Developing analysis pipelines based on statistics beyond two-point functions is critical for extracting a maximal amount of cosmological information from current and upcoming weak lensing surveys. In this paper, we study the impact of the intrinsic alignment of galaxies (IA) on three promising probes measured from aperture mass maps -- the lensing peaks, minima and full PDF, in comparison and in combination with the shear two-point correlation functions ($γ$-2PCFs). Our two-dimensional IA infusion method converts the light-cone-projected mass sheets into projected tidal tensors, which are then linearly coupled to an intrinsic ellipticity component with a strength controlled by the coupling parameter $A_{\rm IA}$. We validate our method with the $γ$-2PCFs statistics, recovering well the analytical calculations from the linear alignment model of Bridle \& King in a full tomographic setting, and for different $A_{\rm IA}$ values. We next use our method to infuse at the galaxy catalogue level a non-linear IA model that includes the density-weighting term introduced in \citet{Blazek2015}, and compute the impact on the three aperture mass map statistics. We find that large \snr peaks are maximally affected, with deviations reaching 30\% (10\%) for a {\it Euclid}-like (KiDS-like) survey. Modelling the signal in a $w$CDM cosmology universe with $N$-body simulations, we forecast the cosmological bias caused by unmodelled IA for 100 deg$^2$ of {\it Euclid}-like data, finding very large offsets in $w_0$ (5-10$σ_{\rm stat}$), $Ω_{\rm m}$ (4-6$σ_{\rm stat}$), and $S_8 \equiv σ_8\sqrt{Ω_{\rm m}/0.3}$ ($\sim$3$σ_{\rm stat}$). The method presented in this paper offers a compelling avenue to account for IA in beyond-two-point weak lensing statistics, with a flexibility comparable to that of current $γ$-2PCFs IA analytical models.
We present a method to recover and study the projected gravitational tidal forces from a galaxy survey containing little or no redshift information. The method and the physical interpretation of the recovered tidal maps as a tracer of the cosmic web are described in detail. We first apply the method to a simulated galaxy survey and study the accuracy with which the cosmic web can be recovered in the presence of different observational effects, showing that the projected tidal field can be estimated with reasonable precision over large regions of the sky. We then apply our method to the 2MASS s…
Imprints of gravitational-wave polarizations on projected tidal tensor in three dimensions
Institute of Astronomy and Astrophysics, Academia Sinica（中央研究院天文及天文物理研究所）；Kavli Institute for the Physics and Mathematics of the Universe (WPI), UTIAS, The University of Tokyo（东京大学宇宙射线研究所卡弗里宇宙物理学与数学研究所）；Asia Pacific Center for Theoretical Physics (APCTP)（亚太理论物理中心）；Center for Gravitational Physics, Yukawa Institute for Theoretical Physics, Kyoto University（京都大学汤川理论物理研究所引力物理中心）；Leung Center for Cosmology and Particle Astrophysics, National Taiwan University（台湾大学梁林杰宇宙论与粒子天体物理中心）
We investigate the effect of orientation-dependent selection effects on galaxy clustering in redshift space. It is found that if galaxies are aligned by large-scale tidal fields, then these selection effects give rise to a dependence of the observed galaxy density on the local tidal field, in addition to the well-known dependences on the matter density and radial velocity gradient. This alters the galaxy power spectrum in a way that is different for Fourier modes parallel to and perpendicular to the line of sight. These tidal galaxy alignments can thus mimic redshift space distortions, and thu…
We present results from GMRT HI 21 cm line observations of the interacting galaxy pair Arp 181 (NGC 3212 and NGC 3215) at z =0.032. We find almost all of the detected HI (90%) displaced well beyond the optical disks of the pair with the highest density HI located ~70 kpc west of the pair. An HI bridge extending between the optical pair and the bulk of the HI together with their HI deficiencies provide strong evidence that the interaction between the pair has removed most of their HI to the current projected position. HI to the west of the pair has two approximately equal intensity peaks. The H…
We determine an optimized clustering statistic to be used for galaxy samples with significant redshift uncertainty, such as those that rely on photometric redshifts. To do so, we study the baryon acoustic oscillation (BAO) information content as a function of the orientation of galaxy clustering modes with respect to their angle to the line-of-sight (LOS). The clustering along the LOS, as observed in a redshift-space with significant redshift uncertainty, has contributions from clustering modes with a range of orientations with respect to the true LOS. For redshift uncertainty $σ_z \geq 0.02(1…
Gravitational lensing observations of massive X-ray clusters imply a steep characteristic density profile marked by a central concentration of dark matter. The observed mass fraction within a projected radius of 150 kpc is twice that found in state-of-the-art dark matter simulations of the standard Lambda-CDM cosmology. A central baryon enhancement that could explain this discrepancy is not observed, leaving a major puzzle. We propose a solution based on the merger histories of clusters. A significant fraction of the final dark matter content of a cluster halo originates within galaxy-sized ha…
Using a high resolution N-body simulation of a two-component dwarf galaxy orbiting in the potential of the Milky Way, we study two effects that lead to significant biases in mass estimates of dwarf spheroidal galaxies. Both are due to the strong tidal interaction of initially disky dwarfs with their host. The tidal stripping of dwarf stars leads to the formation of strong tidal tails that are typically aligned with the line of sight of an observer positioned close to the host center. The stars from the tails contaminate the kinematic samples leading to a velocity dispersion profile increasing …
With the aim of finding evidence of tidal stripping of globular clusters (GCs) we analysed a sample of 13 elliptical galaxies taken from the ACS Virgo Cluster Survey (VCS). These galaxies belong to the main concentration of the Virgo cluster (VC) and present absolute magnitudes $-18.5<M_z<-22.5$. We used the public GC catalog of Jordán et al. (2008) and separated the GC population into metal poor (blue) and metal rich (red) according to their integrated colors. The galaxy properties were taken from \citet{Peng:2008}. We found that: 1) The specific frequencies ($S_N$) of total and blue GC popul…
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 equ…
We extend the analysis of Pace et al., JCAP, 2019, 060, by considering the virialization process in the extended spherical collapse model for clustering dark-energy models, i.e., accounting for dark-energy fluctuations. Differently from the standard approach, here virialization is naturally achieved by properly modelling deviations from sphericity due to shear and rotation induced by tidal interactions. We investigate the time evolution of the virial overdensity $Δ_\mathrm{vir}$ in seven clustering dynamical dark energy models and compare the results to the $Λ$CDM model and to the correspondin…
We present a method to couple N-body star cluster simulations to a cosmological tidal field, using the Astrophysical Multipurpose Software Environment. We apply this method to star clusters embedded in the CosmoGrid dark matter-only LambdaCDM simulation. Our star clusters are born at z = 10 (corresponding to an age of the Universe of about 500 Myr) by selecting a dark matter particle and initializing a star cluster with 32,000 stars on its location. We then follow the dynamical evolution of the star cluster within the cosmological environment. We compare the evolution of star clusters in two M…
We present the 3-{\it dimensional} intrinsic alignment power spectra between the projected 2d galaxy shape/spin and the 3d tidal field across $0.1<k/h{\rm Mpc}^{-1}<60$ using cosmological hydrodynamical simulation, Illustris-TNG300, at redshifts ranging from $0.3$ to $2$. The shape-tidal field alignment increases with galaxy mass and the linear alignment coefficient $A_{\rm IA}$, defined with respect to the primordial tidal field, is found to have weak redshift dependence. We also show a promising detection of the shape/spin-tidal field alignments for stellar mass limited samples and a weak or…
We present the results of a Keck/DEIMOS survey of Ultra Compact Dwarfs (UCDs) in the Perseus Cluster core. We confirm cluster membership for 14 UCDs, with radial velocities ~5300 km s$^{-1}$. Two of these confirmed Perseus UCDs have extremely blue colours ($B-R < 0.6$ mag), reside in star forming filaments surrounding NGC 1275, and have likely formed as massive star clusters in the last ~100 Myr. We also measure a central velocity dispersion of a third, UCD13 ($σ_0 = 38 \pm 8$ km s$^{-1}$), the most extended UCD in our sample. We determine it to have radius $R_{e} = 85 \pm 1.1$ pc, a dynamical…
Tidal streams in the Milky Way are sensitive probes of the population of dark-matter subhalos predicted in cold-dark-matter (CDM) simulations. We present a new calculus for computing the effect of subhalo fly-bys on cold tidal streams based on the action-angle representation of streams. The heart of this calculus is a line-of-parallel-angle approach that calculates the perturbed distribution function of a given stream segment by undoing the effect of all impacts. This approach allows one to compute the perturbed stream density and track in any coordinate system in minutes for realizations of t…
We report the discovery of a diffuse stellar cloud with an angular extent $\gtrsim30^{\prime\prime}$, which we term "Sumo Puff", in data from the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP). While we do not have a redshift for this object, it is in close angular proximity to a post-merger galaxy at redshift $z=0.0431$ and is projected within a few virial radii (assuming similar redshifts) of two other ${\sim}L_\star$ galaxies, which we use to bracket a potential redshift range of $0.0055 < z < 0.0431$. The object's light distribution is flat, as characterized by a low Sersic index ($n…
A tidal disruption event (TDE) occurs when a star is destroyed by the strong tidal shear of a massive black hole (MBH). The accumulation of TDE observations over the last years has revealed that post-starburst galaxies are significantly overrepresented in the sample of TDE hosts. Here we address the post-starburst preference by investigating the decline of TDE rates in a Milky-Way like nuclear stellar cluster featuring either a monochromatic (1 M$\odot$) or a complete, evolved stellar mass function. In the former case, the decline of TDE rates with time is very mild, and generally up to a fact…
