The Herschel Virgo Cluster Survey. III. A constraint on dust grain lifetime in early-type galaxies

Passive early-type galaxies (ETGs) provide an ideal laboratory for studying the interplay between dust formation around evolved stars and its subsequent destruction in a hot gas. Using Spitzer-IRS and Herschel data we compare the dust production rate in the envelopes of evolved AGB stars with a constraint on the total dust mass. Early-type galaxies which appear to be truly passively evolving are not detected by Herschel. We thus derive a distance independent upper limit to the dust grain survival time in the hostile environment of ETGs of <46 ± 25 Myr for amorphous silicate grains. This implies that ETGs which are detected at far-infrared wavelengths have acquired a cool dusty medium via interaction. Given likely time-scales for ram-pressure stripping, this also implies that only galaxies with dust in a cool (atomic) medium can release dust into the intra-cluster medium

Detecting entanglement in spatial interference

We discuss an experimentally amenable class of two-particle states of motion giving rise to nonlocal spatial interference under position measurements. Using the concept of modular variables, we derive a separability criterion which is violated by these non-Gaussian states. While we focus on the free motion of material particles, the presented results are valid for any pair of canonically conjugate continuous variable observables and should apply to a variety of bipartite interference phenomena.Comment: 4 pages; corresponds to published versio

Bell test for the free motion of material particles

We present a scheme to establish non-classical correlations in the motion of two macroscopically separated massive particles without resorting to entanglement in their internal degrees of freedom. It is based on the dissociation of a diatomic molecule with two temporally separated Feshbach pulses generating a motional state of two counter-propagating atoms that is capable of violating a Bell inequality by means of correlated single particle interferometry. We evaluate the influence of dispersion on the Bell correlation, showing it to be important but manageable in a proposed experimental setup. The latter employs a molecular BEC of fermionic Lithium atoms, uses laser-guided atom interferometry, and seems to be within the reach of present-day technology.Comment: 4 pages, 1 figure; corresponds to published versio

Model-independent determination of the gluon condensate in four-dimensional SU(3) gauge theory

We determine the non-perturbative gluon condensate of four-dimensional SU(3) gauge theory in a model independent way. This is achieved by carefully subtracting high order perturbation theory results from non-perturbative lattice QCD determinations of the average plaquette. No indications of dimension two condensates are found. The value of the gluon condensate turns out to be of a similar size as the intrinsic ambiguity inherent to its definition.Comment: 5 pages, 5 figures, v2: references added, conclusions improved, contrast of figures improved, 1 typo correcte

Mid-infrared colour gradients and the colour-magnitude relation in Virgo early-type galaxies

We make use of Spitzer imaging between 4 and 16 micron and near-infrared data at 2.2 micron to investigate the nature and distribution of the mid-infrared emission in a sample of early-type galaxies in the Virgo cluster. These data allow us to conclude, with some confidence, that the emission at 16 micron in passive ETGs is stellar in origin, consistent with previous work concluding that the excess mid-infrared emission comes from the dusty envelopes around evolved AGB stars. There is little evidence for the mid-infrared emission of an unresolved central component, as might arise in the presence of a dusty torus associated with a low-luminosity AGN. We nonetheless find that the 16 micron emission is more centrally peaked than the near-infrared emission, implying a radial stellar population gradient. By comparing with independent evidence from studies at optical wavelengths, we conclude that a metallicity that falls with increasing radius is the principal driver of the observed gradient. We also plot the mid-infrared colour-magnitude diagram and combine with similar work on the Coma cluster to define the colour-magnitude relation for absolute K-band magnitudes from -26 to -19. Because a correlation between mass and age would produce a relation with a gradient in the opposite sense to that observed, we conclude that the relation reflects the fact that passive ETGs of lower mass also have a lower average metallicity. The colour-magnitude relation is thus driven by metallicity effects. In contrast to what is found in Coma, we do not find any objects with anomalously bright 16 micron emission relative to the colour-magnitude relation. Although there is little overlap in the mass ranges probed in the two clusters, this may suggest that observable ``rejuvenation'' episodes are limited to intermediate mass objects.Comment: 8 pages, 4 figure

An Exploration of Spotted White Dwarfs from K2

The 21st European Workshop on White Dwarfs was held in Austin, TX from July 23rd to 27th of 2018The Kepler K2 mission has discovered a significant population of white dwarf stars that exhibit photometric variability due to surface inhomogeneities likely related to magnetism. These “spotted” white dwarfs present not only in temperature regimes where we expect convection to dominate white dwarf photospheres, but also where radiation should dominate. We present an exploration of spotted white dwarfs as a function of various physical characteristics, including temperature, magnetic field strength, and rotational period, in order to better understand the origins of these photometric variations.Astronom

Changes in Post-Marital Residence Rules in an Era of National Reform: The Urban to Rural Disjunction in Contemporary China

Alternatives to the traditional practice of patrilocal postmarital residence exist in modern day China and vary from urban to rural areas. Social and economic reforms that were instituted in postMao China had an influence on post-marital residence rules. These reforms include marriage laws, reproduction restrictions, the return to family farms, and greater access to employment. Government reforms had different impacts on urban and rural families, creating different family structures and compositions. Family customs, like post-marital residence, also diverged along rural and urban lines. In rural areas, patrilocality persists, but matrilocal marriage arrangements are increasing. In urban areas, a strong preference for neolocality is evident. There are also indications that patrilocal and matrilocal residence arrangements are becoming short-term transitions to neolocal residence. Using a collection of post-Mao literature, this paper examines the relationship between government policies and changes in urban and rural post-marital residence rules in contemporary China