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arXiv · 2110.07316

Spectroscopically Identified Emission Line Galaxy Pairs in the WISP survey

Y. Sophia Dai·Matthew M. Malkan·Harry I. Teplitz·Claudia Scarlata·Anahita Alavi·Hakim Atek·Micaela Bagley·Ivano Baronchelli·Andrew Battisti·Andrew J Bunker·Nimish P. Hathi·Alaina Henry·Jiasheng Huang·Gaoxiang Jin·Zijian Li·Crystal Martin·Vihang Mehta·John Phillips·Marc Rafelski·Michael Rutkowski·Hai Xu·Cong K Xu·Anita Zanella
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Abstract

We identify a sample of spectroscopically measured emission line galaxy (ELG) pairs up to z=1.6 from the 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 Wide Field Camera Three (WFC3) on the Hubble Space Telescope (HST). From our search of 419 WISP fields covering an area of ~0.5 deg$^{2}$, we find 413 ELG pair systems, mostly Halpha emitters. We then derive reliable star formation rates (SFRs) based on the attenuation-corrected Halpha 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 (Delta_v < 300 km/s). 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 $f \propto (1+z)^\alpha$, where the power-law index \alpha=0.58$\pm$0.17 from $z\sim$0.2 to $z\sim$1.6. The fraction of Active galactic Nuclei (AGNs), is found to be the same in the ELG pairs as compared to isolated ELGs.

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Y. Sophia Dai, Matthew M. Malkan, Harry I. Teplitz, Claudia Scarlata, Anahita Alavi, Hakim Atek, Micaela Bagley, Ivano Baronchelli, Andrew Battisti, Andrew J Bunker, Nimish P. Hathi, Alaina Henry, Jiasheng Huang, Gaoxiang Jin, Zijian Li, Crystal Martin, Vihang Mehta, John Phillips, Marc Rafelski, Michael Rutkowski, Hai Xu, Cong K Xu, Anita Zanella. 2021-10-14. Spectroscopically Identified Emission Line Galaxy Pairs in the WISP survey. https://doi.org/10.3847/1538-4357%2Fac2f96

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