cont):

R adio sources selected from th e P ark es catalogue.

P K S nam e R .A . D ec.

(1950)

I.D . m a g n itu d e

( e s t i m a t e d )

S 2 . 7 G H Z

( J a n s k y )

1254-300 12-38 12 54 39.8 - 3 0 05 49 D 16 0 .6 2

1258-229 12 58 17.4 - 2 2 56 01 E 1 7 .5 0 .6 0

1323-271 13 23 27.0 - 2 7 10 47 E 1 5 .0 0 .9 4

1324-300 O P-342 13 24 57.4 - 3 0 02 29 E 18 0 .5 8

1329-328 13 29 33.1 - 3 2 52 56 D 1 5 .5 0 .7 7

1329-257 13 29 44.7 - 2 5 44 25 D 1 8 .0 0 .9 3

1358-113 13-117 13 58 59.0 - 1 1 21 57 E 1 5 .0 1.06

1405-298 14 05 36.2 - 2 9 50 11 G 1 8 .0 0.5S

1414-212 14-26 14 14 38.6 - 2 1 12 53 D 18.0 0 .6 5

1417-192 14-15 14 17 02.6 - 1 9 14 42 N 1 7 .5 1.1

1423-177 OQ-139 14 23 11.6 - 1 7 43 16 E 18.0 0 .7 0

1449-129 14-119 14 49 51.6 - 1 2 58 59 E 18 0 .7 9

1514-2414 A P LIB 15 14 45.3 - 2 4 11 23 E 15.0 2.0

1517-283 15 17 06.0 - 2 8 23 37 E 17.5 0.61

1553-328 15 53 30.6 - 3 2 53 50 E 17.5 0 .6 9

1555-140 15 55 33.8 - 1 4 01 26 DB 1 6 .5 0 .7 3

1 6 1 7 -2 3 5 f 16 17 59.9 - 2 3 35 23 E 1 6 .5 0 .6 8

1654-137 OS-191 16 54 22 0 - 1 3 44 23 G? 18 0 .9 5

1712-120 17 12 51.2 - 1 2 02 57 D 1 7 .5 0.6

1 9 1 5 -1 2 1 f 19-15 19 15 06.4 - 1 2 09 19 DB 18 0.8

2013-308 20 13 08.7 - 3 0 50 39 E 1 6 .5 0 .5 0

2030-230 20-28 20 30 20.7 - 2 3 03 33 N 17.3 1.5

2 040-267 20-212 20 40 44.6 - 2 6 43 55 E 1 5 .4 1.56

2053-201 20-214 20 53 11.3 - 2 0 08 07 E 17.8 1.6

2058-282 20-215 20 58 39.1 - 2 8 13 49 E 15.6 3.1

2058-135 20-119 20 58 56.7 - 1 3 30 38 E 15.2 0.6

2104-256 21-21 21 04 24.9 - 2 5 39 06 E 16.8 6.2

2 117-269 21 17 49.0 - 2 6 57 33 N 18 0 .5 9

2134-281 21 34 18.5 - 2 8 08 25 E 16 0 .6 4

2159-335 21 59 00.8 - 3 3 35 33 E 17.5 0 .8 6

2 206-237 OY-211 22 06 32.6 - 2 3 46 39 N 17.0 1.33

2211-172 3C444 22 11 42.3 - 1 7 16 38 D 17.8 4 .6 2

2225-308 22 25 01.2 - 3 0 49 00 N 16.5 0 .5 5

2236-176 OY-161 22 36 30.2 - 1 7 36 07 E 16 1.06

2 317-277 23-24 23 17 14.9 - 2 7 44 27 E 17.5 1.91

2322-123 23-112 23 22 43.5 - 1 2 23 57 E 15.4 0 .8 8

2 331-240 OZ-252 23 31 17.9 - 2 4 00 16 E 16.5 1.04

(33)

Of th e 78 sources in tab le 2.1, five sources have been dro p p ed from the sam ple because acc u ra te VLA positions have shown the original optical identifications to be erroneous w ith no a lte rn ativ e c o u n terp art available. These sources are m arked in colum n 1 of tab le 2.1 w ith a “f ” sym bol and are discussed below.

Table 2.2:

References to 2.7GHz survey.

S u r v e y p a rt

R .A . ra n g e

D e c . R a n g e

S l i m i t

( J a n s k y )

R e fe r e n c e

3 3 \ l l \ l 9 \ 2 3 h - 3 3 ° to - 7 5 ° 0 . 2 5 S h i m m i n s ( 1 9 7 1 ) 6 9h to 16h30m

18h30m to 7h15m

- 3 0 ° to - 3 5 ° 0.20 S h i m m i n s & B o l t o n ( 1 9 7 1 ) 7 8h to 17h

19h30m to 6h30m

o O C O 1 0 -4-3 O 1 0.6

B o l t o n et al. ( 1 9 7 5 )

11 22h to 5h

o O C O 1 0 o

1 0 . 2 5 W a l l et al. ( 1 9 7 6 )

13 10h to 15h - 1 5 ° to - 3 0 ° 0 . 2 5 S a v a g e et al. ( 1 9 7 7 ) 14 10h to 15h - 4 ° to - 3 0 ° 0 . 2 5 B o l t o n et al. ( 1 9 7 9 )

Table 2.3 p resen ts th e resu lts of a lite ra tu re survey for all observations of th e sources in ou r sam ple (excluding radio observations as p a rt of th e Parkes su r­ vey). This lite ra tu re survey was carried o u t m ainly by searching th ro u g h indexes of various jo u rn als as well as A stro n o m y and Astrophysics Abstracts for papers referring to radio surveys or radio sources in the so u th ern hem isphere. References w ith in these p ap ers were also followed up. M ost of th e p apers containing o p ti­ cal identifications come from investigators engaged in th e original P arkes surveys an d are published in th e Australian Journal of Physics Astrophysical Supplement.

R edshift d a ta come from m an y different sources. A p articu larly useful source- book for redshifts is th e Catalogue of Radial Velocities of Galaxies (P alum bo, T anzella-N itti &; V ettolani, 1983) which contains an extensive list of references and galaxy ra d ia l velocities m easured before th e end of 1980. In all cases the publications referenced in ta b le 2.3 were checked for accuracy. C om parisons were m ade w ith o th e r publications where applicable. T he inform ation listed in table 2.3 is:

C o lu m n 1: Parkes designation.

(34)

C o lu m n 3: References to m easurem ents of redshift for th e identified galaxies.

C o lu m n 4: O th er references. This is a ra th e r heterogeneous category con­ taining any oth er references to the source. Some m ay merely m en tio n the object in a table while others are in -d ep th studies. G enerally these references contain optical sp ectra, p hotom etry or radio m aps. Of p a rtic u la r signifigance is reference 28 (Ekers

et al. 1988) which presents pre-com pletion VLA observations of a num b er of P arkes radio sources. O ptical d a ta are also presented in com panion papers.

References corresponding to th e num bers in tab le 2.3 are given in table 2.4.

2.4:

Optical identifications.

Some of th e sources in tab le 2.3 have m ore th a n one reference for the optical identifications. These m ultiple identifications are in agreem ent for m ost of the sources. In th e light of b e tte r radio m aps available to us we are able to distinguish th e correct identification where m ore th a n one has been proposed. F urtherm ore, on th e basis of accu rate positions for th e radio core we find some sources where a previous identification m ust be rejected b u t no a lte rn ativ e identification is found.

T h e sources discussed below are only those for which new inform ation re­ garding th e o p tical identification has been found. Any sources ap p earin g in table 2.1 an d not discussed in th is section m ust be regarded as having a reliable op­ tical identification. Sources listed in tab le 2.3 w ith m ore th a n one reference to an o ptical identification an d no t discussed here m ay be assum ed to have all cited identifications in agreem ent.

D iscussion of individual sources w ith new inform ation on th e optical id en ti­ fication follows:

0 2 0 7 -2 2 4 : B olton, Shim m ins and W all (1975) identified this radio source w ith a m ag n itu d e 15.5 elliptical galaxy. O ur VLA m ap shows the source to be unresolved and lying in a blank field approxim ately 5.6 arcm in u tes n o rth of th e original identification. No obvious optical c o u n terp art is seen on eith er th e ESO B or R plates. A ccurate coordinates from th e VLA m ap are: 02 07 50.96 ± 0.04 - 2 2 27 44.0 ± 0 .6 .

(35)

Table 2.3:

R eferences to previous work.

P K S n a m e I d e n t i f i c a t i o n

R e f e r e n c e ( s )

R e d s h i f t R e f e r e n c e ( s )

O t h e r R e f e r e n c e s ( s )

0057-180 7

0108-142 7,48 70 31

0114-211 3

0115-261 12 27 27

0116-190 53

0207-224 12

0208-240 53

0229-208 12,14 27 27

0240-217 12,19 73,27 27

0247-207 12 27 27

0304-122 7 13,46,47,50

0307-305 60 27 27

0326-288 12

0344-345 3,41,65 27 27,77

0349-278 3 73,27 57,27,18,66,75

0424-268 3 27 27

0434-225 12

0449-175 7 70

0453-206 3 16,70

0456-301 32

0502-103 6 71

0511-305 3 27 27

0521-329 43

0523-327 3

0533-120 6

0541-243 43

0545-199 12

0546-329 60 27 27

0548-317 60 23,27 27

0600-131 7

0611-254 5 12,61

0614-349 60 63 38

0634-205 3 57,27 21,61,66,55,27,76,77

0718-340 3,41 16

0719-119 51

0745-191 6 39 77,78,79,81

0806-103

0915-118 42 22,28,69,37,29,81

0921-213 19 49

1053-282 12

(36)

Table 2.3 (cont):

References to previous work.

P K S n a m e I d e n t i f i c a t i o n

R e f e r e n c e ( s )

R e d s h if t R e f e r e n c e ( s )

O t h e r R e f e r e n c e ( s )

1254-300 10,60 27 27

1258-229 43,54 56

1323-271 12 27 27

1324-300 60

1329-328

1329-257 10

1358-113 6 1,57 22

1405-298 40

1414-212 44

1417-192 6 15 39,34,2

1423-177 12

1449-129 10 29,56

1514-241 3 27 24,27

1517-283 12

1553-328 60,40

1555-140 12 49

1617-235 12 27 27

1654-137 12 33

1712-120 6

1915-121 10

2013-308 60 27 40,27

2030-230 39 38

2040-267 3 64,70 69

2053-201 3 36,38

2058-282 3 64,70,27 27,68,18

2058-135 6 70 62,56,30

2104-256 3 27 18,27,17

2117-269 12

2134-281 12

2159-335 60 40

2206-237 12,19 73,27 27

2211-172 6,74 25,68

2225-308 60,40 40,27 27

2236-176 11 27 35,27

2317-277 3 26

2322-123 6,14 58 81,42,34,20,2

Figure

Table 2.1: Radio sources selected from the Parkes catalogue.

Table 2.1:

Radio sources selected from the Parkes catalogue. p.31
Table 2.1 (cont): Radio sources selected from the Parkes catalogue.

Table 2.1

(cont): Radio sources selected from the Parkes catalogue. p.32
Table 3.5(cont): Core fluxes and spectra.

Table 3.5(cont):

Core fluxes and spectra. p.79
Figure 3.7: Plot of VLA core power as a function of VLA core spectral index. Note the apparent lack of sources with spectral index in the range 0 to 0.5.

Figure 3.7:

Plot of VLA core power as a function of VLA core spectral index. Note the apparent lack of sources with spectral index in the range 0 to 0.5. p.81
Figure 3.8: The Kaplan-Meier estimator for the cumulative distribution of VLA core spectral index

Figure 3.8:

The Kaplan-Meier estimator for the cumulative distribution of VLA core spectral index p.81
Table 3.7: PTI system parameters.

Table 3.7:

PTI system parameters. p.83
Table 3.8: 2.29 GHz PTI fluxes.

Table 3.8:

2.29 GHz PTI fluxes. p.83
Figure 3.9: Comparison of PTI flux-densities and VLA flux-densities for the "radio cores of a subset of sources in our sample

Figure 3.9:

Comparison of PTI flux-densities and VLA flux-densities for the "radio cores of a subset of sources in our sample p.85
Table 3.9a: Moment analysis parameters (1.4GHz).

Table 3.9a:

Moment analysis parameters (1.4GHz). p.89
Table 3.9a cont: Moment analysis parameters (1.4GHz).

Table 3.9a

cont: Moment analysis parameters (1.4GHz). p.90
Table 3.9b: Moment analysis spatial dimensions.

Table 3.9b:

Moment analysis spatial dimensions. p.92
Figure 3.10: Comparison of moment analysis param eters for 5 GHz data and 5 GHz tapered data

Figure 3.10:

Comparison of moment analysis param eters for 5 GHz data and 5 GHz tapered data p.93
Figure 3.11a: Comparison of moment analysis lengths for 1.4 GHz data and 5 GHz data. Scatter is mainly due to spectral effects

Figure 3.11a:

Comparison of moment analysis lengths for 1.4 GHz data and 5 GHz data. Scatter is mainly due to spectral effects p.94
Figure 3.11b: Comparison of moment analysis widths for 1.4 GHz data and 5 GHz data.

Figure 3.11b:

Comparison of moment analysis widths for 1.4 GHz data and 5 GHz data. p.94
Figure 3.12a: Comparison of moment analysis lengths at 1.4 GHz with distance between hotspots for class II sources.

Figure 3.12a:

Comparison of moment analysis lengths at 1.4 GHz with distance between hotspots for class II sources. p.95
Figure 3.12b: Comparison of moment analysis widths at 1.4 GHz with widths derived from slices across class II radio sources.

Figure 3.12b:

Comparison of moment analysis widths at 1.4 GHz with widths derived from slices across class II radio sources. p.95
Figure 3.13: Comparison of the central brightness param eter, sources (top histogram), class C i, for class I I/II sources (central histogram) and class II sources (bottom  histogram )

Figure 3.13:

Comparison of the central brightness param eter, sources (top histogram), class C i, for class I I/II sources (central histogram) and class II sources (bottom histogram ) p.97
Table 3.10: Surface brightness and lobe minimum energies.

Table 3.10:

Surface brightness and lobe minimum energies. p.101
Table 3.10: Surface brightness and lobe minimum energies.

Table 3.10:

Surface brightness and lobe minimum energies. p.102
Table 4.1: Age analysis parameters and their normalisation.

Table 4.1:

Age analysis parameters and their normalisation. p.107
Figure 4.1a: A rtist’s impression of a class II radio source illustrating the slices brightness of the lobe

Figure 4.1a:

A rtist’s impression of a class II radio source illustrating the slices brightness of the lobe p.111
Figure 4.1b: Schematic diagram depicting the process of estimating velocities from the spectral index, surface brightness and width variation along a radio jet or backflow

Figure 4.1b:

Schematic diagram depicting the process of estimating velocities from the spectral index, surface brightness and width variation along a radio jet or backflow p.112
Figure 4.2: Contour map of PKS 0344-345 at 1.4 GHz. Contour levels are at -28, 28, 56, 84, 112, 140, 168, 196, 224, 252 280

Figure 4.2:

Contour map of PKS 0344-345 at 1.4 GHz. Contour levels are at -28, 28, 56, 84, 112, 140, 168, 196, 224, 252 280 p.116
Figure 4.3: Variation of physical parameters and derived velocities for the east­ern jet of PKS 0344-345

Figure 4.3:

Variation of physical parameters and derived velocities for the east­ern jet of PKS 0344-345 p.117
Figure 4.3 cont: Variation of physical parameters and derived velocities for the eastern jet of PKS 0344-345

Figure 4.3

cont: Variation of physical parameters and derived velocities for the eastern jet of PKS 0344-345 p.118
Figure 4.4: Variation of physical parameters and derived velocities for the west­ern jet of PKS 0344-345

Figure 4.4:

Variation of physical parameters and derived velocities for the west­ern jet of PKS 0344-345 p.119
Figure 4.4 cont: Variation of physical parameters and derived velocities for the western jet of PKS 0344-345

Figure 4.4

cont: Variation of physical parameters and derived velocities for the western jet of PKS 0344-345 p.120
Figure 4.5: Contour map of PKS 0349-278 at 1.4 GHz. Contour levels are at -18, 18, 46, 92, 138, 184, 230, 276, 368, 460, 552, 644, 736, 828 and 920 mJy/beam.

Figure 4.5:

Contour map of PKS 0349-278 at 1.4 GHz. Contour levels are at -18, 18, 46, 92, 138, 184, 230, 276, 368, 460, 552, 644, 736, 828 and 920 mJy/beam. p.122
Figure 4.6: Variation of physical parameters and derived velocities for the east­ern lobe of PKS 0349-278

Figure 4.6:

Variation of physical parameters and derived velocities for the east­ern lobe of PKS 0349-278 p.123
Figure 4.6 cont: Variation of physical parameters and derived velocities for the eastern lobe of PKS 0349-278

Figure 4.6

cont: Variation of physical parameters and derived velocities for the eastern lobe of PKS 0349-278 p.124

References

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