Examinando por Autor "Malkan, M."

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    A CO molecular gas wind 340 pc away from the Seyfert 2 nucleus in ESO 420-G13 probes an elusive radio jet
    (EDP Sciences, 2020) Fernández-Ontiveros, J.; Dasyra, K.; Hatziminaoglou, E.; Malkan, M.; Pereira-Santaella, M.; Papachristou, M.; Spinoglio, L.; Combes, F.; Aalto, S.; Nagar, N.; Imanishi, M.; Andreani, P.; Ricci, C.; Slater, R.
    A prominent jet-driven outflow of CO(2-1) molecular gas is found along the kinematic minor axis of the Seyfert 2 galaxy ESO 420-G13, at a distance of 340-600  pc from the nucleus. The wind morphology resembles the characteristic funnel shape, formed by a highly collimated filamentary emission at the base, and likely traces the jet propagation through a tenuous medium, until a bifurcation point at 440  pc. Here the jet hits a dense molecular core and shatters, dispersing the molecular gas into several clumps and filaments within the expansion cone. We also trace the jet in ionised gas within the inner ≲ 340  pc using the [Ne » II]12.8  μm line emission, where the molecular gas follows a circular rotation pattern. The wind outflow carries a mass of ∼8  ×  106  M⊙ at an average wind projected speed of ∼160  km  s-1, which implies a mass outflow rate of ∼14  M⊙   yr-1. Based on the structure of the outflow and the budget of energy and momentum, we discard radiation pressure from the active nucleus, star formation, and supernovae as possible launching mechanisms. ESO 420-G13 is the second case after NGC 1377 where a previously unknown jet is revealed through its interaction with the interstellar medium, suggesting that unknown jets in feeble radio nuclei might be more common than expected. Two possible jet-cloud configurations are discussed to explain an outflow at this distance from the AGN. The outflowing gas will likely not escape, thus a delay in the star formation rather than quenching is expected from this interaction, while the feedback effect would be confined within the central few hundred parsecs of the galaxy
  • Miniatura
    Ítem
    Megaparsec-scale structure around the protocluster core SPT2349-56 at z = 4.3
    (Oxford University Press, 2020-05) Hill, R.; Chapman, S.; Scott, D.; Apostolovski, Y.; Aravena, M.; Béthermin, M.; Bradford, C.M.; Canning, R.E.A.; De Breuck, C.; Dong, C.; González, A.; Greve, T.R.; Hayward, C.C.; Hezaveh, Y.; Litke, K.; Malkan, M.; Marrone, D.P.; Phadke, K.; Reuter, C.; Rotermund, K.; Spilker, J.; Vieira, J.D.; Weiß, A.
    We present an extensive ALMA spectroscopic follow-up programme of the $z\, {=}\, 4.3$ structure SPT2349-56, one of the most actively star-forming protocluster cores known, to identify additional members using their [C ii] 158 μm and CO(4-3) lines. In addition to robustly detecting the 14 previously published galaxies in this structure, we identify a further 15 associated galaxies at $z\, {=}\, 4.3$, resolving 55$\, {\pm }\,$5 per cent of the 870 μm flux density at 0.5 arcsec resolution compared to 21 arcsec single-dish data. These galaxies are distributed into a central core containing 23 galaxies extending out to 300 kpc in diameter, and a northern extension, offset from the core by 400 kpc, containing three galaxies. We discovered three additional galaxies in a red Herschel-SPIRE source 1.5 Mpc from the main structure, suggesting the existence of many other sources at the same redshift as SPT2349-56 that are not yet detected in the limited coverage of our data. An analysis of the velocity distribution of the central galaxies indicates that this region may be virialized with a mass of (9$\pm 5)\, {\times }\, 10^{12}$ M⊠, while the two offset galaxy groups are about 30 and 60 per cent less massive and show significant velocity offsets from the central group. We calculate the [C ii] and far-infrared number counts, and find evidence for a break in the [C ii] luminosity function. We estimate the average SFR density within the region of SPT2349-56 containing single-dish emission (a proper diameter of 720 kpc), assuming spherical symmetry, to be roughly 4$\, {\times }\, 10^4$ M⊠yr-1 Mpc-3; this may be an order of magnitude greater than the most extreme examples seen in simulations. © 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.