Browsing by Author "Bielby, R. M."
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- ItemThe nature of sub-millimetre galaxies II: an ALMA comparison of SMG dust heating mechanisms(2022) Ansarinejad, B.; Shanks, T.; Bielby, R. M.; Metcalfe, N.; Infante, L.; Murphy, D. N. A.; Rosario, D. J.; Stach, S. M.We compare the contribution of active galactic nuclei (AGNs) and star formation towards dust heating in sub-mm galaxies (SMGs). We have used ALMA at 0.1-arcsec resolution to image a complete flux-limited sample of seven sub-mm sources previously shown to have spectral energy distributions that were as well-fitted by obscured AGN as star-forming galaxy templates. Indeed, two sub-mm sources were known to be quasars from their absorbed X-ray emission. We find the sub-mm sizes of all SMGs to be small (approximate to 1-2 kpc) and generally similar to 3 times smaller than any host detected in the near-infrared (NIR). In all cases, the five SMGs are comparable in sub-mm size to the two known quasars and four z approximate to 6 quasars, also observed with ALMA. We detect no evidence of diffuse spiral arms in this complete sample. We then convert the far-infrared (FIR) luminosities to star formation rate (SFR) surface densities and find that the SMGs occupy the same range as the known quasars in our sample. We conclude that in terms of sub-mm size, extent relative to host and SFR density as well as luminosity and mid-IR (MIR) colour, there is little distinction between the SMGs and sub-mm bright quasars. Finally, we present preliminary evidence that SMGs with higher MIR luminosities and sub-mm loud quasars tend to have dust components that range to hotter temperatures than their less luminous SMG counterparts. In light of these results, we continue to suggest that luminous SMGs may host dust-absorbed quasars that may simultaneously dominate the FIR and hard X-ray backgrounds.
- ItemThe nature of sub-millimetre galaxies II: an ALMA comparison of SMG dust heating mechanisms(2022) Ansarinejad, B.; Shanks, T.; Bielby, R. M.; Metcalfe, N.; Infante, L.; Murphy, D. N. A.; Rosario, D. J.; Stach, S. M.We compare the contribution of active galactic nuclei (AGNs) and star formation towards dust heating in sub-mm galaxies (SMGs). We have used ALMA at 0.1-arcsec resolution to image a complete flux-limited sample of seven sub-mm sources previously shown to have spectral energy distributions that were as well-fitted by obscured AGN as star-forming galaxy templates. Indeed, two sub-mm sources were known to be quasars from their absorbed X-ray emission. We find the sub-mm sizes of all SMGs to be small (approximate to 1-2 kpc) and generally similar to 3 times smaller than any host detected in the near-infrared (NIR). In all cases, the five SMGs are comparable in sub-mm size to the two known quasars and four z approximate to 6 quasars, also observed with ALMA. We detect no evidence of diffuse spiral arms in this complete sample. We then convert the far-infrared (FIR) luminosities to star formation rate (SFR) surface densities and find that the SMGs occupy the same range as the known quasars in our sample. We conclude that in terms of sub-mm size, extent relative to host and SFR density as well as luminosity and mid-IR (MIR) colour, there is little distinction between the SMGs and sub-mm bright quasars. Finally, we present preliminary evidence that SMGs with higher MIR luminosities and sub-mm loud quasars tend to have dust components that range to hotter temperatures than their less luminous SMG counterparts. In light of these results, we continue to suggest that luminous SMGs may host dust-absorbed quasars that may simultaneously dominate the FIR and hard X-ray backgrounds.
- ItemThe VLT LBG redshift survey - V. Characterizing the z = 3.1 Lyman α emitter population(2016) Bielby, R. M.; Tummuangpak, P.; Shanks, T.; Francke Henríquez, Harold Johanns Phillippe; Crighton, N.H.M.; Bañados, E.; González López, Jorge; Infante Lira, Leopoldo; Orsi, A.
- ItemThe VLT LBG redshift survey - VI. Mapping HI in the proximity of z similar to 3 LBGs with X-Shooter(OXFORD UNIV PRESS, 2017) Bielby, R. M.; Shanks, T.; Crighton, N. H. M.; Bornancini, C. G.; Infante, L.; Lambas, D. G.; Minniti, D.; Morris, S. L.; Tummuangpak, P.We present an analysis of the spatial distribution and dynamics of neutral hydrogen gas around galaxies using new X-Shooter observations of z similar to 2.5-4 quasars. Adding the X-Shooter data to our existing data set of high-resolution quasar spectroscopy, we use a total sample of 29 quasars alongside similar to 1700 Lyman Break Galaxies (LBGs) in the redshift range 2 less than or similar to z less than or similar to 3.5. We measure the Ly alpha forest auto-correlation function, finding a clustering length of s(0) = 0.081 +/- 0.006 h(-1) Mpc, and the cross-correlation function with LBGs, finding a cross-clustering length of s0 = 0.27 +/- 0.14 h(-1) Mpc and power-law slope gamma = 1.1 +/- 0.2. Our results highlight the weakly clustered nature of neutral hydrogren systems in the Ly alpha forest. Building on this, we make a first analysis of the dependence of the clustering on absorber strength, finding a clear preference for stronger Ly alpha forest absorption features to be more strongly clustered around the galaxy population, suggesting that they trace on average higher mass haloes. Using the projected and 2-D cross-correlation functions, we constrain the dynamics of Ly alpha forest clouds around z similar to 3 galaxies. We find a significant detection of large-scale infall of neutral hydrogen, with a constraint on the Ly alpha forest infall parameter of beta(F) = 1.02 +/- 0.22.
- ItemThe VLT LBG redshift survey - VI. Mapping HI in the proximity of z ~ 3 LBGs with X-Shooter(2017) Bielby, R. M.; Shanks, T.; Crighton, N. H. M.; Bornancini, C. G.; Infante Lira, Leopoldo; Lambas, D. G.; Minniti, D.; Morris, S. L.; Tummuangpak, P.