Redshifts of Galaxies Around Arp 220 and Serendipitous Discovery of Three Star-Forming Dwarf Galaxies at Redshift $z\sim$ 0.5

Abstract

We present redshift measurements of four faint galaxies around the archetypal ultraluminous infrared galaxy Arp 220. These galaxies have significantly higher redshifts ($z\sim$ 0.036 -- 0.091) than that of Arp 220 ($z\simeq 0.018$). Therefore, we conclude that they are background objects not physically related to Arp 220. Three of these faint galaxies located to the south of Arp 220 are a group of galaxies (or the brightest members in a cluster of galaxies) at $z\simeq 0.09$, as suggested by Heckman et al. [1996, ApJ, 457, 616] on the basis of their associated soft X-ray emission. We also report the serendipitous discovery of three additional galaxies at redshift $z\sim 0.5$, found along one of the slit positions. All three galaxies exhibit an [O ii] λ3727 emission line. The spectrum of the brightest galaxy ($m_R\simeq 24.4$) shows other strong emission lines: Mg ii λ2798, H β, [O iii] λ4959, and [O iii] λ5007. The emission-line properties of these galaxies as well as their intrinsically low luminosities ($M_R\ge -18.4$) indicate that they are star-forming dwarf galaxies.

12 pages including 6 tables and 5 figures. Accepted for publication in AJ

References in corpus (5)

• What Powers Ultra-luminous IRAS Galaxies?
• Faint Blue Galaxies
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Cited by in corpus (10)

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• MUSE view of Arp220: Kpc-scale multi-phase outflow and evidence for positive feedback
• A Search for Lyman alpha Emitters at Redshift 3.7
• A hard X-ray constraint on the presence of an AGN in the ultra-luminous infrared galaxy Arp220
• X-ray Emitting QSOs Ejected from Arp 220
• The field surrounding NGC 7603: cosmological or non-cosmological redshifts?
• Lyman$\alpha$ Emitters beyond Redshift 5:The Dawn of Galaxy Formation
• Low-Metallicity Star Formation in High-Redshift Galaxies at z~8
• Dust masses, compositions, and luminosities in the nuclear disks and the diffuse circumnuclear medium of Arp220
• The Surroundings of Disturbed, Active Galaxies