Browsing by Subject "GALAXIES"

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    Isolated and non-isolated dwarfs in terms of modified Newtonian dynamics
    (2012) Gentile, G; Angus, G W; Famaey, B; Oh, S-H; de Blok, W J G
    Within the framework of modified Newtonian dynamics (MOND), we investigate the kinematics of two dwarf spiral galaxies belonging to very different environments, namely KK 246 in the Local Void and Holmberg II in the M 81 group. A mass model of the rotation curve of KK 246 is presented for the first time, and we show that its observed kinematics are consistent with MOND. We re-derive the outer rotation curve of Holmberg II, by modelling its HI data cube, and find that its inclination should be closer to face-on than previously derived. This implies that Holmberg II has a higher rotation velocity in its outer parts, which, although not very precisely constrained, is consistent with the MOND prediction.
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    Open Access
    WISE J233237.05–505643.5: A DOUBLE-PEAKED, BROAD-LINED ACTIVE GALACTIC NUCLEUS WITH A SPIRAL-SHAPED RADIO MORPHOLOGY
    (2013) Tsai, Chao-Wei; Jarrett, T H; Stern, Daniel; Emonts, Bjorn; Barrows, R Scott; Assef, Roberto J; Norris, Ray P; Eisenhardt, Peter R M; Lonsdale, Carol; Blain, Andrew W; Benford, Dominic J; Wu, Jingwen; Stalder, Brian; Stubbs, Christopher W; High, F William; Li, K L; Kong, Albert K H
    We present radio continuum mapping, optical imaging and spectroscopy of the newly discovered double-peaked broad-lined AGN WISE J233237.05-505643.5 at redshift z = 0.3447. This source exhibits an FR-I and FR-II hybrid-morphology, characterized by bright core, jet, and Doppler-boosted lobe structures in ATCA continuum maps at 1.5, 5.6, and 9 GHz. Unlike most FR-II objects, W2332-5056 is hosted by a disk-like galaxy. The core has a projected 5" linear radio feature that is perpendicular to the curved primary jet, hinting at unusual and complex activity within the inner 25 kpc. The multi-epoch optical-near-IR photometric measurements indicate significant variability over a 3-20 year baseline from the AGN component. Gemini-South optical data shows an unusual double-peaked emission-line features: the centroids of the broad-lined components of H-alpha and H-beta are blueshifted with respect to the narrow lines and host galaxy by ~ 3800 km/s. We examine possible cases which involve single or double supermassive black holes in the system, and discuss required future investigations to disentangle the mystery nature of this system.