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A Study of 53 Radio Galaxies Selected from the Astronomical Database

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A Study of 53 Radio Galaxies Selected from the Astronomical Database ΢ρνιή Θεηηθώλ Δπηζηεκώλ & Σερλνινγίαο Πξνρσξεκέλεο ΢πνπδέο ζηε Φπζηθή (Π΢Φ) Πηπρηαθή / Γηπισκαηηθή Δξγαζία Μειέηε δείγκαηνο 53 ξαδηνπεγώλ από ηε βάζε δεδνκέλσλ Galex, θαη δύν ξαδηνγαιαμηώλ, ησλ Hercules A θαη 3C 310. Ξαλζνύια Σζαγθαιίδνπ Δπηβιέπσλ θαζεγεηήο: Νεθηαξία Γθηδάλε Αμηνινγεηήο Β: Βαζίιεο Υαξκαλδάξεο Πάηξα, Ινύιηνο 2020 Tsagkalidou X., A study of 55 radiosources. Περίληψη ΢ηελ παξνύζα εξγαζία παξνπζηάδνπκε ηε κειέηε ελόο δείγκαηνο 53 ξαδηνπεγώλ, νη νπνίεο βξίζθνληαη ζε ζρεηηθά θνληηλέο απνζηάζεηο, θαη παξνπζηάδνπλ κεηαηόπηζε ζην εξπζξό (redshift) κε ηηκέο από 0,001 έσο 0,008. Έμη εθ ησλ ξαδηνπεγώλ ηνπ δείγκαηνο (νη NGC 6822, LGS 3, Bol 520, Andromeda X, Andromeda XI θαη Andromeda XVI) θαίλεηαη λα έρνπλ αξλεηηθέο ηηκέο redshift, άξα παξνπζηάδνπλ κεηαηόπηζε πξνο ην θπαλό. Η έξεπλα πνπ δηεμήγακε ζηε βηβιηνγξαθία θαηέδεημε όηη 52 από ηα αληηθείκελα ηνπ δείγκαηόο καο είλαη γαιαμίεο, ελώ έλα, ν Bol 520, ζεσξείηαη ζθαηξηθό ζκήλνο (globular cluster) θαη όρη γαιαμίαο. Λακβάλνληαο ππόςε ηηο ηηκέο ππθλόηεηαο καγλεηηθώλ ξνώλ ζηελ πεξηνρή ησλ ξαδηνζπρλνηήησλ πνπ έρνπλ θαηαγξαθεί ζηε βηβιηνγξαθία, πξνρσξήζακε ζηνλ ππνινγηζκό ηεο ηζρύνο 38 γαιαμηώλ εθ ηνπ ζπλόινπ. Γηα λα δηεμάγνπκε ηνπο ππνινγηζκνύο, πηνζεηήζακε ΛCDM θνζκνινγία, κε ηηκέο παξακέηξσλ πνπ θαζνξίζηεθαλ από ηελ ηειεπηαία έθδνζε ηεο απνζηνιήο ηνπ δηαζηεκηθνύ ηειεζθνπίνπ Planck. Από ηα απνηειέζκαηα ησλ ππνινγηζκώλ ζπκπεξαίλνπκε όηη νη 38 γαιαμίεο είλαη ζρεηηθά κηθξήο ηζρύνο ζηελ πεξηνρή ησλ ξαδηνθπκάησλ. Ο ιόγνο γηα ηνλ νπνίν δελ πξνβήθακε ζε εθηηκήζεηο θαη γηα ηηο ππόινηπεο δεθαπέληε ξαδηνπεγέο ηνπ δείγκαηνο ήηαλ ε έιιεηςε θαηάιιεισλ ηηκώλ ππθλνηήησλ ξνώλ, θαζώο ε έξεπλα καο δελ απέδσζε αμηνπνηήζηκεο θαηαγεγξακκέλεο ηηκέο ζηελ πεξηνρή ησλ ξαδηνθπκάησλ. Δθ παξαιιήινπ, αμηνπνηώληαο ηα επξήκαηα ηεο έξεπλάο καο πξνζπαζήζακε λα παξνπζηάζνπκε κία ζύληνκε πεξηγξαθή θάζε ξαδηνπεγήο, εζηηάδνληαο –όπνπ ήηαλ εθηθηό– ζηα ραξαθηεξηζηηθά γλσξίζκαηά ηνπο πνπ είλαη εκθαλή ζηα ξαδηνθύκαηα. Μεγάιν ελδηαθέξνλ παξνπζηάδνπλ δέθα γαιαμίεο, νη νπνίνη ραξαθηεξίδνληαη από ηελ ύπαξμε ελεξγνύ γαιαμηαθνύ ππξήλα, θαζώο θαη έλαο starburst γαιαμίαο, ν NGC 5236. Οη δέθα γαιαμίεο κε ελεξγνύο γαιαμηαθνύο ππξήλεο ηαμηλνκνύληαη σο εμήο: πέληε (νη NGC 4945, NGC 0253, NGC4826, NGC 5322 θαη NGC 4736) είλαη Seyfert γαιαμίεο, δύν (νη Circinus θαη NGC 4136) είλαη ηύπνπ Seyfert I θαη ηξεηο (νη NGC 6744, NGC 2787 θαη NGC 2403) ζεσξνύληαη LINER γαιαμίεο. Ιδηαίηεξα νη NGC 4945, NGC 0253 θαη Circinus απνηεινύλ εμαηξεηηθά ελδηαθέξνληα αληηθείκελα, θαζώο ραξαθηεξίδνληαη από ηε ζπλύπαξμε έληνλεο starburst δξαζηεξηόηεηαο θαη ελεξγνύ γαιαμηαθνύ ππξήλα. Δπηπξνζζέησο, πξνζπαζήζακε λα παξνπζηάζνπκε κηα εκπεξηζηαησκέλε βηβιηνγξαθηθή αλαζθόπεζε δύν κνλαδηθώλ ξαδηνγαιαμηώλ, ηνπ Ηξαθιή Α (3C 348) θαη ηνπ 3C 310 (VV 204). Η ξαδηνεθπνκπή απηώλ ησλ γαιαμηώλ ραξαθηεξίδεηαη από ηελ ύπαξμε δηπιώλ Πηπρηαθή / Γηπισκαηηθή Δξγαζία v Tsagkalidou X., A study of 55 radiosources. ξαδηνινβώλ, ηελ παξνπζία ελεξγνύ γαιαμηαθνύ ππξήλα αιιά έρεη ηελ ηδηαηηεξόηεηα ηεο παξνπζίαο θάπνησλ θνηλώλ –κεηαμύ ηνπο– ραξαθηεξηζηηθώλ, ηα νπνία είλαη αζπλήζηζηα γηα ξαδηνγαιαμίεο θαη ελεξγνύο γαιαμηαθνύο ππξήλεο ελ γέλεη. Η ύπαξμε ησλ ξαδηνινβώλ (jets) ππνδεηθλύεη ηελ ελεξγνπνίεζε ελόο κεραληζκνύ jet-mode θαηά ηελ αλαηξνθνδόηεζε ηνπ ελεξγνύ γαιαμηαθνύ ππξήλα θαη επνκέλσο νπηηθά ραξαθηεξίδνληαη σο low-excitation radio galaxies. Οη καύξεο ηξύπεο πνπ θηινμελνύλ εθηηκώληαη όηη έρνπλ 9 κάδα ηεο ηάμεο ησλ 10 Μ☉ πεξίπνπ γηα ηνλ 3C 348, ελώ γηα ηνλ 3C 310 ε αληίζηνηρε 8 κάδα θαηά πξνζέγγηζε είλαη ηεο ηάμεο ησλ 10 Μ☉. Η βηβιηνγξαθηθή αλαζθόπεζε ησλ Ηξαθιή Α θαη 3C 310 πνπ θάλακε πξνζπαζεί λα παξνπζηάζεη όια ηα ηειεπηαία δεδνκέλα από ην έηνο 2016 κέρξη θαη ζήκεξα. Λέξεις – Κλειδιά Ραδηνπεγέο, GALEX, ξαδηνηζρύο, Ηξαθιήο Α (3C 348), 3C 310 Πηπρηαθή / Γηπισκαηηθή Δξγαζία vi Tsagkalidou X., A study of 55 radiosources. A study of 53 radio sources selected from GALEX and of two radio galaxies, Hercules A and 3C 310. Xanthoula Tsagkalidou Abstract We present a study of 53 relatively nearby radio sources that are characterized by redshifts within the range of 0.001 < z < 0.008. Six radio sources (NGC 6822, LGS 3, Bol 520, Andromeda X, Andromeda XI and Andromeda XVI) demonstrate negative redshift values and therefore are classified as blueshifted. Searching the literature, it became evident that 52 objects in our sample are galaxies and the remaining one, Bol 520, is a globular cluster and not a galaxy. Assuming radio flux density measurements obtained by the literature, we estimated the radio power for 38 of the galaxies, using the concordance cosmological model with cosmological constants obtained by the latest release of the Planck mission. The results showed that they are relatively low-power radio sources. For the remaining 15 radio objects of our sample no flux density measurements exist in the literature that would enable us to estimate their radio powers. We also attempted a brief presentation of each one of the 53 radio objects, especially focusing on their radio properties. Galaxies which present very interesting features, are the starburst galaxy NGC 5236 and ten galaxies that are characterized as active galactic nuclei and are classified as follows: five are Seyfert galaxies (NGC 4945, NGC 0253, NGC4826, NGC 5322, NGC 4736), two (Circinus, NGC 4136) have been identified as Seyfert type I and three (NGC 6744, NGC 2787, NGC 2403) are LINER galaxies. NGC 4945, NGC 0253 and Circinus pose very interesting cases, as they are characterized as composite starburst/active galactic nucleus systems. We have also conducted a literature review concerning the study of two exceptional radio galaxies, Hercules A (3C 348) and 3C 310 (VV 204). The two double-lobed radio galaxies Πηπρηαθή / Γηπισκαηηθή Δξγαζία vii Tsagkalidou X., A study of 55 radiosources. are classified as active galactic nuclei and appear to have features akin to each other that are uncommon to radiogalaxies and active galactic nuclei in general. They appear to be driven by jet-mode mechanisms and are optically designated as low-excitation radio 9 galaxies. They host supermassive black holes with estimated mass of ≃ 10 Μ☉ for 8 Hercules A and ≃ 10 Μ☉ for 3C 310. Our literature review attempted to keep track of the latest data concerning Hercules A and 3C 310, which were published over the last four years to date. 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