ORCID Profile
0000-0002-8956-7024
Current Organisation
University of St Andrews
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Publisher: Oxford University Press (OUP)
Date: 27-10-2017
Publisher: Oxford University Press (OUP)
Date: 02-09-2010
Publisher: Oxford University Press (OUP)
Date: 02-10-2017
Publisher: American Association of Physics Teachers
Date: 10-10-2021
Publisher: EDP Sciences
Date: 10-2016
Publisher: Oxford University Press (OUP)
Date: 07-02-2013
DOI: 10.1093/MNRAS/STT030
Publisher: Cambridge University Press (CUP)
Date: 08-2006
DOI: 10.1017/S174392130601026X
Abstract: BACKGROUND: In the process of galaxy formation, super-nova driven feedback from low-mass galaxies is the process that most readily account for the galaxy mass-metallicity relation and for the shallower galaxy luminosity function (LF) compared to the halo mass function. Absorption-selected galaxies are prime candidates for the sites of starburst activity as (1) they probe the gaseous halos of galaxies up to ~50 kpc (Steidel 1995), and (2) galaxies on the faint end of the LF are likely dominating the statistics. Galaxies selected via their MgII λ2796/2803 doublet absorption against background QSOs are especially well suited as Mg is produced by type II supernova. GOAL: Our project was to constrain the physical models of the gaseous halos by measuring the dark matter halo-mass ( M h ) of the MgII host-galaxies statistically , i.e. without identifying spectroscopically the host-galaxy. METHOD: We have used the cross-correlation w ( r θ ) (over co-moving scales r θ :0.05–13 h −1 Mpc) between our s le of 1800 z ≃ 0.5 MgII absorbers with equivalent w width W 2796 r −0.3 Å, and 250,000 Luminous Red Galaxies (LRGs), both selected from SDSS/DR3. The cross-correlation relies on the LRG photometric redshifts, but is not affected from contaminants such as stars or foreground and background galaxies as shown theoretically in Bouché et al. 2005 and empirically in Bouché et al . 2006. RESULTS: From the cross-correlation analysis, we found (Bouché et al . 2006) (i) that the absorber host-halo mean mass is 〈 log M h ( M ⊙ )〉 = 11.94 ±0.31(stat) +0.24 −0.25 (sys), i.e. about 1/2 L *, and (ii) an anti-correlation between halo mass M h and equivalent width W 2796 r . INTERPRETATION: One SDSS MgII absorber (system) is made of several sub-components or clouds and the stronger the equivalent with of the absorber, the more clouds per system spread over a larger velocity range (Δ v ). This follows since each sub-component has a velocity width of ~ 5 kms s −1 (Churchill 1997). As result, the equivalent width W 2796 r is a measure of velocity width (Δ v ) as demonstrated by Ellison 2006. Together with our SDSS results, these relations imply a mass–velocity M h –Δ v anti-correlation. If the clouds in the host-halos were virialized, velocity and mass would have been correlated. CONCLUSION: Therefore, our M h –Δ v anti-correlation shows that the clouds are not virialized in the gaseous halos of the hosts. This conclusion is best understood in the context of starburst driven outflows where the velocity Δ v is related to bulk motion. This opens the possibility to study M82-analogs up to z ~ 2.0 using the MgII selection.
Publisher: Oxford University Press (OUP)
Date: 22-02-2010
Publisher: Oxford University Press (OUP)
Date: 14-06-2017
Publisher: EDP Sciences
Date: 21-12-2016
Publisher: EDP Sciences
Date: 27-01-2017
Publisher: Oxford University Press (OUP)
Date: 05-02-2015
Publisher: Oxford University Press (OUP)
Date: 08-2006
Publisher: Oxford University Press (OUP)
Date: 20-09-2022
Abstract: Post-starburst galaxies (PSBs) are defined as having experienced a recent burst of star formation, followed by a prompt truncation in further activity. Identifying the mechanism(s) causing a galaxy to experience a post-starburst phase therefore provides integral insight into the causes of rapid quenching. Galaxy mergers have long been proposed as a possible post-starburst trigger. Effectively testing this hypothesis requires a large spectroscopic galaxy survey to identify the rare PSBs as well as high-quality imaging and robust morphology metrics to identify mergers. We bring together these critical elements by selecting PSBs from the overlap of the Sloan Digital Sky Survey and the Canada–France Imaging Survey and applying a suite of classification methods: non-parametric morphology metrics such as asymmetry and Gini-M20, a convolutional neural network trained to identify post-merger galaxies, and visual classification. This work is therefore the largest and most comprehensive assessment of the merger fraction of PSBs to date. We find that the merger fraction of PSBs ranges from 19 per cent to 42 per cent depending on the merger identification method and details of the PSB s le selection. These merger fractions represent an excess of 3–46× relative to non-PSB control s les. Our results demonstrate that mergers play a significant role in generating PSBs, but that other mechanisms are also required. However, applying our merger identification metrics to known post-mergers in the IllustrisTNG simulation shows that 70 per cent of recent post-mergers (≲200 Myr) would not be detected. Thus, we cannot exclude the possibility that nearly all PSBs have undergone a merger in their recent past.
Publisher: IOP Publishing
Date: 26-12-2022
Publisher: American Astronomical Society
Date: 25-06-2020
Abstract: This paper documents the 16th data release (DR16) from the Sloan Digital Sky Surveys (SDSS), the fourth and penultimate from the fourth phase (SDSS-IV). This is the first release of data from the Southern Hemisphere survey of the Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) new data from APOGEE-2 North are also included. DR16 is also notable as the final data release for the main cosmological program of the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), and all raw and reduced spectra from that project are released here. DR16 also includes all the data from the Time Domain Spectroscopic Survey and new data from the SPectroscopic IDentification of ERosita Survey programs, both of which were co-observed on eBOSS plates. DR16 has no new data from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey (or the MaNGA Stellar Library “MaStar”). We also preview future SDSS-V operations (due to start in 2020), and summarize plans for the final SDSS-IV data release (DR17).
Publisher: American Astronomical Society
Date: 12-03-2018
Publisher: EDP Sciences
Date: 28-11-2019
DOI: 10.1051/0004-6361/201936413
Abstract: We present the apparent stellar angular momentum over the optical extent of 300 galaxies across the Hubble sequence using integral-field spectroscopic (IFS) data from the CALIFA survey. Adopting the same λ R parameter previously used to distinguish between slow and fast rotating early-type (elliptical and lenticular) galaxies, we show that spiral galaxies are almost all fast rotators, as expected. Given the extent of our data, we provide relations for λ R measured in different apertures (e.g. fractions of the effective radius: 0.5 R e , R e , 2 R e ), including conversions to long-slit 1D apertures. Our s le displays a wide range of λ Re values, consistent with previous IFS studies. The fastest rotators are dominated by relatively massive and highly star-forming Sb galaxies, which preferentially reside in the main star-forming sequence. These galaxies reach λ Re values of ∼0.85, and they are the largest galaxies at a given mass, while also displaying some of the strongest stellar population gradients. Compared to the population of S0 galaxies, our findings suggest that fading may not be the dominant mechanism transforming spirals into lenticulars. Interestingly, we find that λ Re decreases for late-type Sc and Sd spiral galaxies, with values that occasionally set them in the slow-rotator regime. While for some of them this can be explained by their irregular morphologies and/or face-on configurations, others are edge-on systems with no signs of significant dust obscuration. The latter are typically at the low-mass end, but this does not explain their location in the classical ( V / σ , ε ) and ( λ Re , ε ) diagrams. Our initial investigations, based on dynamical models, suggest that these are dynamically hot disks, probably influenced by the observed important fraction of dark matter within R e .
Publisher: American Astronomical Society
Date: 22-04-2016
Publisher: Oxford University Press (OUP)
Date: 16-07-2020
Abstract: We use deep, spatially resolved spectroscopy from the Large Early Galaxy Astrophysics Census Survey to study radial variations in the stellar population of 17 spectroscopically selected post-starburst (PSB) galaxies. We use spectral fitting to measure two Lick indices, H δA and Fe 4383 , and find that, on average, PSB galaxies have radially decreasing H δA and increasing Fe 4383 profiles. In contrast, a control s le of quiescent, non-PSB galaxies in the same mass range shows outwardly increasing H δA and decreasing Fe 4383 . The observed gradients are weak (≈−0.2 Å/Re), mainly due to seeing convolution. A two-SSP (simple stellar population) model suggests that intrinsic gradients are as strong as observed in local PSB galaxies (≈−0.8 Å/Re). We interpret these results in terms of inside-out growth (for the bulk of the quiescent population) versus star formation occurring last in the centre (for PSB galaxies). At z ≈ 0.8, central starbursts are often the result of gas-rich mergers, as evidenced by the high fraction of PSB galaxies with disturbed morphologies and tidal features (40 per cent). Our results provide additional evidence for multiple paths to quiescence: a standard path, associated with inside-out disc formation and with gradually decreasing star formation activity, without fundamental structural transformation, and a fast path, associated with centrally concentrated starbursts, leaving an inverse age gradient and smaller half-light radius.
Publisher: American Astronomical Society
Date: 29-06-2017
Publisher: Oxford University Press (OUP)
Date: 28-06-2018
Publisher: Elsevier BV
Date: 02-2007
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Vivienne Wild.