Unit:
Κατεύθυνση Αστροφυσική, Αστρονομία και Μηχανική (ΒΑΣΙΚΗ ΦΥΣΙΚΗ)Library of the School of Science
Author:
Fotopoulou Konstantina-Maria
Supervisors info:
Δέσποινα Χατζηδημητρίου, Αναπληρώτρια Καθηγήτρια, Τμήμα Φυσικής, Εθνικό και Καποδιστριακό Πανεπιστήμιο Αθηνών
Απόστολος Μαστιχιάδης, Καθηγητής, Εθνικό και Καποδιστριακό Πανεπιστήμιο Αθηνών
Νεκτάριος Βλαχάκης, Αναπληρωτής Καθηγητής, Εθνικό και Καποδιστριακό Πανεπιστήμιο Αθηνών
Original Title:
Μελέτη της Κινηματικής και της Διέγερσης του Μοριακού Αερίου στο Ραδιογαλαξία 4C12.50 μέσω της ALMA
Translated title:
Study of the Kinematics and the Excitation of Molecular Gas in Radio-galaxy 4C12.50 using ALMA
Summary:
We carried out observations of the CO(1-0), CO(3-2) and CO(4-3) lines in the ultra-luminous infrared and radio galaxy 4C12.50, with Atacama Large Millimeter Array (ALMA) and used the acquired data along with archival observations in order to determine the extent, the mass, and the excitation of the kinematically distorted gas in 4C12.50 and to look for potential undiscovered cold (~25K) molecular gas outflows. 4C12.50, the merger of gas-rich galaxies which shows infrared and radio activity, has a perturbed interstellar medium (ISM) and a dense configuration of gas and dust around the nucleus. The presence of circumnuclear radio emission and of a large, X-ray cavity in 4C12.50 supports the idea that 4C12.50 has a young or restarted radio jet that can sweep up gas. The results of our research reveal the distinct kinematics of the gas, as well as elongated regions in which the kinematics differ from that of the bulk of the disk. The CO(1-0) data indicate the presence of a molecular outflow in emission close to center of 4C12.50, which was previously seen in absorption. This enabled us to compute the mass of accelerated molecular gas, which is equal to 4.3(±0.7)×10^8 M☉sun for a CO-intensity-to-H2-mass conversion factor α=0.8 M☉sun/(K‧ km/s pc^2). For comparison, the mass of the cold molecular gas disk is 9.7(±0.2)×10^8 M☉sun, so the wind is entraining ~4% of the total reservoir with high velocity (>500 km/s). Previous observations of Η2 with the Spitzer space telescope, indicated that the warm (~400K) molecular gas in 4C12.50 is made up of a 1.4(±0.2)×10^8 M☉sun ambient reservoir and a 5.2(±1.7)×10^7 M☉sun wind. The higher fraction of accelerated gas in the 400K H2 phase is a possible indication of heating in the wind. The CO excitation, as studied by the (4-3), (3-2), and (1-0) flux ratio reveals the presence of highly-excited, optically-thin gas close to the nucleus, which is likely linked with the molecular wind. It is, thus, possible that the energy deposition affects even the cold molecular gas and could result in impediment of star formation in the wind-affected areas.
Main subject category:
Science
Other subject categories:
Physics
Keywords:
ISM, radio-jet, molecular outflows, kinematics, excitation, ULRGs, AGN
