2007.04656
Constraining the growth rate by combining multiple future surveys
Vilijoen, Fonesca, Maartens
The growth rate of large-scale structure provides a powerful consistency test of the standard cosmological model and a probe of possible deviations from general relativity. We use a Fisher analysis to forecast constraints on the growth rate from a combination of next-generation spectroscopic surveys. In the overlap survey volumes, we use a multi-tracer analysis to significantly reduce the effect of cosmic variance. The non-overlap individual survey volumes are included in the Fisher analysis in order to utilise the entire volume. We use the observed angular power spectrum, which naturally includes all wide-angle and lensing effects and circumvents the need for an Alcock-Paczynski correction. Cross correlations between redshift bins are included by using a novel technique to avoid computation of the sub-dominant contributions. Marginalising over the standard cosmological parameters, as well as the clustering bias in each redshift bin, we find that the precision on $\gamma$ improves on the best single-tracer precision by up to $\sim$50\%.
2007.04703
Lopsided satellite distributions around isolate host galaxies
Brainerd, Samuels
We investigate the spatial distribution of the satellites of bright, isolated host galaxies. In agreement with previous studies, we find that, on average, the satellites of red hosts are found preferentially close to their hosts' major axes, while the satellites of blue hosts are distributed isotropically. We compute the pairwise clustering of the satellites and find a strong tendency for pairs of satellites to be located on the same side of their host, resulting in lopsided distributions. The signal is most pronounced for the satellites of blue hosts, where the number of pairs on the same side of their host exceeds the number of pairs on opposite sides of their by a factor of 1.8 +/- 0.1. For the satellites of red hosts, the number of pairs on the same side of their host exceeds the number of pairs on opposite sides of their host by a factor of 1.08 +/- 0.03. Satellites that are far from their hosts (r_p > 300 kpc) show a strong preference for being located on the same side of their hosts; satellites that are near to their hosts (r_p < 100 kpc) show a weak preference for being located on opposite sides of their hosts. While lopsided distributions have been found previously for the satellites of bright pairs of galaxies, ours is the first study to find lopsided distributions for the satellites of isolated bright galaxies.
2007.04892
Detectability of thermal emission from sub-relativistic objects
Hoang, Loeb
We calculate the surface temperature and the resulting brightness of sub-relativistic objects moving through the Solar system due to collisional heating by gas and radiative heating by solar radiation. The thermal emission from objects of size $\gtrsim 100$ m and speed of $\gtrsim 0.1c$, can be detected by the upcoming {\it James Webb Space Telescope} out to a distance of $\sim 100$ au. Future surveys could therefore set interesting limits on the abundance of fast-moving interstellar objects or spacecraft.
2007.04988
The universe at z>10: predictions for jWST from the UniverseMachine DR1
Behroozi, Conroy, Wechsler, Hearin, et al
The James Webb Space Telescope (JWST) is expected to observe galaxies at $z>10$ that are presently inaccessible. Here, we use a self-consistent empirical model, the UniverseMachine, to generate mock galaxy catalogues and lightcones over the redshift range $z=0-15$. These data include realistic galaxy properties (stellar masses, star formation rates, and UV luminosities), galaxy-halo relationships, and galaxy-galaxy clustering. Mock observables are also provided for different model parameters spanning observational uncertainties at $z<10$. We predict that Cycle 1 JWST surveys will very likely detect galaxies with $M_*>10^7 M_\odot$ and/or $M_{1500}<-17$ out to at least $z\sim 13.5$. Number density uncertainties at $z>12$ expand dramatically, so efforts to detect $z>12$ galaxies will provide the most valuable constraints on galaxy formation models. The faint-end slopes of the stellar mass/luminosity functions at a given mass/luminosity threshold steepen as redshift increases. This is because observable galaxies are hosted by haloes in the exponentially falling regime of the halo mass function at high redshifts. Hence, these faint-end slopes are robustly predicted to become shallower below current observable limits ($M_\ast < 10^7M_\odot$ or $M_\mathrm{1500}>-17$). For reionization models, extrapolating luminosity functions with a constant faint-end slope from $M_{1500}=-17$ down to $M_{1500}=-12$ gives the most reasonable upper limit for the total UV luminosity and cosmic star formation rate up to $z\sim 12$. We compare to three other empirical models and one semi-analytic model, showing that the range of predicted observables from our approach encompasses predictions from other techniques. Public catalogues and lightcones for common fields are available online.
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