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Abstract The GAMA J0913−0107 system is a rare conjunction of a submillimeter galaxy (SMG) atz≈ 2.7 and two background QSOs with projected separations <200 kpc. Previous high-resolution QSO absorption-line spectroscopy has revealed high Hicolumn density, extremely metal-poor (∼1% solar) gas streams in the circumgalactic medium of the SMG. Here we present deep optical integral-field spectroscopy of the system with the Keck Cosmic Web Imager (KCWI). Reaching a 2σsurface brightness limit ≈10−19erg s−1cm−2arcsec−2with ∼2 hr of integration time, we detect a filamentary Lyαnebula stretching ∼180 kpc from the SMG intercepting both QSO sightlines. This Lyαfilament may correspond to the same cool gas stream penetrating through the hot halo seen in the absorption. In contrast to Lyαnebulae around QSOs, there is no obvious local source for photoionization due to the massive dust content. While uncertain, we consider the possibility that the nebula is ionized by shocks induced by the infall, obscured star formation, and/or a boosted UV background. The SMG–QSOs conjunction multiplied the efficiency of the KCWI observations, allowing a direct comparison of Lyαnebulae in two distinct environments. We find that the nebulae around the QSOs are much brighter and show steeper surface brightness profiles than the SMG nebula. This is consistent with the additional photoionization and Lyαscattering provided by the QSOs. While illustrating the challenges of detecting Lyαnebulae around SMGs, our work also demonstrates that important insights can be gained from comparative studies of high-zLyαnebulae.
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Mapping the Morphology and Kinematics of a Lyα-selected Nebula at z = 3.15 with MUSE
Abstract Recent wide-field integral-field spectroscopy has revealed the detailed properties of high-redshift Lyαnebulae, most often targeted due to the presence of an active galactic nucleus (AGN). Here, we use VLT/MUSE to resolve the morphology and kinematics of a nebula initially identified due to strong Lyαemission atz∼ 3.2 (LABn06). Our observations reveal a two-lobed Lyαnebula, at least ∼173 pkpc in diameter, with a light-weighted centroid near a mid-infrared source (within ≈17.2 pkpc) that appears to host an obscured AGN. The Lyαemission near the AGN is also coincident in velocity with the kinematic center of the nebula, suggesting that the nebula is both morphologically and kinematically centered on the AGN. Compared to AGN-selected Lyαnebulae, the surface-brightness profile of this nebula follows a typical exponential profile at large radii (>25 pkpc), although at small radii, the profile shows an unusual dip at the location of the AGN. The kinematics and asymmetry are similar to, and the Civand Heiiupper limits are consistent with, other AGN-powered Lyαnebulae. Double-peaked and asymmetric line profiles suggest that Lyαresonant scattering may be important in this nebula. These results support the picture of the AGN being responsible for powering a Lyαnebula that is oriented roughly in the plane of the sky. Further observations will explore whether the central surface-brightness depression is indicative of either an unusual gas or dust distribution or variation in the ionizing output of the AGN over time.
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- Award ID(s):
- 1813016
- PAR ID:
- 10485913
- Publisher / Repository:
- DOI PREFIX: 10.3847
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 923
- Issue:
- 2
- ISSN:
- 0004-637X
- Format(s):
- Medium: X Size: Article No. 252
- Size(s):
- Article No. 252
- Sponsoring Org:
- National Science Foundation
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