TY - JOUR
T1 - A ~ 12 kpc H i extension and other H i asymmetries in the isolated galaxy CIG 340 (IC 2487)
AU - Scott, T. C.
AU - Sengupta, C.
AU - Verdes Montenegro, L.
AU - Bosma, A.
AU - Athanassoula, E.
AU - Sulentic, J.
AU - Espada, D.
AU - Yun, M. S.
AU - Argudo-Fernández, M.
N1 - Funding Information:
We are grateful to the anonymous referee for his/her helpful remarks, which have improved the presentation of this paper. This work has been supported by Grant AYA2011-30491-C02-01 co-financed by MICINN and FEDER funds, and the Junta de Andalucia (Spain) grants P08-FQM-4205 and TIC-114. We also thankthe AMIGA team for their comments and suggestions. We thank the staff of the GMRT who have made these observations possible. GMRT is run by the National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research. The Nasa Extragalactic Database, NED, is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. We acknowledge the usage of the HyperLeda database9. Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the US Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England10. The SDSS is managed by the Astrophysical Research Consortium for the Participating Institutions. The Participating Institutions are the American Museum of Natural History, Astrophysical Institute Potsdam, University of Basel, University of Cambridge, Case Western Reserve University, University of Chicago, Drexel University, Fermilab, the Institute for Advanced Study, the Japan Participation Group, Johns Hopkins University, the Joint Institute for Nuclear Astrophysics, the Kavli Institute for Particle Astrophysics and Cosmology, the Korean Scientist Group, the Chinese Academy of Sciences (LAMOST), Los Alamos National Laboratory, the Max-Planck-Institute for Astronomy (MPIA), the Max-Planck-Institute for Astrophysics (MPA), New Mexico State University, Ohio State University, University of Pittsburgh, University of Portsmouth, Princeton University, the United States Naval Observatory, and the University of Washington. Based on observations made with the NASA Galaxy Evolution Explorer. GALEX is operated for NASA by the California Institute of Technology under NASA contract NAS5-98034.
PY - 2014/7
Y1 - 2014/7
N2 - Context. H i kinematic asymmetries are common in late-type galaxies irrespective of environment, although the amplitudes are strikingly low in isolated galaxies. As part of our studies of the H i morphology and kinematics in isolated late-type galaxies we have chosen several very isolated galaxies from the AMIGA sample for H i mapping. We present here the results of H i mapping of CIG 340 (IC 2487) which was selected because its integrated H i spectrum has a very symmetric profile (Aflux = 1.03 ± 0.02). Aims. Optical images of the galaxy hinted at a warped disk in contrast to the symmetric integrated H i spectrum profile. Our aim is to determine the extent to which the optical asymmetry is reflected in the resolved H i morphology and kinematics. Methods. Resolved 21-cm H i line mapping has been carried out using the Giant Metrewave Radio Telescope (GMRT). The H! i morphology and kinematics from this mapping together with other multi-wavelength data have been used to study the relationship between the H i and stellar components of CIG 340. Results. GMRT observations reveal significant H i morphological asymmetries in CIG 340 despite it's overall symmetric optical form and highly symmetric H i spectrum. The most notable H i features are: 1) a warp in the H i disk (with an optical counterpart), 2) the H i north/south flux ratio = 1.32 is much larger than expected from the integrated H i spectrum profile, and 3) a ~ 45′′ (12 kpc) H i extension containing ~6% of the detected H i mass on the northern side of the disk. Conclusions. Overall, we conclude that in isolated galaxies a highly symmetric H i spectrum can mask significant H i morphological asymmetries which can be revealed by H i interferometric mapping. The northern H i extension appears to be the result of a recent perturbation (108 yr), possibly by a satellite which is now disrupted or projected within the disk. But, we cannot rule out that the H i extension and the other observed asymmetries are the result of a long lived dark matter halo asymmetry. This study provides an important step in our ongoing programme to determine the predominant source of H i asymmetries in isolated galaxies. For CIG 340 the isolation from major companions, symmetric H i spectrum, optical morphology and interaction timescales have allowed us to narrow the possible causes the H i asymmetries and identify tests to further constrain the source of the asymmetries.
AB - Context. H i kinematic asymmetries are common in late-type galaxies irrespective of environment, although the amplitudes are strikingly low in isolated galaxies. As part of our studies of the H i morphology and kinematics in isolated late-type galaxies we have chosen several very isolated galaxies from the AMIGA sample for H i mapping. We present here the results of H i mapping of CIG 340 (IC 2487) which was selected because its integrated H i spectrum has a very symmetric profile (Aflux = 1.03 ± 0.02). Aims. Optical images of the galaxy hinted at a warped disk in contrast to the symmetric integrated H i spectrum profile. Our aim is to determine the extent to which the optical asymmetry is reflected in the resolved H i morphology and kinematics. Methods. Resolved 21-cm H i line mapping has been carried out using the Giant Metrewave Radio Telescope (GMRT). The H! i morphology and kinematics from this mapping together with other multi-wavelength data have been used to study the relationship between the H i and stellar components of CIG 340. Results. GMRT observations reveal significant H i morphological asymmetries in CIG 340 despite it's overall symmetric optical form and highly symmetric H i spectrum. The most notable H i features are: 1) a warp in the H i disk (with an optical counterpart), 2) the H i north/south flux ratio = 1.32 is much larger than expected from the integrated H i spectrum profile, and 3) a ~ 45′′ (12 kpc) H i extension containing ~6% of the detected H i mass on the northern side of the disk. Conclusions. Overall, we conclude that in isolated galaxies a highly symmetric H i spectrum can mask significant H i morphological asymmetries which can be revealed by H i interferometric mapping. The northern H i extension appears to be the result of a recent perturbation (108 yr), possibly by a satellite which is now disrupted or projected within the disk. But, we cannot rule out that the H i extension and the other observed asymmetries are the result of a long lived dark matter halo asymmetry. This study provides an important step in our ongoing programme to determine the predominant source of H i asymmetries in isolated galaxies. For CIG 340 the isolation from major companions, symmetric H i spectrum, optical morphology and interaction timescales have allowed us to narrow the possible causes the H i asymmetries and identify tests to further constrain the source of the asymmetries.
KW - Galaxies: ISM
KW - Galaxies: individual: CIG 340 (IC 2487)
KW - Radio lines: galaxies
UR - http://www.scopus.com/inward/record.url?scp=84904201589&partnerID=8YFLogxK
U2 - 10.1051/0004-6361/201423701
DO - 10.1051/0004-6361/201423701
M3 - Article
AN - SCOPUS:84904201589
SN - 0004-6361
VL - 567
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
M1 - A56
ER -