Multi-Wavelength Lens Reconstruction of a Planck and Herschel-Detected Star-Bursting Galaxy

Abstract

We present a source-plane reconstruction of a Herschel and Planck-detected gravitationally lensed dusty starforming galaxy (DSFG) at z=1.68 using Hubble, Submillimeter Array (SMA), and Keck observations. The background submillimeter galaxy (SMG) is strongly lensed by a foreground galaxy cluster at z=0.997 and appears as an arc with alength of ∼15″ in the optical images. The continuum dust emission, as seen by SMA, is limited to a single knot within this arc. We present a lens model with source-plane reconstructions at several wavelengths to show the difference in magnification between the stars and dust, and highlight the importance ofmulti-wavelength lens models for studies involving lensed DSFGs. We estimate the physical properties of the galaxy by fitting the flux densities to model spectral energy distributions leading to a magnification-corrected starformation rate (SFR) of 390±60 M  yr −1 and a stellar mass of 1.1 0.4 10 11  M . These values are consistent with high-redshift massive galaxies that have formed most of their stars already. The estimated gas-to-baryon fraction, molecular gas surface density, and SFR surface density have values of 0.43±0.13, 350±200  M pc −2 , and~ 12 7 M  yr −1 kpc −2 , respectively. The ratio of SFR surface density to molecular gas surface density puts this among the most star-forming systems, similar to other measured SMGs and local ULIRGs.

Planck’s dusty GEMS

“…This shows that the impact of differential lensing between the gas and the dust is not larger than other systematic effects when deriving spatially-integrated results for the Emerald. The difference in magnification between the dust and stellar components are also minor compared to the multiwavelength configurations of other high-redshift SMGs strongly lensed by galaxy clusters (e.g., MacKenzie et al 2014;Timmons et al 2016). Magnification factors change by up to 30% in our alternative models and are consistent with those measured from lighttraces-mass models in Frye et al (2018), suggesting that the remaining model degeneracies are not a major concern for the analysis of the Emerald.…”

“…We demagnified the optical and near-infrared stellar continuum fluxes by the gravitational magnification factor µ stars = 34.1 ± 6.8 and the dust continuum fluxes by µ dust = 29.4 ± 5.9, both derived from our best-fitting lensing model. Since the stellar and dust components likely have similar contibutions to the observed WISE emission, we used the average value of µ to correct the fluxes in the W3 and W4 bands (as done in Timmons et al 2016). We also give the 3σ upper limits of nondetection in MEGACAM r-and z-bands.…”

SCUBA-2 observations of candidate starbursting protoclusters selected by Planck and Herschel-SPIRE

“…Only deeper observations and/or multi-wavelength follow-up observations can determine whether they are protoclusters. Note than even though NGP1 has a 3.2 σ overdensity at 500 µm, it is classified as a lensed far-infrared source in Gr18 due to the bright Herschel source in the central region of this field, which is also a confirmed lensed object (Bussmann et al 2013;Calanog et al 2014;Timmons et al 2016). Thus NGP1 is not classified as (ii).…”

Multi-wavelength extragalactic astronomy at Ghent University

“…wide-area submillimeter surveys (Negrello et al 2010(Negrello et al , 2017. The detailed analysis of these sources, through follow-up observations and detailed lens modelling, proves to be an important way to probe star formation in the high-redshift Universe (Bussmann et al 2012;Calanog et al 2014;Timmons et al 2016;Amvrosiadis et al 2018;Dye et al 2018).…”