Ryley Hill's research while affiliated with University of British Columbia and other places

... Given the sensitivity and resolution of MIRI/MRS, we now resolve polycyclic aromatic hydrocarbon (PAH) destruction and ionization as a function of radiation field harshness within individual galaxies (e.g., Lai et al. 2022;Armus et al. 2023). Spatial variations in PAH emission have even been resolved in a lensed galaxy at z = 4.2 (Spilker et al. 2023). The high spectral resolution has also enabled kinematic studies of shocks and outflows (e.g., Vivian et al. 2022;Goold et al. 2023;Rich et al. 2023). ...

... As a result, conventional methods of detecting galaxy clusters such as the Sunyaev-Zeldovich effect and X-ray emission are not as effective. In recent years, high-redshift protoclusters have been discovered as overdensities of Lyα emitters (e.g., Kurk et al. 2000;Steidel et al. 2000;Hayashino et al. 2004;Lee et al. 2014;Dey et al. 2016;Shi et al. 2019a;Higuchi et al. 2019), Hα emitters (Kurk et al. 2004;Tanaka et al. 2011;Hayashi et al. 2012;Koyama et al. 2013), Lyman break galaxies (LBGs; e.g., Steidel et al. 1998;Toshikawa et al. 2012;Shi et al. 2019b), and dusty star-forming galaxies (DSFGs; e.g., Chapman et al. 2009;Casey et al. 2015;Oteo et al. 2018), and through infrared color selection (e.g., Galametz et al. 2012). Recently, observatories designed to map the cosmic microwave background (CMB) such as Planck and the South Pole Telescope have identified bright millimeter and/or submillimeter sources, which, when followed up with observations at higher resolution, resolve into overdensities of dusty galaxies that are candidate protoclusters (Planck Collaboration et al. 2015;Miller et al. 2018; Wang et al. 2021). ...

... With smaller beam sizes and higher resolution, SMGs can be deblended to reveal that the most extreme systems are comprised of smaller interacting galaxies and structures Karim et al. 2013;Hayward et al. 2013aHayward et al. , 2018. This is demonstrated in Section 3.3 with the mock rest-frame optical and FIR imaging as well as in recent ALMA observations of a high-redshift SMG presented in Spilker et al. (2022). In the context of comparisons between galaxy formation models and observations from the literature, consideration of the limitations of far-IR imaging is necessary to avoid biases in quantities like observed luminosity and sizes and to understand the impacts on galaxy SMG classifications (Hayward et al. 2011). ...

... As shown by Hirashita & Aoyama ( 2019 ), the grain size distribution tends to converge to the MRN shape in metal-enriched environments such as in the Milky Way. Some metal-line observations suggest that high-redshift intense starbursts are hosted by metal-enriched (solar or supersolar) environments (Rigopoulou et al. 2018 ;Shapley et al. 2020 ;Litke et al. 2022 ). ...

... Gullberg et al. 2016;Riechers et al. 2017;Casey et al. 2019;Lehnert et al. 2020;Li et al. 2020;Stanley et al. 2021;Pensabene et al. 2021) and gravitationally amplified (e.g. Omont et al. 2011;Lis et al. 2011;Bradford et al. 2011;Combes et al. 2012;Omont et al. 2013;Riechers et al. 2013;Bothwell et al. 2013;Yang et al. 2016;Jarugula et al. 2019Jarugula et al. , 2021Apostolovski et al. 2019;Yang et al. 2019aYang et al. ,b, 2020Berta et al. 2021). The similarity found in profiles between water and mid-to high-level CO transitions strongly suggests that water emission originates from regions of active star formation (e.g. ...

... In recent years, high-redshift protoclusters have been discovered as overdensities of Lyα emitters (e.g., Kurk et al. 2000;Steidel et al. 2000;Hayashino et al. 2004;Lee et al. 2014;Dey et al. 2016;Shi et al. 2019a;Higuchi et al. 2019), Hα emitters (Kurk et al. 2004;Tanaka et al. 2011;Hayashi et al. 2012;Koyama et al. 2013), Lyman break galaxies (LBGs; e.g., Steidel et al. 1998;Toshikawa et al. 2012;Shi et al. 2019b), and dusty star-forming galaxies (DSFGs; e.g., Chapman et al. 2009;Casey et al. 2015;Oteo et al. 2018), and through infrared color selection (e.g., Galametz et al. 2012). Recently, observatories designed to map the cosmic microwave background (CMB) such as Planck and the South Pole Telescope have identified bright millimeter and/or submillimeter sources, which, when followed up with observations at higher resolution, resolve into overdensities of dusty galaxies that are candidate protoclusters (Planck Collaboration et al. 2015;Miller et al. 2018; Wang et al. 2021). While these selection techniques have been proven effective in identifying protoclusters, they target specific types of galaxies and thus do not provide a complete picture of protocluster formation (Kubo et al. 2013;Shi et al. 2019b). ...

... The choice of features to input into an ML model plays a crucial role in successful classification (see e.g. Liu et al. 2019 ), in this case the identification of gravitationally lensed galaxies. Due to the small Downloaded from https://academic.oup.com/mnras/article/514/4/5004/6604889 by guest on 10 June 2023 training sample size and the unresolved nature of high-z galaxies in SPIRE maps, we find that convolutional neural networks trained on images of sources struggle to successfully distinguish between lensed and non-lensed galaxies. ...

... We estimate the fraction of the total SFR and stellar mass of the PC15 protoclusters from galaxies which are undetected on the SPIRE images, by comparing the total SFR and stellar mass from our total light stacking to the sum of the SFR and stellar mass from spectroscopically confirmed bright DSFGs in protoclusters: four protoclusters at z ∼ 2 (Casey 2016), one Planck-selected protocluster at z = 2.16 , and two protoclusters at z ∼ 4 (Hill et al. 2020;Long et al. 2020;Hill et al. 2022). The individual protoclusters have halo masses greater than 10 13 M e at their respective redshifts, which places them on similar evolutionary tracks as those from the PC15 protoclusters (Chiang et al. 2013). ...

... We make a similar determination in the spectral axis, including the three central frequency channels in the stack aperture (93.75 MHz). This corresponds to a velocity width ∼ 950 km/s, roughly the largest CO linewidth that has been observed in similar eBOSS quasars in our redshift range (Riechers et al. 2011;Hill et al. 2019;Muñoz-Elgueta et al. 2022). Additionally, as many quasars have CO linewidths much smaller than this, this chosen spectral width allows for some velocity offset between the CO emission and the optical lines used to determine the eBOSS redshifts (see §4.1). ...

... Martinache et al. (2018) follow up 83 of the PC15 and PHz protocluster candidates with Spitzer IRAC and determine that around 46% of the fields are 3σ overdense compared to the field. Three individual Planck protocluster candidates were spectroscopically observed to identify member galaxies (Flores-Cacho et al. 2016;Kneissl et al. 2019;Polletta et al. 2021). One of these protocluster candidates is observed to be an overdensity of Hα-emitter galaxies (Koyama et al. 2021). ...