SDSS IV MaNGA: Discovery of an $H_{\alpha }$ blob associated with a dry galaxy pair -- ejected gas or a `dark' galaxy candidate?

Abstract

We report the discovery of a mysterious giant $H_{\alpha }$ blob that is $\sim 8$ kpc away from the main MaNGA target 1-24145, one component of a dry galaxy merger, identified in the first-year SDSS-IV MaNGA data. The size of the $H_{\alpha }$ blob is $\sim$ 3-4 kpc in radius, and the $H_{\alpha }$ distribution is centrally concentrated. However, there is no optical continuum counterpart in deep broadband images reaching $\sim$26.9 mag arcsec${}^{-2}$ in surface brightness. We estimate that the masses of ionized and cold gases are $3.3\times 10^5$ ${\mathrm{M}}_{\odot }$ and $<1.3\times 10^9$ ${\mathrm{M}}_{\odot }$, respectively. The emission-line ratios indicate that the $H_{\alpha }$ blob is photoionized by a combination of massive young stars and AGN. Furthermore, the ionization line ratio decreases from MaNGA 1-24145 to the $H_{\alpha }$ blob, suggesting that the primary ionizing source may come from MaNGA 1-24145, likely a low-activity AGN. Possible explanations of this $H_{\alpha }$ blob include AGN outflow, the gas remnant being tidally or ram-pressure stripped from MaNGA 1-24145, or an extremely low surface brightness (LSB) galaxy. However, the stripping scenario is less favoured according to galaxy merger simulations and the morphology of the $H_{\alpha }$ blob. With the current data, we can not distinguish whether this $H_{\alpha }$ blob is ejected gas due to a past AGN outburst, or a special category of `ultra-diffuse galaxy' (UDG) interacting with MaNGA 1-24145 that further induces the gas inflow to fuel the AGN in MaNGA 1-24145.

13 pages, 11 figures, ApJ accepted

References in corpus (24)

• The 2.5 m Telescope of the Sloan Digital Sky Survey
• The Host Galaxies and Classification of Active Galactic Nuclei
• Overview of the SDSS-IV MaNGA Survey: Mapping Nearby Galaxies at Apache Point Observatory
• The MAPPINGS III Library of Fast Radiative Shock Models
• Evolutionary Stellar Population Synthesis with MILES. Part I: The Base Models and a New Line Index System
• Forty-Seven Milky Way-Sized, Extremely Diffuse Galaxies in the Coma Cluster
• The MaNGA Integral Field Unit Fiber Feed System for the Sloan 2.5 m Telescope
• Star formation efficiency in galaxy interactions and mergers: a statistical study
• The Data Reduction Pipeline for the SDSS-IV MaNGA IFU Galaxy Survey
• The Discovery of the First "Changing Look" Quasar: New Insights into the Physics & Phenomenology of AGN
• NIHAO XI: Formation of Ultra-Diffuse Galaxies by outflows
• MegaPipe: the MegaCam image stacking pipeline at the Canadian Astronomical Data Centre
• AGN Type-casting: Mrk 590 No Longer Fits the Role
• The SAMI Galaxy Survey: Shocks and Outflows in a normal star-forming galaxy
• The Close AGN Reference Survey (CARS) - Mrk 1018 returns to the shadows after 30 years as a Seyfert 1
• SDSS-IV MaNGA: Properties of galaxies with kinematically decoupled stellar and gaseous components
• The ALFALFA "Almost Darks" Campaign: Pilot VLA HI Observations of Five High Mass-to-Light Ratio Systems
• Starburst-AGN mixing: II. Optically-selected active galaxies
• The growth of the central region by acquisition of counter-rotating gas in star-forming galaxies
• Cold gas in group-dominant elliptical galaxies
• Integral Field Spectroscopy of the Extended Emission-Line Region of 4C 37.43
• A Common Origin for Quasar Extended Emission-Line Regions and Their Broad-Line Regions
• The Host Galaxy and The Extended Emission-Line Region of The Radio Galaxy 3C 79
• SDSS-IV MaNGA: A serendipitous observation of a potential gas accretion event

Cited by in corpus (8)

• HI-MaNGA: HI Followup for the MaNGA Survey
• SDSS-IV MaNGA: Inside-out vs. outside-in quenching in different local environments
• Ionised gas structure of 100 kpc in an over-dense region of the galaxy group COSMOS-Gr30 at z ~ 0.7
• MaNGA 8313-1901: gas accretion observed in a blue compact dwarf galaxy?
• Outlying H$\alpha$ emitters in SDSS IV MaNGA
• Feedback in the merging galaxy group NGC6338
• SDSS-IV MaNGA: The Nature of an Off-galaxy H$\alpha$ Blob -- A Multi-wavelength View of Offset Cooling in a Merging Galaxy Group
• SDSS-IV MaNGA: the physical origin of off-galaxy H$\alpha$ blobs in the local Universe