Wilkinson, Aaron, Almaini, Omar, Wild, Vivienne, Maltby, David, Hartley, William G., Simpson, Chris, and Rowlands, Kate
We present the first study of the large-scale clustering of post-starburst (PSB) galaxies in the high redshift Universe ($0.5
Krishnan, Charutha, Almaini, Omar, Hatch, Nina A., Wilkinson, Aaron, Maltby, David T., Conselice, Christopher J., Kocevski, Dale, Suh, Hyewon, and Wild, Vivienne
We present evidence that AGN do not reside in ``special'' environments, but instead show large-scale clustering determined by the properties of their host galaxies. Our study is based on an angular cross-correlation analysis applied to X-ray selected AGN in the COSMOS and UDS fields, spanning redshifts from $z\sim4.5$ to $z\sim0.5$. Consistent with previous studies, we find that AGN at all epochs are on average hosted by galaxies in dark matter halos of $10^{12}-10^{13}$ M$_{\odot}$, intermediate between star-forming and passive galaxies. We find, however, that the same clustering signal can be produced by inactive (i.e. non-AGN) galaxies closely matched to the AGN in spectral class, stellar mass and redshift. We therefore argue that the inferred bias for AGN lies in between the star-forming and passive galaxy populations because AGN host galaxies are comprised of a mixture of the two populations. Although AGN hosted by higher mass galaxies are more clustered than lower mass galaxies, this stellar mass dependence disappears when passive host galaxies are removed. The strength of clustering is also largely independent of AGN X-ray luminosity. We conclude that the most important property that determines the clustering in a given AGN population is the fraction of passive host galaxies. We also infer that AGN luminosity is likely not driven by environmental triggering, and further hypothesise that AGN may be a stochastic phenomenon without a strong dependence on environment., Comment: 13 pages, 10 figures
Wild, Vivienne, Aldeen, Laith Taj, Carnall, Adam, Maltby, David, Almaini, Omar, Werle, Ariel, Wilkinson, Aaron, Rowlands, Kate, Bolzonella, Micol, Castellano, Marco, Garguilo, Adriana, McLure, Ross, Pentericci, Laura, and Pozzetti, Lucia
We present the star formation histories of 39 galaxies with high quality rest-frame optical spectra at 0.5
Maltby, David T., Almaini, Omar, McLure, Ross J., Wild, Vivienne, Dunlop, James, Rowlands, Kate, Hartley, William G., Hatch, Nina A., Socolovsky, Miguel, Wilkinson, Aaron, Amorin, Ricardo, Bradshaw, Emma J., Carnall, Adam C., Castellano, Marco, Cimatti, Andrea, Cresci, Giovanni, Cullen, Fergus, De Barros, Stephane, Fontanot, Fabio, Garilli, Bianca, Koekemoer, Anton M., McLeod, Derek J., Pentericci, Laura, and Talia, Margherita
We investigate the prevalence of galactic-scale outflows in post-starburst (PSB) galaxies at high redshift ($1 < z < 1.4$), using the deep optical spectra available in the UKIDSS Ultra Deep Survey (UDS). We use a sample of $\sim40$ spectroscopically confirmed PSBs, recently identified in the UDS field, and perform a stacking analysis in order to analyse the structure of strong interstellar absorption features such as Mg ii ($\lambda2800$ Ang.). We find that for massive ($M_* > 10^{10}\rm\,M_{\odot}$) PSBs at $z > 1$, there is clear evidence for a strong blue-shifted component to the Mg ii absorption feature, indicative of high-velocity outflows ($v_{\rm out}\sim1150\pm160\rm\,km\,s^{-1}$) in the interstellar medium. We conclude that such outflows are typical in massive PSBs at this epoch, and potentially represent the residual signature of a feedback process that quenched these galaxies. Using full spectral fitting, we also obtain a typical stellar velocity dispersion $\sigma_*$ for these PSBs of $\sim200\rm\,km\,s^{-1}$, which confirms they are intrinsically massive in nature (dynamical mass $M_{\rm d}\sim10^{11}\rm\,M_{\odot}$). Given that these high-$z$ PSBs are also exceptionally compact ($r_{\rm e}\sim1$--$2\rm\,kpc$) and spheroidal (Sersic index $n\sim3$), we propose that the outflowing winds may have been launched during a recent compaction event (e.g. major merger or disc collapse) that triggered either a centralised starburst or active galactic nuclei (AGN) activity. Finally, we find no evidence for AGN signatures in the optical spectra of these PSBs, suggesting they were either quenched by stellar feedback from the starburst itself, or that if AGN feedback is responsible, the AGN episode that triggered quenching does not linger into the post-starburst phase., Comment: 13 pages, 6 figures, accepted for publication in MNRAS
Wilkinson, Aaron Raymond and Fishwick, Colin W. G.
A larger percentage of the world's population is at risk of developing a protozoan parasitic infection. Current treatments are failing due to the development of anti-parasitic drug resistance and the associated toxicity of these treatments. Therefore, research into new drug targets and drugs is required. The work presented herein aims to identify new drug leads for the treatment of parasitic infections by targeting a membrane-integral pyrophosphatase (M-PPase) using a structure-based drug design approach. Three approaches were employed to identify novel inhibitors of M-PPase, which lead to the identification of three different classes of inhibitors. The first approach involved the SPROUT design of a indole based putative inhibitor. Due to a number of synthetic difficulties this putative inhibitor could not be synthesised. However, simplification of the indole moiety lead to the identification of the first inhibitor of a M-PPase that was designed using SBDD. The second approach involved the substrate inspired design of a sulfamide fragment, which had a moderate activity when biologically evaluated against TmPPase. This fragment was designed to mimic phosphate in the hydrolytic centre of M-PPase. Expansion of this fragment using SPROUt lead to the identification of a second generation sulfamide fragment, which had an improved potency. Finally, a heterocyclic fragment library was synthesised and biologically evaluated. This library was based upon a heterocyclic fragment identified by collaborators using vHTS. This lead to the identification of a potent thiazole fragment. However, the binding site of this fragment could not be identified so further design could not occur.
Wilkinson, Aaron K. R.
Submillimetre galaxies (SMGs) and post-starburst (PSB) galaxies are among the most rare and interesting classes of objects in extragalactic study. SMGs are extremely active dust-obscured galaxies in the early Universe, forming stars with an immense rate of up to 1000 solar masses per year. PSB galaxies are characterised by strong Balmer absorption lines in their spectra, consistent with a recent burst of star formation before being rapidly quenched. The origin of both of these objects and how they relate to the more common populations of red-sequence and blue-cloud galaxies remain elusive. My thesis involves weighing the dark matter halos inhabited by these rare galaxies, by investigating their clustering at 0.5 < z < 3.5. To achieve this, I use data from two deep large-scale near-infrared surveys: the UKIDSS Ultra Deep Survey (UDS) and the Cosmic Evolution Survey (COSMOS). The former survey is complemented by 850 micron maps from the SCUBA-2 Cosmology Legacy Survey, from which SMGs are identified. Both UDS and COSMOS fields also benefit from a wide range of multi-wavelength imaging, vital for the photometric selection of PSB galaxies. I begin this thesis with a review of a novel Principal Component Analysis (PCA) technique used to select PSB galaxies with broad-band photometry. I implement this technique to identify ~4000 PSB candidates in the COSMOS field up to z=2.5, making this the largest high-redshift sample of its kind. The photometric selection of PSB candidates is confronted with spectroscopy, revealing that the PCA is robust. In Chapter 3, I set out to investigate the clustering of 610 SMG counterparts identified in the UDS field. Using angular cross-correlation techniques, I found that the SMGs, on average, occupy high-mass dark matter halos (M_halo > 10^13 solar masses) at redshifts z > 2.5, consistent with being the progenitors of massive quiescent galaxies in present day clusters. I also find evidence of halo downsizing, in which SMG activity shifts to lower mass haloes at lower redshifts. In terms of their clustering and halo masses, SMGs appear to be consistent with normal star-forming galaxies at any given redshift. In Chapter 4, I obtain clustering measurements for the PCA-selected populations in the UDS and COSMOS fields, using the same methodology as Chapter 3. Low-mass, low-redshift (0.5 < z < 1.0) PSB galaxies preferentially reside in very high-mass dark matter halos (M_halo > 10^14 solar masses) and are likely to be infalling satellite galaxies in cluster-like environments. Conversely, high-mass PSB galaxies are not as clustered. These key results indicate two main channels are responsible for the rapid quenching of galaxies. High-redshift (z > 1) galaxies tend to be quenched by feedback mechanisms related to the stellar mass of the galaxy ('mass-quenching'). Processes associated with dense environments ('environmental-quenching') are likely to be the key driver of rapid quenching of galaxies in the low-redshift Universe (z < 1). Finally, we present tentative evidence that SMGs pass through a PSB phase before migrating to the red-sequence, over timescales of ~500 Myr.
Chen, Chian-Chou, Smail, Ian, Swinbank, A. M., Simpson, James M., Almaini, Omar, Conselice, Christopher J., Hartley, Will G., Mortlock, Alice, Simpson, Chris, and Wilkinson, Aaron
The properties of submillimeter galaxies (SMGs) that are fainter than the confusion limit of blank-field single-dish surveys ($S_{850} \lesssim$ 2 mJy) are poorly constrained. Using a newly developed color selection technique, Optical-Infrared Triple Color (OIRTC), that has been shown to successfully {select} such faint SMGs, we identify a sample of 2938 OIRTC-selected galaxies, dubbed Triple Color Galaxies (TCGs), in the UKIDSS-UDS field. We show that these galaxies have a median 850 $\mu$m flux of S$_{850} = 0.96\pm0.04$ mJy (equivalent to a star-formation rate SFR $\sim60-100$ M$_\odot$ yr$^{-1}$ based on SED fitting), representing the first large sample of faint SMGs that bridges the gap between bright SMGs and normal star-forming galaxies in S$_{850}$ and $L_{\rm IR}$. We assess the basic properties of TCGs and their relationship with other galaxy populations at $z\sim2$. We measure the two-point autocorrelation function for this population and derive a typical halo mass of log$_{10}$(M$_{\rm halo}$) $=12.9^{+0.2}_{-0.3}$, $12.7^{+0.1}_{-0.2}$, and $12.9^{+0.2}_{-0.3}$ $h^{-1}$M$_\odot$ at $z=1-2$, $2-3$, and $3-5$, respectively. Together with the bright SMGs (S$_{850} \gtrsim 2$ mJy) and a comparison sample of less far-infrared luminous star-forming galaxies, we find a lack of dependence between spatial clustering and S$_{850}$ (or SFR), suggesting that the difference between these populations may lie in their local galactic environment. Lastly, on the scale of $\sim8-17$ kpc at $1
Cowley, William I., Lacey, Cedric G., Baugh, Carlton M., Cole, Shaun, and Wilkinson, Aaron
Placing bright sub-millimetre galaxies (SMGs) within the broader context of galaxy formation and evolution requires accurate measurements of their clustering, which can constrain the masses of their host dark matter halos. Recent work has shown that the clustering measurements of these galaxies may be affected by a `blending bias,' which results in the angular correlation function of the sources extracted from single-dish imaging surveys being boosted relative to that of the underlying galaxies. This is due to confusion introduced by the coarse angular resolution of the single-dish telescope and could lead to the inferred halo masses being significantly overestimated. We investigate the extent to which this bias affects the measurement of the correlation function of SMGs when it is derived via a cross-correlation with a more abundant galaxy population. We find that the blending bias is essentially the same as in the auto-correlation case and conclude that the best way to reduce its effects is to calculate the angular correlation function using SMGs in narrow redshift bins. Blending bias causes the inferred host halo masses of the SMGs to be overestimated by a factor of $\sim6$ when a redshift interval of $\delta z=3$ is used. However, this reduces to a factor of $\sim2$ for $\delta z=0.5$. The broadening of photometric redshift probability distributions with increasing redshift can therefore impart a mild halo `downsizing' effect onto the inferred host halo masses, though this trend is not as strong as seen in recent observational studies., Comment: 10 pages, 9 figures, 1 table. Accepted to MNRAS
Conselice, Christopher J., Wilkinson, Aaron, Duncan, Kenneth, and Mortlock, Alice
The evolution of the number density of galaxies in the universe, and thus also the total number of galaxies, is a fundamental question with implications for a host of astrophysical problems including galaxy evolution and cosmology. However there has never been a detailed study of this important measurement, nor a clear path to answer it. To address this we use observed galaxy stellar mass functions up to $z\sim8$ to determine how the number densities of galaxies changes as a function of time and mass limit. We show that the increase in the total number density of galaxies ($\phi_{\rm T}$), more massive than M$_{*} = 10^{6}$ M_0, decreases as $\phi_{\rm T} \sim t^{-1}$, where $t$ is the age of the universe. We further show that this evolution turns-over and rather increases with time at higher mass lower limits of M$_{*}>10^{7}$ M_0. By using the M$_{*}=10^{6}$ M_0 lower limit we further show that the total number of galaxies in the universe up to $z = 8$ is $2.0^{+0.7}_{-0.6} \times 10^{12}$ (two trillion), almost a factor of ten higher than would be seen in an all sky survey at Hubble Ultra-Deep Field depth. We discuss the implications for these results for galaxy evolution, as well as compare our results with the latest models of galaxy formation. These results also reveal that the cosmic background light in the optical and near-infrared likely arise from these unobserved faint galaxies. We also show how these results solve the question of why the sky at night is dark, otherwise known as Olbers' paradox., Comment: Accepted to AAS journals (ApJ), 22 pages, matches final published version
Wilkinson, Aaron, Almaini, Omar, Chen, Chian-Chou, Smail, Ian, Arumugam, Vinodiran, Blain, Andrew, Chapin, Edward L., Chapman, Scott C., Conselice, Christopher J., Cowley, William I., Dunlop, James S., Farrah, Duncan, Geach, James, Hartley, William G., Ivison, Rob J., Maltby, David T., Michałowski, Michał J., Mortlock, Alice, Scott, Douglas, Simpson, Chris, Simpson, James M., van der Werf, Paul, and Wild, Vivienne
Submillimetre galaxies (SMGs) are among the most luminous dusty galaxies in the Universe, but their true nature remains unclear; are SMGs the progenitors of the massive elliptical galaxies we see in the local Universe, or are they just a short-lived phase among more typical star-forming galaxies? To explore this problem further, we investigate the clustering of SMGs identified in the SCUBA-2 Cosmology Legacy Survey. We use a catalogue of submillimetre ($850\mu$m) source identifications derived using a combination of radio counterparts and colour/IR selection to analyse a sample of 914 SMGs in the UKIDSS Ultra Deep Survey (UDS), making this the largest high redshift sample of these galaxies to date. Using angular cross-correlation techniques, we estimate the halo masses for this large sample of SMGs and compare them with passive and star-forming galaxies selected in the same field. We find that SMGs, on average, occupy high-mass dark matter halos (M$_{\text{halo}} >10^{13}$M$_{\odot}$) at redshifts $z > 2.5$, consistent with being the progenitors of massive quiescent galaxies in present-day galaxy clusters. We also find evidence of downsizing, in which SMG activity shifts to lower mass halos at lower redshifts. In terms of their clustering and halo masses, SMGs appear to be consistent with other star-forming galaxies at a given redshift., Comment: Accepted for publication in MNRAS, 14 pages, 5 figures
Chen, Chian-Chou, Smail, Ian, Ivison, Rob J., Arumugam, Vinodiran, Almaini, Omar, Conselice, Christopher J., Geach, James E., Hartley, Will G., Ma, Cheng-Jiun, Mortlock, Alice, Simpson, Chris, Simpson, James M., Swinbank, A. Mark, Aretxaga, Itziar, Blain, Andrew, Chapman, Scott C., Dunlop, James S., Farrah, Duncan, Halpern, Mark, Michałowski, Michał J., van der Werf, Paul, Wilkinson, Aaron, and Zavala, Jorge A.
We present multiwavelength identifications for the counterparts of 1088 submillimeter sources detected at 850$\mu$m in the SCUBA-2 Cosmology Legacy Survey study of the UKIDSS-UDS field. By utilising an ALMA pilot study on a subset of our bright SCUBA-2 sample as a training set, along with the deep optical-near-infrared data available in this field, we develop a novel technique, Optical-IR Triple Color (OIRTC), using $z-K$, $K-[3.6]$, $[3.6]-[4.5]$ colors to select the candidate submillimeter galaxy (SMG) counterparts. By combining radio identification and the OIRTC technique, we find counterpart candidates for 80% of the Class = 1 $\geq4\,\sigma$ SCUBA-2 sample, defined as those that are covered by both radio and OIR imaging and the base sample for our scientific analyses. Based on the ALMA training set, we expect the accuracy of these identifications to be $82\pm20$%, with a completeness of $69\pm16$%, essentially as accurate as the traditional $p$-value technique but with higher completeness. We find that the fraction of SCUBA-2 sources having candidate counterparts is lower for fainter 850$\mu$m sources, and we argue that for follow-up observations sensitive to SMGs with $S_{850}\gtrsim 1$ mJy across the whole ALMA beam, the fraction with multiple counterparts is likely to be $>40$% for SCUBA-2 sources at $S_{850} \gtrsim 4$ mJy. We find that the photometric redshift distribution for the SMGs is well fit by a lognormal distribution, with a median redshift of $z=2.3\pm0.1$. After accounting for the sources without any radio and/or OIRTC counterpart, we estimate the median redshift to be $z=2.6\pm0.1$ for SMGs with $S_{850} >1$ mJy. We also use this new large sample to study the clustering of SMGs and the the far-infrared properties of the unidentified submillimeter sources by stacking their Herschel SPIRE far-infrared emission., Comment: ApJ in press, 23 pages, 17 figures
Wilkinson, Aaron D., primary and Rennaker, Mark, additional
Shek, Daniel T.L., primary and Wilkinson, Aaron D., additional
Wilkinson, Aaron D., primary
Wilkinson, Aaron
Wilkinson, Aaron
Wilkinson, Aaron, primary, Almaini, Omar, additional, Wild, Vivienne, additional, Maltby, David, additional, Hartley, William G, additional, Simpson, Chris, additional, and Rowlands, Kate, additional
Bentley, Sarah, Nicholls, Rickie, Price, Maxine, Wilkinson, Aaron, Purcell, Matthew, Woodhall, Martin, and Walmsley, Jan
Krishnan, Charutha, primary, Almaini, Omar, primary, Hatch, Nina A, primary, Wilkinson, Aaron, primary, Maltby, David T, primary, Conselice, Christopher J, primary, Kocevski, Dale, primary, Suh, Hyewon, primary, and Wild, Vivienne, primary
Wild, Vivienne, primary, Taj Aldeen, Laith, primary, Carnall, Adam, primary, Maltby, David, primary, Almaini, Omar, primary, Werle, Ariel, primary, Wilkinson, Aaron, primary, Rowlands, Kate, primary, Bolzonella, Micol, primary, Castellano, Marco, primary, Gargiulo, Adriana, primary, McLure, Ross, primary, Pentericci, Laura, primary, and Pozzetti, Lucia, primary
Johansson, Niklas G., primary, Turku, Ainoleena, additional, Vidilaseris, Keni, additional, Dreano, Loïc, additional, Khattab, Ayman, additional, Ayuso Pérez, Daniel, additional, Wilkinson, Aaron, additional, Zhang, Yuezhou, additional, Tamminen, Matti, additional, Grazhdankin, Evgeni, additional, Kiriazis, Alexandros, additional, Fishwick, Colin W. G., additional, Meri, Seppo, additional, Yli-Kauhaluoma, Jari, additional, Goldman, Adrian, additional, Boije af Gennäs, Gustav, additional, and Xhaard, Henri, additional
Wilkinson, Aaron and None
Post-starburst (PSB) galaxies are among the most rare and interesting classes of objects in extragalactic astronomy. Characterised by strong Balmer absorption lines in their spectra and consistent with a recent burst of star formation before a rapid quenching phase, PSB galaxies are thought to represent the transition between the blue cloud and red-sequence populations. To address the question of how the transition of galaxies occurs, we study the clustering of PSB galaxies in the combined UKIDSS UDS and COSMOS fields. We apply a novel PCA technique to identify a total of ~6000 PSB candidates in these two fields at redshifts 0.510^14M_solar. There is tentative evidence that high-mass (log(M*/M_solar)>10.5) PSB galaxies undergo halo downsizing, occupying smaller halos as the Universe ages. I will also use measurements of halo masses to link various galaxy populations across cosmic time. In particular, I will show that the extreme star-forming dusty galaxies, known as submillimetre galaxies (SMGs), are possible progenitors of high-mass PSB galaxies. These findings, combined with measurements of mass functions and structural properties, lead us to propose that PSB galaxies originated in two ways: (1) low-mass PSB galaxies are thought to be gas-rich star-forming satellites infalling into massive halos and are being rapidly quenched by environmental processes; (2) mass-quenching is likely to be the dominant driver of rapid quenching at high redshifts (z>1.5), where the progenitors of PSB galaxies undergo rapid dissipational collapse and gas-rich mergers, followed by a short period of extreme star-forming activity.
Maltby, David T, primary, Almaini, Omar, additional, McLure, Ross J, additional, Wild, Vivienne, additional, Dunlop, James, additional, Rowlands, Kate, additional, Hartley, William G, additional, Hatch, Nina A, additional, Socolovsky, Miguel, additional, Wilkinson, Aaron, additional, Amorin, Ricardo, additional, Bradshaw, Emma J, additional, Carnall, Adam C, additional, Castellano, Marco, additional, Cimatti, Andrea, additional, Cresci, Giovanni, additional, Cullen, Fergus, additional, De Barros, Stephane, additional, Fontanot, Fabio, additional, Garilli, Bianca, additional, Koekemoer, Anton M, additional, McLeod, Derek J, additional, Pentericci, Laura, additional, and Talia, Margherita, additional
Chen (陳建州), Chian-Chou, Smail, Ian, Swinbank, A.M., Simpson, James M., Almaini, Omar, Conselice, Christopher J., Hartley, Will G., Mortlock, Alice, Simpson, Chris, and Wilkinson, Aaron
The properties of submillimeter galaxies (SMGs) that are fainter than the confusion limit of blank-field single-dish surveys (S850 2 mJy) are poorly constrained. Using a newly developed color selection technique, Optical-Infrared Triple Color (OIRTC), that has been shown to successfully select such faint SMGs, we identify a sample of 2938 OIRTC-selected galaxies, dubbed Triple Color Galaxies (TCGs), in the UKIDSS-UDS field. We show that these galaxies have a median 850 μm flux of S850 = 0.96 +/- 0.04 mJy (equivalent to a star formation rate SFR ~60–100 M yr−1 based on spectral energy distribution fitting), representing the first large sample of faint SMGs that bridges the gap between bright SMGs and normal star-forming galaxies in S850 and LIR. We assess the basic properties of TCGs and their relationship with other galaxy populations at z ~ 2. We measure the two-point autocorrelation function for this population and derive a typical halo mass of log10(Mhalo) = -12.9+0.2-0.3, 12.7+0.1,-0.2, and 12.9+0.2,-0,3 h-1 M at z = 1–2, 2–3, and 3–5, respectively. Together with the bright SMGs (S850 >/~ 2 mJy) and a comparison sample of less far-infrared luminous star-forming galaxies, we find a lack of dependence between spatial clustering and S850 (or SFR), suggesting that the difference between these populations may lie in their local galactic environment. Lastly, on the scale of ~8–17 kpc at 1 < z < 5 we find a tentative enhancement of the clustering of TCGs over the comparison star-forming galaxies, suggesting that some faint SMGs are physically associated pairs, perhaps reflecting a merging origin in their triggering.
Cowley, William I., primary, Lacey, Cedric G., additional, Baugh, Carlton M., additional, Cole, Shaun, additional, and Wilkinson, Aaron, additional
Chen (陳建州), Chian-Chou, primary, Smail, Ian, additional, Swinbank, A. M., additional, Simpson, James M., additional, Almaini, Omar, additional, Conselice, Christopher J., additional, Hartley, Will G., additional, Mortlock, Alice, additional, Simpson, Chris, additional, and Wilkinson, Aaron, additional
Conselice, Christopher J., primary, Wilkinson, Aaron, additional, Duncan, Kenneth, additional, and Mortlock, Alice, additional
Wilkinson, Aaron, primary, Almaini, Omar, additional, Chen, Chian-Chou, additional, Smail, Ian, additional, Arumugam, Vinodiran, additional, Blain, Andrew, additional, Chapin, Edward L., additional, Chapman, Scott C., additional, Conselice, Christopher J., additional, Cowley, William I., additional, Dunlop, James S., additional, Farrah, Duncan, additional, Geach, James, additional, Hartley, William G., additional, Ivison, Rob J., additional, Maltby, David T., additional, Michałowski, Michał J., additional, Mortlock, Alice, additional, Scott, Douglas, additional, Simpson, Chris, additional, Simpson, James M., additional, van der Werf, Paul, additional, and Wild, Vivienne, additional
Chen (陳建州), Chian-Chou, primary, Smail, Ian, additional, Ivison, Rob J., additional, Arumugam, Vinodiran, additional, Almaini, Omar, additional, Conselice, Christopher J., additional, Geach, James E., additional, Hartley, Will G., additional, Ma, Cheng-Jiun, additional, Mortlock, Alice, additional, Simpson, Chris, additional, Simpson, James M., additional, Swinbank, A. Mark, additional, Aretxaga, Itziar, additional, Blain, Andrew, additional, Chapman, Scott C., additional, Dunlop, James S., additional, Farrah, Duncan, additional, Halpern, Mark, additional, Michałowski, Michał J., additional, van der Werf, Paul, additional, Wilkinson, Aaron, additional, and Zavala, Jorge A., additional
Wilkinson, Aaron, Almaini, Omar, Chian-Chou Chen, Smail, Ian, Arumugam, Vinodiran, Blain, Andrew, Chapin, Edward L., Chapman, Scott C., Conselice, Christopher J., Cowley, William I., Dunlop, James S., Farrah, Duncan, Geach, James, Hartley, William G., Ivison, Rob J., Maltby, David T., Michałowski, Michał J., Mortlock, Alice, Scott, Douglas, and Simpson, Chris
Submillimetre galaxies (SMGs) are among the most luminous dusty galaxies in the Universe, but their true nature remains unclear; are SMGs the progenitors of the massive elliptical galaxies we see in the local Universe, or are they just a short-lived phase among more typical star-forming galaxies? To explore this problem further, we investigate the clustering of SMGs identified in the SCUBA-2 Cosmology Legacy Survey. We use a catalogue of submillimetre (850 µm) source identifications derived using a combination of radio counterparts and colour/infrared selection to analyse a sample of 610 SMG counterparts in the United Kingdom Infrared Telescope (UKIRT) Infrared Deep Survey (UKIDSS) Ultra Deep Survey (UDS), making this the largest high-redshift sample of these galaxies to date. Using angular cross-correlation techniques, we estimate the halo masses for this large sample of SMGs and compare them with passive and star-forming galaxies selected in the same field. We find that SMGs, on average, occupy high-mass dark matter haloes (Mhalo > 1013 M⊙) at redshifts z > 2.5, consistent with being the progenitors of massive quiescent galaxies in present-day galaxy clusters. We also find evidence of downsizing, in which SMG activity shifts to lower mass haloes at lower redshifts. In terms of their clustering and halo masses, SMGs appear to be consistent with other star-forming galaxies at a given redshift. [ABSTRACT FROM AUTHOR]
Wilkinson, Aaron
Andrew Byers is deeply concerned for the Christian cynic. In Faith Without Illusions: Following Jesus as a Cynic-Saint (IVP), Byers admits to falling in and out of cynicism himself. He [...]
Welby, Christine E., primary, Armitage, Georgina K., additional, Bartley, Harry, additional, Wilkinson, Aaron, additional, Sinopoli, Alessandro, additional, Uppal, Baljinder S., additional, Rice, Craig R., additional, and Elliott, Paul I. P., additional
Welby, Christine E., Armitage, Georgina K., Bartley, Harry, Wilkinson, Aaron, Sinopoli, Alessandro, Uppal, Baljinder S., Rice, Craig R., and Elliott, Paul I. P.
We report the unprecedented observation and unequivocal crystallographic characterization of the meta-stable ligand loss intermediate solvento complex trans-[Ru(bpy)(κ
Conselice, Christopher J., Wilkinson, Aaron, Duncan, Kenneth, Mortlock, Alice, Conselice, Christopher J., Wilkinson, Aaron, Duncan, Kenneth, and Mortlock, Alice
The evolution of the number density of galaxies in the universe, and thus also the total number of galaxies, is a fundamental question with implications for a host of astrophysical problems including galaxy evolution and cosmology. However there has never been a detailed study of this important measurement, nor a clear path to answer it. To address this we use observed galaxy stellar mass functions up to z _ 8 to determine how the number densities of galaxies changes as a function of time and mass limit. We show that the increase in the total number density of galaxies (_T), more massive than M∗ = 106 M⊙ , decreases as _T _ t−1, where t is the age of the universe. We further show that this evolution turns-over and rather increases with time at higher mass lower limits of M∗ > 107 M⊙ . By using the M∗ = 106 M⊙ lower limit we further show that the total number of galaxies in the universe up to z = 8 is 2.0+0.7 −0.6 × 1012 (two trillion), almost a factor of ten higher than would be seen in an all sky survey at Hubble Ultra-Deep Field depth. We discuss the implications for these results for galaxy evolution, as well as compare our results with the latest models of galaxy formation. These results also reveal that the cosmic background light in the optical and near-infrared likely arise from these unobserved faint galaxies. We also show how these results solve the question of why the sky at night is dark, otherwise known as Olbers’ paradox.
Conselice, Christopher J., Wilkinson, Aaron, Duncan, Kenneth, Mortlock, Alice, Conselice, Christopher J., Wilkinson, Aaron, Duncan, Kenneth, and Mortlock, Alice
The evolution of the number density of galaxies in the universe, and thus also the total number of galaxies, is a fundamental question with implications for a host of astrophysical problems including galaxy evolution and cosmology. However there has never been a detailed study of this important measurement, nor a clear path to answer it. To address this we use observed galaxy stellar mass functions up to z _ 8 to determine how the number densities of galaxies changes as a function of time and mass limit. We show that the increase in the total number density of galaxies (_T), more massive than M∗ = 106 M⊙ , decreases as _T _ t−1, where t is the age of the universe. We further show that this evolution turns-over and rather increases with time at higher mass lower limits of M∗ > 107 M⊙ . By using the M∗ = 106 M⊙ lower limit we further show that the total number of galaxies in the universe up to z = 8 is 2.0+0.7 −0.6 × 1012 (two trillion), almost a factor of ten higher than would be seen in an all sky survey at Hubble Ultra-Deep Field depth. We discuss the implications for these results for galaxy evolution, as well as compare our results with the latest models of galaxy formation. These results also reveal that the cosmic background light in the optical and near-infrared likely arise from these unobserved faint galaxies. We also show how these results solve the question of why the sky at night is dark, otherwise known as Olbers’ paradox.
Conselice, Christopher J., Wilkinson, Aaron, Duncan, Kenneth, Mortlock, Alice, Conselice, Christopher J., Wilkinson, Aaron, Duncan, Kenneth, and Mortlock, Alice
The evolution of the number density of galaxies in the universe, and thus also the total number of galaxies, is a fundamental question with implications for a host of astrophysical problems including galaxy evolution and cosmology. However there has never been a detailed study of this important measurement, nor a clear path to answer it. To address this we use observed galaxy stellar mass functions up to z _ 8 to determine how the number densities of galaxies changes as a function of time and mass limit. We show that the increase in the total number density of galaxies (_T), more massive than M∗ = 106 M⊙ , decreases as _T _ t−1, where t is the age of the universe. We further show that this evolution turns-over and rather increases with time at higher mass lower limits of M∗ > 107 M⊙ . By using the M∗ = 106 M⊙ lower limit we further show that the total number of galaxies in the universe up to z = 8 is 2.0+0.7 −0.6 × 1012 (two trillion), almost a factor of ten higher than would be seen in an all sky survey at Hubble Ultra-Deep Field depth. We discuss the implications for these results for galaxy evolution, as well as compare our results with the latest models of galaxy formation. These results also reveal that the cosmic background light in the optical and near-infrared likely arise from these unobserved faint galaxies. We also show how these results solve the question of why the sky at night is dark, otherwise known as Olbers’ paradox.
Wilkinson, Aaron K.R. and Wilkinson, Aaron K.R.
Submillimetre galaxies (SMGs) and post-starburst (PSB) galaxies are among the most rare and interesting classes of objects in extragalactic study. SMGs are extremely active dust-obscured galaxies in the early Universe, forming stars with an immense rate of up to 1000 solar masses per year. PSB galaxies are characterised by strong Balmer absorption lines in their spectra, consistent with a recent burst of star formation before being rapidly quenched. The origin of both of these objects and how they relate to the more common populations of red-sequence and blue-cloud galaxies remain elusive. My thesis involves weighing the dark matter halos inhabited by these rare galaxies, by investigating their clustering at 0.5
Conselice, Christopher J., Wilkinson, Aaron, Duncan, Kenneth, Mortlock, Alice, Conselice, Christopher J., Wilkinson, Aaron, Duncan, Kenneth, and Mortlock, Alice
The evolution of the number density of galaxies in the universe, and thus also the total number of galaxies, is a fundamental question with implications for a host of astrophysical problems including galaxy evolution and cosmology. However there has never been a detailed study of this important measurement, nor a clear path to answer it. To address this we use observed galaxy stellar mass functions up to z _ 8 to determine how the number densities of galaxies changes as a function of time and mass limit. We show that the increase in the total number density of galaxies (_T), more massive than M∗ = 106 M⊙ , decreases as _T _ t−1, where t is the age of the universe. We further show that this evolution turns-over and rather increases with time at higher mass lower limits of M∗ > 107 M⊙ . By using the M∗ = 106 M⊙ lower limit we further show that the total number of galaxies in the universe up to z = 8 is 2.0+0.7 −0.6 × 1012 (two trillion), almost a factor of ten higher than would be seen in an all sky survey at Hubble Ultra-Deep Field depth. We discuss the implications for these results for galaxy evolution, as well as compare our results with the latest models of galaxy formation. These results also reveal that the cosmic background light in the optical and near-infrared likely arise from these unobserved faint galaxies. We also show how these results solve the question of why the sky at night is dark, otherwise known as Olbers’ paradox.
Wilkinson, Aaron
Reports that the Jefferson Parish Economic Development & Port District in New Orleans, Louisiana has convinced the US Army Corps of Engineers to reconsider its July 30, 1998 decision against dredging silted areas of the channel that leads from the Gulf Intracoastal Waterway to Bayou Segnette to Weswego. Impact of the previous dredging on the channel; Findings of the port district's evaluation on the project.
Wilkinson, Aaron
Discusses the things that a businessman should look into when planning to sell his business. Importance of figuring out the total value of the business; Role of appraisers in establishing a fair price; Consideration of ways to structure a deal with fewer tax implications.
Wilkinson, Aaron
Reports on developments concerning the oil and gas industry in the United States as of May 25, 1998. Includes Chalmette Refining LLC's multinational board of directors' development of capital investment strategies for its first year of operation; Chevron Chemical Co. LLC's plan to spend $15 million to build a facility to produce polyisobutene to reduce its raw materials costs.
Wilkinson, Aaron
Presents news briefs relating to the economy of New Orleans, Louisiana. Actions taken by business owners on the Chef Menteur Highway against prostitutes who frequent their store fronts; Who came up with the plan; Comments from Gus Deruise, quality of life officer for the New Orleans Police Department's 7th District; Launch of the New Orleans East Economic Development Foundation's second phase of its image building campaign.
Wilkinson, Aaron
The article provides an update on the Peterlee Parachute Centre in Great Britain as of August 2014 including jumps completed, weather and coaches.
Wilkinson, Aaron
The article reports the activities at Skydive Academy (skydiveacademy.org.uk) in Peterlee, Durham, England as of June 2014, including the British Collegiate Parachute Association (BCPA) event in March 2014 and the return of member/instructor Bryan Dyas from Spain.
Welby, Christine E., Armitage, Georgina K., Bartley, Harry, Wilkinson, Aaron, Sinopoli, Alessandro, Uppal, Baljinder S., Rice, Craig R., and Elliott, Paul I. P.
We report the unprecedented observation and unequivocal crystallographic characterization of the meta-stable ligand loss intermediate solvento complex trans-[Ru(bpy)(κ2-btz)(κ1-btz)(NCMe)]2+ ( 1 a) that contains a monodentate chelate ligand. This and analogous complexes can be observed during the photolysis reactions of a family of complexes of the form [Ru( $\widehat{NN}$)(btz)2]2+ ( 1 a- d: btz=1,1′-dibenzyl-4,4′-bi-1,2,3-triazolyl; $\widehat{NN}$=a) 2,2′-bipyridyl (bpy), b) 4,4′-dimethyl-2,2′-bipyridyl (dmbpy), c) 4,4′-dimethoxy-2,2′-bipyridyl (dmeobpy), d) 1,10-phenanthroline (phen)). In acetonitrile solutions, 1 a- d eventually convert to the bis-solvento complexes trans-[Ru( $\widehat{NN}$)(btz)(NCMe)2]2+ ( 3 a- d) along with one equivalent of free btz, in a process in which the remaining coordinated bidentate ligands undergo a new rearrangement such that they become coplanar. X-ray crystal structure of 3 a and 3 d confirmed the co-planar arrangement of the $\widehat{NN}$ and btz ligands and the trans coordination of two solvent molecules. These conversions proceed via the observed intermediate complexes 2 a- d, which are formed quantitatively from 1 a- d in a matter of minutes and to which they slowly revert back on being left to stand in the dark over several days. The remarkably long lifetime of the intermediate complexes (>12 h at 40 °C) allowed the isolation of 2 a in the solid state, and the complex to be crystallographically characterized. Similarly to the structures adopted by complexes 3 a and d, the bpy and κ2-btz ligands in 2 a coordinate in a square-planar fashion with the second monodentate btz ligand coordinated trans to an acetonitrile ligand. [ABSTRACT FROM AUTHOR]
Ricardo Amorín, Nina A. Hatch, Anton M. Koekemoer, Kate Rowlands, Fabio Fontanot, Andrea Cimatti, Bianca Garilli, Fergus Cullen, James Dunlop, Vivienne Wild, Ross J. McLure, William G. Hartley, Margherita Talia, David T. Maltby, Miguel Socolovsky, D. J. McLeod, Giovanni Cresci, A. C. Carnall, Omar Almaini, Marco Castellano, Aaron Wilkinson, Laura Pentericci, E. J. Bradshaw, Stephane de Barros, Maltby, David T, Almaini, Omar, McLure, Ross J, Wild, Vivienne, Dunlop, Jame, Rowlands, Kate, Hartley, William G, Hatch, Nina A, Socolovsky, Miguel, Wilkinson, Aaron, Amorin, Ricardo, Bradshaw, Emma J, Carnall, Adam C, Castellano, Marco, Cimatti, Andrea, Cresci, Giovanni, Cullen, Fergu, De Barros, Stephane, Fontanot, Fabio, Garilli, Bianca, Koekemoer, Anton M, McLeod, Derek J, Pentericci, Laura, Talia, Margherita, and University of St Andrews. School of Physics and Astronomy
We investigate the prevalence of galactic-scale outflows in post-starburst (PSB) galaxies at high redshift ($1 < z < 1.4$), using the deep optical spectra available in the UKIDSS Ultra Deep Survey (UDS). We use a sample of $\sim40$ spectroscopically confirmed PSBs, recently identified in the UDS field, and perform a stacking analysis in order to analyse the structure of strong interstellar absorption features such as Mg ii ($\lambda2800$ Ang.). We find that for massive ($M_* > 10^{10}\rm\,M_{\odot}$) PSBs at $z > 1$, there is clear evidence for a strong blue-shifted component to the Mg ii absorption feature, indicative of high-velocity outflows ($v_{\rm out}\sim1150\pm160\rm\,km\,s^{-1}$) in the interstellar medium. We conclude that such outflows are typical in massive PSBs at this epoch, and potentially represent the residual signature of a feedback process that quenched these galaxies. Using full spectral fitting, we also obtain a typical stellar velocity dispersion $��_*$ for these PSBs of $\sim200\rm\,km\,s^{-1}$, which confirms they are intrinsically massive in nature (dynamical mass $M_{\rm d}\sim10^{11}\rm\,M_{\odot}$). Given that these high-$z$ PSBs are also exceptionally compact ($r_{\rm e}\sim1$--$2\rm\,kpc$) and spheroidal (Sersic index $n\sim3$), we propose that the outflowing winds may have been launched during a recent compaction event (e.g. major merger or disc collapse) that triggered either a centralised starburst or active galactic nuclei (AGN) activity. Finally, we find no evidence for AGN signatures in the optical spectra of these PSBs, suggesting they were either quenched by stellar feedback from the starburst itself, or that if AGN feedback is responsible, the AGN episode that triggered quenching does not linger into the post-starburst phase., 13 pages, 6 figures, accepted for publication in MNRAS
Welby CE, Armitage GK, Bartley H, Wilkinson A, Sinopoli A, Uppal BS, Rice CR, and Elliott PI
We report the unprecedented observation and unequivocal crystallographic characterization of the meta-stable ligand loss intermediate solvento complex trans-[Ru(bpy)(κ(2) -btz)(κ(1) -btz)(NCMe)](2+) (1 a) that contains a monodentate chelate ligand. This and analogous complexes can be observed during the photolysis reactions of a family of complexes of the form [Ru({NN})(btz)(2)](2+) (1 a-d: btz=1,1'-dibenzyl-4,4'-bi-1,2,3-triazolyl; {NN}=a) 2,2'-bipyridyl (bpy), b) 4,4'-dimethyl-2,2'-bipyridyl (dmbpy), c) 4,4'-dimethoxy-2,2'-bipyridyl (dmeobpy), d) 1,10-phenanthroline (phen)). In acetonitrile solutions, 1 a-d eventually convert to the bis-solvento complexes trans-[Ru({NN})(btz)(NCMe)(2)](2+) (3 a-d) along with one equivalent of free btz, in a process in which the remaining coordinated bidentate ligands undergo a new rearrangement such that they become coplanar. X-ray crystal structure of 3 a and 3 d confirmed the co-planar arrangement of the {NN} and btz ligands and the trans coordination of two solvent molecules. These conversions proceed via the observed intermediate complexes 2 a-d, which are formed quantitatively from 1 a-d in a matter of minutes and to which they slowly revert back on being left to stand in the dark over several days. The remarkably long lifetime of the intermediate complexes (>12 h at 40 °C) allowed the isolation of 2 a in the solid state, and the complex to be crystallographically characterized. Similarly to the structures adopted by complexes 3 a and d, the bpy and κ(2) -btz ligands in 2 a coordinate in a square-planar fashion with the second monodentate btz ligand coordinated trans to an acetonitrile ligand., (2014 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.)
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