Search Results
Warm ionized gas in the blue compact galaxy Haro 14 viewed by MUSE
2022, Cairós, L. M., González-Pérez, J.N., Weilbacher, P.M., Manso Sainz, R.
We investigate the warm ionized gas in the blue compact galaxy (BCG) Haro 14 by means of integral field spectroscopic observations taken with the Multi Unit Spectroscopic Explorer (MUSE) at the Very Large Telescope. The large field of view of MUSE and its unprecedented sensitivity enable observations of the galaxy nebular emission up to large galactocentric distances, even in the important but very faint [O i] λ6300 diagnostic line. This allowed us to trace the ionized gas morphology and ionization structure of Haro 14 up to kiloparsec scales and, for the first time, to accurately investigate the excitation mechanism operating in the outskirts of a typical BCG. The intensity and diagnostic maps reveal at least two highly distinct components of ionized gas: the bright central regions, mostly made of individual clumps, and a faint component which extends up to kiloparsec scales and consists of widespread diffuse emission, well-delineated filamentary structures, and faint knots. Noteworthy are the two curvilinear filaments extending up to 2 and 2.3 kpc southwest, which likely trace the edges of supergiant expanding bubbles driven by galactic outflows. We find that while the central clumps in Haro 14 are Hii-region complexes, the morphology and line ratios of the whole low-surface-brightness component are not compatible with star formation photoionization. In the spatially resolved emission-line-ratio diagnostic diagrams, spaxels above the maximum starburst line form the majority (∼75% and ∼50% in the diagnostic diagrams involving [O i] and [S ii] respectively). Moreover, our findings suggest that more than one alternative mechanism is ionizing the outer galaxy regions. The properties of the diffiuse component are consistent with ionization by diluted radiation and the large filaments and shells are most probably shocked areas at the edge of bubbles. The mechanism responsible for the ionization of the faint individual clumps observed in the galaxy periphery is more difficult to assess. These clumps could be the shocked debris of fragmented shells or regions where star formation is proceeding under extreme conditions.
An Hα Imaging Survey of All (Ultra)luminous Infrared Galaxies at Decl. ≥ -30 in the GOALS Sample
2019, Jin, Jun-Jie, Zhu, Yi-Nan, Wu, Hong, Lei, Feng-Jie, Cao, Chen, Meng, Xian-Min, Zhou, Zhi-Min, Lam, Man I.
This paper presents the result of Hα imaging for luminous and ultraluminous infrared galaxies. It is a complete subsample of the Great Observatories All-sky LIRG Survey (GOALS) with decl. ≥ -30 , and consists of 148 galaxies with log(L IR/L ) ≥ 11.0. All the Hα images were carried out using the 2.16 m telescope at the Xinglong Station of the National Astronomy Observatories, Chinese Academy of Sciences (NAOC), during the year from 2006 to 2009. We obtained the pure Hα luminosity for each galaxy and corrected the luminosity for [N ii] emission, filter transmission, and extinction. We also classified these galaxies based on their morphology and interaction. We found that the distribution of star-forming regions in these galaxies is related to this classification. As the merging process advanced, these galaxies tended to have a more compact distribution of star-forming regions, higher L IR, and warmer IR-color (f 60/f 100). These results imply that the degree of dynamical disturbance plays an important role in determining the distribution of a star-forming region.