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

Abstract

Asymmetries in 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, yet some present significant asymmetries. CIG 96 (NGC 864) is a representative case reaching a 16% level. Our aim is to investigate the HI asymmetries of this spiral galaxy and what processes have triggered the star-forming regions observed in the XUV pseudoring. We performed deep optical observations at CAHA 1.23m, 2.2m and VST telescopes. We reach surface brightness (SB) limits of mu_2.2m = 27.5 mag arcsec-2 (Cous R) and mu_VST = 28.7mag arcsec-2 (r) that show the XUV pseudoring of the galaxy in detail. Additionally, a wavelet filtering of the HI data cube from our deep observations with E/VLA telescope allowed us to reach a column density of N_HI = 8.9x10^18 cm -2 (5sigma) (28"x28" beam), lower than in any isolated galaxy. We confirm that the HI extends farther than 4xr_25 in all directions. Furthermore, we detect for the first time two gaseous structures (10^6 Msol) in the outskirts. The g-r colour index image from 1.23m shows extremely blue colours in certain regions of the pseudoring where N_HI>8.5x10^20 cm-2 , whereas the rest show red colours. Galactic cirrus contaminate the field, setting an unavoidable detection limit at 28.5mag arcsec-2 (r). We detect no stellar link within 1degx1deg or gaseous link within 40'x40' between CIG 96 and any companion. The isolation criteria rule out interactions with other similar-sized galaxies for at least 2.7Gyr. Using existing stellar evolution models, the age of the pseudoring is estimated at 1Gyr or older. Undetected previously accreted companions and cold gas accretion remain as the main hypothesis to explain the optical pseudoring and HI features of CIG 96.

arXiv comment23 pages, 18 figures, 4 tables

References in corpus (58)

• Astropy: A Community Python Package for Astronomy
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• Correcting for the Effects of Interstellar Extinction
• Planck 2013 results. I. Overview of products and scientific results
• Secular Evolution and the Formation of Pseudobulges in Disk Galaxies
• Color Separation of Galaxy Types in the Sloan Digital Sky Survey Imaging Data
• The Ninth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-III Baryon Oscillation Spectroscopic Survey
• Astrophysics Source Code Library
• Tracing Galaxy Formation with Stellar Halos I: Methods
• Galactic stellar haloes in the CDM model
• Forty-Seven Milky Way-Sized, Extremely Diffuse Galaxies in the Coma Cluster
• A Catalog of Detailed Visual Morphological Classifications for 14034 Galaxies in the Sloan Digital Sky Survey
• Tracing Galaxy Formation with Stellar Halos II: Relating Substructure in Phase- and Abundance-Space to Accretion Histories
• The Atlas3D project -- XXIX. The new look of early-type galaxies and surrounding fields disclosed by extremely deep optical images
• A Classical Morphological Analysis of Galaxies in the Spitzer Survey of Stellar Structure in Galaxies (S4G)
• Cold Dark Matter Substructure and Galactic Disks I: Morphological Signatures of Hierarchical Satellite Accretion
• Galaxy Masses
• A High Stellar Velocity Dispersion and ~100 Globular Clusters for the Ultra Diffuse Galaxy Dragonfly 44
• The extended halo of Centaurus A: uncovering satellites, streams, and substructures
• Measures of Galaxy Environment - I. What is "Environment"?
• A comprehensive model for the Monoceros tidal stream
• Beyond 31 mag/arcsec^2: the low surface brightness frontier with the largest optical telescopes
• Lopsided spiral galaxies: evidence for gas accretion
• Do Moderate-Luminosity Active Galactic Nuclei Suppress Star Formation?
• The ghost of a dwarf galaxy: fossils of the hierarchical formation of the nearby spiral galaxy NGC 5907
• Cold Dark Matter Substructure and Galactic Disks II: Dynamical Effects of Hierarchical Satellite Accretion
• The AMIGA project. I. Optical characterization of the CIG catalog
• The AMIGA sample of isolated galaxies. V. Quantification of the isolation
• Discovery of a Giant Stellar Tidal Stream Around the Disk Galaxy NGC 4013
• The Distribution of Bar and Spiral Strengths in Disk Galaxies
• A Lonely Giant: The Sparse Satellite Population of M94 Challenges Galaxy Formation
• Lopsided Spiral Galaxies
• The nearest ultra diffuse galaxy: UGC2162
• The Fornax Deep Survey with VST. II. Fornax A: a two-phase assembly caught on act
• The AMIGA sample of isolated galaxies: VIII. The rate of asymmetric HI profiles in spiral galaxies
• The AMIGA sample of isolated galaxies III. IRAS data and infrared diagnostics
• Probing interstellar turbulence in cirrus with deep optical imaging: no sign of energy dissipation at 0.01 pc scale
• The Astro-WISE Optical Image Pipeline: Development and Implementation
• Systematic search for tidal features around nearby galaxies: I. Enhanced SDSS imaging of the Local Volume
• Discovery of a stellar tidal stream around the Whale galaxy, NGC 4631
• Diffuse far-infrared and ultraviolet emission in the NGC4435/4438 system: tidal stream or Galactic cirrus?
• Galactic Rings Revisited. I. CVRHS Classifications of 3962 Ringed Galaxies from the Galaxy Zoo 2 Database
• The AMIGA sample of isolated galaxies XII. Revision of the isolation degree for AMIGA galaxies using the SDSS
• Revised positions for the CIG galaxies
• The AMIGA sample of isolated galaxies XIII. The HI content of an almost "nurture free" sample
• The AMIGA sample of isolated galaxies. XI. Optical characterisation of nuclear activity
• The AMIGA sample of isolated galaxies XI. A First Look at Isolated Galaxy Colors
• Quantified HI Morphology III: Merger Visibility Times from HI in Galaxy Simulations
• Are (pseudo)bulges in isolated galaxies actually primordial relics?
• The Optical Green Valley vs Mid-IR Canyon in Compact Groups
• The large asymmetric HI envelope of the isolated galaxy NGC 864 (CIG 96)
• Effects of the environment on galaxies in the Catalogue of Isolated Galaxies: physical satellites and large scale structure
• Hα Kinematics of S4G spiral galaxies-I. NGC 864
• Asymmetry in Isolated, Morphologically Normal Sa Galaxies
• Star formation in the extended gaseous disk of the isolated galaxy CIG 96
• A ~ 12 kpc HI extension and other HI asymmetries in the isolated galaxy CIG 340 (IC 2487)
• Anatomy of a blazar in the (sub-)millimeter: ALMA Observations of PKS 0521-365
• HI asymmetry in the isolated galaxy CIG 85 (UGC 1547)

Cited by in corpus (7)

• Galactic cirri in deep optical imaging
• xGASS: Robust quantification of asymmetries in global HI spectra and their relationship to environmental processes
• Galaxy and Mass Assembly (GAMA): Extended Intra-Group Light in a group at $z=0.2$ from deep Hyper-Suprime Cam images
• Faint and fading tails : the fate of stripped HI gas in Virgo cluster galaxies
• The AMIGA sample of isolated galaxies. XIV. Disc breaks and interactions through ultra-deep optical imaging
• On the relationship between gas content, star-formation, and global HI asymmetry of galaxies on the star-forming main-sequence
• SAMI-HI: the connection between global asymmetry in the ionised and neutral atomic hydrogen gas in galaxies