Dust Properties of [CII] Detected z $\sim$ 5.5 Galaxies: New HST/WFC3 Near-IR Observations

Abstract

We examine the rest-frame ultra-violet (UV) properties of 10 [CII]$\lambda 158\mu \mathrm{m}$$-$detected galaxies at $z\sim 5.5$ in COSMOS using new HST/WFC3 near-infrared imaging. Together with pre-existing $158\mu \mathrm{m}-$continuum and [CII] line measurements by ALMA, we study their dust attenuation properties on the IRX-$\beta$ diagram, which connects the total dust emission ($\propto$ IRX=log($L_{FIR}/L_{1600}$)) to the line-of-sight dust column ($\propto \beta$). We find systematically bluer UV continuum spectral slopes ($\beta$) compared to previous low-resolution ground-based measurements, which relieves some of the tension between models of dust attenuation and observations at high redshifts. While most of the galaxies are consistent with local starburst or Small Magellanic cloud like dust properties, we find galaxies with low IRX values and a large range in $\beta$ that cannot be explained by models of a uniform dust distribution well mixed with stars. A stacking analysis of Keck/DEIMOS optical spectra indicates that these galaxies are metal-poor with young stellar populations which could significantly alter their spatial dust distribution.

9 pages, 3 figures, 1 table. Accepted for publication in The Astrophysical Journal

References in corpus (9)

• The Cosmic Evolution Survey (COSMOS) -- Overview
• Combined CO & Dust Scaling Relations of Depletion Time and Molecular Gas Fractions with Cosmic Time, Specific Star Formation Rate and Stellar Mass
• Strong Nebular Line Ratios in the Spectra of z~2-3 Star-forming Galaxies: First Results from KBSS-MOSFIRE
• A dusty, normal galaxy in the epoch of reionization
• ALMA Imaging of Gas and Dust in a Galaxy Protocluster at Redshift 5.3: [CII] Emission in "Typical" Galaxies and Dusty Starbursts ~1 Billion Years after the Big Bang
• Are Dusty Galaxies Blue? Insights on UV Attenuation from Dust-Selected Galaxies
• New constraints on dust emission and UV attenuation of z=6.5-7.5 galaxies from millimeter observations
• ALMA Reveals Weak [NII] Emission in "Typical" Galaxies and Intense Starbursts at z=5-6
• ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: implications for spectral line intensity mapping at millimeter wavelengths and CMB spectral distortions

Cited by in corpus (2)

• Are high redshift Galaxies hot? - Temperature of z > 5 Galaxies and Implications on their Dust Properties
• ALMA reveals metals yet no dust within multiple components in CR7