We present analysis of the normalised 21-cm bispectrum from fully-numerical simulations intergalactic-medium heating by stellar sources and high-mass X-ray binaries (HMXB) during cosmic dawn. Lyman-$\alpha$ coupling is assumed to be saturated, we therefore probe nature non-Gaussianities produced processes. find evolution very different that power spectrum. It exhibits a turnover whose peak moves large small scales with decreasing redshift, corresponds typical separation emission regions....

We use cosmological hydrodynamical galaxy formation simulations from the NIHAO project to investigate impact of threshold for star on response dark matter (DM) halo baryonic processes. The fiducial threshold, $n=10\, {\rm cm}^{-3}$, results in strong expansion DM galaxies with stellar masses range $10^{7.5} < M_{star} 10^{9.5} M_{\odot}$. find that lower thresholds such as $n=0.1$ (as employed by EAGLE/APOSTLE and Illustris/AURIGA projects) do not result significant at any mass scale....

The upcoming SKA1-Low radio interferometer will be sensitive enough to produce tomographic imaging data of the redshifted 21-cm signal from Epoch Reionization. Due non-Gaussian distribution signal, a power spectrum analysis alone not provide complete description its properties. Here, we consider an additional metric which could derived data, namely bubble size ionized regions. We study three methods that have previously been used characterize distributions in simulation for hydrogen...

Observations of the epoch reionization give us clues about nature and evolution sources ionizing photons, or early stars galaxies. We present a new suite structure formation radiative transfer simulations from PRACE4LOFAR project designed to investigate whether mechanism feedback, suppression star in ionized regions UV radiation, can be inferred these observations. Our source halo mass extends down $10^8 M_\odot$, with range $10^8$ $10^9 M_\odot$ expected particularly susceptible feedback we...

Upcoming observations of the 21-cm signal from epoch reionization will soon provide first direct detection this era. This is influenced by many astrophysical effects, including long-range X-ray heating intergalactic gas. During preceding cosmic dawn era, impact on particularly prominent, especially before spin temperature saturation. We present largest volume (349 Mpc comoving = 244 h−1Mpc) full numerical radiative transfer simulations to date which include effects helium and multifrequency...

We introduce a novel technique, called "granulometry", to characterize and recover the mean size distribution of HII regions from 21-cm tomography. The technique is easy implement, but places previously not very well defined concept morphology on firm mathematical foundation. cold spots in tomography can be used as direct tracer underlying probability region sizes. explore capability method using large-scale reionization simulations mock observational data cubes while considering...

The upcoming radio interferometer Square Kilometre Array (SKA) is expected to directly detect the redshifted 21-cm signal from neutral hydrogen present during Cosmic Dawn. Temperature fluctuations X-ray heating of intergalactic medium can dominate in this time. This depends on abundance, clustering, and properties sources present, which remain highly uncertain. We a suite three new large-volume, 349 Mpc side, fully numerical radiative transfer simulations including QSO-like sources,...

We use hydrodynamical cosmological simulations to show that it is possible create, via tidal interactions, galaxies lacking dark matter in a dominated universe. select dwarf from the NIHAO project, obtained standard Cold Dark Matter model and them as initial conditions for of satellite-central interactions. After just one pericentric passage on an orbit with strong radial component, can lose up 80 per~cent their content, but, most interestingly, central ($\approx 8$~kpc) stellar ratio...

ABSTRACT The 21-cm signal from the Cosmic Dawn (CD) is likely to contain large fluctuations, with most extreme astrophysical models on verge of being ruled out by observations radio interferometers. It therefore vital that we understand not only processes governing this signal, but also other inherent impacting itself, and in particular line-of-sight effects. Using our suite fully numerical radiative transfer simulations, investigate impact redshifted CD one these processes, namely...

Abstract An unprecedented array of new observational capabilities are starting to yield key constraints on models the epoch first light in Universe. In this Letter we discuss implications UV radiation background at cosmic dawn inferred by recent JWST observations for radio experiments aimed detecting redshifted 21 cm hyperfine transition diffuse neutral hydrogen. Under basic assumption that signal is activated Ly α photon field produced metal-poor stellar systems, show a detection low...

Abstract We present the prospects of extracting information about epoch reionization by identifying remaining neutral regions, referred to as islands, in tomographic observations redshifted 21-cm signal. Using simulated data sets we show that at late times power spectrum is fairly insensitive details process but properties islands can distinguish between different scenarios. compare these with those ionized bubbles. At equivalent volume-filling fractions, tend be fewer number larger compared...

A proposed method for dealing with foreground emission in upcoming 21-cm observations from the epoch of reionization is to limit an uncontaminated window Fourier space. Foreground can be avoided this way, since it limited a wedge-shaped region k∥, k⊥ However, power spectrum anisotropic owing redshift-space distortions peculiar velocities. Consequently, measured avoidance – which samples only range angles close line-of-sight direction differs full spherically averaged requires average over...

We use cosmological hydrodynamical galaxy formation simulations from the NIHAO project to investigate response of cold dark matter (CDM) haloes baryonic processes. Previous work has shown that halo is primarily a function ratio between stellar mass and total virial mass, density threshold above which gas eligible form stars, $n [{\rm cm}^{-3}]$. At low $n$ all in literature agree dwarf are cuspy, but at high $n\ge 100$ there no consensus. trace contraction galaxies with reported some...

The observed 21-cm signal from the epoch of reionization will be distorted along line-of-sight by peculiar velocities matter particles. These redshift-space distortions affect contrast in and also make it anisotropic. This anisotropy contains information about cross-correlation between density field neutral hydrogen field, could thus potentially used to extract sources reionization. In this paper, we study a collection simulated scenarios assuming different models for We show that is best...

The light-cone (LC) effect causes the mean as well statistical properties of redshifted 21-cm signal $T_{\rm b}(\hat{\bf n},ν)$ to change with frequency $ν$ (or cosmic time). Consequently, homogeneity (ergodicity) along line sight (LoS) direction is broken. This a severe problem particularly during Epoch Reionization (EoR) when neutral hydrogen fraction ($\bar{x}_{\rm HI}$) changes rapidly universe evolves. will also pose complications for large bandwidth observations. These effects imply...

Large variations in the effective optical depth of He ii Lyα forest have been observed at z ≳ 2.7, but physical nature these is uncertain: either Universe still undergoing process reionization, or highly ionized ii-ionizing background fluctuates significantly on large scales. In an effort to build upon our understanding latter scenario, we present a novel model for evolution ionizing fluctuations. Previous models assumed mean free path photons be spatially uniform, ignoring dependence that...

We examine large-scale fluctuations in the He ii Lyα forest transmission during and after reionization. use a simple Monte Carlo model to distribute quasars throughout large volume compute resulting radiation field along one-dimensional skewers. In agreement with previous studies, we find that rarity of these sources induces order unity mean optical depth reionization, even when averaged over segments (∼10–100Mpc across). compare our models existing data five lines sight spanning z ∼ 2–3.2....

Recent observations suggest that helium became fully ionized around redshift z ∼ 3. The He ii optical depth derived from the Lyα forest decreases substantially this period to 2; moreover, it fluctuates strongly near 3 and then evolves smoothly at lower redshifts. From these opacities, we compute, using a semi-analytic model, evolution of mean photoionization rate attenuation length for over range 2.0 ≲ 3.2. This model includes an inhomogeneous metagalactic radiation background, which is...

Photographic surface photometry of the giant elliptical galaxy M87 in B and V wavebands is presented. Problems background subtraction are discussed, two independent methods determination used. These shown to agree sufficiently well permit a faint limit around 28th mag/sq arcsec both wavebands. This suggests that outer parts somewhat brighter than has been suggested by previous photographic investigations (Oemler 1976; Kormendy 1977; King 1978) photoelectric work deVaucouleurs Nieto (1978),...

We propose a novel technique to separate the late-time, post-reionization component of kinetic Sunyaev-Zeldovich (kSZ) effect from contribution it (poorly understood and probably patchy) reionization history. The kSZ is one most promising probe {\em missing baryons} in Universe. study possibility reconstructing three dimensions (3D), using future spectroscopic surveys such as Euclid survey. By 3D template galaxy density peculiar velocity fields we cross-correlate estimator against CMB maps....

Radiative feedback from stars and galaxies has been proposed as a potential solution to many of the tensions with simplistic galaxy formation models based on $\Lambda$CDM, such faint end UV luminosity function. The total energy budget radiation could exceed that galactic winds supernovae combined, which driven development sophisticated algorithms evolve both field hydrodynamical response gas simultaneously, in cosmological context. We probe self-feedback scales using adaptive mesh...

Observations of the Milky Way (MW), M31, and their vicinity, known as Local Group (LG), can provide clues about sources reionization. We present a suite radiative transfer simulations based on initial conditions provided by Constrained UniversE Simulations (CLUES) project that are designed to recreate Universe, including realistic MW-M31 pair nearby Virgo. Our box size (91 Mpc) is large enough incorporate relevant ionizing photons for LG. employ range source models, mimicking potential...

In this third paper of the series, we investigate effects warm dark matter with a particle mass $m_\mathrm{WDM}=3\,\mathrm{keV}$ on smallest galaxies in our Universe. We present sample 21 hydrodynamical cosmological simulations dwarf and 20 satellite-host galaxy interaction that performed both Cold Dark Matter (CDM) Warm (WDM) scenario. WDM simulations, observe higher critical for onset star formation. Structure growth is delayed WDM, as result haloes have stellar population average two Gyrs...

Abstract We investigate how the NIHAO galaxies match observed star formation main sequence (SFMS) and what origin of its scatter is. The reproduce SFMS generally agree with observations, but slope is about unity thus significantly larger than values. This because at large stellar masses, although still being part SFMS, are already influenced by quenching. partial suppression AGN feedback leads to lower rates therefore slopes. confirm that including effects in our slopes agreement...

ABSTRACT Supersonic relative motion between baryons and dark matter due to the decoupling of from primordial plasma after recombination affects growth first small-scale structures. Large box sizes (greater than a few hundred Mpc) are required sample full range scales pertinent velocity, while effect velocity is strongest on small (less kpc). This separation naturally lends itself use ‘zoom’ simulations, here we present our methodology self-consistently incorporate in zoom including its...