50years ago Peter Mitchell proposed the chemiosmotic hypothesis for which he was awarded the Nobel Prize for Chemistry in 1978. His comprehensive review on chemiosmotic coupling known as the first ...“Grey Book”, has been reprinted here with permission, to offer an electronic record and easy access to this important contribution to the biochemical literature. This remarkable account of Peter Mitchell's ideas originally published in 1966 is a landmark and must-read publication for any scientist in the field of bioenergetics. As far as was possible, the wording and format of the original publication have been retained. Some changes were required for consistency with BBA formats though these do not affect scientific meaning. A scanned version of the original publication is also provided as a downloadable file in Supplementary Information. See also Editorial in this issue by Peter R. Rich. Original title: CHEMIOSMOTIC COUPLING IN OXIDATIVE AND PHOTOSYNTHETIC PHOSPHORYLATION, by Peter Mitchell, Glynn Research Laboratories, Bodmin, Cornwall, England.
We present velocities of galactic outflows in seven star-forming galaxies at z = 5-6 with stellar masses of M* ∼ 1010.1 . Although it is challenging to observationally determine the outflow ...velocities, we overcome this by using ALMA C ii 158 m emission lines for systemic velocities and deep Keck spectra with metal absorption lines for velocity profiles available to date. We construct a composite Keck spectrum of the galaxies at z = 5-6 with the C ii-systemic velocities, and fit outflow-line profiles to the Si ii λ1260, C ii λ1335, and Si iv λλ1394,1403 absorption lines in the composite spectrum. We measure the maximum (90%) and central outflow velocities to be and on average, respectively, showing no significant differences between the outflow velocities derived with the low- to high-ionization absorption lines. For M* ∼ 1010.1 , we find that the value of our z = 5-6 galaxies is 3 times higher than those of z ∼ 0 galaxies and comparable to z ∼ 2 galaxies. Estimating the halo circular velocity from the stellar masses and the abundance matching results, we investigate a - relation. Interestingly, for galaxies with M* = 1010.0-10.8 shows a clear positive correlation with and/or the galaxy star formation rate over z = 0-6 with a small scatter of dex, which is in good agreement with theoretical predictions. This positive correlation suggests that the outflow velocity is physically related to the halo circular velocity, and that the redshift evolution of at fixed M* is explained by the increase in toward high redshift.
Africa has the longest record - some 2.5 million years - of human occupation of any continent. For nearly all of this time, its inhabitants have made tools from stone and have acquired their food ...from its rich wild plant and animal resources. Archaeological research in Africa is crucial for understanding the origins of humans and the diversity of hunter-gatherer ways of life. This book is a synthesis of the record left by Africa's earliest hominin inhabitants and hunter-gatherers, combining the insights of archaeology with those of other disciplines, such as genetics and palaeo-environmental science. African evidence is critical to important debates, such as the origins of stone tool making, the emergence of recognisably modern forms of cognition and behaviour, and the expansion of successive hominins from Africa to other parts of the world.
ABSTRACT
The difference in shape between the observed galaxy stellar mass function and the predicted dark matter halo mass function is generally explained primarily by feedback processes. Feedback ...can shape the stellar–halo mass (SHM) relation by driving gas out of galaxies, by modulating the first-time infall of gas on to galaxies (i.e. preventative feedback), and by instigating fountain flows of recycled wind material. We present and apply a method to disentangle these effects for hydrodynamical simulations of galaxy formation. We build a model of linear coupled differential equations that by construction reproduces the flows of gas on to and out of galaxies and haloes in the eaglecosmological simulation. By varying individual terms in this model, we isolate the relative effects of star formation, ejection via outflow, first-time inflow, and wind recycling on the SHM relation. We find that for halo masses $M_{200} \lt 10^{12} \, \mathrm{M_\odot }$ the SHM relation is shaped primarily by a combination of ejection from galaxies and haloes, while for larger M200 preventative feedback is also important. The effects of recycling and the efficiency of star formation are small. We show that if, instead of M200, we use the cumulative mass of dark matter that fell in for the first time, the evolution of the SHM relation nearly vanishes. This suggests that the evolution is due to the definition of halo mass rather than to an evolving physical efficiency of galaxy formation. Finally, we demonstrate that the mass in the circumgalactic medium is much more sensitive to gas flows, especially recycling, than is the case for stars and the interstellar medium.
ABSTRACT
The role of galactic wind recycling represents one of the largest unknowns in galaxy evolution, as any contribution of recycling to galaxy growth is largely degenerate with the inflow rates ...of first-time infalling material, and the rates with which outflowing gas and metals are driven from galaxies. We present measurements of the efficiency of wind recycling from the eagle cosmological simulation project, leveraging the statistical power of large-volume simulations that reproduce a realistic galaxy population. We study wind recycling at the halo scale, i.e. gas that has been ejected beyond the halo virial radius, and at the galaxy scale, i.e. gas that has been ejected from the interstellar medium to at least $\approx 10 \, {{\ \rm per\ cent}}$ of the virial radius. Galaxy-scale wind recycling is generally inefficient, with a characteristic return time-scale that is comparable to or longer than a Hubble time, and with an efficiency that clearly peaks at the characteristic halo mass of $M_{200} = 10^{12} \, \mathrm{M_\odot }$. Correspondingly, the majority of gas being accreted on to galaxies in eagle is infalling for the first time. Recycling is more efficient at the halo scale, with values that differ by orders of magnitude from those assumed by semi-analytical galaxy formation models. Differences in the efficiency of wind recycling with other hydrodynamical simulations are currently difficult to assess, but are likely smaller. We find that cumulative first-time gas accretion rates at the virial radius are reduced relative to the expectation from dark matter accretion for haloes with mass $M_{200} \lt 10^{12} \, \mathrm{M_\odot }$, indicating efficient preventative feedback on halo scales.
Galactic outflow rates in the EAGLE simulations Mitchell, Peter D; Schaye, Joop; Bower, Richard G ...
Monthly notices of the Royal Astronomical Society,
2020, Letnik:
494, Številka:
3
Journal Article
Recenzirano
Odprti dostop
ABSTRACT
We present measurements of galactic outflow rates from the eagle suite of cosmological simulations. We find that gas is removed from the interstellar medium (ISM) of central galaxies with a ...dimensionless mass loading factor that scales approximately with circular velocity as $V_{\mathrm{c}}^{-3/2}$ in the low-mass regime where stellar feedback dominates. Feedback from active galactic nuclei causes an upturn in the mass loading for halo masses ${\gt}10^{12} \, \mathrm{M_\odot }$. We find that more gas outflows through the halo virial radius than is removed from the ISM of galaxies, particularly at low redshifts, implying substantial mass loading within the circumgalactic medium. Outflow velocities span a wide range at a given halo mass/redshift, and on average increase positively with redshift and halo mass up to $M_{200} \sim 10^{12} \, \mathrm{M_\odot }$. Outflows exhibit a bimodal flow pattern on circumgalactic scales, aligned with the galactic minor axis. We present a number of like-for-like comparisons to outflow rates from other recent cosmological hydrodynamical simulations, and show that comparing the propagation of galactic winds as a function of radius reveals substantial discrepancies between different models. Relative to some other simulations, eagle favours a scenario for stellar feedback where agreement with the galaxy stellar mass function is achieved by removing smaller amounts of gas from the ISM, but with galactic winds that then propagate and entrain ambient gas out to larger radii.
We present a new, open source, free, semi-analytic model (SAM) of galaxy formation, SHARK, designed to be highly flexible and modular, allowing easy exploration of different physical processes and ...ways of modelling them. We introduce the philosophy behind SHARK and provide an overview of the physical processes included in the model. SHARK is written in C++11 and has been parallelized with OpenMP. In the released version (V1.1), we implement several different models for gas cooling, active galactic nuclei, stellar and photo-ionization feedback, and star formation (SF). We demonstrate the basic performance of SHARK using the Planck Collaboration et al. (2016) cosmology SURFS simulations, by comparing against a large set of observations, including: the stellar mass function (SMF) and stellar-halo mass relation at z = 0-4; the cosmic evolution of the star formation rate density (SFRD), stellar mass, atomic and molecular hydrogen; local gas scaling relations; and structural galaxy properties, finding excellent agreement. Significant improvements over previous SAMs are seen in the mass-size relation for discs/bulges, the gas-stellar mass and stellar mass-metallicity relations. To illustrate the power of SHARK in exploring the systematic effects of the galaxy formation modelling, we quantify how the scatter of the SF main sequence and the gas scaling relations changes with the adopted SF law, and the effect of the starbursts H2 depletion time-scale on the SFRD and Ω _H_2. We compare SHARK with other SAMs and the hydrodynamical simulation EAGLE, and find that SAMs have a much higher halo baryon fractions due to large amounts of intra-halo gas, which in the case of EAGLE is in the intergalactic medium.
Island archaeology is a well-established field within the wider discipline, but African contributions to it remain scarce. The Canary Islands are unusual in the broader African context for their ...relatively long history of occupation (~2000 years) and the intensity with which archaeological research has been, and is, undertaken there. Much of that research, however, has focused on specifically Canarian issues, including efforts to demonstrate connections between the islands’ initial settlement and the Classical Mediterranean world. Relatively little of it has been conducted within the broader comparative framework that an island archaeology perspective provides. Additionally, much of the Canarian literature is not directly accessible to non-Hispanophones. In response, I synthesize what is currently known about the archaeology of the Canary Islands, focusing on determining when, how, and by whom they were first settled; the impacts of human settlement on their environments; inter-island variability in precolonial subsistence, social, and political trajectories; and the record left by European contact and subsequent colonization, which began in the 14th century AD. As well as pointing to further opportunities for research within the archipelago, I simultaneously map out several areas where archaeological work there could contribute to wider debates in island archaeology as a whole.
ABSTRACT
Feedback processes are expected to shape galaxy evolution by ejecting gas from galaxies and their associated dark matter haloes, and also by preventing diffuse gas from ever being accreted. ...We present predictions from the eaglesimulation project for the mass budgets associated with ‘ejected’ and ‘prevented’ gas, as well as for ejected metals. We find that most of the baryons that are associated with haloes of mass $10^{11} \lt M_{200} \, /\mathrm{M_\odot } \lt 10^{13}$ at z = 0 have been ejected beyond the virial radius after having been accreted. When the gas ejected from satellites (and their progenitors) is accounted for, the combined ejected mass represents half of the total baryon budget even in the most massive simulated galaxy clusters ($M_{200} \approx 10^{14.5} \, \mathrm{M_\odot }$), with the consequence that the total baryon budget exceeds the cosmic average if ejected gas is included. We find that gas is only prevented from being accreted on to haloes for $M_{200} \lt 10^{12} \, \mathrm{M_\odot }$, and that this component accounts for about half the total baryon budget for $M_{200} \lt 10^{11} \, \mathrm{M_\odot }$, with ejected gas making up most of the remaining half. For metals, most of the mass that is not locked into stars has been ejected beyond the virial radius, at least for $M_{200} \lt 10^{13} \, \mathrm{M_\odot }$. Finally, within the virial radius we find that most of the mass in the circumgalactic medium (CGM) has not passed through the ISM of a progenitor galaxy, for all halo masses and redshifts. About half of the CGM within half the virial radius has passed through the ISM in the past however.
Quantitative NMR spectroscopy (qNMR) has been examined for purity assessment using a range of organic calibration standards of varying structural complexities, certified using the traditional mass ...balance approach. Demonstrated equivalence between the two independent purity values confirmed the accuracy of qNMR and highlighted the benefit of using both methods in tandem to minimise the potential for hidden bias, thereby conferring greater confidence in the overall purity assessment. A comprehensive approach to purity assessment is detailed, utilising, where appropriate, multiple peaks in the qNMR spectrum, chosen on the basis of scientific reason and statistical analysis. Two examples are presented in which differences between the purity assignment by qNMR and mass balance are addressed in different ways depending on the requirement of the end user, affording fit-for-purpose calibration standards in a cost-effective manner.
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