Gravitational lens flux-ratio anomalies provide a powerful technique for measuring dark matter substructure in distant galaxies. However, before using these flux-ratio anomalies to test galaxy formation models, it is imperative to ascertain that the given anomalies are indeed due to the presence of dark matter substructure and not due to some other component of the lensing galaxy halo or to propagation effects. Here we present the case of CLASS~B1555+375, which has a strong radio-wavelength flux-ratio anomaly. Our high-resolution near-infrared Keck~II adaptive optics imaging and archival Hubble Space Telescope data reveal the lensing galaxy in this system to have a clear edge-on disc component that crosses directly over the pair of images that exhibit the flux-ratio anomaly. We find simple models that include the disc can reproduce the cm-wavelength flux-ratio anomaly without requiring additional dark matter substructure. Although further studies are required, our results suggest the assumption that all flux-ratio anomalies are due to a population of dark matter sub-haloes may be incorrect, and analyses that do not account for the full complexity of the lens macro-model may overestimate the substructure mass fraction in massive lensing galaxies
Deriving the expansion history of the Universe is a major goal of modern cosmology. To date, the most accurate measurements have been obtained with Type Ia Supernovae and Baryon Acoustic Oscillations, providing evidence for the existence of a transition epoch at which the expansion rate changes from decelerated to accelerated. However, these results have been obtained within the framework of specific cosmological models that must be implicitly or explicitly assumed in the measurement. It is therefore crucial to obtain measurements of the accelerated expansion of the Universe independently of assumptions on cosmological models. Here we exploit the unprecedented statistics provided by the Baryon Oscillation Spectroscopic Survey (BOSS) Data Release 9 to provide new constraints on the Hubble parameter $H(z)$ using the em cosmic chronometers approach. We extract a sample of more than 130000 of the most massive and passively evolving galaxies, obtaining five new cosmology-independent $H(z)$ measurements in the redshift range $0.3<z<0.5$, with an accuracy of $\sim$11-16\% incorporating both statistical and systematic errors. Once combined, these measurements yield a 6\% accuracy constraint of $H(z=0.4293)=91.8\pm5.3$ km/s/Mpc. The new data are crucial to provide the first cosmology-independent determination of the transition redshift at high statistical significance, measuring $z_{t}=0.4\pm0.1$, and to significantly disfavor the null hypothesis of no transition between decelerated and accelerated expansion at 99.9\% confidence level. This analysis highlights the wide potential of the cosmic chronometers approach: it permits to derive constraints on the expansion history of the Universe with results competitive with standard probes, and most importantly, being the estimates independent of the cosmological model, it can constrain cosmologies beyond -and including- the $\Lambda$CDM model.
Cosmography is a model-independent description to the cosmic evolution, but suffers a serious convergence issue in confront of the supernova data, especially for high redshift $z>1$. To ensure data in the convergence radius, $y=z/(1+z)$ redshift was defined. However, discussions about the usefulness of $y$-redshift and the leading cause of the issue are commonly absent. In the present paper, we study the cosmography in both $z$ and $y$ redshift using the supernova and mock redshift drift data. By introducing the bias-variance tradeoff, we reveal that the large bias square between cosmography and Union2.1 supernova data is the "chief culprit" of convergence issue. Moreover, expansion up to higher order and introduction of the $y$-redshift both are not effective to reconcile this contradiction. Minimizing risk, it suggests that Taylor expansion up to the second term is a better choice for available supernova data. Forecast from future supernova data and redshift drift shows that redshift drift can give much tighter constraints on the cosmography. We also investigate the effect of convergence issue on the deceleration parameter and dark energy. It inspires us that dynamical observations including redshift drift can give more detailed information on cosmic evolution.
We compute the mass function of galactic dark matter halos for different values of the Warm Dark Matter (WDM) particle mass m_X and compare it with the abundance of ultra-faint galaxies derived from the deepest UV luminosity function available so far at redshift z~2. The magnitude limit M_UV=-13 reached by such observations allows us to probe the WDM mass functions down to scales close to or smaller than the half-mass mode mass scale ~10^9 M_sun. This allowed for an efficient discrimination among predictions for different m_X which turn out to be independent of the star formation efficiency adopted to associate the observed UV luminosities of galaxies to the corresponding dark matter masses. Adopting a conservative approach to take into account the existing theoretical uncertainties in the galaxy halo mass function, we derive a robust limit m_X>1.8 keV for the mass of thermal relic WDM particles when comparing with the measured abundance of the faintest galaxies, while m_X>1.5 keV is obtained when we compare with the Schechter fit to the observed luminosity function. The corresponding lower limit for sterile neutrinos depends on the modeling of the production mechanism; for instance m_sterile > 4 keV holds for the Shi-Fuller mechanism. We discuss the impact of observational uncertainties on the above bound on m_X. As a baseline for comparison with forthcoming observations from the HST Frontier Field, we provide predictions for the abundance of faint galaxies with M_UV=-13 for different values of m_X and of the star formation efficiency, valid up to z~4.
Observations of the microwave background fluctuations suggest a scale-dependent amplitude asymmetry of roughly 2.5 sigma significance. Inflationary explanations for this 'anomaly' require non-Gaussian fluctuations which couple observable modes to those on much larger scales. In this Letter we describe an analysis of such scenarios which significantly extends previous treatments. We identify the non-Gaussian 'response function' which characterizes the asymmetry, and show that it is non-trivial to construct a model which yields a sufficient amplitude: many independent fine tunings are required, often making such models appear less likely than the anomaly they seek to explain. We present an explicit model satisfying observational constraints and determine for the first time how large its bispectrum would appear to a Planck-like experiment. Although this model is merely illustrative, we expect it is a good proxy for the bispectrum in a sizeable class of models which generate a scale-dependent response using a large eta parameter.
We present a ray tracing code to compute integrated cosmological observables on the fly in AMR N-body simulations. Unlike conventional ray tracing techniques, our code takes full advantage of the time and spatial resolution attained by the N-body simulation by computing the integrals along the line of sight on a cell-by-cell basis through the AMR simulation grid. Moroever, since it runs on the fly in the N-body run, our code can produce maps of the desired observables without storing large (or any) amounts of data for post-processing. We implemented our routines in the RAMSES N-body code and tested the implementation using an example of weak lensing simulation. We analyse basic statistics of lensing convergence maps and find good agreement with semi-analytical methods. The ray tracing methodology presented here can be used in several cosmological analysis such as Sunyaev-Zel'dovich and integrated Sachs-Wolfe effect studies as well as modified gravity. Our code can also be used in cross-checks of the more conventional methods, which can be important in tests of theory systematics in preparation for upcoming large scale structure surveys.
The string/$M$ theory Axiverse -- a plethora of very light Axion Like Particles (ALPs) with a vast range of masses -- is arguably a generic prediction of string/$M$ theory. String/$M$ theory also tends to predict that the early Universe is dominated by moduli fields. When the heavy moduli decay, before nucleosynthesis, they produce dark radiation in the form of relativistic ALPs. Generically one estimates that the number of relativistic species grows with the number of axions in the Axiverse, in contradiction to the observations that $N_{eff} \leq 4$. We explain this problem in detail and suggest some possible solutions to it. The simplest solution requires that the lightest modulus decays only into its own axion superpartner plus Standard Model particles and this severely constrains the moduli Kahler potential and mass matrix.
We use the Hubble Space Telescope (HST) archive of ultraviolet (UV) quasar spectroscopy to conduct the first blind survey for damped Ly-alpha absorbers (DLAs) at low redshift (z < 1.6). Our statistical sample includes 463 quasars with spectral coverage spanning a total redshift path, dz = 123.3 or an absorption path, dX = 229.7. Within this survey path, we identify 4 DLAs, defined as absorbers with HI column density N(HI) >= 10^20.3cm-2, which implies an incidence per absorption length, l(X)= 0.017(+0.014-0.008) at a median survey path redshift of z=0.623. While our estimate of l(X) is lower than earlier estimates at z ~ 0 from HI 21cm emission studies, the results are consistent within the measurement uncertainties. Our dataset is too small to properly sample the N(HI) frequency distribution function f(N(HI),X), but the observed distribution agrees with previous estimates at z > 2. Adopting the z > 2 shape of f(N(HI),X), we infer an HI mass density at z ~ 0.6 of rho_HI = 0.25(+0.20-0.12) x 10^8 Msol Mpc-3. This is significantly lower than previous estimates from targeted DLA surveys with the HST, but consistent with results from low-z HI 21cm observations, and suggests that the neutral gas density of the universe has been decreasing over the past 10 Gyrs.
Compact binary mergers may have already been observed as they are the leading model for short gamma-ray bursts (sGRBs). Radioactive decay within the ejecta from these mergers is expected to produce an infra-red flare, dubbed macronova (or kilonova), on a time scale of a week. Recently two such macronova candidates were identified in followup observations of sGRBs, strengthening the possibility that those indeed arise from mergers. The same ejecta will also produce a long term (months to years) radio emission due to its interaction with the surrounding ISM. In search for this emission, we observed the two macronova candidates, GRB 130603B and GRB 060614 with the Jansky very large array (VLA) and the Australia Telescope Compact Array (ATCA). Our observations resulted in null-detections, putting strong upper limits on the kinetic energy and mass of the ejecta. A possible outcome of a merger is a highly magnetized neutron star (a magnetar), which has been suggested as the central engine for GRBs. Such a magnetar will deposit a significant fraction of its energy into the ejecta leading to a brighter radio flare. Our results, therefore, rule out magnetars in these two events.
We provide the power spectrum of small scalar perturbations propagating in an inflationary scenario within loop quantum cosmology. We consider the hybrid quantization approach applied to a Friedmann--Robertson--Walker spacetime with flat spatial sections coupled to a massive scalar field. We study the quantum dynamics of scalar perturbations on an effective background within this hybrid approach. We consider in our study adiabatic states of different orders. For them, we find that the hybrid quantization is in good agreement with the predictions of the dressed metric approach. We also propose an initial vacuum state for the perturbations, and compute the primordial and the anisotropy power spectrum in order to qualitatively compare with the current observations of Planck mission. We find that our vacuum state is in good agreement with them, showing a suppression of the power spectrum for large scale anisotropies. We compare with other choices already studied in the literature.
I give a brief review of the status of research on the nature of initial conditions required to obtain a period of cosmological inflation. It is shown that there is good evidence that in the case of large field models, the inflationary slow-roll trajectory is a local attractor in initial condition space, whereas it is not in the case of small field models.
We consider the Universe at the late stage of its evolution and deep inside the cell of uniformity. At such scales, the Universe is highly inhomogeneous and is filled with inhomogeneities in the form of galaxies and the groups of galaxies. We also suggest that the Universe is filled with a perfect fluid, and its fluctuations have peculiar velocities of the same (non-relativistic) order of magnitude as for the inhomogeneities. In this sense, the inhomogeneities (e.g. galaxies) and fluctuations of perfect fluids are coupled with each other. We clarify some important points of this approach and present a brief review of previous studies (e.g. CPL model and Chaplygin gas). We demonstrate that considered perfect fluids which satisfy our approach are really coupled to galaxies concentrating around them. The averaged (over the whole Universe) value of their fluctuations is equal to zero.
We present the results of a survey for HI 21-cm and OH 18-cm absorption in seven strong CO emitters at z > 3. Despite reaching limits comparable to those required to detect 21-cm absorption at lower redshifts, we do not detect either transition in any of the objects searched. We believe that this is due to the high redshift selection causing all of our targets to have ultra-violet luminosities above the critical value, where all of the atomic gas in the host galaxy disk is suspected to be ionised. However, not only are all of our targets bright in CO emission, but detection of CO above the critical UV luminosity is generally not uncommon. This suggests that the molecular gas is shielded from the radiation or is physically remote from the source of the continuum emission, as it appears to be from CO observations of high redshift radio galaxies.
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We present the first measurement of individual cluster mass estimates using weak lensing size and flux magnification. Using data from the HST-STAGES survey of the A901/902 supercluster we detect the four known groups in the supercluster at high significance using magnification alone. We discuss the application of a fully Bayesian inference analysis, and investigate a broad range of potential systematics in the application of the method. We compare our results to a previous weak lensing shear analysis of the same field finding the recovered signal-to-noise of our magnification-only analysis to range from 45% to 110% of the signal-to-noise in the shear-only analysis. On a case-by-case basis we find consistent magnification and shear constraints on cluster virial radius, and finding that for the full sample, magnification constraints to be a factor $0.77 \pm 0.18$ lower than the shear measurements.
We use the $f^{2}FF$ model to study the generation of primordial magnetic fields (PMF) in the context of large field inflation (LFI), described by the potential, $V \sim M \phi^{p}$. We compute the magnetic and electric spectra for all possible values of the model parameters under de Sitter and power law expansion. We show that scale invariant PMF are not obtained in LFI to first order in the slow roll approximation, if we impose the constraint $V(\phi=0)\sim 0$. Alternatively, if these constraints are relaxed, the scale invariant PMF can be generated. The associated electric field energy can fall below the energy density of inflation, $\rho_{\rm{Inf}}$ for the ranges of comoving wavenumbers, $ k > 8 \times 10^{-7} \rm{Mpc^{-1}}$ and $ k > 4 \times 10^{-6} \rm{Mpc^{-1}}$ in de Sitter and power law (PL) expansion. Further, it can drop below $\rho_{\rm{Inf}}$ on the ranges, e-foldings $N > 51$, $p<1.66$, $p >2.03$, $l_0 > 3 \times 10^5 {M_{\rm{Pl}}}^{-1} (H_i < 3.3 \times 10^{-6} M_{\rm{Pl}})$, and $M > 2.8 \times 10^{-3} M_{\rm{Pl}}$. All of the above ranges fit with the observational constraints.
The power spectrum of Near InfraRed Background (NIRB) fluctuations measured at 3.6 $\mu$m by {\tt Spitzer} shows a clustering excess over the known galaxies signal that has been interpreted in terms of early ($z\simgt 13$), accreting (direct collapse) black holes (DCBH) or low-$z$ intrahalo light (IHL). In addition, these fluctuations correlate with the cosmic X-ray background (CXB) measured at (0.5-2) keV, supporting the black hole explanation. This scenario has been questioned by the recent detection of a correlation between the two {\tt CIBER} 1.1/1.6 $\mu$m bands with the 3.6 $\mu$m {\tt Spitzer} one. This correlation is hardly explained by early DCBHs that, due to intergalactic absorption, cannot contribute to the shortest wavelength bands. Here we show that the new correlation is caused instead by a Diffuse Galactic Light (DGL) component arising from Galactic stellar light scattered by dust. The black hole interpretation of the excess remains perfectly valid and, actually, the inclusion of DGL allows less demanding (by up to about 30\%) requirements on the DCBH abundance/mass.
The evolution of the perturbations in the energy density and the particle number density in a flat Friedmann-Lemaitre-Robertson-Walker universe in the radiation-dominated era and in the epoch after decoupling of matter and radiation is studied. For large-scale perturbations the outcome is in accordance with treatments in the literature. For small-scale perturbations the differences are conspicuous. Firstly, in the radiation-dominated era small-scale perturbations grew proportional to the square root of time. Secondly, perturbations in the Cold Dark Matter particle number density were, due to gravitation, coupled to perturbations in the total energy density. This implies that structure formation has commenced successfully only after decoupling of matter and radiation. Finally, after decoupling density perturbations evolved diabatically, i.e., they exchanged heat with their environment. This heat exchange may have enhanced the growth rate of its mass sufficiently to explain structure formation in the early universe, a phenomenon which cannot be understood from adiabatic density perturbations.
We analyzed a large sample of radio-loud and radio-quiet quasar spectra at redshift 1.0 < z < 1.2 to compare the inferred underlying quasar continuum slopes (after removal of the host galaxy contribution) with accretion disk models. The latter predict redder (decreasing) alpha_3000 continuum slopes (L_\nu~\nu^alpha at 3000Ang) with increasing black hole mass, bluer alpha_3000 with increasing luminosity at 3000Ang, and bluer alpha_3000 with increasing spin of the black hole, when all other parameters are held fixed. We find no clear evidence for any of these predictions in the data. In particular we find that: (i) alpha_3000 shows no significant dependence on black hole mass or luminosity. Dedicated Monte Carlo tests suggest that the substantial observational uncertainties in the black hole virial masses can effectively erase any intrinsic dependence of alpha_3000 on black hole mass, in line with some previous studies. (ii) The mean slope alpha_3000 of radio-loud sources, thought to be produced by rapidly spinning black holes, is comparable to, or even redder than, that of radio-quiet quasars. Indeed, although quasars appear to become more radio loud with decreasing luminosity, we still do not detect any significant dependence of alpha_3000 on radio loudness. The predicted mean alpha_3000 slopes tend to be bluer than in the data. Disk models with high inclinations and dust extinction tend to produce redder slopes closer to empirical estimates. Our mean alpha_3000 values are close to the ones independently inferred at z<0.5 suggesting weak evolution with redshift, at least for moderately luminous quasars.
The colour-magnitude diagrams of some intermediate-age clusters (1-2 Gyr) star clusters show unexpectedly broad main-sequence turnoffs, raising the possibility that these clusters have experienced more than one episode of star formation. Such a scenario predicts the existence of an extended main sequence turn off (eMSTO) only in clusters with escape velocities above a certain threshold ($>15$ km s$^{-1}$), which would allow them to retain or accrete gas that eventually would fuel a secondary extended star-formation episode. This paper presents a test of this scenario based on the study of the young and massive cluster NGC 7252: W3. We use the HST photometry from WFPC2 and WFC3 images obtained with UV and optical filters, as well as MagE echellette spectrograph data from the Las Campanas Clay 6.5m telescope, in order to construct the observed UV/optical SED of NGC 7252: W3. The observations are then compared with synthetic spectra based on different star formation histories consistent with those of the eMSTO clusters. We find that the SED of this cluster is best fitted by a synthetic spectrum with a single stellar population of age $570^{+70}_{-62}$ Myr and mass $1.13^{+0.14}_{-0.13}\times 10^8$ M$_\odot$, confirming earlier works on NGC 7252: W3. We also estimate the lower limit on the central escape velocity of 193 km s$^{-1}$. We rule out extended star-formation histories, like those inferred for the eMSTO clusters in the Magellanic Clouds, at high confidence. We conclude that the escape velocity of a cluster does not dictate whether a cluster can undergo extended periods of star formation.
Detection of the cosmological neutral hydrogen signal from the Epoch of Reionization, and estimation of its basic physical parameters, is the principal scientific aim of many current low-frequency radio telescopes. Here we describe the Cosmological HI Power Spectrum Estimator (CHIPS), an algorithm developed and implemented with data from the Murchison Widefield Array (MWA), to compute the two-dimensional and spherically-averaged power spectrum of brightness temperature fluctuations. The principal motivations for CHIPS are the application of realistic instrumental and foreground models to form the optimal estimator, thereby maximising the likelihood of unbiased signal estimation, and allowing a full covariant understanding of the outputs. CHIPS employs an inverse-covariance weighting of the data through the maximum likelihood estimator, thereby allowing use of the full parameter space for signal estimation ("foreground suppression"). We describe the motivation for the algorithm, implementation, application to real and simulated data, and early outputs. Upon application to a set of 3 hours of data, we set a 2$\sigma$ upper limit on the EoR dimensionless power at $k=0.05$~h.Mpc$^{-1}$ of $\Delta_k^2<7.6\times{10^4}$~mK$^2$ in the redshift range $z=[6.2-6.6]$, consistent with previous estimates.
We investigate the role of supermassive black holes in the global context of galaxy evolution by measuring the host galaxy stellar mass function (HGMF) and the specific accretion rate i.e., lambda_SAR, distribution function (SARDF) up to z~2.5 with ~1000 X-ray selected AGN from XMM-COSMOS. Using a maximum likelihood approach, we jointly fit the stellar mass function and specific accretion rate distribution function, with the X-ray luminosity function as an additional constraint. Our best fit model characterizes the SARDF as a double power-law with mass dependent but redshift independent break whose low lambda_SAR slope flattens with increasing redshift while the normalization increases. This implies that, for a given stellar mass, higher lambda_SAR objects have a peak in their space density at earlier epoch compared to the lower lambda_SAR ones, following and mimicking the well known AGN cosmic downsizing as observed in the AGN luminosity function. The mass function of active galaxies is described by a Schechter function with a almost constant Mstar* and a low mass slope alpha that flattens with redshift. Compared to the stellar mass function, we find that the HGMF has a similar shape and that, up to log((Mstar/Msun)~11.5 the ratio of AGN host galaxies to star forming galaxies is basically constant (~10%). Finally, the comparison of the AGN HGMF for different luminosity and specific accretion rate sub-classes with the phenomenological model prediction by Peng et al. (2010) for the "transient" population, i.e. galaxies in the process of being mass-quenched, reveals that low-luminosity AGN do not appear to be able to contribute significantly to the quenching and that at least at high masses, i.e. Mstar>10^(10.7) Msun , feedback from luminous AGN (log(Lbol)>~46 [erg/s]) may be responsible for the quenching of star formation in the host galaxy.
We consider a cosmologically consistent scenario with a heavy Polonyi field. The Polonyi field with a mass of ${\cal O}(100){\rm\,TeV}$ decays before the Big-Bang Nucleosynthesis (BBN) and avoids the severe constraint from the BBN. However, the abundance of the Lightest Supersymmetric Particle (LSP) produced from the decay often exceeds the observed dark matter density. In our scenario, the dark matter density is obtained by the LSP abundance with an aid of entropy production, and baryon asymmetry is generated by the Affleck-Dine mechanism. We show that the observed baryon-to-dark matter ratio of ${\cal O}(0.1\mathchar`-1)$ is naturally explained in sequestering models with a QCD axion.
In this work we study the cosmological perturbations in massive bigravity in the presence of non-minimal derivative couplings. For this purpose we consider a specific subclass of Horndeski scalar-tensor interactions that live on the unique composite effective metric. For the viability of the model both metrics have to be dynamical. Nevertheless, the number of allowed kinetic terms is crucial. We adapt to the restriction of having one single kinetic term. After deriving the full set of equations of motion for flat Friedmann-Lemaitre-Robertson-Walker background, we study linear perturbations on top of it. We show explicitly that only four tensor, two vector and two scalar degrees of freedom propagate, one of which being the Horndeski scalar, while the Boulware-Deser ghost can be integrated out.
We propose a simple and totally covariant model which may solve one of the problems in the cosmological constant. The model is a kind of topological field theories and the contributions to the vacuum energy from the quantum corrections from the matters are absorbed into a redefinition of one of the scalar fields and the quantum corrections become irrelevant to the dynamics.
We use new near-infrared spectroscopic observations to investigate the nature and evolution of the most luminous H\alpha (Ha) emitters at z~0.8-2.23, which evolve strongly in number density over this period, and compare them to more typical Ha emitters. We study 59 luminous Ha emitters with $L_{H\alpha}>L_{H\alpha}^*$, roughly equally split per redshift slice at z~0.8, 1.47 and 2.23 from the HiZELS and CF-HiZELS surveys. We find that, overall, 30$\pm$8% are AGN (80$\pm$30% of these AGN are broad-line AGN, BL-AGN), and we find little to no evolution in the AGN fraction with redshift, within the errors. However, the AGN fraction increases strongly with Ha luminosity and correlates best with $L_{H\alpha}/L_{H\alpha}^*(z)$. While $L_{H\alpha}<L_{\rm H\alpha}^*(z)$ Ha emitters are largely dominated by star-forming galaxies (>80%), the most luminous Ha emitters ($L_{H\alpha}>10L_{H\alpha}^*(z)$) at any cosmic time are essentially all BL-AGN. Using our AGN-decontaminated sample of luminous star-forming galaxies, and integrating down to a fixed Ha luminosity, we find a factor of ~1300x evolution in the star formation rate density from z=0 to z=2.23. This is much stronger than the evolution from typical Ha star-forming galaxies and in line with the evolution seen for constant luminosity cuts used to select "Ultra-Luminous" Infrared Galaxies and/or sub-millimetre galaxies. By taking into account the evolution in the typical Ha luminosity, we show that the most strongly star-forming Ha-selected galaxies at any epoch ($L_{H\alpha}>L^*_{H\alpha}(z)$) contribute the same fractional amount of ~15% to the total star-formation rate density, at least up to z=2.23.
Using the Newman and Penrose spin coefficient (NP) formalism, we provide a derivation of the Dyer-Roeder equation for the angular diameter distance in cosmological space-times. We show that the geodesic deviation equation written in NP formalism is precisely the Dyer-Roeder equation for a general Friedman-Robertson-Walker (FRW) space-time, and then we examine the angular diameter distance to redshift relation in the case that a flat FRW metric is perturbed by a gravitational potential. We examine the perturbation in the case that the gravitational potential exhibits the properties of a thin gravitational lens, demonstrating how the weak lensing shear and convergence act as source terms for the perturbed Dyer-Roeder equation.
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We show that the cumulative CO emission from galaxies throughout cosmic history distorts the spectrum of the cosmic microwave background (CMB) at a level that is well above the detection limit of future instruments, such as the Primordial Inflation Explorer (PIXIE). Most of the CO foreground originates from modest redshifts, z ~ 2-5, and needs to be efficiently removed for more subtle distortions from the earlier universe to be detected.
We use a suite of cosmological simulations to study the mass-concentration-redshift relation, $c({\rm M},z)$, of dark matter halos assembled hierarchically. Our runs include both standard $\Lambda$-cold dark matter (CDM) models, as well as several additional simulations with sharply truncated density fluctuation power spectra, such as those expected in a thermal warm dark matter (WDM) scenario. As in earlier work, we find that the mass profiles of CDM and WDM halos are self-similar and well approximated by the Navarro-Frenk-White (NFW) profile. The $c({\rm M},z)$ relation of CDM halos is monotonic: concentrations decrease with increasing virial mass at fixed redshift, and decrease with increasing redshift at fixed mass. The main-progenitor mass accretion histories (MAHs) of CDM halos are also scale-free, a result that has been used to infer halo concentrations directly from MAHs. These results do not apply to WDM halos: their MAHs are not scale-free because of the characteristic scale imposed by the power-spectrum suppression. Further, the WDM $c({\rm M},z)$ relation is not monotonic: concentrations peak at a halo mass scale dictated by the truncation scale, and decrease at higher and lower masses. We show that the assembly history of a halo can still be used to infer its concentration, provided that the total mass of its collapsed progenitors is considered (the "collapsed mass history"; CMH), rather than just that of its main ancestor. This follows the original NFW proposal, and exploits the scale-free nature of CMHs to derive a simple scaling that reproduces the mass-concentration-redshift relation of both CDM and WDM halos in our simulations over a vast range of halo masses and cosmic time. Our model therefore provides a robust account of the mass, redshift, cosmology and power spectrum dependence of the concentrations of dark matter halos assembled hierarchically.
The Lagrangian dynamics of a single fluid element within a self-gravitational matter field is intrinsically non-local due to the presence of the tidal force. This complicates the theoretical investigation of the non-linear evolution of various cosmic objects, e.g. dark matter halos, in the context of Lagrangian fluid dynamics, since a fluid parcel with given initial density and shape may evolve differently depending on their environments. In this paper, we provide a statistical solution that could decouple this environmental dependence. After deriving the probability distribution evolution equation of the matter field, our method produces a set of closed ordinary differential equations whose solution is uniquely determined by the initial condition of the fluid element. Mathematically, it corresponds to the projected characteristic curve of the transport equation of the density-weighted probability density function (PDF). Consequently it is guaranteed that the one-point PDF would be preserved by evolving these local, yet non-linear, curves with the same set of initial data as the real system. Physically, these trajectories describe the mean evolution averaged over all environments by substituting the tidal tensor with its conditional average. For Gaussian distributed dynamical variables, this mean tidal tensor is simply proportional to the velocity shear tensor, and the dynamical system would recover the prediction of Zel'dovich approximation (ZA) with the further assumption of the linearized continuity equation. For Weakly non-Gaussian field, the averaged tidal tensor could be expanded perturbatively as a function of all relevant dynamical variables whose coefficients are determined by the statistics of the field.
The combination of galaxy-galaxy lensing (GGL) and galaxy clustering is a promising route to measuring the amplitude of matter clustering and testing modified gravity theories of cosmic acceleration. Halo occupation distribution (HOD) modeling can extend the approach down to nonlinear scales, but galaxy assembly bias could introduce systematic errors by causing the HOD to vary with large scale environment at fixed halo mass. We investigate this problem using the mock galaxy catalogs created by Hearin & Watson (2013, HW13), which exhibit significant assembly bias because galaxy luminosity is tied to halo peak circular velocity and galaxy colour is tied to halo formation time. The preferential placement of galaxies (especially red galaxies) in older halos affects the cutoff of the mean occupation function $\langle N_\text{cen}(M_\text{min}) \rangle$ for central galaxies, with halos in overdense regions more likely to host galaxies. The effect of assembly bias on the satellite galaxy HOD is minimal. We introduce an extended, environment dependent HOD (EDHOD) prescription to describe these results and fit galaxy correlation measurements. Crucially, we find that the galaxy-matter cross-correlation coefficient, $r_{gm} \equiv \xi_{gm} \cdot [ \xi_{mm} \xi_{gg} ]^{-1/2}$, is insensitive to assembly bias on scales $r \gtrsim 1 \; h^{-1}\text{Mpc}$, even though $\xi_{gm} $ and $\xi_{gg} $ are both affected individually. We can therefore recover the correct $\xi_{mm} $ from the HW13 galaxy-galaxy and galaxy-matter correlations using either a standard HOD or EDHOD fitting method. For $M_r \leq -19$ or $M_r \leq -20$ samples the recovery of $\xi_{mm}$ is accurate to 2% or better. For a sample of red $M_r \leq -20$ galaxies we achieve 2% recovery at $r \gtrsim 2\;h^{-1}\text{Mpc}$ with EDHOD modeling but lower accuracy at smaller scales or with a standard HOD fit.
Astrophysical tests of the stability of fundamental couplings, such as the fine-structure constant $\alpha$, are a powerful probe of new physics. Recently these measurements, combined with local atomic clock tests and Type Ia supernova and Hubble parameter data, were used to constrain the simplest class of dynamical dark energy models where the same degree of freedom is assumed to provide both the dark energy and (through a dimensionless coupling, $\zeta$, to the electromagnetic sector) the $\alpha$ variation. One caveat of these analyses was that it was based on fiducial models where the dark energy equation of state was described by a single parameter (effectively its present day value, $w_0$). Here we relax this assumption and study broader dark energy model classes, including the Chevallier-Polarski-Linder and Early Dark Energy parametrizations. Even in these extended cases we find that the current data constrains the coupling $\zeta$ at the $10^{-6}$ level and $w_0$ to a few percent (marginalizing over other parameters), thus confirming the robustness of earlier analyses. On the other hand, the additional parameters are typically not well constrained. We also highlight the implications of our results for constraints on violations of the Weak Equivalence Principle and improvements to be expected from forthcoming measurements with high-resolution ultra-stable spectrographs.
We test a free {\it ad hoc} parametrization of the Tolman-Oppenheimer-Volkoff (TOV) equation. We do not have in mind any specific extended theory of gravity (ETG) but each new parameter introduced has a physical interpretation. Our aim is fully pedagogical rather than a proposal for a new ETG. Given a realistic neutron star equation of state we map the contributions of each new parameter into a shift in trajectories of the mass-radius diagram. This exercise allows us to make the correspondence between each TOV sector with possible modifications of gravity and clarifies how neutron star observations are helpful for distinguishing theories.
In this letter, we explore the nature of the electroweak phase transition with both the particle colliders and the gravitational wave (GW) detection. With the observed Higgs mass, the shape of the Higgs potential is fully determined in the standard model of particle physics, however, it could be physically different. Working with the effective field theory, we will show the Higgs potential with a sextic term of the Higgs field included could give the 125 GeV Higgs mass , but a different Higgs potential. Furthermore, this Higgs scenario can produce a strong first order phase transition for the electroweak baryogenesis, and interestingly predict new physics in the Higgs sector, which can be tested at colliders such as the Large Hadron Collider (LHC) and the planning Circular Electron Positron Collider (CEPC). And we will also point out this strong first order phase transition will lead to a detectable GW signal for the GW interferometers , such as eLISA, DECIGO and BBO. Our study in this letter on the electroweak phase transition bridges the particle physics at colliders with the astrophysics and cosmology in the early universe.
We study the impact on electroweak baryogenesis from a swifter cosmological expansion induced by dark matter. We detail the experimental bounds that one can place on models that realize it, and we investigate the modifications of these bounds that result from a non-standard cosmological history. The modifications can be sizeable if the expansion rate of the Universe increases by several orders of magnitude. We illustrate the impact through the example of scalar field dark matter, which can alter the cosmological history enough to enable a strong-enough first-order phase transition in the Standard Model when it is supplemented by a dimension six operator directly modifying the Higgs boson potential. We show that due to the modified cosmological history, electroweak baryogenesis can be realized, while keeping deviations of the triple Higgs coupling below HL-LHC sensitivies. The required scale of new physics to effectuate a strong-enough first order phase transition can change by as much as twenty percent as the expansion rate increases by six orders of magnitude.
Luminous type-2 quasars in which the glow from the central black hole is obscured by dust are ideal targets for studying their host galaxies and the quasars' effect on galaxy evolution. Such feedback appears ubiquitous in luminous obscured quasars where high velocity ionized nebulae have been found. We present rest-frame yellow-band (~5000 Angstroms) observations using the Hubble Space Telescope for a sample of 20 luminous quasar host galaxies at 0.2 < z < 0.6 selected from the Sloan Digital Sky Survey. For the first time, we combine host galaxy observations with geometric measurements of quasar illumination using blue-band HST observations and [OIII] integral field unit observations probing the quasar winds. The HST images reveal bright merger signatures in about half the galaxies; a significantly higher fraction than in comparison inactive ellipticals. We show that the host galaxies are primarily bulge-dominated, with masses close to M*, but belong to < 30% of elliptical galaxies that are highly star-forming at z ~ 0.5. Ionized gas signatures are uncorrelated with faint stellar disks (if present), confirming that the ionized gas is not concentrated in a disk. Scattering cones and [OIII] ionized gas velocity field are aligned with the forward scattering cones being co-spatial with the blue-shifted side of the velocity field, suggesting the high velocity gas is indeed photo-ionized by the quasar. Based on the host galaxies' high star-formation rates and bright merger signatures, we suggest that this low-redshift outbreak of luminous quasar activity is triggered by recent minor mergers. Combining these novel observations, we present new quasar unification tests, which are in agreement with expectations of the orientation-based unification model for quasars.
We present multiwavelength identifications for the counterparts of 1088 submillimeter sources detected at 850$\mu$m in the SCUBA-2 Cosmology Legacy Survey study of the UKIDSS-UDS field. By utilising an ALMA pilot study on a subset of our bright SCUBA-2 sample as a training set, along with the deep optical-near-infrared data available in this field, we develop a novel technique, Optical-IR Triple Color (OIRTC), using $z-K$, $K-[3.6]$, $[3.6]-[4.5]$ colors to select the candidate submillimeter galaxy (SMG) counterparts. By combining radio identification and the OIRTC technique, we find counterpart candidates for 80% of the Class = 1 $\geq4\,\sigma$ SCUBA-2 sample, defined as those that are covered by both radio and OIR imaging and the base sample for our scientific analyses. Based on the ALMA training set, we expect the accuracy of these identifications to be $82\pm20$%, with a completeness of $69\pm16$%, essentially as accurate as the traditional $p$-value technique but with higher completeness. We find that the fraction of SCUBA-2 sources having candidate counterparts is lower for fainter 850$\mu$m sources, and we argue that for follow-up observations sensitive to SMGs with $S_{850}\gtrsim 1$ mJy across the whole ALMA beam, the fraction with multiple counterparts is likely to be $>40$% for SCUBA-2 sources at $S_{850} \gtrsim 4$ mJy. We find that the photometric redshift distribution for the SMGs is well fit by a lognormal distribution, with a median redshift of $z=2.3\pm0.1$. After accounting for the sources without any radio and/or OIRTC counterpart, we estimate the median redshift to be $z=2.6\pm0.1$ for SMGs with $S_{850} >1$ mJy. We also use this new large sample to study the clustering of SMGs and the the far-infrared properties of the unidentified submillimeter sources by stacking their Herschel SPIRE far-infrared emission.
Dynamical analysis of compact groups provides important tests of models of compact group formation and evolution. By compiling 2066 redshifts from FLWO/FAST, from the literature, and from SDSS DR12 in the fields of compact groups in \citet{McC09}, we construct the largest sample of compact groups with complete spectroscopic redshifts in the redshift range $0.01 < z < 0.22$. This large redshift sample shows that the interloper fraction in the \citet{McC09} compact group candidates is $\sim 42\%$. A secure sample of 332 compact groups includes 192 groups with four or more member galaxies and 140 groups with three members. The fraction of early-type galaxies in these compact groups is 62\%, slightly higher than for the original Hickson compact groups. The velocity dispersions of early- and late-type galaxies in compact groups change little with groupcentric radius; the radii sampled are less than $100 ~h^{-1}$ kpc, smaller than the radii typically sampled by members of massive clusters of galaxies. The physical properties of our sample compact groups include size, number density, velocity dispersion, and local environment; these properties slightly differ from those derived for the original Hickson compact groups and for the DPOSS II compact groups. Differences result from subtle differences in the way the group candidates were originally selected. The space density of the compact groups changes little with redshift over the range covered by this sample. The approximate constancy of the space density for this sample is a potential constraint on the evolution of compact groups on a few Gigayear timescale.
The use of background quasars provides a powerful tool to probe the cool gas in the circum-galactic medium of foreground galaxies. Here, we present new observations with SINFONI and X-Shooter of absorbing-galaxy candidates at z=0.7-1. We report the detection with both instruments of the H-alpha emission line of one sub-DLA at z_abs=0.94187 with log N(HI)=19.38^+0.10_-0.15 towards SDSS J002133.27+004300.9. We estimate the star formation rate: SFR=3.6+/-2.2 solar masses per year in that system. A detailed kinematic study indicates a dynamical mass M_dyn=10^9.9+/-0.4 solar masses and a halo mass M_halo=10^11.9+/-0.5 solar masses. In addition, we report the OII detection with X-Shooter of another DLA at z_abs=0.7402 with log N(HI)=20.4+/-0.1 toward Q0052+0041 and an estimated SFR of 5.3+/-0.7 solar masses per year. Three other objects are detected in the continuum with X-Shooter but the nature and redshift of two of these objects are unconstrained due to the absence of emission lines, while the third object might be at the redshift of the quasar. We use the objects detected in our whole N(HI)-selected SINFONI survey to compute the metallicity difference between the galaxy and the absorbing gas, delta_HI(X), where a positive (negative) value indicates infall (outflow). We compare this quantity with the quasar line of sight alignment with the galaxy's major (minor) axis, another tracer of infall (outflow). We find that these quantities do not correlate as expected from simple assumptions. Additional observations are necessary to relate these two independent probes of gas flows around galaxies.
Since mid 2014 Gaia mission delivers daily millions of observations of the whole sky. Among them we search for transient events, e.g., supernovae, microlensing events, cataclysmic variables, etc. In my talk I describe the near-real-time Gaia data processing pipeline for anomaly detection, show first scientific results from years 2014/2015 and describe the organization of the ground-based network for the photometric and spectroscopic follow-up of Gaia alerts.
Life is dependent on the income of energy with low entropy and the disposal of energy with high entropy. On Earth, the low-entropy energy is provided by solar radiation and the high-entropy energy is disposed as infrared radiation emitted into the cold space. Here we turn the situation around and assume cosmic background radiation as the low-entropy source of energy for a planet orbiting a black hole into which the high-entropy energy is disposed. We estimate the power that can be produced by thermodynamic processes on such a planet, with a particular interest in planets orbiting a fast rotating Kerr black hole as in the science fiction movie {\em Interstellar}. We also briefly discuss a reverse Dyson sphere absorbing cosmic background radiation from the outside and dumping waste energy to a black hole inside.
In this Letter we focus our attention on the IceCube events in the energy range between 60 and 100 TeV, which show an order 2-sigma excess with respect to a power-law with spectral index 2. We analyze the possible origin of such an excess by comparing the distribution of the arrival directions of IceCube events with the angular distributions of simply distributed astrophysical galactic/extragalactic sources, as well as with the expected flux coming from DM interactions (decay and annihilation) for different DM profiles. The statistical analysis performed seems to disfavor the correlation with the galactic plane, whereas clearly rules out the DM annihilation scenario. The small statistics till now collected does not allow to scrutinize the cases of astrophysical isotropic distribution and DM decay scenarios. For this reason we perform a forecast analysis in order to stress the role of future Neutrino Telescopes.
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As a result of our limited data on reionization, the total optical depth for electron scattering, $\tau$, limits precision measurements of cosmological parameters from the Cosmic Microwave Background (CMB). It was recently shown that the predicted 21-cm signal of neutral hydrogen contains enough information to reconstruct $\tau$ with sub-percent accuracy, assuming that the neutral gas was much hotter than the CMB throughout the entire epoch of reionization. Here we relax this assumption and use the global 21-cm signal alone to extract $\tau$ for realistic X-ray heating scenarios. We test our model-independent approach using mock data for a wide range of ionization and heating histories and show that an accurate measurement of the reionization optical depth at a sub-percent level is possible in most of the considered scenarios even when heating is not saturated during the epoch of reionization, assuming that the foregrounds are mitigated. However, we find that in cases where heating sources had hard X-ray spectra and their luminosity was close to or lower than what is predicted based on low-redshift observations, the global 21-cm signal alone is not a good tracer of the reionization history.
We construct two simple effective field theory versions of {\it Hybrid Natural Inflation (HNI)} that illustrate the range of its phenomenological implications. The resulting inflationary sector potential, $V=\Delta^4(1+a\cos(\phi/f))$, arises naturally, with the inflaton field a pseudo-Nambu-Goldstone boson. The end of inflation is triggered by a waterfall field and the conditions for this to happen are determined. Also of interest is the fact that the slow-roll parameter $\epsilon$ (and hence the tensor $r$) is a non-monotonic function of the field with a maximum where observables take universal values that determines the maximum possible tensor to scalar ratio $r$. In one of the models the inflationary scale can be as low as the electroweak scale. We explore in detail the associated HNI phenomenology, taking account of the constraints from Black Hole production, and perform a detailed fit to the Planck 2015 temperature and polarisation data.
We study induced gravity dark energy models coupled with a simple monomial potential $\propto \sigma^n$ and a positive exponent $n$. These simple potentials lead to viable dark energy models with a weak dependence on the exponent, which characterizes the accelerated expansion of the cosmological model in the asymptotic attractor, when ordinary matter becomes negligible. We use recent cosmological data to constrain the coupling $\gamma$ to the Ricci curvature, under the assumptions that the scalar field starts at rest deep in the radiation era and that the gravitational constant in the Einstein equations is compatible with the one measured in a Cavendish-like experiment. By using $Planck$ 2015 data only, we obtain the 95 % CL bound $\gamma < 0.0017$ for $n=4$, which is further tightened to $\gamma < 0.00075$ by adding Baryonic Acoustic Oscillations (BAO) data. This latter bound improves by $\sim 30$ % the limit obtained with the $Planck$ 2013 data and the same compilation of BAO data. We discuss the dependence of the $\gamma$ and $\dot G_N/G_N (z=0)$ on $n$.
In this paper we review all the up-to-date Ultra High Energy Cosmic Rays (UHECR) events reported by AUGER, by Telescope Array (TA) and by AGASA in common coordinate maps. We also confirm our earliest (2008-2013) model, where UHECR are mostly made by light nuclei (namely He, Be, B), which explains the Virgo absence and confirms M82 as the main source for North TA Hot Spot. Many more sources, such as NGC253 and several galactic ones, are possible candidates for most of the 376 UHECR events. Several correlated map, already considered in recent years, are then reported to show all the events, with their statistical correlation values.
Observable primordial tensor modes in the cosmic microwave background (CMB) would point to a high scale of inflation $H_{I}$. If the scale of Peccei-Quinn (PQ) breaking $f_a$ is greater than $\frac{H_{I}}{2\pi}$, CMB constraints on isocurvature na\"ively rule out QCD axion dark matter. This assumes the potential of the axion is unmodified during inflation. We revisit models where inflationary dynamics modify the axion potential and discuss how isocurvature bounds can be relaxed. We find that models that rely solely on a larger PQ-breaking scale during inflation require late-time dilution of the axion abundance. Even then, $f_a$ must be below the grand unification scale. Models that have enhanced explicit breaking of the PQ symmetry during inflation may allow $f_a$ close to the Planck scale. Avoiding disruption of inflationary dynamics provides important limits on the parameter space.
We report the discovery of a quasar pair at z=5 separated by 21 arcsec. Both objects were identified as quasar candidates using simple color selection techniques applied to photometric catalogs from the CFHT Legacy Survey (CFHTLS). Spectra obtained with the MMT present no discernible offset in redshift between the two objects; on the other hand, there are clear differences in the emission line profiles and in the multiwavelength spectral energy distributions that strongly disfavor the hypothesis that they are gravitationally lensed images of a single quasar. Both quasars are surprisingly bright given their proximity (a projected separation of ~135 kpc), with i=19.4 and i=21.4. Previous measurements of the luminosity function demonstrate that luminous quasars are extremely rare at z=5; the existence of this pair suggests that quasars have strong small-scale clustering at high redshift. Assuming a real-space correlation function of the form $\xi(r) \propto (r/r_0)^{-2}$, this discovery implies a correlation length $r_0 > 20 h^{-1}$ Mpc, consistent with a rapid strengthening of quasar clustering at high redshift as seen in previous observations and predicted by theoretical models where feedback effects are inefficient at shutting down black hole growth at high redshift.
Aims. We present a spectroscopic study of the properties of 64 Balmer break
galaxies that show signs of star formation. The studied sample of star-forming
galaxies spans a redshift range from 0.094 to 1.475 with stellar masses in the
range 10$^{8}-$10$^{12}$ $M_{\odot}$. The sample also includes eight broad
emission line galaxies with redshifts between 1.5 $<z<$ 3.0.
Methods. We derived star formation rates (SFRs) from emission line
luminosities and investigated the dependence of the SFR and specific SFR (SSFR)
on the stellar mass and color. Furthermore, we investigated the evolution of
these relations with the redshift.
Results. We found that the SFR correlates with the stellar mass, our data is
consistent with previous results from other authors in that there is a break in
the correlation, which reveals the presence of massive galaxies with lower SFR
values (i.e., decreasing star formation). We also note an anticorrelation for
the SSFR with the stellar mass. Again in this case, our data is also consistent
with a break in the correlation, revealing the presence of massive star-forming
galaxies with lower SSFR values, thereby increasing the anticorrelation. These
results might suggest a characteristic mass ($M_{0}$) at which the red sequence
could mostly be assembled. In addition, at a given stellar mass, high-redshift
galaxies have on average higher SFR and SSFR values than local galaxies.
Finally, we explored whether a similar trend could be observed with redshift in
the SSFR$-(u-B)$ color diagram, and we hypothesize that a possible $(u-B)_{0}$
break color may define a characteristic color for the formation of the red
sequence.
We have developed FDPS (Framework for Developing Particle Simulator), which enables researchers and programmers to develop high-performance parallel particle simulation codes easily. The basic idea of FDPS is to separate the program code for complex parallelization including domain decomposition, redistribution of particles, and exchange of particle information for interaction calculation between nodes, from actual interaction calculation and orbital integration. FDPS provides the former part and the users write the latter. Thus, a user can implement a high-performance fully parallelized $N$-body code only in 120 lines. In this paper, we present the structure and implementation of FDPS, and describe its performance on three sample applications: disk galaxy simulation, cosmological simulation and Giant impact simulation. All codes show very good parallel efficiency and scalability on K computer and XC30. FDPS lets the researchers concentrate on the implementation of physics and mathematical schemes, without wasting their time on the development and performance tuning of their codes.
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Provided the quantum fluctuations are amplified in the presence of a classical gauge field configuration the resulting curvature perturbations exhibit a mild statistical anisotropy which should be sufficiently weak not to conflict with current observational data. The curvature power spectra induced by weakly anisotropic initial states are computed here for the first time when the electric and the magnetic gauge couplings evolve at different rates as it happens, for instance, in the relativistic theory of van der Waals interactions. After recovering the results valid for coincident gauge couplings, the constraints imposed by the isotropy and the homogeneity of the initial states are discussed. The obtained bounds turn out to be more stringent than naively expected and cannot be ignored when discussing the underlying magnetogenesis scenarios.
Wei et al 2015 propose an interesting test of Einstein's equivalence
principle (EEP) from the observed lag in arrival times of photons emitted from
extragalactic transient sources. Attributing the lag between photons of
different energies to the gravitational potential of the Milky Way (MW) the
derive new constraints on deviations from EEP.
It is shown here that potential fluctuations form the large scale structure
are at least two orders of magnitude larger than the gravitational potential of
the MW. Combined with the larger distances, the contribution from these
fluctuations should tighten the constraints by about 4 orders of magnitude.
New data are reported from a second run of the 2-liter PICO-2L C$_3$F$_8$ bubble chamber with a total exposure of 129$\,$kg-days at a thermodynamic threshold energy of 3.3$\,$keV. These data show that measures taken to control particulate contamination in the superheated fluid resulted in the absence of the anomalous background events observed in the first run of this bubble chamber. One single nuclear-recoil event was observed in the data, consistent both with the predicted background rate from neutrons and with the observed rate of unambiguous multiple-bubble neutron scattering events. The chamber exhibits the same excellent electron-recoil and alpha decay rejection as was previously reported. These data provide the most stringent direct detection constraints on WIMP-proton spin-dependent scattering to date for WIMP masses $<$ 50$\,$GeV/c$^2$.
We study the embedding of inflation with nilpotent multiplets in supergravity, in particular the decoupling of the sgoldstino scalar field. Instead of being imposed by hand, the nilpotency constraint on the goldstino multiplet arises in the low energy-effective theory by integrating out heavy degrees of freedom. We present explicit supergravity models in which a large but finite sgoldstino mass arises from Yukawa or gauge interactions. In both cases the inflaton potential receives two types of corrections. One is from the backreaction of the sgoldstino, the other from the heavy fields generating its mass. We show that these scale oppositely with the Volkov-Akulov cut-off scale, which makes a consistent decoupling of the sgoldstino nontrivial. Still, we identify a parameter window in which sgoldstino-less inflation can take place, up to corrections which flatten the inflaton potential.
We report the results of the first long-term (1990-2014) optical spectro-photometric monitoring of a binary black hole candidate QSO E1821+643, a low-redshift high-luminosity radio-quiet quasar. In the monitored period the continua and H$\gamma$ fluxes changed for around two times, while the H$\beta$ flux changed around 1.4 times. We found the periodical variations in the photometric flux with the periods of 1200, 1850 and 4000 days, and 4500 days periodicity in the spectroscopic variations. However, the periodicity of 4000-4500 days covers only one cycle of variation and should be confirmed with a longer monitoring campaign. There is an indication of the period around 1300 days in the spectroscopic light curves, but with small significance level, while the 1850 days period could not be clearly identified in the spectroscopic light curves. The line profiles have not significantly changed, showing an important red asymmetry and broad line peak redshifted around +1000 km s$^{-1}$. However, H$\beta$ shows broader mean profile and has a larger time-lag ($\tau\sim120$ days) than H$\gamma$ ($\tau\sim60$ days). We estimate that the mass of the black hole is $\sim2.6\times10^9\rm M_\odot$. The obtained results are discussed in the frame of the binary black hole hypothesis. To explain the periodicity in the flux variability and high redshift of broad lines we discuss a scenario where dense gas-rich cloudy-like structures are orbiting around a recoiling black hole.
We consider a resonant SIMP dark matter in models with two singlet complex scalar fields charged under a local dark $U(1)_D$. After the $U(1)_D$ is broken down to a $Z_5$ discrete subgroup, the lighter scalar field becomes a SIMP dark matter which has the enhanced $3\rightarrow 2$ annihilation cross section near the resonance of the heavier scalar field. Bounds on the SIMP self-scattering cross section and the relic density can be fulfilled at the same time for perturbative couplings of SIMP. A small gauge kinetic mixing between the SM hypercharge and dark gauge bosons can be used to make SIMP dark matter in kinetic equilibrium with the SM during freeze-out.
We study the clustering of galaxies as a function of spectral type and redshift in the range $0.35 < z < 1.1$ using data from the Advanced Large Homogeneous Area Medium Band Redshift Astronomical (ALHAMBRA) survey. The data cover 2.381 deg$^2$ in 7 fields, after applying a detailed angular selection mask, with accurate photometric redshifts [$\sigma_z < 0.014(1+z)$] down to $I_{AB} < 24$. From this catalog we draw five fixed number density, redshift-limited bins. We estimate the clustering evolution for two different spectral populations selected using the ALHAMBRA-based photometric templates: quiescent and star-forming galaxies. For each sample, we measure the real-space clustering using the projected correlation function. Our calculations are performed over the range $[0.03,10.0] h^{-1}$ Mpc, allowing us to find a steeper trend for $r_p \lesssim 0.2 h^{-1}$ Mpc, which is especially clear for star-forming galaxies. Our analysis also shows a clear early differentiation in the clustering properties of both populations: star-forming galaxies show weaker clustering with evolution in the correlation length over the analysed redshift range, while quiescent galaxies show stronger clustering already at high redshifts, and no appreciable evolution. We also perform the bias calculation where similar segregation is found, but now it is among the quiescent galaxies where a growing evolution with redshift is clearer. These findings clearly corroborate the well known colour-density relation, confirming that quiescent galaxies are mainly located in dark matter halos that are more massive than those typically populated by star-forming galaxies.
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