Merger-induced star formation in low-metallicity dwarf galaxy NGC 4809/4810

Abstract

The physical mechanisms driving starbursts in dwarf galaxies are unclear, and the effects of mergers on star formation in these galaxies are still uncertain. We explore how the merger process affects star formation in metal-poor dwarf galaxies by analyzing high-spatial-resolution ($\sim$ 70 pc) integral field spectrograph observations of ionized gas. We use archival data from the Very Large Telescope/Multi Unit Spectroscopic Explorer to map the spatial distribution of strong emission lines (e.g., $\mathrm{H}\beta$, $\mathrm{H}\alpha$, $[\mathrm{OIII}]\lambda 5007$, $[\mathrm{NII}]\lambda 6583$, etc) in the nearby merging star-forming dwarf galaxy system NGC 4809/4810. We identify approximately 112 star-forming knots scattered among the two galaxies, where the gas-phase metallicity distribution is inhomogeneous and mixing with metal-poor and metal-rich ionized gas. Star-forming knots at the interacting region show lower metallicity, the highest star formation rates (SFRs) and SFR to resolved main-sequence-relation (rMSR) ratios. Ionized gas exhibits an obvious northeast-southwest velocity gradient in NGC 4809, while seemingly mixed in NGC 4810. High virial parameters and the stellar mass-size relation of HII regions indicate that these regions are dominated by direct radiation pressure from massive stars/clusters and persistently expanding. We find two different stellar mass surface density-stellar age relations in NGC 4809 and NGC 4810, and the stellar ages of NGC 4810 are systematically younger than in NGC 4809. Our study suggests that the merging stage of two dwarf galaxies can induce starburst activities at the interaction areas, despite the metal-deficient environment. Considering the high specific SFRs and different stellar ages, we propose that the interaction initially triggered star formation in NGC 4809 and then drove star formation in NGC 4810.

13 pages, 12 figures; accepted for publication in A&A

References in corpus (20)

• The Host Galaxies and Classification of Active Galactic Nuclei
• Mass and environment as drivers of galaxy evolution in SDSS and zCOSMOS and the origin of the Schechter function
• A Highly Consistent Framework for the Evolution of the Star-Forming "Main Sequence" from z~0-6
• Initial Performance of the NEOWISE Reactivation Mission
• Understanding Galaxy Evolution through Emission Lines
• The Mass-Metallicity and the Fundamental Metallicity Relation revisited on a fully Te-based abundance scale for galaxies
• The Lyman alpha Reference Sample: Extended Lyman alpha Halos Produced at Low Dust Content
• TiNy Titans: The Role of Dwarf-Dwarf Interactions in the Evolution of Low Mass Galaxies
• The Lyman-alpha Reference Sample: I. Survey outline and first results for Markarian 259
• The Slow Death (or Rebirth?) of Extended Star Formation in z~0.1 Green Valley Early-Type Galaxies
• Neutral carbon and CO in 76 (U)LIRGs and starburst galaxy centers A method to determine molecular gas properties in luminous galaxies
• Warm Molecular Gas in Luminous Infrared Galaxies
• Metallicity gradients in small and nearby spiral galaxies
• The Blue Compact Dwarf Galaxy VCC848 Formed by Dwarf-Dwarf Merging
• SDSS-IV MaNGA: The Radial Profile of Enhanced Star Formation in Close Galaxy Pairs
• Exploring Chemical Homogeneity in Dwarf Galaxies: A VLT-MUSE study of JKB 18
• Two physical regimes for the Giant HII Regions and Giant Molecular Clouds in the Antennae Galaxies
• Spatially resolved mass-metallicity relation at z~0.26 from the MUSE-Wide Survey
• The molecular gas resolved by ALMA in the low-metallicity dwarf merging galaxy Haro 11
• The Local Star Formation Rate Surface Density And Metallicity Relation For Star-forming Galaxies

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