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Abstract We present Keck Cosmic Web Imager integral-field unit observations around extended Lyαhalos of 27 typical star-forming galaxies with redshifts 2.0 <z< 3.2 drawn from the MOSFIRE Deep Evolution Field survey. We examine the average Lyαsurface brightness profiles in bins of star formation rate (SFR), stellar mass (M*), age, stellar continuum reddening, SFR surface density (ΣSFR), and ΣSFRnormalized by stellar mass (ΣsSFR). The scale lengths of the halos correlate with stellar mass, age, and stellar continuum reddening and anticorrelate with SFR, ΣSFR, and ΣsSFR. These results are consistent with a scenario in which the down-the-barrel fraction of Lyαemission is modulated by the low-column-density channels in the interstellar medium, and in which the neutral gas covering fraction is related to the physical properties of the galaxies. Specifically, we find that this covering fraction increases with stellar mass, age, andE(B−V) and decreases with SFR, ΣSFR, and ΣsSFR. We also find that the resonantly scattered Lyαemission suffers greater attenuation than the (nonresonant) stellar continuum emission, and that the difference in attenuation increases with stellar mass, age, and stellar continuum reddening, and decreases with ΣsSFR. These results imply that more reddened galaxies have more dust in their circumgalactic medium.
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The MOSDEF-KCWI Survey: Spectral Properties of Lyα Halos around z ∼ 2 Star-forming Galaxies
Abstract We present Keck Cosmic Web Imager integral field observations of extended Lyαemission in the circumgalactic medium of 27 typical star-forming galaxies atz∼ 2, drawn from the Multi-Object Spectrometer for Infra-Red Exploration (MOSFIRE) Deep Evolution Field (MOSDEF) survey. Using composite spectra in two bins of star formation rate (SFR), star formation rate surface density (ΣSFR), and other galactic properties, we measure spatial variations in the Lyαprofile across three regions in the Lyαhalo. We find single-peaked, redshifted profiles are ubiquitous within a central 7 kpc radius region. Further out in the halo (7–14 and 14–21 kpc), the Lyαprofile of the resonantly scattered emission exhibits more diversity, either transitioning to a double-peaked profile or remaining single peaked across the halo. We find a shorter scale length of the Lyαhalo surface brightness profile for composite halos with faster winds. The composites have a similar average inclination, suggesting those with faster winds clear channels in the interstellar medium (ISM), reducing the fraction of Lyαphotons resonantly scattered to large radii. A uniform expanding shell radiative transfer model reproduces the shape but not the normalization of the observed double-peaked Lyαprofiles. Models that adopt a more realistic, clumpy ISM are likely needed to reproduce both the shape and normalization of the Lyαprofiles.
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- Award ID(s):
- 2009313
- PAR ID:
- 10531232
- Publisher / Repository:
- DOI PREFIX: 10.3847
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 971
- Issue:
- 1
- ISSN:
- 0004-637X
- Format(s):
- Medium: X Size: Article No. 63
- Size(s):
- Article No. 63
- Sponsoring Org:
- National Science Foundation
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