In order to investigate the structure and dynamics of the recently discovered massive (M_* > 10^11 M_sun) compact z~2 galaxies, cosmological hydrodynamical/N-body simulations of a proto-cluster region have been undertaken. At z=2, the highest resolution simulation contains ~5800 resolved galaxies, of which 509, 27 and 5 have M_* > 10^10 M_sun, > 10^11 M_sun and > 4x10^11 M_sun, respectively. Effective radii and characteristic stellar densities have been determined for all galaxies. At z=2, for the definitely well resolved mass range of M_* > 10^11 Msun, the mass-size relation is consistent with observational findings for the most compact z~2 galaxies. The very high velocity dispersion recently measured for a compact z~2 galaxy (~510 km/s; van Dokkum et al 2009) can be matched at about the 1-sigma level, although a somewhat larger mass than the estimated M_* ~ 2 x 10^11 M_sun is indicated. For the above mass range, the galaxies have an average axial ratio <b/a> = 0.64 +/- 0.02 with a dispersion of 0.1, an average rotation to 1D velocity dispersion ratio <v/sigma> = 0.46 +/- 0.06 with a dispersion of 0.3, and a maximum value of v/sigma ~ 1.1. Rotation and velocity anisotropy both contribute in flattening the compact galaxies. Some of the observed compact galaxies appear flatter than any of the simulated galaxies. Finally, it is found that the massive compact galaxies are strongly baryon dominated in their inner parts, with typical dark matter mass fractions of order only 20% inside of r=2R_eff.
The aim of this project is to determine the consistency of an assumed cosmological model by means of a detailed analysis of the brightness profiles of distant galaxies.Starting from the theory developed by Ellis and Perry (1979) connecting the angular diameter distance obtained from a relativistic cosmological model and the detailed photometry of galaxies, we assume the presently most accepted cosmological model with non-zero cosmological constant and attempt to predict the brightness profiles of galaxies of a given redshift. Then this theoretical profile can be compared to observational data …
The accretion of minor satellites is currently proposed as the most likely mechanism to explain the significant size evolution of the massive galaxies during the last ~10 Gyr. In this paper we investigate the rest-frame colors and the average stellar ages of satellites found around massive galaxies (Mstar 10^11Msun) since z~2. We find that the satellites have bluer colors than their central galaxies. When exploring the stellar ages of the galaxies, we find that the satellites have similar ages to the massive galaxies that host them at high redshifts, while at lower redshifts they are, on avera…
We examine the past and current work on the star formation (SF) histories of dwarf galaxies in cosmological hydrodynamic simulations. The results obtained from different numerical methods are still somewhat mixed, but the differences are understandable if we consider the numerical and resolution effects. It remains a challenge to simulate the episodic nature of SF history in dwarf galaxies at late times within the cosmological context of a cold dark matter model. More work is needed to solve the mysteries of SF history of dwarf galaxies employing large-scale hydrodynamic simulations on the nex…
I highlight three results from cosmological hydrodynamic simulations that yield a realistic red sequence of galaxies: 1) Major galaxy mergers are not responsible for shutting off star-formation and forming the red sequence. Starvation in hot halos is. 2) Massive galaxies grow substantially (about a factor of 2 in mass) after being quenched, primarily via minor (1:5) mergers. 3) Hot halo quenching naturally explains why galaxies are red when they either (a) are massive or (b) live in dense environments.
Images of the Hubble Ultra Deep Field are analyzed to obtain a catalog of galaxies for which the angular sizes, surface brightness, photometric redshifts, and absolute magnitudes are found. The catalog contains a total of about 4000 galaxies identified at a high signal-to-noise ratio, which allows the cosmological relations angular size{redshift and surface brightness-redshift to be analyzed. The parameters of the evolution of linear sizes and surface brightness of distant galaxies in the redshift interval 0.5-6.5 are estimated in terms of a grid of cosmological models with different density p…
[Abridged] Using public data from the NMBS and CANDELS surveys, we study the population of massive galaxies at z>3 to identify the potential progenitors of z~2 compact, massive, quiescent (CMQ) galaxies, furthering our understanding of the evolution of massive galaxies. Our work is enabled by high-resolution CANDELS images and accurate photometric redshifts, stellar masses and star formation rates (SFRs) from 37-band NMBS photometry. The total number of z>3 massive galaxies is consistent with the number of massive quiescent (MQ) galaxies at z~2, implying that the SFRs for all of these galaxies…
The paper by Sato and Kobayashi in 1977 studied the cosmological effects of a massive neutrino and obtained constraints on its properties. This paper initiated many studies to use cosmology as a laboratory of particle physics or to use particle physics to explore the very early universe.
We compute the infrared (IR) emission from high-redshift galaxies in cosmological smoothed particle hydrodynamics simulations by coupling the output of the simulation with the population synthesis code `GRASIL' by Silva et al. Based on the stellar mass, metallicity and formation time of each star particle, we estimate the full spectral energy distribution of each star particle from ultraviolet to IR, and compute the luminosity function of simulated galaxies in the Spitzer broadband filters for direct comparison with the available Spitzer observations.
We show that the galaxy 4-Point Correlation Function (4PCF) can test for cosmological parity violation. The detection of cosmological parity violation would reflect previously unknown forces present at the earliest moments of the Universe. Recent developments both in rapidly evaluating galaxy $N$-Point Correlation Functions (NPCFs) and in determining the corresponding covariance matrices make the search for parity violation in the 4PCF possible in current and upcoming surveys such as those undertaken by Dark Energy Spectroscopic Instrument (DESI), the $Euclid$ satellite, and the Vera C. Rubin …
I review the subject of the cosmological evolution of galaxies, including different aspects of growth in disk galaxies, by focussing on the angular momentum problem, mergers, and their by-products. I discuss the alternative to merger-driven growth -- cold accretion and related issues. In the follow-up, I review possible feedback mechanisms and their role in galaxy evolution. Special attention is paid to high-redshift galaxies and their properties. In the next step, I discuss a number of processes, gas- and stellar-dynamical, within the central kiloparsec of disk galaxies, and their effect on t…
We show how Newtonian cosmological simulations can be employed to investigate the non-linear evolution of two particle species in a relativistic context. We discuss the application for massive neutrinos and other multi-species systems such as Cold Dark Matter (CDM) plus baryons or Warm Dark Matter (WDM). We propose a method that allows us to perform simulations including massive neutrinos and general relativistic effects at almost the same computational cost as ordinary CDM only N-body simulations, employing tailor-made initial conditions and a dictionary for the interpretation of the simulati…
Present-day massive galaxies are composed mostly of early-type objects. It is unknown whether this was also the case at higher redshifts. In a hierarchical assembling scenario the morphological content of the massive population is expected to change with time from disk-like objects in the early Universe to spheroid-like galaxies at present. In this paper we have probed this theoretical expectation by compiling a large sample of massive (M_{stellar}>10^{11} h_{70}^{-2} M_{Sun}$) galaxies in the redshift interval 0 < z < 3. Our sample of 1082 objects comprises 207 local galaxies selected from SD…
In this Letter, we analyse the predicted physical properties of massive galaxies, in the framework of recent semi-analytic models of galaxy formation. All models considered account for winds driven by supernovae explosions and suppression of gas condensation at the centre of relatively massive haloes by active galactic nuclei (AGN). We show that, while these models successfully reproduce the old stellar populations observed for massive galaxies, they fail in reproducing their observed chemical abundances. This problem is alleviate but still present if AGN feedback is completely switched off. M…
We present an analysis of ~60 000 massive (stellar mass M_star > 10^{11} M_sun) galaxies out to z = 1 drawn from 55.2 deg2 of the United Kingdom Infrared Telescope (UKIRT) Infrared Deep Sky Survey (UKIDSS) and the Sloan Digital Sky Survey (SDSS) II Supernova Survey. This is by far the largest survey of massive galaxies with robust mass estimates, based on infrared (K-band) photometry, reaching to the Universe at about half its present age. We find that the most massive (M_star > 10^{11.5} M_sun) galaxies have experienced rapid growth in number since z = 1, while the number densities of the les…
An expression for rotational velocity of a test particle around the central mass in the invariant plane is derived. For this, a line element of Schwarzschild de-Sitter space-time is used to study the effect of cosmological constant ($Λ$) on the motion of both massive and massless particles. Using rotation curve data of 15 nearby spiral and barred spiral galaxies, we estimated the mass and $Λ$ of the galaxy. The mass of the galaxies are found to lie in the range 0.13-7.60 $\times$ 10$^{40}$ kg. The cosmological constant ($Λ$) is found to be negative ($-$0.03 to $-$0.10 $\times$ 10$^{-40}$ km$^{…
We present our results on the structure and activity of massive galaxies at z=1-3 using one of the largest (166 with M_star>=5e10 M_sun) and most diverse samples of massive galaxies derived from the GOODS-NICMOS survey: (1) Sersic fits to deep NIC3/F160W images indicate that the rest-frame optical structures of massive galaxies are very different at z=2-3 compared to z~0. Approximately 40% of massive galaxies are ultra-compact (r_e<=2 kpc), compared to less than 1% at z~0. Furthermore, most (~65%) systems at z=2-3 have a low Sersic index n<=2, compared to ~13% at z~0. We present evidence that …
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 st…
We explore the rate and impact of galaxy mergers on the massive galaxy population using the amplitude of the two-point correlation function on small scales for M > 5e10 M_sun galaxies from the COSMOS and COMBO-17 surveys. Using a pair fraction derived from the Sloan Digital Sky Survey as a low-redshift benchmark, the large survey area at intermediate redshifts allows us to determine the evolution of the close pair fraction with unprecedented accuracy for a mass-selected sample: we find that the fraction of galaxies more massive than 5e10M_sun in pairs separated by less than 30 kpc in 3D space …
We present Hubble Space Telescope NIC2 morphologies of a spectroscopic sample of massive galaxies at z~2.3, by extending our sample of 9 compact quiescent galaxies (r_e~0.9 kpc) with 10 massive emission-line galaxies. The emission-line galaxies are classified by the nature of their ionized emission; there are six star-forming galaxies and four galaxies hosting an active galactic nucleus (AGN). The star-forming galaxies are the largest among the emission-line galaxies, with a median size of re = 2.8 kpc. The three galaxies with the highest star formation rates (> 100M \odot/yr) have irregular a…
We present the details and early results from a deep near-infrared survey utilising the NICMOS instrument on the Hubble Space Telescope centred around massive M_* > 10^11 M_0 galaxies at 1.7 < z < 2.9 found within the Great Observatories Origins Deep Survey (GOODS) fields. The GOODS NICMOS Survey (GNS) was designed to obtain deep F160W (H-band) imaging of 80 of these massive galaxies, as well as other colour selected objects such as Lyman-break drop-outs, BzK objects, Distant Red Galaxies, EROs, Spitzer Selected EROs, BX/BM galaxies, as well as sub-mm galaxies. We present in this paper details…
We calculate the real- and redshift-space clustering of massive galaxies at z~0.5 using the first semester of data by the Baryon Oscillation Spectroscopic Survey (BOSS). We study the correlation functions of a sample of 44,000 massive galaxies in the redshift range 0.4<z<0.7. We present a halo-occupation distribution modeling of the clustering results and discuss the implications for the manner in which massive galaxies at z~0.5 occupy dark matter halos. The majority of our galaxies are central galaxies living in halos of mass 10^{13}Msun/h, but 10% are satellites living in halos 10 times more…
Accretion of minor satellites has been postulated as the most likely mechanism to explain the significant size evolution of the massive galaxies over cosmic time. Using a sample of 629 massive (Mstar~10^11 Msun) galaxies from the near-infrared Palomar/DEEP-2 survey, we explore which fraction of these objects has satellites with 0.01 Msat < Mcentral < 1 (1:100) up to z=1 and which fraction has satellites with 0.1 Msat < Mcentral < 1 (1:10) up to z=2 within a projected radial distance of 100 kpc. We find that the fraction of massive galaxies with satellites, after the background correction, rema…
The spatial distributions of luminous and dark matter in massive early-type galaxies reflect the formation processes which shaped these systems. This article reviews the predictions of cosmological simulations for the dark and baryonic components of ETGs, and the observational constraints from lensing, hydrostatic X-ray gas athmospheres, and outer halo stellar dynamics.
Using Gemini North telescope ultra deep and high resolution (sub-kpc) K-band adaptive optics imaging of a sample of 4 nearby (z~0.15) massive (~10^{11}M_sun) compact (R<1.5 kpc) galaxies, we have explored the structural properties of these rare objects with an unprecedented detail. Our surface brightness profiles expand over 12 magnitudes in range allowing us to explore the presence of any faint extended envelope on these objects down to stellar mass densities ~10^{6} M_sun/kpc^{2} at radial distances of ~15 kpc. We find no evidence for any extended faint tail altering the compactness of these…
Clustering properties and peculiar velocities of halos in large-scale structure carry a wealth of cosmological information over a wide range of scales from linear to nonlinear scales. We use halo catalogs in a suite of high-resolution $N$-body simulations to construct mock catalogs of galaxies that resemble the SDSS-like luminous early-type galaxies at three redshift bins in the range $0.15\le z\le 0.7$. To do this we include 10 nuisance parameters to model variations in halo-galaxy connections for each redshift bin; the halo occupation distribution, and the spatial and velocity distributions …
We present the results of a numerical adaptive mesh refinement hydrodynamical and N-body simulation in a $ΛCDM$ cosmology. We focus on the analysis of the main properties of massive galaxies ($M_* > 10^{11}\,M_{\odot}$) at $z=0$. For all the massive virtual galaxies we carry out a careful study of their one dimensional density, luminosity, velocity dispersion, and stellar population profiles. In order to best compare with observational data, the method to estimate the velocity dispersion is calibrated by using an approach similar to that performed in the observations, based on the stellar popu…
We present a clustering analysis of ~60,000 massive (stellar mass Mstar > 10^{11} Msun) galaxies out to z = 1 drawn from 55.2 deg2 of the UKIRT Infrared Deep Sky Survey (UKIDSS) and the Sloan Digital Sky Survey (SDSS) II Supernova Survey. Strong clustering is detected for all the subsamples of massive galaxies characterized by different stellar masses (Mstar = 10^{11.0-11.5} Msun, 10^{11.5-12.0} Msun) or rest-frame colors (blue: U - V < 1.0, red: U - V > 1.0). We find that more mature (more massive or redder) galaxies are more clustered, which implies that more mature galaxies have started ste…
We have used deep, HST, near-IR imaging to study the morphological properties of the most massive galaxies at high z, modelling the WFC3/IR H-band images of the ~200 galaxies in the CANDELS-UDS field with 1 < z_phot < 3, and stellar masses M_star > 10^11 M_sun. We have used both single-Sersic and bulge+disk models, have investigated the errors/biases introduced by uncertainties in the background and the PSF, and have obtained formally-acceptable model fits to >90% of the galaxies. Our results indicate that these massive galaxies at 1 < z < 3 lie both on and below the local size-mass relation, …
We investigate the stellar structure of massive, quiescent galaxies at z~2, based on Hubble Space Telescope/WFC3 imaging from the Early Release Science program. Our sample of 14 galaxies has stellar masses of M* > 10^{10.8} Msol and photometric redshifts of 1.5 < z < 2.5. In agreement with previous work, their half-light radii are <2 kpc, much smaller than equally massive galaxies in the present-day universe. A significant subset of the sample appears highly flattened in projection, which implies, considering viewing angle statistics, that a significant fraction of the galaxies in our sample h…
We examine the relation between surface brightness, velocity dispersion and size$-$the fundamental plane$-$for quiescent galaxies at intermediate redshifts in the COSMOS field. The COSMOS sample consists of $\sim150$ massive quiescent galaxies with an average velocity dispersion $σ\sim 250$ km s$^{-1}$ and redshifts between $0.2<z<0.8$. More than half of the galaxies in the sample are compact. The COSMOS galaxies exhibit a tight relation ($\sim0.1$ dex scatter) between surface brightness, velocity dispersion and size. At a fixed combination of velocity dispersion and size, the COSMOS galaxies …
Cosmological perturbations of FRW solutions in ghost free massive bigravity, including also a second matter sector, are studied in detail. At early time, we find that sub horizon exponential instabilities are unavoidable and they lead to a premature departure from the perturbative regime of cosmological perturbations.
Our current knowledge of cosmic star-formation history during the first two billion years (corresponding to redshift z >3) is mainly based on galaxies identified in rest-frame ultraviolet light. However, this population of galaxies is known to under-represent the most massive galaxies, which have rich dust content and/or old stellar populations. This raises the questions of the true abundance of massive galaxies and the star-formation-rate density in the early universe. Although several massive galaxies that are invisible in the ultraviolet have recently been confirmed at early epochs, most of…
In cold dark matter cosmologies, the most massive dark matter halos are predicted to undergo rapid growth at z<1. While there is the expectation that massive galaxies will also rapidly grow via merging, recent observational studies conclude that the stellar masses of the most massive galaxies grow by just 30 percent at z<1. We have used the observed space density and clustering of z<1 red galaxies in Bootes to determine how these galaxies populate dark matter halos. In the most massive dark matter halos, central galaxy stellar mass is proportional to halo mass to the power of a third and much …
Sterile massive neutrinos are a natural extension of the Standard Model of elementary particles. The energy density of the extra sterile massive states affects cosmological measurements in an analogous way to that of active neutrino species. We perform here an analysis of current cosmological data and derive bounds on the masses of the active and the sterile neutrino states as well as on the number of sterile states. The so-called (3+2) models with three sub-eV active massive neutrinos plus two sub-eV massive sterile species is well within the 95% CL allowed regions when considering cosmologic…
Relevant deformations of gravity present an exciting window of opportunity to probe the rigidity of gravity on cosmological scales. For a single-graviton theory, the leading relevant deformation constitutes a graviton mass term. In this paper, we investigate the classical and quantum stability of massive cosmological gravitons on generic Friedman backgrounds. For a Universe expanding towards a de Sitter epoch, we find that massive cosmological gravitons are self-protected against unitarity violations by a strong coupling phenomenon.
The origin of dwarf spheroidal galaxies (dSphs) is investigated in a global cosmological context by simultaneously following the evolution of the Milky Way Galaxy and its dwarf satellites. This approach enable to study the formation of dSphs in their proper birth environment and to reconstruct their own merging histories. The proposed picture simultaneously accounts for several dSph and Milky Way properties, including the Metallicity Distribution Functions of metal-poor stars. The observed features are interpreted in terms of physical processes acting at high redshifts.
Quenched massive spiral galaxies have attracted great attention recently, as more data is available to constrain their environment and cold gas content. However, the quenching mechanism is still uncertain, as it depends on the mass range and baryon budget of the galaxy. In this letter, we report the identification of a rare population of very massive, quenched spiral galaxies with stellar mass $\gtrsim10^{11}{\rm~M_\odot}$ and halo mass $\gtrsim10^{13}{\rm~M_\odot}$ from the Sloan Digital Sky Survey at redshift $z\sim0.1$. Our CO observations using the IRAM-30m telescope show that these galaxi…
We present a comprehensive analysis of classical scalar, vector and tensor cosmological perturbations in ghost-free massive bigravity. In particular, we find the full evolution equations and analytical solutions in a wide range of regimes. We show that there are viable cosmological backgrounds but, as has been found in the literature, these models generally have exponential instabilities in linear perturbation theory. However, it is possible to find stable scalar cosmological perturbations for a very particular choice of parameters. For this stable subclass of models we find that vector and te…
Once understood as the paradigm of passively evolving objects, the discovery that massive galaxies experienced an enormous structural evolution in the last ten billion years has opened an active line of research. The most significant pending question in this field is the following: which mechanism has made galaxies to grow largely in size without altering their stellar populations properties dramatically? The most viable explanation is that massive galaxies have undergone a significant number of minor mergers which have deposited most of their material in the outer regions of the massive galax…
We study cosmological perturbations around self-accelerating solutions to two extensions of nonlinear massive gravity: the quasi-dilaton theory and the mass-varying theory. We examine stability of the cosmological solutions, and the extent to which the vanishing of the kinetic terms for scalar and vector perturbations of self-accelerating solutions in massive gravity is generic when the theory is extended. We find that these kinetic terms are in general non-vanishing in both extensions, though there are constraints on the parameters and background evolution from demanding that they have the co…
We perform a detailed dynamical analysis of various cosmological scenarios in extended (varying-mass) nonlinear massive gravity. Due to the enhanced freedom in choosing the involved free functions, this cosmological paradigm allows for a huge variety of solutions that can attract the universe at late times, comparing to scalar-field cosmology or usual nonlinear massive gravity. Amongst others, it accepts quintessence, phantom, or cosmological-constant-like late-time solutions, which moreover can alleviate the coincidence problem. These features seem to be general and non-sensitive to the impos…
In the framework of the recently proposed models of massive gravity, defined with respect to a de Sitter reference metric, we obtain new homogeneous and isotropic solutions for arbitrary cosmological matter and arbitrary spatial curvature. These solutions can be classified into three branches. In the first two, the massive gravity terms behave like a cosmological constant. In the third branch, the massive gravity effects can be described by a time evolving effective fluid with rather remarkable features, including the property to behave as a cosmological constant at late time.
We investigate the cosmological perturbations around FLRW solutions to non- linear massive gravity with a new effective coupling to matter proposed recently. Unlike the case with minimal matter coupling, all five degrees of freedom in the gravity sector propagate on generic self-accelerating FLRW backgrounds. We study the stability of the cosmological solutions and put constraints on the parameters of the theory by demanding the correct sign for the kinetic terms for scalar, vector and tensor perturbations.
Galaxies and their dark-matter halos have posed several challenges to the Dark Energy plus Cold Dark Matter (LCDM) cosmological model. These discrepancies between observations and theory intensify for the lowest-mass (`dwarf') galaxies. LCDM predictions for the number, spatial distribution, and internal structure of low-mass dark-matter halos have historically been at odds with observed dwarf galaxies, but this is partially expected, because many predictions modeled only the dark-matter component. Any robust LCDM prediction must include, hand-in-hand, a model for galaxy formation to understand…
We report on an update of the test on the rotation of the plane of linear polarization for light traveling over cosmological distances, using a comparison between the measured direction of the UV polarization in 8 radio galaxies at z>2 and the direction predicted by the model of scattering of anisotropic nuclear radiation, which explains the polarization. No rotation is detected within a few degrees for each galaxy and, if the rotation does not depend on direction, then the all-sky-average rotation is constrained to be θ= -0.8 +/- 2.2. We discuss the relevance of this result for constraining c…
We compare observed far-infrared (FIR) galaxy spectral energy distributions (SEDs) at $z\sim6$ and theoretical predictions for first massive population II (Pop II) galaxies. Observed FIR SEDs at $z\gtrsim5$ are broad and shifted to bluer wavelengths when compared to galaxies at $z\sim3$. By implementing an analytical model for dust emission from Pop II massive galaxies,we were able to reproduce the observed behaviour as a consequence of the high energy densities and silicate-rich dust composition of high-$z$ model galaxies. As noted in a previous work, the non-blackbody nature of galaxy SEDs a…
We investigate a cosmological model resulting from a dimensional reduction of the higher-dimensional dRGT massive gravity. By using the Kaluza-Klein dimensional reduction, we obtain an effective four-dimensional massive gravity theory with a scalar field. It is found that the resulting theory corresponds to a combined description of mass-varying massive gravity and quasi-dilaton massive gravity. By analyzing the cosmological solution, we found that it is possible to obtain the late-time expansion of the universe due to the graviton mass. By using a dynamical system approach, we found regions o…
Certain scalar fields with higher derivative interactions and novel classical and quantum mechanical properties - the Galileons - can be naturally covariantized by coupling to nonlinear massive gravity in such a way that their symmetries and number of degrees of freedom are unchanged. We study the propagating degrees of freedom in these models around cosmologically interesting backgrounds. We identify the conditions necessary for such a theory to remain ghost free, and consider when tachyonic instabilities can be avoided. We show that on the self-accelerating branch of solutions, the kinetic t…
This is a brief introduction to the closing discussion of the IAU Symposium 295, "The Intriguing Life of Massive Galaxies", that was held in Beijing from August 27 through 31, 2012. The discussion was focused on only four hot items, namely 1) the redshift evolution of the size of passively evolving galaxies, 2) the evolution with redshift of the specific star formation rate, 3) quenching of star formation in galaxies and dry merging, and 4) the IMF.
Using fully GPU $N$-body simulations, we demonstrate for the first time that subhalos sink and transfer energy via dynamical friction into the centres of dwarf galaxies. This dynamical heating kicks any central massive black hole (MBH) out to tens of parsecs, especially at early epochs ($z$=1.5-3). This mechanism helps explain the observed off-center BHs in dwarf galaxies and also predicts that off-center BHs are more common in higher mass dwarf galaxies since dynamical friction becomes significantly weaker and BHs take more time to sink back towards the centres of their host galaxies. One con…
The most massive elliptical galaxies have low-density centers or cores that differ dramatically from the high-density centers of less massive ellipticals and bulges of disk galaxies. These cores have been interpreted as the result of mergers of supermassive black hole binaries, which depopulate galaxy centers by gravitationally slingshotting central stars toward large radii. Such binaries naturally form in mergers of luminous galaxies. Here, we analyze the population of central stellar orbits in 11 massive elliptical galaxies that we observed with the integral field spectrograph SINFONI at the…
Aims: Recently, cosmological fast radio bursts (FRBs) have been used to provide the most stringent limit up to date on Einstein's Equivalence Principle (EEP). We study how to further test EEP with FRBs. Methods: Future systematic radio surveys will certainly find abundant FRBs at cosmological distances and some of them will inevitably be located behind clusters of galaxies. Here we suggest to use those FRBs to further test EEP. Results: We find that the robustness and accuracy of testing EEP can be improved further by orders of magnitude with these FRBs. The same methodology can also be applie…
The cosmological collider provides a model-independent probe of particle physics during inflation. We extend the study of cosmological collider physics to much smaller scales through gravitational wave (GW) probes. With a Chern-Simons interaction, a massive vector field can obtain a chemical potential and its particle production can cause significant non-Gaussian GW signals. We calculate the mass and spin dependences of the induced GW 3-point correlation function in the squeezed limit, and estimate its amplitude. Such signals may be detectable in the current and upcoming GW interferometer expe…
In this work we have analysed some cosmological bounds concerning an open FLRW solution of massive gravity. The constraints with recent observational $H(z)$ data were found and the best fit values for the cosmological parameters are in agreement with the $Λ$CDM model, and also point to a nearly open spatial curvature, as expected from the model. The graviton mass dependence with the constant parameters $α_3$ and $α_4$, related to the additional lagrangians terms of the model, are also analysed, and we have obtained a strong dependence with such parameters, although the condition $m_g\simeq H_0…
We use a 27.6 deg$^2$ survey to measure the clustering of $gzK_s$-selected quiescent galaxies at $z\sim1.6$, focusing on ultra-massive quiescent galaxies. We find that $z\sim1.6$ Ultra-Massive Passively Evolving Galaxies (UMPEGs), which have $K_s(AB)<19.75$ (stellar masses of $M_{stars}$ $>\sim 10^{11.4}M_{\odot}$ and mean $<$$M_{stars}$$>$ = $10^{11.5}M_{\odot}$), cluster more strongly than any other known galaxy population at high redshift. Comparing their correlation length, $r_0 = 29.77 \pm 2.75$ $ h^{-1}$Mpc, with the clustering of dark matter halos in the Millennium XXL N-body simulation…
