Eridanus - A Supergroup in the Local Universe?

We examine a possible supergroup in the direction of the Eridanus constellation using 6dF Galaxy Survey second data release (6dFGS DR2) positions and velocities together with 2MASS and HyperLEDA photometry. We perform a friends-of-friends analysis to determine which galaxies are associated with each substructure before examining the properties of the constituent galaxies. The structure is made up of three individual groups that are likely to merge to form a cluster of mass 7x10^13 Msolar. We conclude that this structure is a supergroup. We also examine the colours, morphologies and luminosities of the galaxies in the region with respect to their local projected surface density. We find that the colours of the galaxies redden with increasing density, the median luminosities are brighter with increasing environmental density and the morphologies of the galaxies show a strong morphology-density relation. The colours and luminosities of the galaxies in the supergroup are already similar to those of galaxies in clusters, however the supergroup contains more late-type galaxies, consistent with its lower projected surface density. Due to the velocity dispersion of the groups in the supergroup, which are lower than those of clusters, we conclude that the properties of the constituent galaxies are likely to be a result of merging or strangulation processes in groups outlying this structure.Comment: Accepted for publication in MNRA

Thermo-kinetic mixing for pharmaceutical applications

Compositions and methods for making a pharmaceutical dosage form include making a pharmaceutical composition that includes one or more active pharmaceutical ingredients (API) with one or more pharmaceutically acceptable excipients by thermokinetic compounding into a composite. Compositions and methods of preprocessing a composite comprising one or more APIs with one or more excipients include thermokinetic compounding, comprising thermokinetic processing the APIs with the excipients into a composite, wherein the composite can be further processed by conventional methods known in the art, such as hot melt extrusion, melt granulation, compression molding, tablet compression, capsule filling, film-coating, or injection molding.Board of Regents, University of Texas Syste

Galaxy And Mass Assembly (GAMA) : The mechanisms for quiescent galaxy formation at z<1

© 2016 The Authors. One key problem in astrophysics is understanding how and why galaxies switch off their star formation, building the quiescent population that we observe in the local Universe. From the Galaxy And Mass Assembly and VIsible MultiObject Spectrograph Public Extragalactic Redshift surveys, we use spectroscopic indices to select quiescent and candidate transition galaxies.We identify potentially rapidly transitioning post-starburst (PSB) galaxies and slower transitioning green-valley galaxies. Over the last 8Gyr, the quiescent population has grown more slowly in number density at high masses (M * > 10 11 M ⊙ ) than at intermediate masses (M * > 10 10.6 M ⊙ ). There is evolution in both the PSB and green-valley stellar mass functions, consistent with higher mass galaxies quenching at earlier cosmic times.At intermediatemasses (M * > 10 10.6 M ⊙ ), we find a green-valley transition time-scale of 2.6 Gyr. Alternatively, at z ~ 0.7, the entire growth rate could be explained by fast-quenching PSB galaxies, with a visibility time-scale of 0.5 Gyr. At lower redshift, the number density of PSBs is so low that an unphysically short visibility window would be required for them to contribute significantly to the quiescent population growth. The importance of the fast-quenching route may rapidly diminish at z 10 11 M ⊙ ), there is tension between the large number of candidate transition galaxies compared to the slow growth of the quiescent population. This could be resolved if not all high-mass PSB and green-valley galaxies are transitioning from star forming to quiescent, for example if they rejuvenate out of the quiescent population following the accretion of gas and triggering of star formation, or if they fail to completely quench their star formation

Comparative nanostructure analysis of gasoline turbocharged direct injection and diesel soot-in-oil with carbon black

Two gasoline turbocharged direct injection (GTDI) and two diesel soot-in-oil samples were compared with one flame-generated soot sample. High resolution transmission electron microscopy imaging was employed for the initial qualitative assessment of the soot morphology. Carbon black and diesel soot both exhibit core-shell structures, comprising an amorphous core surrounded by graphene layers; only diesel soot has particles with multiple cores. In addition to such particles, GTDI soot also exhibits entirely amorphous structures, of which some contain crystalline particles only a few nanometers in diameter. Subsequent quantification of the nanostructure by fringe analysis indicates differences between the samples in terms of length, tortuosity, and separation of the graphitic fringes. The shortest fringes are exhibited by the GTDI samples, whilst the diesel soot and carbon black fringes are 9.7% and 15.1% longer, respectively. Fringe tortuosity is similar across the internal combustion engine samples, but lower for the carbon black sample. In contrast, fringe separation varies continuously among the samples. Raman spectroscopy further confirms the observed differences. The GTDI soot samples contain the highest fraction of amorphous carbon and defective graphitic structures, followed by diesel soot and carbon black respectively. The AD1:AG ratios correlate linearly with both the fringe length and fringe separation

Galaxy And Mass Assembly (GAMA): growing up in a bad neighbourhood - how do low-mass galaxies become passive?

Both theoretical predictions and observations of the very nearby Universe suggest that low-mass galaxies (log$_{10}$[M$_{*}$/M$_{\odot}$]<9.5) are likely to remain star-forming unless they are affected by their local environment. To test this premise, we compare and contrast the local environment of both passive and star-forming galaxies as a function of stellar mass, using the Galaxy and Mass Assembly survey. We find that passive fractions are higher in both interacting pair and group galaxies than the field at all stellar masses, and that this effect is most apparent in the lowest mass galaxies. We also find that essentially all passive log$_{10}$[M$_{*}$/M$_{\odot}$]<8.5 galaxies are found in pair/group environments, suggesting that local interactions with a more massive neighbour cause them to cease forming new stars. We find that the effects of immediate environment (local galaxy-galaxy interactions) in forming passive systems increases with decreasing stellar mass, and highlight that this is potentially due to increasing interaction timescales giving sufficient time for the galaxy to become passive via starvation. We then present a simplistic model to test this premise, and show that given our speculative assumptions, it is consistent with our observed results.Comment: 20 pages, 12 figures, Accepted to MNRA

Galaxy and mass assembly (GAMA): the clustering of galaxy groups

We explore the clustering of galaxy groups in the Galaxy and Mass Assembly (GAMA) survey to investigate the dependence of group bias and profile on separation scale and group mass. Due to the inherent uncertainty in estimating the group selection function, and hence the group autocorrelation function, we instead measure the projected galaxy–group cross-correlation function. We find that the group profile has a strong dependence on scale and group mass on scales r⊥≲1h−1 role= presentation style= box-sizing: border-box; margin: 0px; padding: 0px; border: 0px; font-variant: inherit; font-stretch: inherit; line-height: normal; font-family: inherit; vertical-align: baseline; display: inline; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; position: relative; \u3er⊥≲1h−1r⊥≲1h−1⁠. We also find evidence that the most massive groups live in extended, overdense, structures. In the first application of marked clustering statistics to groups, we find that group-mass marked clustering peaks on scales comparable to the typical group radius of r⊥ ≈ 0.5 h−1. While massive galaxies are associated with massive groups, the marked statistics show no indication of galaxy mass segregation within groups. We show similar results from the IllustrisTNG simulations and the L-GALAXIES model, although L-GALAXIES shows an enhanced bias and galaxy mass dependence on small scales

Red riding on hood: Exploring how galaxy colour depends on environment

Galaxy populations are known to exhibit a strong colour bimodality, corresponding to blue star-forming and red quiescent subpopulations. The relative abundance of the two populations has been found to vary with stellar mass and environment. In this paper, we explore the effect of environment considering different types of measurements. We choose a sample of $49, 911$ galaxies with $0.05 < z < 0.18$ from the Galaxy And Mass Assembly survey. We study the dependence of the fraction of red galaxies on different measures of the local environment as well as the large-scale "geometric" environment defined by density gradients in the surround- ing cosmic web. We find that the red galaxy fraction varies with the environment at fixed stellar mass. The red fraction depends more strongly on local environmental measures than on large-scale geometric environment measures. By comparing the different environmental densities, we show that no density measurement fully explains the observed environmental red fraction variation, suggesting the different measures of environmental density contain different information. We test whether the local environmental measures, when combined together, can explain all the observed environmental red fraction variation. The geometric environment has a small residual effect, and this effect is larger for voids than any other type of geometric environment. This could provide a test of the physics applied to cosmological-scale galaxy evolution simulations as it combines large-scale effects with local environmental impact.Comment: Accepted for publication in MNRAS; 16 pages; 10 figures; 2 tables

Galaxy And Mass Assembly (GAMA): blue spheroids within 87 Mpc

© 2017 The Author(s). In this paper, we test if nearby blue spheroid (BSph) galaxies may become the progenitors of star-forming spiral galaxies or passively evolving elliptical galaxies. Our sample comprises 428 galaxies of various morphologies in the redshift range 0.002 < Ζ < 0.02 (8-87 Mpc) with panchromatic data from the Galaxy and Mass Assembly survey. We find that BSph galaxies are structurally (mean effective surface brightness, effective radius) very similar to their passively evolving red counterparts. However, their star formation and other properties such as colour, age, and metallicity are more like star-forming spirals than spheroids (ellipticals and lenticulars). We show that BSph galaxies are statistically distinguishable from other spheroids as well as spirals in the multidimensional space mapped by luminosity-weighted age, metallicity, dust mass, and specific star formation rate. We use HI data to reveal that some of the BSphs are (further) developing their discs, hence their blue colours. They may eventually become spiral galaxies - if sufficient gas accretion occurs - or more likely fade into low-mass red galaxies

Galaxy and Mass Assembly (GAMA): Demonstrating the Power of WISE in the Study of Galaxy Groups to z \u3c 0.1

Combining high-fidelity group characterization from the Galaxy and Mass Assembly survey and source-tailored z \u3c 0.1 photometry from the Wide-Field Infrared Survey Explorer (WISE) survey, we present a comprehensive study of the properties of ungrouped galaxies, compared to 497 galaxy groups (4 ≤ N FoF ≤ 20) as a function of stellar and halo mass. Ungrouped galaxies are largely unimodal in WISE color, the result of being dominated by star-forming, late-type galaxies. Grouped galaxies, however, show a clear bimodality in WISE color, which correlates strongly with stellar mass and morphology. We find evidence for an increasing early-type fraction, in stellar mass bins between 1010 M o˙ ≲ M stellar ≲ 1011 M o˙, with increasing halo mass. Using ungrouped, late-type galaxies with star-forming colors (W2-W3 \u3e 3), we define a star-forming main sequence (SFMS), which we use to delineate systems that have moved below the sequence ( quenched for the purposes of this work). We find that with increasing halo mass, the relative number of late-type systems on the SFMS decreases, with a corresponding increase in early-type, quenched systems at high stellar mass (M stellar \u3e 1010.5 M o˙), consistent with mass quenching. Group galaxies with masses M stellar \u3c 1010.5 M o˙ show evidence of quenching consistent with environmentally driven processes. The stellar mass distribution of late-type, quenched galaxies suggests that it may be an intermediate population as systems transition from being star-forming and late-type to the red sequence. Finally, we use the projected area of groups on the sky to extract groups that are (relatively) compact for their halo mass. Although these show a marginal increase in their proportion of high-mass and early-type galaxies compared to nominal groups, a clear increase in quenched fraction is not evident

The SAMI Galaxy Survey: gas content and interaction as the drivers of kinematic asymmetry

In order to determine the causes of kinematic asymmetry in the H$\alpha$ gas in the SAMI Galaxy Survey sample, we investigate the comparative influences of environment and intrinsic properties of galaxies on perturbation. We use spatially resolved H$\alpha$ velocity fields from the SAMI Galaxy Survey to quantify kinematic asymmetry ($\overline{v_{asym}}$) in nearby galaxies and environmental and stellar mass data from the GAMA survey. {We find that local environment, measured as distance to nearest neighbour, is inversely correlated with kinematic asymmetry for galaxies with $\mathrm{\log(M_*/M_\odot)}>10.0$, but there is no significant correlation for galaxies with $\mathrm{\log(M_*/M_\odot)}<10.0$. Moreover, low mass galaxies ($\mathrm{\log(M_*/M_\odot)}<9.0$) have greater kinematic asymmetry at all separations, suggesting a different physical source of asymmetry is important in low mass galaxies.} We propose that secular effects derived from gas fraction and gas mass may be the primary causes of asymmetry in low mass galaxies. High gas fraction is linked to high $\frac{\sigma_{m}}{V}$ (where $\sigma_m$ is H$\alpha$ velocity dispersion and $V$ the rotation velocity), which is strongly correlated with $\overline{v_{asym}}$, and galaxies with $\log(M_*/M_\odot)<9.0$ have offset $\overline{\frac{\sigma_{m}}{V}}$ from the rest of the sample. Further, asymmetry as a fraction of dispersion decreases for galaxies with $\log(M_*/M_\odot)<9.0$. Gas mass and asymmetry are also inversely correlated in our sample. We propose that low gas masses in dwarf galaxies may lead to asymmetric distribution of gas clouds, leading to increased relative turbulence.Comment: 15 pages, 20 figure