Category: Uncategorized

HALO SAUSAGE “A significant fraction of the halo near the Sun is in the Gaia-Enceladus/sausage, which is the aftermath of a major merger with a M ∼ 108 M⊙ dwarf galaxy (8−10) Gyr ago. The name arises from the fact the stellar component has radially biased orbits, and hence the distribution of vr is sausage like.” (M⊙ = solar mass units). https://lnkd.in/e6ifiQMn View in LinkedIn

COSMIC GEOMETRY. “It’s hard to measure the inner slope of the MW’s density profile, as baryons dominate at small radii. The large measured microlensing optical depth towards the Galactic centre implies large stellar densities in the inner MW, which appears to be in tension with the high DM densities at small radii of ‘cuspy’ density profiles.” (MW = Milky Way; DM = dark matter). https://lnkd.in/e6ifiQMn View in LinkedIn

DOMINANT ERRORS. “It should also be noted that there isn’t a rigid divide between theory/simulations and observations; modelling is required to interpret observations and the statistical errors are often now so small that systematic errors are significant, or even dominant.” https://lnkd.in/e6ifiQMn View in LinkedIn

OUR CORNER OF THE ‘VERSE. “There has been huge progress in understanding the properties and history of the MW in recent years thanks to the Gaia satellite. Gaia is an ongoing ESA space astrometry mission (2013-2022+?), measuring the positions, parallaxes and proper motions (change in apparent position) of > 1 billion stars in the MW (∼ 1% of the total number of stars). (MW = Milky Way). https://lnkd.in/e6ifiQMn View in LinkedIn

THE ORDER OF MATTER. “In CDM cosmologies structure forms hierarchically: small halos (on average) form earlier, and then larger halos form via mergers and accretion. Subhalos are reduced in mass, or destroyed, by tidal stripping as they orbit within larger halos.” (CDM = Cold Dark MatterCold dark matter). https://lnkd.in/e6ifiQMn View in LinkedIn

Gorgeous ornamental daisies. View in LinkedIn

MISPLACED CONCRETENESS. “Reality consists of a hierarchy of intertwined processes. There are very few explicitly processual theories in biology today. As a practising biologist, I’ve always found this utterly baffling and disappointing. We remain strangely fixated on explanation in terms of static unchanging entities.” (Foreword, by Johannes Jaeger). https://lnkd.in/evBZWZaE View in LinkedIn

SO ENDS this Fragment. Dr Fraser, in private correspondence with me revealed the following. “I suspect that few palaeontologists would browse a nutrition journal and those that I have spoken to are mystified by the idea of biological mechanisms for species extinction.” In other words, this very credible and testable hypothesis has been overlooked. https://lnkd.in/e5hTuW74 View in LinkedIn

LAG. “DM self-interactions transfer momentum between the cluster halos, so they lag behind the collisionless galaxies, leading to an offset between the DM and galaxies. Merging clusters also lead to constraints from the cluster surviving the merger.” (DM = dark matter). https://lnkd.in/e6ifiQMn View in LinkedIn

THIN SHELLS AND VITAMIN D. “By comparison with egg biology of modern birds, the thinning of the shells was attributed to abnormal hormonal control of the calcification process, as a result of environmental stress. Strangely, as a possible explanation, there was no mention of cholecalciferol deficiency which is a well-established cause of thin shells in eggs of the domestic hen.” https://lnkd.in/e5hTuW74 View in LinkedIn