We investigate the build-up of galaxies at z~1 using maps of Halpha and stellar continuum emission for a sample of 57 galaxies with rest-frame Halpha equivalent widths >100 Angstroms in the 3D-HST grism survey. We find that the Halpha emission broadly follows the rest-frame R-band light but that it is typically somewhat more extended and clumpy. We quantify the spatial distribution with the half-light radius. The median Halpha effective radius r_e(Halpha) is 4.2+-0.1 kpc but the sizes span a large range, from compact objects with r_e(Halpha) ~ 1.0 kpc to extended disks with r_e(Halpha) ~ 15 kpc. Comparing Halpha sizes to continuum sizes, we find <r_e(Halpha)/r_e(R)>=1.3+-0.1 for the full sample. That is, star formation, as traced by Halpha, typically occurs out to larger radii than the rest-frame R-band stellar continuum; galaxies are growing their radii and building up from the inside out. This effect appears to be somewhat more pronounced for the largest galaxies. Using the measured Halpha sizes, we derive star formation rate surface densities. We find that they range from ~0.05 Msun yr^{-1} kpc^{-2} for the largest galaxies to ~5 Msun yr^{-1} kpc^{-2} for the smallest galaxies, implying a large range in physical conditions in rapidly star-forming z~1 galaxies. Finally, we infer that all galaxies in the sample have very high gas mass fractions and stellar mass doubling times < 500 Myr. Although other explanations are also possible, a straightforward interpretation is that we are simultaneously witnessing the rapid formation of compact bulges and large disks at z~1.
We present high-resolution maps of stars, dust, and molecular gas in a strongly lensed submillimeter galaxy (SMG) at z = 3.259. HATLAS12--00 is selected from the Herschel-Astrophysical Terahertz Large Area Survey (H-ATLAS) as a strong lens candidate mainly based on its unusually high 500um flux density (~300 mJy). It is the only high-redshift Planck detection in the 130 deg^2 H-ATLAS Phase 1 area. Keck Adaptive Optics images reveal a quadruply imaged galaxy in the K-band while the Submillimeter Array and the Extended Very Large Array show doubly imaged 880um and CO(1-0) sources, indicating differentiated distributions of the various components in the galaxy. The stars reside in three major kpc-scale clumps extended over ~1.6 kpc, the dust in a compact (~1 kpc) region ~3 kpc north of the stars, and the cold molecular gas in an extended (~7 kpc) disk ~5 kpc northeast of the stars. The emission from the stars, dust, and gas are magnified by ~17, 8, and 7 times, respectively, by four lensing galaxies at z ~ 1. Intrinsically, the galaxy is a warm (T_dust ~ 40-65 K), hyper-luminous (L_IR ~ 1.6e13 Lsun; SFR ~ 2000 Msun/yr), gas-rich (M_gas/M_baryon ~ 70%), young (M_stellar/SFR ~ 20 Myr), and short-lived (M_gas/SFR ~ 40 Myr) starburst, without a significant active galactic nucleus. With physical properties similar to unlensed z > 2 SMGs, HATLAS12--00 offers a detailed view of a typical SMG through a powerful cosmic microscope.
Galaxy disks are shown to contain a significant population of atomic clouds
of 100pc linear size which are self-opaque in the 21cm transition. These
objects have HI column densities as high as 10^23 and contribute to a global
opacity correction factor of 1.34+/-0.05 that applies to the integrated 21cm
emission to obtain a total HI mass estimate. Opacity-corrected images of the
nearest external galaxies have been used to form a robust z=0 distribution
function of HI, f(N_HI,X,z=0), the probability of encountering a specific HI
column density per unit comoving distance. This is contrasted with previously
published determinations of f(N_HI,X) at z=1 and 3. A systematic decline of
moderate column density (18<log(N_HI)<21) HI is observed that corresponds to a
decline in surface area of such gas by a factor of five since z=3. The number
of equivalent DLA absorbers (log(N_HI)>20.3) has also declined systematically
over this redshift interval by a similar amount, while the cosmological mass
density in such systems has declined by only a factor of two to its current,
opacity corrected value of Omega_HI^DLA(z=0) = 5.4 +/- 0.9x10^-4.
We utilize the tight, but strongly non-linear dependence of 21cm absorption
opacity on column density at z=0 to transform our HI images into ones of 21cm
absorption opacity. These images are used to calculate distribution and
pathlength functions of integrated 21cm opacity. The incidence of deep 21cm
absorption systems is predicted to show very little evolution with redshift,
while that of faint absorbers should decline by a factor of five between z=3
and the present. We explicitly consider the effects of HI absorption against
background sources that are extended relative to the 100pc intervening absorber
size scale. Future surveys of 21cm absorption will require very high angular
resolution, of about 15mas, for their unambiguous interpretation. (Abridged.)
Giving rise to a new and exciting research field, observations of the last 13 years established the accelerated expansion of the Universe. This is a strong indication of new physics, either in the form of a new energy component of the Universe -- dark energy -- or of theories of gravity beyond general relativity. A powerful approach to this problem is the study of complementary cosmological probes in large optical galaxy surveys such as the Dark Energy Survey (DES). We present the expectations for dark energy physics based on the combination of four fundamental probes: galaxy clusters, weak lensing, large scale structure and supernovae. We show that DES data have constraining power to improve current measurements of the dark energy equation-of-state parameter by a factor of 3--5 and to distinguish between general relativity and modified gravity scenarios.
The popular log-linear relation between supermassive black hole mass, M_bh, and the dynamical mass of the host spheroid, M_sph, is shown to require a significant correction. Core galaxies, typically with M_bh > 2x10^8 M_Sun and thought to be formed in dry merger events, are shown to be well described by a linear relation for which the median black hole mass is 0.36% - roughly double the old value of constancy. Of greater significance is that M_bh ~ (M_sph)^2 among the (non-pseudobulge) lower-mass systems: specifically, log[M_bh/M_Sun] = (1.92+/-0.38)log[M_sph/7x10^{10}M_Sun] + (8.38+/-0.17). `Classical' spheroids hosting a 10^6 M_Sun black hole will have M_bh/M_sph ~ 0.025%. These new relations (i) bring consistency to the relation M_bh ~ sigma^5 and the fact that L ~ sigma^x with exponent x equal to 5 and 2 for bright (M_B < -20.5 mag) and faint spheroids, respectively, (ii) mimic the non-(log-linear) behavior in the M_bh-(Sersic n) diagram, (iii) necessitate the existence of a previously over-looked M_bh ~ L^{2.5} relation for Sersic (i.e.\ not core-Sersic) galaxies, and (iv) resolve past conflicts (in mass prediction) with the M_bh-sigma relation at the low-mass end. Furthermore, the bent nature of the M_bh-M_sph relation for `classical' spheroids will have a host of important implications that relate to (i) galaxy/black hole formation theories, (ii) searches for the fundamental black hole scaling relation, (iii) black hole mass predictions in other galaxies, (iv) alleged pseudobulge detections, (v) estimates of the black hole mass function and mass density based on luminosity functions, (vi) predictions for space-based gravitational wave detections, (vii) connections with nuclear star cluster scaling relations, (viii) evolutionary studies over different cosmic epochs, (ix) comparisons and calibrations matching inactive black hole masses with low-mass AGN data, and more.
Using the very deep Subaru images of the GOODS-N region, from the MOIRCS Deep Survey and images from the HST/ACS, we have measured the Luminosity Ratio (LR) of the outer to the central regions of massive (M>10^{10.5}M_{Sun}) galaxies at fixed radii in a single rest-frame for z<3.5 as a new approach to the problem of size evolution. We didn't observe any evolution in the median LR. Had a significant size growth occurred, the outer to central luminosity ratios would have demonstrated a corresponding increase with a decrease in redshift.
Third-order galaxy-galaxy lensing (G3L) is a next generation galaxy-galaxy lensing technique that either measures the excess shear about lens pairs or the excess shear-shear correlations about lenses. It is clear that these statistics assess the three-point correlations between galaxy positions and projected matter density. For future applications of these novel statistics, we aim at a more intuitive understanding of G3L to isolate the main features that possibly can be measured. We construct a toy model ("isolated lens model"; ILM) for the distribution of galaxies and associated matter to determine the measured quantities of the two G3L correlation functions and traditional galaxy-galaxy lensing (GGL) in a simplified context. The ILM presumes single lens galaxies to be embedded inside arbitrary matter haloes that, however, are statistically independent ("isolated") from any other halo or lens position. In the ILM, the average mass-to-galaxy number ratio of clusters of any size cannot change. GGL and galaxy clustering alone cannot distinguish an ILM from any more complex scenario. The lens-lens-shear correlator in combination with second-order statistics enables us to detect deviations from a ILM, though. This can be quantified by a difference signal defined in the paper. We demonstrate with the ILM that this correlator picks up the excess matter distribution about galaxy pairs inside clusters. The shear-shear-lens correlator is sensitive to variations among matter haloes. In principle, it could be devised to constrain the ellipticities of haloes, without the need for luminous tracers, or maybe even random halo substructure. [Abridged]
The tumbling pattern of a bar is the main parameter characterising its dynamics. From numerical simulations, its evolution since bar formation is tightly linked to the dark halo in which the bar is formed through dynamical friction and angular momentum exchange. Observational measurements of the bar pattern speed with redshift can restrict models of galaxy formation and bar evolution. We aim to determine, for the first time, the bar pattern speed evolution with redshift based on morphological measurements. We have selected a sample of 44 low inclination ringed galaxies from the SDSS and COSMOS surveys covering the redshift range 0 <z< 0.8 to investigate the evolution of the bar pattern speed. We have derived morphological ratios between the deprojected outer ring radius (R_{ring}) and the bar size (R_{bar}). This quantity is related to the parameter {\cal R}=R_{CR}/R_{bar} used for classifiying bars in slow and fast rotators, and allow us to investigate possible differences with redshift. We obtain a similar distribution of $R$ at all redshifts. We do not find any systematic effect that could be forcing this result. The results obtained here are compatible with both, the bulk of the bar population (~70%) being fast-rotators and no evolution of the pattern speed with redshift. We argue that if bars are long-lasting structures, the results presented here imply that there has not been a substantial angular momentum exchange between the bar and halo, as predicted by numerical simulations. In consequence, this might imply that the discs of these high surface-brightness galaxies are maximal.
Supermassive black holes (SMBHs) may not always reside right at the centers of their host galaxies. This is a prediction of numerical relativity simulations, which imply that the newly formed single SMBH, after binary coalescence in a galaxy merger, can receive kick velocities up to several 1000 km/s due to anisotropic emission of gravitational waves. Long-lived oscillations of the SMBHs in galaxy cores, and in rare cases even SMBH ejections from their host galaxies, are the consequence. Observationally, accreting recoiling SMBHs would appear as quasars spatially and/or kinematically off-set from their host galaxies. The presence of the "kicks" has a wide range of astrophysical implications which only now are beginning to be explored, including consequences for black hole and galaxy assembly at the epoch of structure formation, black hole feeding, and unified models of Active Galactic Nuclei (AGN). Here, we review the observational signatures of recoiling SMBHs and the properties of the first candidates which have emerged, including follow-up studies of the candidate recoiling SMBH of SDSSJ092712.65+294344.0.
We collected multiband imaging and spectroscopy for two fossil groups (RX J1119.7+2126 and 1RXS J235814.4+150524) and one normal group (NGC 6034). We computed photometric redshifts in the central zones of each group, combining previous data with the SDSS five-band data. For each group we investigated the red sequence (RS) of the color-magnitude relation and computed the luminosity functions, stellar population ages and distributions of the group members. Spectroscopy allowed us to investigate the large-scale surroundings of these groups and the substructure levels in 1RXS J235814.4+150524 and NGC 6034. The large-scale environment of 1RXS J235814.4+150524 is poor, though its galaxy density map shows a clear signature of the surrounding cosmic web. RX J1119.7+2126 appears to be very isolated, while the cosmic environment of NGC 6034 is very rich. At the group scale, 1RXS J235814.4+150524 shows no substructure. Galaxies with recent stellar populations seem preferentially located in the group outskirts. A RS is discernable for all three groups in a color-magnitude diagram. The luminosity functions based on photometric redshift selection and on statistical background subtraction have comparable shapes, and agree with the few points obtained from spectroscopic redshifts. These luminosity functions show the expected dip between first and second brightest galaxies for the fossil groups only. Their shape is also regular and relatively flat at faint magnitudes down to the completeness level for RX J1119.7+2126 and NGC 6034, while there is a clear lack of faint galaxies for 1RXS J235814.4+150524. RX J1119.7+2126 is definitely classified as a fossil group; 1RXS J235814.4+150524 also has properties very close to those of a fossil group, while we confirm that NGC 6034 is a normal group.
With the availability of galaxy distance indicators in weak lensing surveys, lensing tomography can basically be harnessed to constrain the spatial 3D matter power spectrum over a range in redshift and physical scale. Furthermore, by adding galaxy-galaxy lensing and galaxy clustering this can be extended to probe the 3D galaxy-matter and galaxy-galaxy power spectrum or, alternatively, galaxy biasing parameters. To achieve this aim, this paper introduces and discusses minimum variance estimators and a more general Bayesian approach to statistically invert a set of noisy tomography 2-point correlation functions, measured within a confined opening angle. Both methods are constructed such that they probe deviations of the 3D power spectrum from a fiducial power spectrum. Thereby a direct comparison of theory and data is achieved, the physical scale and redshift of deviations can in principle be identified. By devising a new Monte Carlo technique the measurement noise in the correlators is quantified for a fiducial survey, and the performance of the inversion techniques is tested. We conclude that a shear tomography analysis of near future weak lensing surveys promises fruitful insights into the effect of baryons on the nonlinear matter power spectrum at z<~0.3 around k~2 h/Mpc, and into galaxy biasing (z<~0.5). However, a proper treatment of anticipated systematics -- not included in the mock analysis but discussed here -- is likely to reduce the signal-to-noise in the analysis so that a robust assessment of the 3D matter power spectrum probably asks for a survey area of at least 1000 sdeg. [Abridged]
We analyze the time variability of the X-ray emission of RE J1034+396, an active galactic nucleus with the first firm detection of a quasi-periodic oscillations (QPO). Based on the results of a wavelet analysis, we find a drift in the QPO central frequency. The change inthe QPO frequency correlates with the change in the X-ray flux with a short time delay. Linear structures such as shocks, spiral waves, orvery distant flares seem to be a favored explanation for this particular QPO event.
Studies of the molecular interstellar medium that fuels star formation and supermassive black hole growth in galaxies at cosmological distances have undergone tremendous progress over the past few years. Based on the detection of molecular gas in >120 galaxies at z=1 to 6.4, we have obtained detailed insight on how the amount and physical properties of this material in a galaxy are connected to its current star formation rate over a range of galaxy populations. Studies of the gas dynamics and morphology at high spatial resolution allow us to distinguish between gas-rich mergers in different stages along the "merger sequence" and disk galaxies. Observations of the most massive gas-rich starburst galaxies out to z>5 provide insight into the role of cosmic environment for the early growth of present-day massive spheroidal galaxies. Large-area submillimeter surveys have revealed a rare population of extremely far-infrared-luminous gas-rich high-redshift objects, which is dominated by strongly lensed, massive starburst galaxies. These discoveries have greatly improved our understanding of the role of molecular gas in the evolution of massive galaxies through cosmic time.
Certain dark matter interactions with nuclei are mediated possibly by a scalar or pseudoscalar Higgs boson. The estimation of the corresponding cross sections requires a correct evaluation of the couplings between the scalar or pseudoscalar Higgs boson and the nucleons. Progress has been made in two aspects relevant to this study in the past few years. First, recent lattice calculations show that the strange-quark sigma term $\sigma_s$ and the strange-quark content in the nucleon are much smaller than what are expected previously. Second, lattice and model analyses imply sizable SU(3) breaking effects in the determination on the axial-vector coupling constant $g_A^8$ that in turn affect the extraction of the isosinglet coupling $g_A^0$ and the strange quark spin component $\Delta s$ from polarized deep inelastic scattering experiments. Based on these new developments, we re-evaluate the relevant nucleon matrix elements and compute the scalar and pseudoscalar couplings of the proton and neutron. We also find that the strange quark contribution in both types of couplings is smaller than previously thought.
We investigate the impact of recent limits from LHC searches for supersymmetry and from direct and indirect searches for dark matter on global Bayesian inferences of the parameter space of the Constrained MSSM. In particular we apply recent exclusion limits from the CMS $\alpha_T$ analysis of 1.1 fb$^{-1}$ of integrated luminosity, current direct detection dark matter limit from XENON100, as well as recent experimental constraints on $\gamma$-ray fluxes from dwarf spheroidal satellite galaxies of the Milky Way from the FermiLAT satellite, in addition to updated values for other non-LHC experimental constraints. We extend the range of scanned parameters to include a significant fraction of the focus point/hyperbolic branch region. While we confirm earlier conclusions that at present LHC limits provide the strongest constraints on the model's parameters, we also find that the incidence of the recent exclusion limits from FermiLAT and XENON100 on the posterior pdf is strongly dependent on assumptions about theoretical uncertainties. On the other hand, when these uncertainties are not treated in a conservative way, the new bounds from indirect detection have the power to significantly constrain the focus point/hyperbolic branch region. Their effect is then comparable, if not stronger, to that from XENON100. We further analyze the effects of one-year projected sensitivities on a neutrino flux from the Sun in the 86-string IceCube+DeepCore configuration at the South Pole. We show that data on neutrinos from the Sun, expected for the next few months at IceCube and DeepCore, has the potential to further constrain the same region of parameter space, and can yield additional investigating power for the model.
In this paper we investigate the performance of the likelihood ratio method as a tool for identifying optical and infrared counterparts to proposed radio continuum surveys with SKA precursor and pathfinder telescopes. We present a comparison of the infrared counterparts identified by the likelihood ratio in the VISTA Deep Extragalactic Observations (VIDEO) survey to radio observations with 6, 10 and 15 arcsec resolution. We cross-match a deep radio catalogue consisting of radio sources with peak flux density $>$ 60 $\mu$Jy with deep near-infrared data limited to $K_{\mathrm{s}}\lesssim$ 22.6. Comparing the infrared counterparts from this procedure to those obtained when cross-matching a set of simulated lower resolution radio catalogues indicates that degrading the resolution from 6 arcsec to 10 and 15 arcsec decreases the completeness of the cross-matched catalogue by approximately 3 and 7 percent respectively. When matching against shallower infrared data, comparable to that achieved by the VISTA Hemisphere Survey, the fraction of radio sources with reliably identified counterparts drops from $\sim$89%, at $K_{\mathrm{s}}\lesssim$22.6, to 47% with $K_{\mathrm{s}}\lesssim$20.0. Decreasing the resolution at this shallower infrared limit does not result in any further decrease in the completeness produced by the likelihood ratio matching procedure. However, we note that radio continuum surveys with the MeerKAT and eventually the SKA, will require long baselines in order to ensure that the resulting maps are not limited by instrumental confusion noise.
We study cosmological perturbations for a ghost free massive gravity theory formulated with a dynamical extra metric that is needed to massive deform GR. In this formulation FRW background solutions fall in two branches. In the dynamics of perturbations around the first branch solutions, no extra degree of freedom with respect to GR ispresent at linearized level, likewise what is found in the Stuckelberg formulation of massive gravity where the extra metric isflat and non dynamical. In the first branch, perturbations are probably strongly coupled. On the contrary, for perturbations around the second branch solutions all expected degrees of freedom propagate. While tensor and vector perturbations of the physical metric that couples with matter follow closely the ones of GR, scalars develop an exponential Jeans-like instability on sub-horizon scales. On the other hand, around a de Sitter background there is no instability. We argue that one could get rid of the instabilities by introducing a mirror dark matter sector minimally coupled to only the second metric.
We analyze electromagnetic field propagation through a random medium which consists of hyperbolic metamaterial domains separated by regions of normal "elliptic" space. This situation may occur in a problem as common as 9 micrometer light propagation through a pile of sand, or as exotic as electromagnetic field behavior in the early universe immediately after the electro-weak phase transition. We demonstrate that spatial field distributions in random hyperbolic and random "elliptic" media look strikingly different. This effect may potentially be used to evaluate the magnitude of magnetic fields which existed in the early universe.
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