ﻻ يوجد ملخص باللغة العربية
Wright et al. 2014 have embarked on a search for advanced Karadashev Type III civilisations via the compilation of a sample of sources with extreme mid-IR emission and colours. In this scenario, the mid-IR emission is then primarily associated with waste heat energy by-products. I apply the Mid-IR radio correlation to this $hat{G}$ sample (Griffith et al. 2015). I demonstrate that the mid-IR and radio luminosities are correlated for the sample with $q_{22}=1.35pm0.42 $. By comparison, the First Look Survey (FLS) has $q_{22}=0.87pm0.27$. The fact that the G-HAT sample largely follows the Mid-IR radio correlation, strongly suggests the vast majority of these sources are associated with galaxies in which natural astrophysical processes are dominant. This simple application of the mid-IR radio correlation can substantially reduce the number of false positives in the $hat{G}$ catalogue, since galaxies occupied by advanced Kardashev Type III civilisations would be expected to exhibit very high values of $q$. Indeed I identify 9 outliers in the sample with $q_{22} > 2$ of which at least 3 have properties that are relatively well explained via standard astrophysical interpretations e.g. dust emission associated with nascent star formation and/or nuclear activity from a heavily obscured AGN. I also note that the comparison of resolved Mid-IR and radio images of galaxies on sub-galactic (kpc) scales can also be useful in identifying and recognising artificial mid-IR emission from less advanced intermediate Type II/III civilisations. Nevertheless, from the bulk properties of the $hat{G}$ sample, I conclude that Kardashev Type-III civilisations are either very rare or do not exist in the local Universe.
Diagnostics of polarized emission provide us with valuable information on the Galactic magnetic field and the state of turbulence in the interstellar medium, which cannot be obtained from synchrotron intensity alone. In Paper I (Herron et al. 2017b),
As a guide for astronomers new to the field of technosignature search (i.e. SETI), I present an overview of some of its observational and theoretical approaches. I review some of the various observational search strategies for SETI, focusing not on t
The discovery of the ubiquity of habitable extrasolar planets, combined with revolutionary advances in instrumentation and observational capabilities, have ushered in a renaissance in the millenia-old quest to answer our most profound question about
Using extremely deep (rms 3.3 microJy/bm) 1.4GHz sub-arcsecond resolution MERLIN + VLA radio observations of a 8.5 by 8.5 field centred upon the Hubble Deep Field North, in conjunction with Spitzer 24 micron data we present an investigation of the ra
We investigated AGN activity in low-mass galaxies, an important regime that can shed light onto BH formation and evolution, and their interaction with their host galaxies. We identified 336 AGN candidates from a parent sample of $sim 48,000$ nearby l