Spectroscopically Identified Emission Line Galaxy Pairs in the WISP Survey*

Journal article

Abstract We identify a sample of spectroscopically measured emission line galaxy (ELG) Pairs up to z = 1.6 from the Wide Field Camera 3 (WFC3) Infrared Spectroscopic Parallels (WISP) survey. WISP obtained slitless, near-infrared grism spectroscopy along with direct imaging in the J and H bands by observing in the pure-parallel mode with the WFC3 on board the Hubble Space Telescope. From our search of 419 WISP fields covering an area of ∼0.5 deg2, we find 413 ELG pair systems, mostly H α emitters. We then derive reliable star formation rates (SFRs) based on the attenuation-corrected H α fluxes. Compared to isolated galaxies, we find an average SFR enhancement of 40%–65%, which is stronger for major Pairs and Pairs with smaller velocity separations (Δ v < 300 km s−1). Based on the stacked spectra from various subsamples, we study the trends of emission line ratios in pairs, and find a general consistency with enhanced lower ionization lines. We study the pair fraction among ELGs, and find a marginally significant increase with redshift f ∝ (1 + z) α , where the power-law index α = 0.58 ± 0.17 from z ∼ 0.2 to ∼1.6. The fraction of active galactic nuclei is found to be the same in the ELG Pairs as compared to the isolated ELGs.

Authors: Dai, YS; Malkan, MM; Teplitz, HI; Scarlata, C; Alavi, A

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Astronomical Society
• Journal: The Astrophysical Journal
• Volume: 923
• Issue: 2
• Pages: 156-156
• Publication date: 2021-12-20
• DOI: 10.3847/1538-4357/ac2f96
• EISSN: 1538-4357
• ISSN: 0004-637X
• Language: English
• Keywords: Emission spectrum; Astronomy; Star formation; Active galactic nucleus; Spectroscopy; Physics; Doubly ionized oxygen; Spectral line; Redshift; Grism; Galaxy; Hubble space telescope; Wide Field Camera 3; Astrophysics