University of Oulu

Ramírez-Moreta, P., Verdes-Montenegro, L., Blasco-Herrera, J., Leon, S., Venhola, A., Yun, M., Peris, V., Peletier, R., Verdoes Kleijn, G., Unda-Sanzana, E., Espada, D., Bosma, A., Athanassoula, E., Argudo-Fernández, M., Sabater, J., Muñoz-Mateos, J., Jones, M., Huchtmeier, W., Ruiz, J., Iglesias-Páramo, J., Fernández-Lorenzo, M., Beckman, J., Sánchez-Expósito, S., Garrido, J. (2018) Unveiling the environment and faint features of the isolated galaxy CIG 96 with deep optical and HI observations. Astronomy and Astrophysics, 619, A163. doi:10.1051/0004-6361/201833333

Unveiling the environment and faint features of the isolated galaxy CIG 96 with deep optical and HI observations

Saved in:
Author: Ramírez-Moreta, P.1; Verdes-Montenegro, L.1; Blasco-Herrera, J.1;
Organizations: 1Instituto de Astrofísica de Andalucía (IAA-CSIC)
2Joint ALMA Observatory – ESO
3Kapteyn Instituut
4Astronomy Research Unit, University of Oulu
5Department of Astronomy, University of Massachusetts-Amherst
6Observatori Astronòmic de la Universitat de València
7Universidad de Antofagasta, Unidad de Astronomía, Facultad Cs. Básicas
8National Astronomical Observatory of Japan (NAOJ)
9The Graduate University for Advanced Studies (SOKENDAI)
10Aix-Marseille Université, CNRS, CNES, LAM
11Institute for Astronomy, University of Edinburgh, Royal Observatory
12Max-Planck-Institut für Radioastronomie
13Estación Experimental de Zonas Áridas (CSIC)
14Instituto de Astrofísica de Canarias
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 19.5 MB)
Persistent link:
Language: English
Published: EDP Sciences, 2018
Publish Date: 2018-12-28


Context: Asymmetries in atomic hydrogen (HI) in galaxies are often caused by the interaction with close companions, making isolated galaxies an ideal framework to study secular evolution. The AMIGA project has demonstrated that isolated galaxies show the lowest level of asymmetry in their HI integrated profiles compared to even field galaxies, yet some present significant asymmetries. CIG 96 (NGC 864) is a representative case reaching a 16% level.

Aims: Our aim is to investigate the HI asymmetries of the spiral galaxy CIG 96 and what processes have triggered the star-forming regions observed in the XUV pseudo-ring.

Methods: We performed deep optical observations at CAHA1.23m, CAHA2.2m and VST (OmegaCAM wide-field camera) telescopes. We reach surface brightness (SB) limits of μCAHA2.2m = 27.5 mag arcsec⁻² (Cousins R) and μVST = 28.7 mag arcsec⁻² (SDSS r) that show the XUV pseudo-ring of the galaxy in detail. Additionally, a wavelet filtering of the HI data cube from our deep observations with VLA/EVLA telescope allowed us to reach a column density of NHI = 8.9 × 10¹⁸ cm⁻² (5σ) (28″ × 28″ beam), lower than in any isolated galaxy.

Results: We confirm that the HI of CIG 96 extends farther than 4 × r₂₅ in all directions. Furthermore, we detect for the first time two gaseous structures (∼10⁶ M⊙) in the outskirts. The SDSS g - r colour index image from CAHA1.23m shows extremely blue colours in certain regions of the pseudo-ring where NHI > 8.5 × 10²⁰ cm⁻², whereas the rest show red colours. Galactic cirrus contaminate the field, setting an unavoidable detection limit at 28.5 mag arcsec⁻² (SDSS r).

Conclusions: At the current SB and NHI levels, we detect no stellar link within 1° × 1° or gaseous link within 40′ × 40′ between CIG 96 and any companion. The isolation criteria rule out interactions with other similar-sized galaxies for at least ∼2.7 Gyr. Using existing stellar evolution models, the age of the pseudo-ring is estimated at 1 Gyr or older. Undetected previously accreted companions and cold gas accretion remain as the main hypothesis to explain the optical pseudo-ring and HI features of CIG 96.

see all

Series: Astronomy and astrophysics
ISSN: 0004-6361
ISSN-E: 1432-0746
ISSN-L: 0004-6361
Volume: 619
Article number: A163
DOI: 10.1051/0004-6361/201833333
Type of Publication: A1 Journal article – refereed
Field of Science: 115 Astronomy and space science
Funding: P.R.M. is funded by the project AMIGA4GAS project and the FPI Grant AYA2011-30491-C02-01 by the Ministry of Economy and Competitiveness of Spain. P.R.M., L.V.M., J.B.H., M.J., M.F.L., S.S.E., J.G.S. acknowledge support from the grant AYA2015-65973-C3-1-R (MINECO/FEDER, UE). J.I.P. acknowledges financial support from the Spanish Ministerio de Economía y Competitividad under grant AYA2013-47742-C4-1-P, and from Junta de Andalucía Excellence Project PEX2011-FQM-7058. This publication makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. The National Radio Astronomy Observatory (NRAO) Karl G. Jansky Very Large Array (VLA) is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.. This research made use of Astropy, a community-developed core Python package for Astronomy (Astropy Collaboration 2013, 2018) and of APLpy, an open-source plotting package for Python (Robitaille & Bressert 2012). We used the NASA/IPAC Extragalactic Database (NED), operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. IRAF is distributed by the National Optical Astronomy Observatories, which are operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation.
Copyright information: © ESO 2018. Published in this repository with the kind permission of the publisher.