# Archive for category Cosmology and Extragalactic

## Today's Postings

### Effective Field Theory of Cosmic Acceleration: an implementation in CAMB

We implement the effective field theory (EFT) approach to dark energy and modified gravity in the public Einstein-Boltzmann solver CAMB. The resulting code, which we dub EFTCAMB, is a powerful and versatile tool that can be used for several objectives. It can be employed to evolve the full dynamics of linear scalar perturbations in any given single field dark energy or modified gravity model, once the latter is mapped into the EFT formalism. It offers a numerical implementation of EFT as a model-independent framework to test gravity on cosmological scales. EFTCAMB has a built-in check for the fulfillment of general stability conditions such as the absence of ghost and superluminal propagation of perturbations. It handles phantom-divide crossing models and does not contain any quasi-static approximation, but rather evolves the full dynamics of perturbations on linear scales. As we will show, the latter is an important feature in view of the accuracy and scale range of upcoming surveys. We show the reliability and applicability of our code by evolving the dynamics of linear perturbations and extracting predictions for power spectra in several models. In particular we perform a thorough analysis of f(R) theories, comparing our outputs with those of an existing code for LCDM backgrounds, and finding an agreement that can reach 0.1% for models with a Compton wavelength consistent with current cosmological data. We then showcase the flexibility of our code studying two different scenarios. First we produce new results for designer f(R) models with a time-varying dark energy equation of state. Second, we extract predictions for linear observables in some parametrized EFT models with a phantom-divide crossing equation of state for dark energy.

### A covariant treatment of cosmic parallax [Cross-Listing]

The Gaia satellite will soon probe parallax on cosmological distances. Using the covariant formalism and considering the angle between a pair of sources, we find parallax for both spacelike and timelike separation between observation points. Our analysis includes both intrinsic parallax and parallax due to observer motion. We propose a consistency condition that tests the FRW metric using the parallax distance and the angular diameter distance. This test is purely kinematic and relies only on geometrical optics, it is independent of matter content and its relation to the spacetime geometry. We study perturbations around the FRW model, and find that they should be taken into account when analysing observations to determine the parallax distance.

### A covariant treatment of cosmic parallax

The Gaia satellite will soon probe parallax on cosmological distances. Using the covariant formalism and considering the angle between a pair of sources, we find parallax for both spacelike and timelike separation between observation points. Our analysis includes both intrinsic parallax and parallax due to observer motion. We propose a consistency condition that tests the FRW metric using the parallax distance and the angular diameter distance. This test is purely kinematic and relies only on geometrical optics, it is independent of matter content and its relation to the spacetime geometry. We study perturbations around the FRW model, and find that they should be taken into account when analysing observations to determine the parallax distance.

### BBN And The CMB Constrain Light, Electromagnetically Coupled WIMPs

(Abridged) In the presence of a light WIMP (< 30 MeV), there are degeneracies among the nature of the WIMP, its couplings to standard model particles, its mass m_chi, and the number of equivalent neutrinos beyond the standard model, Delta N_nu. These degeneracies cannot be broken by the CMB constraint on the effective number of neutrinos, N_eff. However, big bang nucleosynthesis (BBN) is affected by a light WIMP and equivalent neutrinos, so the combination of BBN and CMB can break some of the degeneracies. Here, BBN predictions for abundances in the presence of a light WIMP and equivalent neutrinos are explored, and estimates of their observationally determined relic abundances are used to limit m_chi, Delta N_nu, and the present Universe baryon density (Omega_B h^2). These constraints are explored for Majorana and Dirac fermion WIMPs as well as for real and complex scalar WIMPs that couple to electrons, positrons, and photons. In a separate paper this analysis is repeated for WIMPs that couple only to the standard model neutrinos, and constraints for the two cases are contrasted. Without a light WIMP but allowing for equivalent neutrinos, the combined BBN and CMB constraints favor N_eff = 3.45 +/- 0.17, Omega_B h^2 = 0.0224 +/- 0.0003, and Delta N_nu = 0.40 +/- 0.17. In this case, standard BBN (Delta N_nu = 0) is disfavored at ~98% confidence, and the presence of one sterile neutrino (Delta N_nu = 1) is disfavored at > 99% confidence. Allowing a light WIMP and Delta N_nu equivalent neutrinos together, the combined BBN and CMB data provide lower limits to the WIMP masses (> 0.5 – 5 MeV) that depend on the nature of the WIMP, favor m_chi ~8 MeV slightly over no WIMP, and loosen constraints on equivalent neutrinos, Delta N_nu = 0.65+0.46-0.35. While Delta N_nu = 0 is still disfavored at ~95% confidence with a light WIMP, Delta N_nu = 1 is now allowed.

### Photometric type Ia supernova surveys in narrow band filters

We study the characteristics of a narrow band type Ia supernova survey through simulations based on the upcoming Javalambre Physics of the accelerating universe Astrophysical Survey (J-PAS). This unique survey has the capabilities of obtaining distances, redshifts, and the SN type from a single experiment thereby circumventing the challenges faced by the resource-intensive spectroscopic follow-up observations. We analyse the flux measurements signal-to-noise ratio and bias, the supernova typing performance, the ability to recover light curve parameters given by the SALT2 model, the photometric redshift precision from type Ia supernova light curves and the effects of systematic errors on the data. We show that such a survey is not only feasible but may yield large type Ia supernova samples (up to 300 supernovae at $z<0.5$ per month of search) with low core collapse contamination ($\sim 3$ per cent), good precision on the SALT2 parameters (average $\sigma_{m_B}=0.063$, $\sigma_{x_1}=0.47$ and $\sigma_c=0.040$) and on the distance modulus (average $\sigma_{\mu}=0.17$, assuming an intrinsic scatter $\sigma_{\mathrm{int}}=0.14$), with identified systematic uncertainties $\sigma_{\mathrm{sys}}\lesssim 0.10 \sigma_{\mathrm{stat}}$. Moreover, the filters are narrow enough to detect most spectral features and obtain excellent photometric redshift precision of $\sigma_z=0.005$, apart from $\sim$ 2 per cent of outliers. We also present a few strategies for optimising the survey’s outcome. Together with the detailed host galaxy information, narrow band surveys can be very valuable for the study of supernova rates, spectral feature relations, intrinsic colour variations and correlations between supernova and host galaxy properties, all of which are important information for supernova cosmological applications.

### Separate Constraints on Early and Late Cosmology

Since the public release of Planck data, several attempts have been made to explain the observed small tensions with other data-sets, most of them involving an extension of the {\Lambda}CDM Model. We try here an alternative approach to the data analysis, based on separating the constraints coming from the different epochs in cosmology, in order to assess which part of the Standard Model generates the tension with the data. To this end, we perform a particular analysis of Planck data probing only the early cosmological evolution, until the time of photon decoupling. Then, we utilise this result to see if the {\Lambda}CDM model can fit all observational constraints probing only the late cosmological background evolution, discarding any information concerning the late perturbation evolution. We find that all tensions between the datasets are removed, suggesting that our standard assumptions on the perturbed late-time history, as well as on reionisation, could sufficiently bias our parameter extraction and be the source of the alleged tensions.

### Backreaction mechanism in multifluid and extended cosmologies

One possible explanation for the present observed acceleration of the Universe is the breakdown of homogeneity and isotropy due to the formation of non-linear structures. How inhomogeneities affect the averaged cosmological expansion rate and lead to late-time acceleration is generally considered to be due to some backreaction mechanism. General Relativity together with pressure-free matter have until recently been considered as the sole ingredients for averaged calculations. In this communication we focus our attention on more general scenarios, including imperfect fluids as well as alternative theories of gravity, and apply an averaging procedure to them in order to determine possible backreaction effects. For illustrative purposes, we present our results for dark energy models, quintessence and Brans-Dicke theories. We also provide a discussion about the limitations of frame choices in the averaging procedure.

### Backreaction mechanism in multifluid and extended cosmologies [Cross-Listing]

One possible explanation for the present observed acceleration of the Universe is the breakdown of homogeneity and isotropy due to the formation of non-linear structures. How inhomogeneities affect the averaged cosmological expansion rate and lead to late-time acceleration is generally considered to be due to some backreaction mechanism. General Relativity together with pressure-free matter have until recently been considered as the sole ingredients for averaged calculations. In this communication we focus our attention on more general scenarios, including imperfect fluids as well as alternative theories of gravity, and apply an averaging procedure to them in order to determine possible backreaction effects. For illustrative purposes, we present our results for dark energy models, quintessence and Brans-Dicke theories. We also provide a discussion about the limitations of frame choices in the averaging procedure.

### The bright end of the galaxy luminosity function at z ~ 7: before the onset of mass quenching?

We present the results of a new search for bright star-forming galaxies at z ~ 7 within the UltraVISTA DR2 and UKIDSS UDS DR10 data, which together provide 1.65 sq deg of near-infrared imaging with overlapping optical and Spitzer data. Using a full photo-z analysis to identify high-z galaxies and reject contaminants, we have selected a sample of 34 luminous (-22.7 < M_UV < -21.2) galaxies with the 6.5 < z < 7.5. Crucially, the deeper imaging provided by UltraVISTA DR2 confirms all of the robust objects previously uncovered by Bowler et al. (2012), validating our selection technique. Our sample includes the most massive galaxies known at z ~ 7, with M_* ~ 10^{10} M_sun, and the majority are resolved, consistent with larger sizes (r_{1/2} ~ 1 – 1.5 kpc) than displayed by less massive galaxies. From our final sample, we determine the form of the bright end of the rest-frame UV galaxy luminosity function (LF) at z ~ 7, providing strong evidence that the bright end of the z = 7 LF does not decline as steeply as predicted by the Schechter function fitted to fainter data. We consider carefully, and exclude the possibility that this is due to either gravitational lensing, or significant contamination of our galaxy sample by AGN. Rather, our results favour a double power-law form for the galaxy LF at high z, or, more interestingly, a LF which simply follows the form of the dark-matter halo mass function at bright magnitudes. This suggests that the physical mechanism which inhibits star-formation activity in massive galaxies (i.e. AGN feedback or some other form of mass quenching’) has yet to impact on the observable galaxy LF at z ~ 7, a conclusion supported by the estimated masses of our brightest galaxies which have only just reached a mass comparable to the critical quenching mass’ of M_* = 10 ^{10.2} M_sun derived from studies of the mass function of star-forming galaxies at lower z.

### Exploring Multi-Modal Distributions with Nested Sampling

In performing a Bayesian analysis, two difficult problems often emerge. First, in estimating the parameters of some model for the data, the resulting posterior distribution may be multi-modal or exhibit pronounced (curving) degeneracies. Secondly, in selecting between a set of competing models, calculation of the Bayesian evidence for each model is computationally expensive using existing methods such as thermodynamic integration. Nested Sampling is a Monte Carlo method targeted at the efficient calculation of the evidence, but also produces posterior inferences as a by-product and therefore provides means to carry out parameter estimation as well as model selection. The main challenge in implementing Nested Sampling is to sample from a constrained probability distribution. One possible solution to this problem is provided by the Galilean Monte Carlo (GMC) algorithm. We show results of applying Nested Sampling with GMC to some problems which have proven very difficult for standard Markov Chain Monte Carlo (MCMC) and down-hill methods, due to the presence of large number of local minima and/or pronounced (curving) degeneracies between the parameters. We also discuss the use of Nested Sampling with GMC in Bayesian object detection problems, which are inherently multi-modal and require the evaluation of Bayesian evidence for distinguishing between true and spurious detections.

### Secondary CMB anisotropies from bulk motions in the presence of stochastic magnetic fields

Bulk motions of electrons along the line of sight induce secondary temperature fluctuations in the post-decoupling, reionized universe. In the presence of a magnetic field not only the scalar mode but also the vector mode act as a source for the bulk motion. The resulting angular power spectrum of temperature anisotropies of the cosmic microwave background is calculated assuming a simple model of reionization.Contributions from the standard adiabatic, curvature mode and a non helical magnetic field are included. The contribution due to magnetic fields with field strengths of order nG and negative magnetic spectral indices dominates for multipoles larger than $\ell \sim 10^4$.

### Probing the accelerating Universe with radio weak lensing in the JVLA Sky Survey

We outline the prospects for performing pioneering radio weak gravitational lensing analyses using observations from a potential forthcoming JVLA Sky Survey program. A large-scale survey with the JVLA can offer interesting and unique opportunities for performing weak lensing studies in the radio band, a field which has until now been the preserve of optical telescopes. In particular, the JVLA has the capacity for large, deep radio surveys with relatively high angular resolution, which are the key characteristics required for a successful weak lensing study. We highlight the potential advantages and unique aspects of performing weak lensing in the radio band. In particular, the inclusion of continuum polarisation information can greatly reduce noise in weak lensing reconstructions and can also remove the effects of intrinsic galaxy alignments, the key astrophysical systematic effect that limits weak lensing at all wavelengths. We identify a VLASS "deep fields" program (total area ~10-20 square degs), to be conducted at L-band and with high-resolution (A-array configuration), as the optimal survey strategy from the point of view of weak lensing science. Such a survey will build on the unique strengths of the JVLA and will remain unsurpassed in terms of its combination of resolution and sensitivity until the advent of the Square Kilometre Array. We identify the best fields on the JVLA-accessible sky from the point of view of overlapping with existing deep optical and near infra-red data which will provide crucial redshift information and facilitate a host of additional compelling multi-wavelength science.

### Large-Scale Structure and Gravitational Waves III: Tidal Effects

The leading locally observable effect of a long-wavelength metric perturbation corresponds to a tidal field. We derive the tidal field induced by scalar, vector, and tensor perturbations, and use second order perturbation theory to calculate the effect on the locally measured small-scale density fluctuations. For sub-horizon scalar perturbations, we recover the standard perturbation theory result ($F_2$ kernel). For tensor modes of wavenumber $k_L$, we find that effects persist for $k_L\tau \gg 1$, i.e. even long after the gravitational wave has entered the horizon and redshifted away, i.e. it is a "fossil" effect. We then use these results, combined with the "ruler perturbations" of arXiv:1204.3625, to predict the observed distortion of the small-scale matter correlation function induced by a long-wavelength tensor mode. We also estimate the observed signal in the B mode of the cosmic shear from a gravitational wave background, including both tidal (intrinsic alignment) and projection (lensing) effects. The non-vanishing tidal effect in the $k_L\tau \gg 1$ limit significantly increases the intrinsic alignment contribution to shear B modes, especially at low redshifts $z \lesssim 2$.

### Large-Scale Structure and Gravitational Waves III: Tidal Effects [Cross-Listing]

The leading locally observable effect of a long-wavelength metric perturbation corresponds to a tidal field. We derive the tidal field induced by scalar, vector, and tensor perturbations, and use second order perturbation theory to calculate the effect on the locally measured small-scale density fluctuations. For sub-horizon scalar perturbations, we recover the standard perturbation theory result ($F_2$ kernel). For tensor modes of wavenumber $k_L$, we find that effects persist for $k_L\tau \gg 1$, i.e. even long after the gravitational wave has entered the horizon and redshifted away, i.e. it is a "fossil" effect. We then use these results, combined with the "ruler perturbations" of arXiv:1204.3625, to predict the observed distortion of the small-scale matter correlation function induced by a long-wavelength tensor mode. We also estimate the observed signal in the B mode of the cosmic shear from a gravitational wave background, including both tidal (intrinsic alignment) and projection (lensing) effects. The non-vanishing tidal effect in the $k_L\tau \gg 1$ limit significantly increases the intrinsic alignment contribution to shear B modes, especially at low redshifts $z \lesssim 2$.

### Accounting for selection effects in the BH-bulge relations: No evidence for cosmological evolution

The redshift evolution of the black hole – bulge relations is an essential observational constraint for models of black hole – galaxy coevolution. In addition to the observational challenges for these studies, conclusions are complicated by the influence of selection effects. We demonstrate that there is presently no statistical significant evidence for cosmological evolution in the black hole-bulge relations, once these selection effects are taken into account and corrected for. We present a fitting method, based on the bivariate distribution of black hole mass and galaxy property, that accounts for the selection function in the fitting and is therefore able to recover the intrinsic black hole – bulge relation unbiased. While prior knowledge is restricted to a minimum, we at least require knowledge of either the sample selection function and the mass dependence of the active fraction, or the spheroid distribution function and the intrinsic scatter in the black hole – bulge relation. We employed our fitting routine to existing studies of the black hole-bulge relation at z~1.5 and z~6, using our current best knowledge of the distribution functions. There is no statistical significant evidence for positive evolution in the MBH-M* ratio out to z~2. At z~6 the current constraints are less strong, but we demonstrate that the large observed apparent offset from the local black hole-bulge relation at z~6 is fully consistent with no intrinsic offset. The method outlined here provides a tool to obtain more reliable constraints on black hole – galaxy co-evolution in the future.

### Multiwavelength observations of the gamma-ray emitting narrow-line Seyfert 1 PMN J0948+0022 in 2011

We report on radio-to-gamma-ray observations during 2011 May-September of PMN J0948+0022, the first narrow-line Seyfert 1 (NLSy1) galaxy detected in gamma-rays by Fermi-LAT. Strong variability was observed in gamma-rays, with two flaring periods peaking on 2011 June 20 and July 28. The variability observed in optical and near-infrared seems to have no counterpart in gamma-rays. This different behaviour could be related to a bending and inhomogeneous jet or a turbulent extreme multi-cell scenario. The radio spectra showed a variability pattern typical of relativistic jets. The XMM spectrum shows that the emission from the jet dominates above 2 keV, while a soft X-ray excess is evident in the low-energy part of the X-ray spectrum. Models where the soft emission is partly produced by blurred reflection or Comptonisation of the thermal disc emission provide good fits to the data. The X-ray spectral slope is similar to that found in radio-quiet NLSy1, suggesting that a standard accretion disc is present, as expected from the high accretion rate. Except for the soft X-ray excess, unusual in jet-dominated AGNs, PMN J0948+0022 shows all characteristics of the blazar class.

### Accurate Shear Measurement with Faint Sources

For cosmic shear to become an accurate cosmological probe, systematic errors in the shear measurement method must be unambiguously identified and corrected for. Previous work of this series has demonstrated that cosmic shears can be measured accurately in Fourier space in the presence of background noise and finite pixel size, without assumptions on the morphologies of galaxy and PSF. The remaining major source of error is source Poisson noise, due to the finiteness of source photon number. This problem is particularly important for faint galaxies in space-based weak lensing measurements. In this work, we propose a simple and rigorous way of removing the shear bias from the source Poisson noise. Our noise treatment can be generalized for images made of multiple exposures through MultiDrizzle. This is demonstrated with the COSMOS/ACS data. With a large ensemble of mock galaxy images of unrestricted morphologies, we show that our shear measurement method can achieve sub-percent accuracy even for images of signal-to-noise ratio less than 5 in general, making it the most promising technique for cosmic shear measurement in the ongoing and upcoming large scale galaxy surveys.

### Large Scale Structure Observations

Galaxy Surveys are enjoying a renaissance thanks to the advent of multi-object spectrographs on ground-based telescopes. The last 15 years have seen the fruits of this experimental advance, including the 2-degree Field Galaxy Redshift Survey (2dFGRS; Colless et al. 2003) and the Sloan Digital Sky Survey (SDSS; York et al. 2000). Most recently, the Baryon Oscillation Spectroscopic Survey (BOSS; Dawson et al. 2013), part of the SDSS-III project (Eisenstein et al. 2011), has provided the largest volume of the low-redshift Universe ever surveyed with a galaxy density useful for high-precision cosmology. This set of lecture notes looks at some of the physical processes that underpin these measurements, the evolution of measurements themselves, and looks ahead to the next 15 years and the advent of surveys such as the enhanced Baryon Oscillation Spectroscopic Survey (eBOSS), the Dark Energy Spectroscopic Instrument (DESI) and the ESA Euclid satellite mission.

### Towards a realistic population of simulated galaxy groups and clusters

We present a new suite of large-volume cosmological hydrodynamical simulations called cosmo-OWLS. They form an extension to the OverWhelmingly Large Simulations (OWLS) project, and have been designed to help improve our understanding of cluster astrophysics and non-linear structure formation, which are now the limiting systematic errors when using clusters as cosmological probes. Starting from identical initial conditions in either the Planck or WMAP7 cosmologies, we systematically vary the most important ‘sub-grid’ physics, including feedback from supernovae and active galactic nuclei (AGN). We compare the properties of the simulated galaxy groups and clusters to a wide range of observational data, such as X-ray luminosity and temperature, gas mass fractions, entropy and density profiles, Sunyaev-Zel’dovich flux, I-band mass-to-light ratio, dominance of the brightest cluster galaxy, and central massive black hole (BH) masses, by producing synthetic observations and mimicking observational analysis techniques. These comparisons demonstrate that some AGN feedback models can produce a realistic population of galaxy groups and clusters, broadly reproducing both the median trend and, for the first time, the scatter in physical properties over approximately two decades in mass (1E13 < M500/Msun < 1E15) and 1.5 decades in radius (0.05 < r/r500 < 1.5). However, in other models, the AGN feedback is too violent (even though they reproduce the observed BH scaling relations), implying calibration of the models is required. The production of realistic populations of simulated groups and clusters, as well as models that bracket the observations, opens the door to the creation of synthetic surveys for assisting the astrophysical and cosmological interpretation of cluster surveys, as well as quantifying the impact of selection effects.

### Catalog of narrow $C~IV$ absorption lines in BOSS (I): for quasars with $z_{em} \leq 2.4$

We have assembled absorption systems by visually identifying $C~IV\lambda\lambda1548,1551$ absorption doublets in the quasar spectra of the Baryon Oscillation Spectroscopic Survey (BOSS) one by one. This paper is the first of the series work. In this paper, we concern quasars with relatively low redshifts and high signal-to-noise ratios for their spectra, and hence we limit our analysis on quasars with $z_{em}\le2.4$ and on the doublets with $W_r\lambda1548\ge0.2$ \AA. Out of the more than 87,000 quasars in the Data Release 9, we limit our search to 10,121 quasars that have the appropriate redshifts and spectra with high enough signal-to-noise ratios to identify narrow C IV absorption lines. Among them, 5,442 quasars are detected to have at least one $C~IV\lambda\lambda1548,1551$ absorption doublet. We obtain a catalog containing 8,368 $C~IV\lambda\lambda1548,1551$ absorption systems, whose redshifts are within $z_{abs}=1.4544$ – $2.2805$. In this catalog, about $33.7\%$ absorbers have $0.2$ \AA$\le W_r\lambda1548<0.5$ \AA, about $45.9\%$ absorbers have $0.5$ \AA$\le W_r\lambda1548<1.0$ \AA, about $19.2\%$ absorbers have $1.0$ \AA$\le W_r\lambda1548<2.0$ \AA, and about $1.2\%$ absorbers have $W_r\lambda1548\ge2.0$ \AA.

### AGN torus properties with WISE

The Wide-field Infrared Survey Explorer (WISE) has scanned the entire sky with unprecedented sensitivity in four infrared bands, at 3.4, 4.6, 12, and 22 micron. The WISE Point Source Catalog contains more than 560 million objects, among them hundreds of thousands of galaxies with Active Nuclei (AGN). While type 1 AGN, owing to their bright and unobscured nature, are easy to detect and constitute a rather complete and unbiased sample, their type 2 counterparts, postulated by AGN unification, are not as straightforward to identify. Matching the WISE catalog with known QSOs in the Sloan Digital Sky Survey we confirm previous identification of the type 1 locus in the WISE color space. Using a very large database of the popular CLUMPY torus models, we find the colors of the putative type 2 counterparts, and also, for the first time, predict their number vs. flux relation that can be expected to be observed in any given WISE color range. This will allow us to put statistically very significant constraints on the torus parameters. Our results are a successful test of the AGN unification scheme.

### Clusters, Groups, and Filaments in the Chandra Deep Field-South up to Redshift 1

We present a comprehensive structure detection analysis of the 0.3 square degree area of the MUSYC-ACES field which covers the Chandra Deep Field-South (CDFS). Using a density-based clustering algorithm on the MUSYC and ACES photometric and spectroscopic catalogues we find 62 over-dense regions up to redshifts of 1, including, clusters, groups and filaments. All structures are confirmed using the DBSCAN method, including the detection of nine structures previously reported in the literature. We present a catalogue of all structures present including their central position, mean redshift, velocity dispersions, and classification based on their morphological and spectroscopic distributions. In particular we find 13 galaxy clusters and 6 large groups/small clusters. Comparison of these massive structures with published XMM-Newton imaging (where available) shows that $80\%$ of these structures are associated with diffuse, soft-band (0.4 – 1 keV) X-ray emission including $90\%$ of all objects classified as clusters. The presence of soft-band X-ray emission in these massive structures (${\rm M}_{200} \geq 4.9 \times 10^{13} {\rm M}_{\odot}$) provides a strong independent confirmation of our methodology and classification scheme. Nearly $60\%$ of the clusters, groups and filaments are detected in the known enhanced density regions of the CDFS at $z\simeq0.13$, $z\simeq0.52$, $0.68$, and $0.73$. Additionally, all of the clusters, bar the most distant, are found in these over-dense redshifts regions. Many of the clusters and groups exhibit signs of on-going formation seen in their velocity distributions, position within the detected cosmic web and in one case through the presence of tidally disrupted central galaxies exhibiting trails of stars. These results all provide strong support for hierarchical structure formation up to redshifts of 1.

### Cosmic star formation probed via parametric stack-fitting of known sources to radio imaging

The promise of multi-wavelength astronomy has been tempered by the large disparity in sensitivity and resolution between different wavelength regimes. Here we present a statistical approach which attempts to overcome this by fitting parametric models directly to image data. Specifically, we fit a model for the radio luminosity function (LF) of star-forming galaxies to pixel intensity distributions at 1.4 GHz coincident with near-IR selected sources in COSMOS. Taking a mass-limited sample in redshift bins across the range $0<z<4$ we are able to fit the radio LF with ~0.2 dex precision in the key parameters (e.g. Phi*,L*). Good agreement is seen between our results and those using standard methods at radio and other wavelengths. Integrating our luminosity functions to get the star formation rate density we find that galaxies with a stellar mass greater than $10^{9.5}\,$M$_{\odot}$ contribute at least 50 per cent of cosmic star formation at since $z=4$. The scalability of our approach is empirically estimated, with the precision in LF parameter estimates found to scale with the number of sources in the stack as $\sqrt{N}$. This type of approach will be invaluable in the multi-wavelength analysis of upcoming surveys with the SKA pathfinder facilities; LOFAR, ASKAP and MeerKAT.

### The thermal Sunyaev Zel'dovich effect power spectrum in light of Planck

(Abridged) The amplitude of the thermal Sunyaev Zel’dovich effect (tSZ) power spectrum is extremely sensitive to the abundance of galaxy clusters and therefore to fundamental cosmological parameters that control their growth, such as sigma_8 and Omega_m. Here we explore the sensitivity of the tSZ power spectrum to important non-gravitational (‘sub-grid’) physics by employing the cosmo-OWLS suite of large-volume cosmological hydrodynamical simulations, run in both the Planck and WMAP7 best-fit cosmologies. On intermediate and small angular scales (ell > ~1000, or theta < ~10 arcmin), accessible with the South Pole Telescope and the Atacama Cosmology Telescope, the predicted tSZ power spectrum is highly model dependent, with AGN feedback having a particularly large effect. However, at large scales, observable with the Planck telescope, the effects of sub-grid physics are minor. Comparing the simulations with observations, we find a significant amplitude offset on all measured angular scales (including large scales), if the Planck best-fit cosmology is assumed by the simulations. This is shown to be a generic result for all current tSZ models. By contrast, if the WMAP7 cosmology is adopted, there is full consistency with the Planck power spectrum measurements on large scales and agreement at the 2-sigma level with the SPT/ACT measurements at intermediate scales for our fiducial AGN model, which Le Brun et al. (2014) have shown reproduces the ‘resolved’ properties of the local cluster population remarkably well. These findings strongly suggest that there are significantly fewer massive galaxy clusters than expected for the Planck best-fit cosmology, which is consistent with recent measurements of the tSZ number counts. Our findings therefore pose a significant challenge to the cosmological parameter values preferred (and/or the model adopted) by the Planck primary CMB analyses.

### Constraining the Variation in Fine-Structure Constant Using SDSS DR8 QSO Spectra

We report a robust constrain on the possible variation of fine-structure constant, alpha = e^2/(hbar*c), obtained using O III 4959,5007, nebular emission lines from QSOs. We find Delta-alpha/alpha=-(2.1 +/- 1.6) x 10^(-5) based on a well selected sample of 2347 QSOs from Sloan Digital Sky Survey Data Release 8 with 0.02 < z < 0.74. Our result is consistent with a non-varying alpha at a level of 2 x 10^(-5) over approximately 7 Gyr. This is the largest sample of extragalactic objects yet used to constrain the variation of alpha. While this constraint is not as stringent as those determined using many-multiplet method it is free from various systematic effects. A factor of ~ 4 improvement in Delta-alpha/alpha achieved here compared to the previous study (Bahcall et al. 2004) is just consistent with what is expected based on a factor of 14 times bigger sample used here. This suggests that errors are mainly dominated by the statistical uncertainty. We also find the ratio of transition probabilities corresponding to the O III 5007 A and 4959 A lines to be 2.933+/-0.002, in good agreement with the National Institute of Standards and Technology measurements.

### Constraining the Variation in Fine-Structure Constant Using SDSS DR8 QSO Spectra [Cross-Listing]

We report a robust constrain on the possible variation of fine-structure constant, alpha = e^2/(hbar*c), obtained using O III 4959,5007, nebular emission lines from QSOs. We find Delta-alpha/alpha=-(2.1 +/- 1.6) x 10^(-5) based on a well selected sample of 2347 QSOs from Sloan Digital Sky Survey Data Release 8 with 0.02 < z < 0.74. Our result is consistent with a non-varying alpha at a level of 2 x 10^(-5) over approximately 7 Gyr. This is the largest sample of extragalactic objects yet used to constrain the variation of alpha. While this constraint is not as stringent as those determined using many-multiplet method it is free from various systematic effects. A factor of ~ 4 improvement in Delta-alpha/alpha achieved here compared to the previous study (Bahcall et al. 2004) is just consistent with what is expected based on a factor of 14 times bigger sample used here. This suggests that errors are mainly dominated by the statistical uncertainty. We also find the ratio of transition probabilities corresponding to the O III 5007 A and 4959 A lines to be 2.933+/-0.002, in good agreement with the National Institute of Standards and Technology measurements.

### Metal abundances in the high-redshift intergalactic medium

Twenty years of high-resolution spectroscopy at the 8-10 m class telescopes have drastically expanded our view of the gas-phase metallicity in the z>2 universe. This contribution briefly summarizes how these studies reveal a widespread metal pollution in the intergalactic medium with a median abundance [C/H] ~ -3.5 at z~3 that is increasing by a factor of ~2-3 from z~4.3 to z~2.4. At the higher densities that are typical of galactic halos, observations uncover a metallicity spread of five orders of magnitude in Lyman limit systems, ranging from super-solar ([M/H]~+0.7) to pristine ([M/H]< -4) gas clouds. Finally, the neutral damped Ly-alpha systems are enriched to a median metallicity of [M/H] ~ -1.5 that slowly declines with redshift up to z ~ 4.5, at which point it appears to more rapidly evolve as one approaches the end of reionization.

### Metal-free galaxy candidates discovered in CLASH

The first metals in the universe are expected to form in population III stars – primordial stars consisting entirely of hydrogen and helium. However, these stars have so far remained elusive. Simulations indicate that galaxies consisting exclusively, or almost exclusively, of population III stars may form at z>6, and such galaxies may provide one of the best probes of the properties of the population III star formation mode. By fitting Yggdrasil model spectra to multiband photometry data, we have identified four population III galaxy candidates in the Cluster Lensing and Supernova survey with Hubble (CLASH). We rule out alternative mundane galaxies and low redshift interlopers through similar fits to catalogs of spectra from more mundane objects. If confirmed through spectroscopy, this would constitute the first detection of the "missing link" between the early pristine universe and the metal-enriched universe.

### Constraints on the merging channel of massive galaxies since z~1

(Abridged) We probe the merging channel of massive galaxies over the z=0.3-1.3 redshift window by studying close pairs in a sample of 226 galaxies with stellar mass >1E11Msun, from the deep (m<26.5AB, 3 sigma) SHARDS survey. SHARDS provides medium band photometry equivalent to low-resolution optical spectra (R~50), allowing us to obtain extremely accurate photometric redshifts (|Dz|/(1+z)~0.8%, median) and to improve the constraints on the age distribution of the stellar populations. A strong correlation is found between the age difference of central and satellite galaxy and stellar mass ratio, from negligible age differences in major mergers to age differences ~4 Gyr for 1:100 minor mergers. This correlation is inherited from the general mass-age trend, suggesting that no significant bias is found between the satellites of massive centrals and galaxies with similar stellar mass in other environments. The dominant contributor to the growth of massive galaxies corresponds to mass ratios Omega=Msat/Mcen>0.3, followed by a decrease in the fractional mass growth rate linearly proportional to log Omega, at least down to Omega~0.01, suggesting a decreasing role of mergers involving low-mass satellites, especially if dynamical friction timescales are taken into account. A simple model results in an upper limit for the average mass growth rate of massive galaxies of DM/M/Dt~ 0.12+-0.06 per Gyr, over the z<1 range, with a ~60% fractional contribution from (major) mergers with Omega>0.3. The net mass growth from mergers in massive galaxies between z=1 and z=0 is M(z=0)/M(z=1)=1.9 (-0.5) (+0.7). These results suggest that the majority of the stellar mass contributed by satellites does not introduce significantly younger populations, in agreement with the small radial age gradients observed in present-day early-type galaxies.

### Simulated star formation rate functions at $\bf{z\sim4-7}$, and the role of feedback in high-$\bf{z}$ galaxies

We study the role of feedback from supernovae and black holes in the evolution of the star formation rate function (SFRF) of $z\sim4-7$ galaxies. We use a new set of cosmological hydrodynamic simulations, ANGUS (AustraliaN GADGET-3 early Universe Simulations), run with a modified and improved version of the parallel TreePM-smoothed particle hydrodynamics code GADGET-3 called P-GADGET3(XXL), that includes a self-consistent implementation of stellar evolution and metal enrichment. In our simulations both Supernova (SN) driven galactic winds and Active Galactic Nuclei (AGN) act simultaneously in a complex interplay. The SFRF is insensitive to feedback prescription at $z>5$, meaning that it cannot be used to discriminate between feedback models during reionisation. However, the SFRF is sensitive to the details of feedback prescription at lower redshift. By exploring different SN driven wind velocities and regimes for the AGN feedback, we find that the key factor for reproducing the observed SFRFs is a combination of "strong" SN winds and early AGN feedback in low mass galaxies. Conversely, we show that the choice of initial mass function and inclusion of metal cooling have less impact on the evolution of the SFRF. When variable winds are considered, we find that a non-aggressive wind scaling is needed to reproduce the SFRFs at $z\ge4$. Otherwise, the amount of objects with low SFRs is greatly suppressed and at the same time winds are not effective enough in the most massive systems.

### Observable physical modes of modified gravity [Cross-Listing]

At linear order in cosmological perturbations, departures from the growth in the cosmological standard model can be quantified in terms of two functions of redshift z and Fourier number k. Previous studies have performed principal component forecasts for several choices of these two functions, based on expected capabilities of upcoming large structure surveys. It is typically found that there will be many well-constrained degrees of freedom. However, not all and, probably most, of these degrees of freedom were physical if the parametrization had allowed for an arbitrary k-dependence. In this paper, we restrict the k-dependence to that allowed in local theories of gravity under the quasi-static approximation, i.e. ratios of polynomials in k, and identify the best constrained features in the (z,k)-dependence of the commonly considered functions $\mu$ and $\gamma$ as measured by an LSST-like weak lensing survey. We find that about 10 eigenmodes of modified growth can be constrained with a better than a percent accuracy when one considers the combined effect of the two functions.

### Observable physical modes of modified gravity

At linear order in cosmological perturbations, departures from the growth in the cosmological standard model can be quantified in terms of two functions of redshift z and Fourier number k. Previous studies have performed principal component forecasts for several choices of these two functions, based on expected capabilities of upcoming large structure surveys. It is typically found that there will be many well-constrained degrees of freedom. However, not all and, probably most, of these degrees of freedom were physical if the parametrization had allowed for an arbitrary k-dependence. In this paper, we restrict the k-dependence to that allowed in local theories of gravity under the quasi-static approximation, i.e. ratios of polynomials in k, and identify the best constrained features in the (z,k)-dependence of the commonly considered functions $\mu$ and $\gamma$ as measured by an LSST-like weak lensing survey. We find that about 10 eigenmodes of modified growth can be constrained with a better than a percent accuracy when one considers the combined effect of the two functions.

### Primordial Magnetic Field Limits from CMB Trispectrum - Scalar Modes and Planck Constraints [Cross-Listing]

Cosmic magnetic fields are observed to be coherent on large scales and could have a primordial origin. Non-Gaussian signals in the cosmic microwave background (CMB) are generated by primordial magnetic fields as the magnetic stresses and temperature anisotropy they induce depend quadratically on the magnetic field. We compute the CMB scalar trispectrum on large angular scales, for nearly scale-invariant magnetic fields, sourced via the Sachs-Wolfe effect. The trispectra induced by magnetic energy density and by magnetic scalar anisotropic stress are found to have typical magnitudes of approximately $10^{-29}$ and $10^{-19}$, respectively. The scalar anisotropic stress trispectrum is also calculated in the flat-sky approximation and yields a similar result. Observational limits on CMB non-Gaussianity from the Planck mission data allow us to set upper limits of $B_0 \lesssim 0.6$ nG on the present value of the primordial cosmic magnetic field. Considering the inflationary magnetic curvature mode in the trispectrum can further tighten the magnetic field upper limit to $B_0 \lesssim 0.05$ nG. These sub-nanoGauss constraints from the magnetic trispectrum are the most stringent limits so far on the strength of primordial magnetic fields, on megaparsec scales, significantly better than the limits obtained from the CMB bispectrum and the CMB power spectrum.

### Primordial Magnetic Field Limits from CMB Trispectrum - Scalar Modes and Planck Constraints

Cosmic magnetic fields are observed to be coherent on large scales and could have a primordial origin. Non-Gaussian signals in the cosmic microwave background (CMB) are generated by primordial magnetic fields as the magnetic stresses and temperature anisotropy they induce depend quadratically on the magnetic field. We compute the CMB scalar trispectrum on large angular scales, for nearly scale-invariant magnetic fields, sourced via the Sachs-Wolfe effect. The trispectra induced by magnetic energy density and by magnetic scalar anisotropic stress are found to have typical magnitudes of approximately $10^{-29}$ and $10^{-19}$, respectively. The scalar anisotropic stress trispectrum is also calculated in the flat-sky approximation and yields a similar result. Observational limits on CMB non-Gaussianity from the Planck mission data allow us to set upper limits of $B_0 \lesssim 0.6$ nG on the present value of the primordial cosmic magnetic field. Considering the inflationary magnetic curvature mode in the trispectrum can further tighten the magnetic field upper limit to $B_0 \lesssim 0.05$ nG. These sub-nanoGauss constraints from the magnetic trispectrum are the most stringent limits so far on the strength of primordial magnetic fields, on megaparsec scales, significantly better than the limits obtained from the CMB bispectrum and the CMB power spectrum.

### The effective gravitational decoupling between dark matter and the CMB

We present a detailed and self-contained analytical derivation of the evolution of sub-horizon cosmological perturbations before decoupling, based on previous work by S. Weinberg. These solutions are valid in the minimal LCDM scenario, to first order in perturbation theory, in the tight-coupling limit and neglecting neutrino shear stress. We compare them to exact numerical solutions computed by a Boltzmann code, and we find the two to be in very good agreement. The analytic solutions show explicitly that CDM and the baryon-photon fluid effectively behave as separate self-gravitating fluids until the epoch of baryon drag. This in turn leads to the surprising conclusion that the CMB is much less sensitive to the clustering properties of specific Dark Matter models than what would be naively expected.

### Large-scale structure growth rate measurement cosmological constraints

We compile a list of $14$ independent measurements of large-scale structure growth rate between redshifts $0.067 \leq z \leq 0.8$ and use this to place constraints on model parameters of constant and time-evolving general-relativistic dark energy cosmologies. With the assumption that gravity is well-modeled by general relativity, we discover that growth-rate data provide restrictive cosmological parameter constraints. In combination with type Ia supernova apparent magnitude versus redshift data and Hubble parameter measurements, the growth rate data are consistent with the standard spatially-flat $\Lambda$CDM model, as well as with mildly evolving dark energy density cosmological models.

### Analysis of nuclear activity of ten polar ring galaxies

The accumulation of mass from the interaction process that forms the polar ring galaxies is a factor that favors the conditions necessary to trigger nonthermal nuclear activities.. This fact encouraged the chemical analysis of ten polar ring galaxies. In order to verify the presence of an active nucleus in these galaxias, we built diagnostic diagrams using lines H{\beta}, [OIII], [HI], H{\alpha}, [NII], and [SII] and classified the type of nuclear activity. For galaxies that do not show shock, the parameters N2 and O3N2 were also determined. From this sample, we identified seven galaxies with an active nucleus and three that behave as HII regions. One galaxy with an active nucleus was classified as Seyfert. Although our data do not provide a statistically significant sample, we can speculate that polar ring galaxies are a setting conducive to trigger non-thermal nuclear activities.

Using our previously derived simple analytic expression for the bolometric light curves of supernovae, we demonstrate that the collision of the fast debris of ordinary supernova explosions with relatively slow-moving shells from pre-supernova eruptions can produce the observed bolometric light curves of superluminous supernovae (SLSNe) of all types. These include both, those which can be explained as powered by spinning-down millisecond magnetars and those which cannot. That and the observed close similarity between the bolometric light-curves of SLSNe and ordinary interacting SNe suggest that SLSNe are powered mainly by collisions with relatively slow moving circumstellar shells from pre-supernova eruptions rather than by the spin-down of millisecond magnetars born in core collapse supernova explosions.

### Cosmological Perturbation Theory as a Tool for Estimating Box-Scale Effects in N-body Simulations

In performing cosmological N-body simulations, it is widely appreciated that the growth of structure on the largest scales within a simulation box will be inhibited by the finite size of the simulation volume. Following ideas set forth in Seto 1999, this paper shows that standard (a.k.a. 1-loop) cosmological perturbation theory (SPT) can be used to predict at an order-of-magnitude level the deleterious effect of the box scale on the power spectrum of density fluctuations in simulation volumes. Alternatively, this approach can be used to quickly estimate post facto the effect of the box scale on power spectrum results from existing simulations. In this way SPT can help determine whether larger box sizes or other more-sophisticated methods are needed to achieve a particular level of precision for a given application (e.g. simulations to measure the non-linear evolution of baryon acoustic oscillations). I focus on SPT in this note and show that its predictions are order-of-magnitude accurate compared to N-body simulations, but doubtless the estimation of box-scale numerical effects would be improved using more-sophisticated perturbation theory models. An appendix compares the simulation results at outputs where box-scale effects are minimal to the SPT-based prediction of Scoccimarro 1997 and the corrected SPT formula from Pajer & Zaldarriaga 2013. The power spectrum measurements from simulation are made available for future comparisons to other perturbation theory models.

### Signatures of anisotropic sources in the trispectrum of the cosmic microwave background

Soft limits of $N$-point correlation functions, in which one wavenumber is much smaller than the others, play a special role in constraining the physics of inflation. Anisotropic sources such as a vector field during inflation generate distinct angular dependence in all these correlators. In this paper we focus on the four-point correlator (the trispectrum $T$). We adopt a parametrization motivated by models in which the inflaton $\phi$ is coupled to a vector field through a $I^2 \left( \phi \right) F^2$ interaction, namely $T_{\zeta}({\bf k}_1, {\bf k}_2, {\bf k}_3, {\bf k}_4) \equiv \sum_n d_n [ P_n(\hat{\bf k}_1 \cdot \hat{\bf k}_3) + P_n(\hat{\bf k}_1 \cdot \hat{\bf k}_{12}) + P_n(\hat{\bf k}_3 \cdot \hat{\bf k}_{12}) ] P_{\zeta}(k_1) P_{\zeta}(k_3) P_\zeta(k_{12}) + (23~{\rm perm})$, where $P_n$ denotes the Legendre polynomials. This shape is enhanced when the wavenumbers of the diagonals of the quadrilateral are much smaller than the sides, ${\bf k}_i$. The coefficient of the isotropic part, $d_0$, is equal to $\tau_{\rm NL}/6$ discussed in the literature. A $I^2 \left( \phi \right) F^2$ interaction generates $d_2 = 2 d_0$ which is, in turn, related to the quadrupole modulation parameter of the power spectrum, $g_*$, as $d_2 \approx 14 |g_*| N^2$ with $N \approx 60$. We show that $d_0$ and $d_2$ can be equally well-constrained: the expected $68 \%$ CL error bars on these coefficients from a cosmic-variance-limited experiment measuring temperature anisotropy of the cosmic microwave background up to $\ell_{\rm max}=2000$ are $\delta d_2 \approx 4 \delta d_0 = 105$. Therefore, we can reach $|g_*|=10^{-3}$ by measuring the angle-dependent trispectrum. The current upper limit on $\tau_{\rm NL}$ from the ${\it Planck}$ temperature maps yields $|g_*|<0.02$ ($95 \%$ CL).

### Signatures of anisotropic sources in the trispectrum of the cosmic microwave background [Cross-Listing]

Soft limits of $N$-point correlation functions, in which one wavenumber is much smaller than the others, play a special role in constraining the physics of inflation. Anisotropic sources such as a vector field during inflation generate distinct angular dependence in all these correlators. In this paper we focus on the four-point correlator (the trispectrum $T$). We adopt a parametrization motivated by models in which the inflaton $\phi$ is coupled to a vector field through a $I^2 \left( \phi \right) F^2$ interaction, namely $T_{\zeta}({\bf k}_1, {\bf k}_2, {\bf k}_3, {\bf k}_4) \equiv \sum_n d_n [ P_n(\hat{\bf k}_1 \cdot \hat{\bf k}_3) + P_n(\hat{\bf k}_1 \cdot \hat{\bf k}_{12}) + P_n(\hat{\bf k}_3 \cdot \hat{\bf k}_{12}) ] P_{\zeta}(k_1) P_{\zeta}(k_3) P_\zeta(k_{12}) + (23~{\rm perm})$, where $P_n$ denotes the Legendre polynomials. This shape is enhanced when the wavenumbers of the diagonals of the quadrilateral are much smaller than the sides, ${\bf k}_i$. The coefficient of the isotropic part, $d_0$, is equal to $\tau_{\rm NL}/6$ discussed in the literature. A $I^2 \left( \phi \right) F^2$ interaction generates $d_2 = 2 d_0$ which is, in turn, related to the quadrupole modulation parameter of the power spectrum, $g_*$, as $d_2 \approx 14 |g_*| N^2$ with $N \approx 60$. We show that $d_0$ and $d_2$ can be equally well-constrained: the expected $68 \%$ CL error bars on these coefficients from a cosmic-variance-limited experiment measuring temperature anisotropy of the cosmic microwave background up to $\ell_{\rm max}=2000$ are $\delta d_2 \approx 4 \delta d_0 = 105$. Therefore, we can reach $|g_*|=10^{-3}$ by measuring the angle-dependent trispectrum. The current upper limit on $\tau_{\rm NL}$ from the ${\it Planck}$ temperature maps yields $|g_*|<0.02$ ($95 \%$ CL).

### Starobinsky-type Inflation in Dynamical Supergravity Breaking Scenarios [Cross-Listing]

In the context of dynamical breaking of local supersymmetry (supergravity), including the Deser-Zumino super-Higgs effect, for the simple but quite representative cases of N=1, D=4 supergravity, we discuss the emergence of Starobinsky-type inflation, due to quantum corrections in the effective action arising from integrating out gravitino fields in their massive phase. This type of inflation may occur after a first-stage small-field inflation that characterises models near the origin of the one-loop effective potential, and it may occur at the non-trivial minima of the latter. Phenomenologically realistic scenarios, compatible with the Planck data, may be expected for the conformal supergravity variants of the basic model.

### Starobinsky-type Inflation in Dynamical Supergravity Breaking Scenarios

In the context of dynamical breaking of local supersymmetry (supergravity), including the Deser-Zumino super-Higgs effect, for the simple but quite representative cases of N=1, D=4 supergravity, we discuss the emergence of Starobinsky-type inflation, due to quantum corrections in the effective action arising from integrating out gravitino fields in their massive phase. This type of inflation may occur after a first-stage small-field inflation that characterises models near the origin of the one-loop effective potential, and it may occur at the non-trivial minima of the latter. Phenomenologically realistic scenarios, compatible with the Planck data, may be expected for the conformal supergravity variants of the basic model.

### The particle content of low-power radio galaxies in groups and clusters

The synchrotron-radiating particles and magnetic fields in low-power radio galaxies (including most nearby cluster-centre sources), if at equipartition, can provide only a small fraction of the total internal energy density of the radio lobes or plumes, which is now well constrained via X-ray observations of their external environments. We consider the constraints on models for the dominant energy contribution in low-power radio-galaxy lobes obtained from a detailed comparison of how the internal equipartition pressure and external pressure measured from X-ray observations evolve with distance for two radio galaxies, 3C 31 and Hydra A. We rule out relativistic-lepton dominance of the radio lobes, and conclude that models in which magnetic field or relativistic protons/ions carried up the jet dominate lobe energetics are unlikely. Finally, we argue that entrainment of material from the jet surroundings can provide the necessary pressure, and construct a simple self-consistent model of the evolution of the entrainment rate required for pressure balance along the 100-kpc scale plumes of 3C 31. Such a model requires that the entrained material is heated to temperatures substantially above that of the surrounding intra-group or cluster medium, and that the temperature of the thermal component of the jet increases with distance, though remaining sub-relativistic.

### Potential of LOFT telescope for the search of dark matter

Large Observatory For X-ray Timing (LOFT) is a next generation X-ray telescope selected by European Space Agency as one of the space mission concepts within the “Cosmic Vision” programme. The Large Area Detector on board of LOFT will be a collimator-type telescope with an unprecedentedly large collecting area of about 10 square meters in the energy band between 2 and 100 keV. We demonstrate that LOFT will be a powerful dark matter detector, suitable for the search of the X-ray line emission expected from decays of light dark matter particles in galactic halos. We show that LOFT will have sensitivity for dark matter line search more than an order of magnitude higher than that of all existing X-ray telescopes. In this way, LOFT will be able to provide a new insight into the fundamental problem of the nature of dark matter.

### Using correlations between CMB lensing and large-scale structure to measure primordial non-Gaussianity

We present a new method to measure primordial non-Gaussianity, using the cross-correlation between galaxy surveys and the CMB lensing signal to measure galaxy bias on very large scales, where local-type primordial non-Gaussianity predicts a $k^2$ divergence. We use the CMB lensing map recently published by the Planck collaboration, and measure its external correlations with a suite of six galaxy catalogues spanning a broad redshift range. We then consistently combine correlation functions to extend the recent analysis by Giannantonio et al. (2013), where the density-density and the density-CMB temperature correlations were used. Due to the intrinsic noise of the Planck lensing map, which affects the largest scales most severely, we find that the constraints on the galaxy bias are similar to the constraints from density-CMB temperature correlations. Including lensing constraints only improves the previous statistical measurement errors marginally, and we obtain $f_{\mathrm{NL}} = 12 \pm 21$ (1$\sigma$) from the combined data set. However, the lensing measurements serve as an excellent test of systematic errors: we now have three methods to measure the large-scale, scale-dependent bias from a galaxy survey: auto-correlation, and cross-correlation with both CMB temperature and lensing. As the publicly available Planck lensing maps have had their largest-scale modes at multipoles $l<10$ removed, which are the most sensitive to the scale-dependent bias, we consider mock CMB lensing data covering all multipoles. We find that, while the effect of $f_{\mathrm{NL}}$ indeed increases significantly on the largest scales, so do the contributions of both cosmic variance and the intrinsic lensing noise, so that the improvement is small.

### Using correlations between CMB lensing and large-scale structure to measure primordial non-Gaussianity [Replacement]

We apply a new method to measure primordial non-Gaussianity, using the cross-correlation between galaxy surveys and the CMB lensing signal to measure galaxy bias on very large scales, where local-type primordial non-Gaussianity predicts a $k^2$ divergence. We use the CMB lensing map recently published by the Planck collaboration, and measure its external correlations with a suite of six galaxy catalogues spanning a broad redshift range. We then consistently combine correlation functions to extend the recent analysis by Giannantonio et al. (2013), where the density-density and the density-CMB temperature correlations were used. Due to the intrinsic noise of the Planck lensing map, which affects the largest scales most severely, we find that the constraints on the galaxy bias are similar to the constraints from density-CMB temperature correlations. Including lensing constraints only improves the previous statistical measurement errors marginally, and we obtain $f_{\mathrm{NL}} = 12 \pm 21$ (1$\sigma$) from the combined data set. However, the lensing measurements serve as an excellent test of systematic errors: we now have three methods to measure the large-scale, scale-dependent bias from a galaxy survey: auto-correlation, and cross-correlation with both CMB temperature and lensing. As the publicly available Planck lensing maps have had their largest-scale modes at multipoles $l<10$ removed, which are the most sensitive to the scale-dependent bias, we consider mock CMB lensing data covering all multipoles. We find that, while the effect of $f_{\mathrm{NL}}$ indeed increases significantly on the largest scales, so do the contributions of both cosmic variance and the intrinsic lensing noise, so that the improvement is small.

### Testing chameleon gravity with the Coma cluster

We propose a novel method to test the gravitational interactions in the outskirts of galaxy clusters. When gravity is modified, this is typically accompanied by an introduction of an additional scalar degree of freedom, which mediates an attractive fifth force. The presence of an extra gravitational coupling, however, is tightly constrained by local measurements. In chameleon modifications of gravity, local tests can be evaded by employing a screening mechanism that suppresses the fifth force in dense environments. While the chameleon field may be screened in the interior of the cluster, its outer region can still be affected by the extra force, introducing a deviation between the hydrostatic and lensing mass of the cluster. Thus, the chameleon modification can be tested by combining the gas and lensing measurements of the cluster. We demonstrate the operability of our method with the Coma cluster, for which both a lensing measurement and gas observations from the X-ray surface brightness, the X-ray temperature, and the Sunyaev-Zel’dovich effect are available. Using the joint observational data set, we perform a Markov chain Monte Carlo analysis of the parameter space describing the different profiles in both the Newtonian and chameleon scenarios. We report competitive constraints on the chameleon field amplitude and its coupling strength to matter. In the case of f(R) gravity, corresponding to a specific choice of the coupling, we find an upper bound on the background field amplitude of |f_{R0}|<6*10^{-5}, which is currently the tightest constraint on cosmological scales.

### The Fundamental Manifold of spiral galaxies: ordered versus random motions and the morphology dependence of the Tully-Fisher relation

(Abridged) We investigate the morphology dependence of the Tully-Fisher relation, and the expansion of the relation into a three-dimensional manifold defined by luminosity, total circular velocity and a third dynamical parameter, to fully characterise spiral galaxies across all morphological types. We use a semi-analytic hierarchical model of galaxy evolution to build the theoretical TF relation. With this tool, we analyse a unique dataset of galaxies for which we cross-match luminosity with total circular velocity and central velocity dispersion. We provide a theoretical framework to calculate such measurable quantities from semi-analytic models. We establish the morphology dependence of the TF relation in both model and data. We analyse the dynamical properties of the model galaxies and determine that the parameter ‘sigma/Vc’, i.e. the ratio between random and total motions defined by velocity dispersion and circular velocity, accurately characterises the varying slope of the TF relation for different model galaxy types. We apply these dynamical cuts to the observed galaxies and find that such selection produces a differential slope of the TF relation. The TF slope in different ranges of ‘sigma/Vc’ is consistent with that for the photometric classification in Sa, Sb, Sc. We conclude that ‘sigma/Vc’ is a good parameter to classify galaxy type, and we argue that such classification based on dynamics more closely mirrors the physical properties of the observed galaxies, compared to visual classification. We also argue that dynamical classification is useful for samples where eye inspection is not reliable or impractical. We conclude that ‘sigma/Vc’ is a suitable parameter to characterise the hierarchical assembly history that determines the disk-to-bulge ratio, and to expand the TF relation into a three-dimensional manifold, defined by luminosity, circular velocity and ‘sigma/Vc’.

### Current signatures and search for Pop. III stars in the Local Universe

Recent numerical studies argue that low-mass stars can be formed even at zero-metallicity environment. These low-mass Population III(Pop.~III) stars are thought to be still shining and able to be observed in the Local Universe. Most low-mass Pop.~III stars are thought to be formed as secondary companions in binary systems. They can be escaped from their host mini-halos when their primary companions explode as supernovae. In this paper, we estimate the escape probability of the low-mass Pop.~III stars from their host mini-halos. We find that $\sim 100$ Pop.~III stars are expected. We also compute spatial distribution of these escaped Pop.~III survivors by means of the semi-analytic hierarchical chemical evolution model. Typically, they are distributed around $\sim 2$Mpc away from the Milky Way but 5 — $35\%$ of the escaped stars fall into the Milky Way halo. These escaped Pop.~III stars are possibly detected by very large scaled surveys being planned.