119069361
Radio Observations of the Hubble Deep Field South region: I. Survey Description and Initial Results
This paper is the first of a series describing the results of the Australia Telescope Hubble Deep Field–South radio survey. The survey was conducted at four wavelengths, 20, 11, 6, and 3 cm, over a 4 year period and achieves an rms sensitivity of about 10 μJy at each wavelength. We describe the observations and data reduction processes and present data on radio sources close to the center of the Hubble Deep Field–South. We discuss in detail the properties of a subset of these sources. The sources include both starburst galaxies and galaxies powered by an active galactic nucleus and range in redshift from 0.1 to 2.2. Some of them are characterized by unusually high radio-to-optical luminosities, presumably caused by dust extinction.
14097040
Extragalactic radio source evolution&unification: clues to the demographics of blazars
In this paper we discuss the demographics of the radio blazar population: (i) what are their parent ('unbeamed') sources and (ii) what magnitude and/or type of evolution have they undergone ? The discussion is based on models of radio source evolution and beaming based on a 'dual population' unification paradigm. These models, developed from radio blazar properties in bright samples, predict blazar demographic trends at the lower flux-density levels; samples from deep mJy-level surveys (e.g. NVSS and FIRST) may now provide direct tests of these predictions. All galaxies are radio galaxies in a sense. The scale of activity ranges from 'normal' galaxies (like our own) whose radio emission emanates from supernova remnants. At higher radio powers are the 'starburst' galaxies, greatly-enhanced stellar activity resulting in stronger radio emission. At similar radio powers are the Seyfert galaxies with their small-scale radio core-jet structures and with clear indication of AGN activity. At the top end of the scale are the powerful radio galaxies, together with BL Lacs and quasars, the latter two being collectively termed blazars. Radio galaxies tend to have steep radio spectra and therefore dominate low radio-frequency (ν < 0.5 GHz) surveys. The structures are predominantly double-lobed; Fanaroff & Riley (1974) compared the distances between central maxima of the radio structures to overall size and discovered a dichotomy. Sources with regions of maximum brightness separated by more than 0.5 times the overall source size are edge-brightened (FRII), while when the regions of maximum brightness lies within this limit the source has diffuse outer lobes (FRI) (centrally concentrated); and the highest radio power objects are predominantly FRIIs whilst those of lower radio power are usually FRIs. The overlap between the classes at middling radio powers is seen in the local radio luminos-ity function (Figure 1), and the division is known to be a function of optical luminosity as well as radio (Owen and Ledlow 1993).
118994394
Radio Galaxy Spectra
Radio spectra of radio galaxies are often ascribed a simple power law form ($S_{\nu} \propto \nu^{\alpha}$) with the spectral index, $\alpha$, being of order -0.7. However, all radio galaxies deviate from this simple power law behaviour. In this paper we derive simple expressions for the average rest-frame spectra of FRI and FRII radio galaxies. These will be used to describe the spectral curvature of the parent (FRI and FRII) populations in models of radio source evolution.
56011481
The Australia Telescope 20 GHz (AT20G) Survey: analysis of the extragalactic source sample
The Australia Telescope 20 GHz (AT20G) survey is a blind survey of the whole Southern sky at 20 GHz with follow-up observations at 4.8, 8.6 and 20 GHz carried out with the Australia Telescope Compact Array (ATCA) from 2004 to 2008. In this paper we present an analysis of radio spectral properties in total intensity and polarization, sizes, optical identifications and redshifts of the sample of the 5808 extragalactic sources in the survey catalogue of confirmed sources over 6.1 sr in the Southern sky (i.e. the whole Southern sky excluding the strip at Galactic latitude |b| < ). 
 
 
 
The sample has a flux density limit of 40 mJy. Completeness has been measured as a function of scan region and flux density. Averaging over the whole survey area the follow-up survey is 78 per cent complete above 50 mJy and 93 per cent complete above 100 mJy. 3332 sources with declination δ − 0.5 (S∝να). The fraction of flat-spectrum sources decreases from 81 per cent for S20 GHz > 500 mJy to 60 per cent for S20 GHz < 100 mJy. There is also a clear spectral steepening at higher frequencies with the median α decreasing from −0.16 between 4.8 and 8.6 GHz to −0.28 between 8.6 and 20 GHz. 
 
 
 
Simultaneous observations in polarization are available for all the sources at all the frequencies. 768 sources have a good-quality detection of polarized flux density at 20 GHz; 467 of them were also detected in polarization at 4.8 and/or at 8.6 GHz so that it has been possible to compare the spectral behaviour in total intensity and polarization. We have found that the polarized fraction increases slightly with frequency and decreases with flux density. The spectral indices in total intensity and in polarization are, on average, close to each other, but we also found several sources for which the spectral shape of the polarized emission is substantially different from the spectral shape in total intensity. The correlation between the spectral indices in total intensity and in polarization is weaker for flat-spectrum sources. 
 
 
 
Cross-matches and comparisons have been made with other catalogues at lower radio frequencies, and in the optical, X-ray and γ-ray bands. Redshift estimates are available for 825 sources.
117637282
The Redshift Distribution of Extragalactic Radio Sources
Extragalactic radio sources are a unique cosmological probe in that they trace large-scale structure on scales inaccessible to other wavelengths. However as radio survey data is inherently 2D, the redshift distribution, N(z), is necessary to derive spatial information. To obtain this distribution either we measure thousands of radio source redshifts to directly determine N(z) or we derive N(z) from statistical analyses of radio source count and identification data. 
In this paper we show how the dual-population unification scheme can be incorporated into a rigorous statistical analysis of radio source count data, with the result that our simple parametric evolution and beaming model revises previous estimations of N(z), specifically at low flux densites. This revision is particularly pertinent given that the new generation of radio surveys extend to milli-jansky flux density levels: sampling source densities high enough to reveal spatial structure. In turn, these new radio surveys will provide potent tests which will refine our model.
957517
Galaxy groups in the 2dFGRS: the luminous content of the groups
The 2dFGRS Percolation-Inferred Galaxy Group (2PIGG) catalogue of ~29000 objects is used to study the luminous content of galaxy systems of various sizes. Mock galaxy catalogues constructed from cosmological simulations are used to gauge the accuracy with which intrinsic group properties can be recovered. A Schechter function is found to be a reasonable fit to the galaxy luminosity functions in groups of different mass in the real data. The characteristic luminosity L* is larger for more massive groups. However, the mock data show that the shape of the recovered luminosity function is expected to differ from the true shape, and this must be allowed for when interpreting the data. The variation of halo mass-to-light ratio with group size is studied in both these wavebands. A robust trend of increasing M/L with increasing group luminosity is found in the 2PIGG data. From groups with L_bj=10^{10}Lsol to those 100 times more luminous, the typical bj-band M/L increases by a factor of 5, whereas the rf-band M/L grows by a factor of 3.5. These trends agree well with the simulations, which also predict a minimum M/L on a scale corresponding to the Local Group. Our data indicate that if such a minimum exists, then it must occur at L<~10^{10}Lsol, below the range accurately probed by the 2PIGG catalogue. According to the mock data, the bj M/Ls of the largest groups are expected to be approximately 1.1 times the global value. Assuming that this correction applies to the real data yields an estimate of Omega_m=0.26+/-0.03 (statistical).
118342809
Gamma ray lines from a universal extra dimension
Indirect Dark Matter searches are based on the observation of secondary particles produced by the annihilation or decay of Dark Matter. Among them, gamma-rays are perhaps the most promising messengers, as they do not suffer deflection or absorption on Galactic scales, so their observation would directly reveal the position and the energy spectrum of the emitting source. Here, we study the detailed gamma-ray energy spectrum of Kaluza-Klein Dark Matter in a theory with 5 Universal Extra Dimensions. We focus in particular on the two body annihilation of Dark Matter particles into a photon and another particle, which produces monochromatic photons, resulting in a line in the energy spectrum of gamma rays. Previous calculations in the context of the five dimensional UED model have computed the line signal from annihilations into ??, but we extend these results to include ?Z and ?H final states. We find that these spectral lines are subdominant compared to the predicted ?? signal, but they would be important as follow-up signals in the event of the observation of the ?? line, in order to distinguish the 5d UED model from other theoretical scenarios.
119997511
Probing the mechanism of neutrinoless double beta decay with SuperNEMO
Abstract The SuperNEMO experiment is being designed to search for neutrinoless double beta decay. Its experimental technique of tracking and calorimetry provides the means to discriminate different underlying mechanisms for neutrinoless double beta decay by measuring the angular and energy distributions of electrons. The results of a study by the SuperNEMO Collaboration and F. Deppisch (in preparation)  [7] for identifying light Majorana neutrino exchange and right-handed currents are presented.
27307688
New physics in resonant production of Higgs boson pairs.
We advocate a search for an extended scalar sector at the LHC via hh production, where h is the 125 GeV Higgs boson. A resonance feature in the hh invariant mass is a smoking gun of an s-channel heavy Higgs resonance, H. With one h decaying to two photons and the other decaying to b quarks, the resonant signal may be discoverable above the hh continuum background for M(H)<1  TeV. The product of the scalar and top Yukawa couplings can be measured to better than 10%-20% accuracy, and its sign can be inferred from the hh line shape via interference effects.
73704343
WIMP-induced gamma ray spectrum of active Galactic nuclei
As direct and indirect dark matter detection experiments continue to place stringent constraints on WIMP masses and couplings, it becomes imperative to expand the scope of the search for particle dark matter by looking in new and exotic places. One such place may be the core of active galactic nuclei where the density of dark matter is expected to be extremely high. Recently, several groups have explored the possibility of observing signals of dark matter from its interactions with the high-energy jets emanating from these galaxies. In this work, we build upon these analyses by including the other components of the WIMP-induced gamma ray spectrum of active galactic nuclei; namely, (1) the continuum from WIMP annihilation into light standard model states which subsequently radiate and/or decay into photons and (2) the direct (loop-induced) decay into photons. We work in the context of models of universal extra dimensions (in particular, a model with two extra dimensions) and compute all three components of the gamma ray spectrum and compare with current data. We find that the model with two extra dimensions exhibits several interesting features which may be observable with the Fermi gamma ray telescope. We also show that, in conjunction with other measurements, the gamma ray spectrum from AGN can be an invaluable tool for restricting WIMP parameter space.
121807969
Dark matter search with PICASSO
PICASSO at SNOLAB searches primarily for spin-dependent WIMP interactions on 19F using the superheated droplet technique. This technique is based on the bubble chamber principle, where phase transitions in superheated liquid droplets can be triggered by WIMP induced nuclear recoils. The physics of the detection process allows a highly efficient suppression of backgrounds from cosmic muons, γ- and β-rays. We will discuss qualitatively recent progress in PICASSO and its sensitivity reach for spin-dependent and spin-independent WIMP searches.