Cosmic infrared background: how to model it and how to beat the confusion

Неоднородный космический инфракрасный фон, созданный далекими галактиками, представляет существенную проблему для будущих наблюдений в дальнем ИК диапазоне, на длинах волн 100-1000 мкм. Галактик в этом диапазоне на небе оказывается так много, что разрешения телескопов ближайшего будущего не хватит для наблюдения этих галактик по отдельности. Для борьбы с фоном в будущем необходимо научиться его моделировать, чему и посвящена настоящая лекция.The inhomogenious infrared background created by distant galaxies poses a serious problem for future observations in the Far InfraRed wavelenght range, on the wavelengths of 100—1000 microns. There are so many galaxies in the sky in this range, so the resolution of the telescopes of the near future will be insufficient to observe all these galaxies separately. In order to beat the effects of background, it is needed to learn how to model it, and this is the subject of the current lecture.Работа выполнена при поддержке гранта РФФИ 16-02-01043

Globular clusters as indicators of Galactic evolution

We have studied the system of globular clusters (GCs) that formed in other galaxies and eventually accreted onto the Milky Way. Thus, the samples of GCs belonging to different tidal streams, obtained on the basis of the latest data from the Gaia observatory, were taken from the literature. We measured the anisotropy of the distribution of these GCs using the gyration tensor and found that the distribution of GCs in the streams is isotropic. Nevertheless, it can be seen that some of the accreted GCs included into existing samples actually belong to the disk of the Galaxy. To clarify the origin of GCs, we investigated the ``age--metallicity'' relation. This dependence demonstrates bimodality and its two different branches clearly show the difference between the clusters formed in the streams and in the disk of the Galaxy. Furthermore, we have studied the influence of the large--scale environment of the Galaxy (i.e., the Local Supercluster) on the distribution of satellite galaxies and Galactic GCs. The satellite galaxies of the Milky Way are known to form an anisotropic planar structure, so we included them in our analysis too. An inspection has shown that the plane of the satellite galaxies is perpendicular both to the disk of the Galaxy and the supergalactic plane. For GCs more distant than 100~Kpc, a similar picture is observed.Comment: 15 pages, 3 figure

Excess of high-zz galaxies as a test for bumpy power spectrum of density perturbations

Modified matter power spectra with approximately Gaussian bump on sub-Mpc scales can be a result of a complex inflation. We consider five spectra with different Gaussian amplitudes $A$ and locations $k_0$ and run N-body simulations in a cube $(5 Mpc/h)^3$ at $z>8$ to reveal the halo mass functions and their evolution with redshift. We have found that the Sheth-Tormen formula provides a good approximation to a such kind of halo mass functions. In the considered models the dark matter halo formation starts much more earlier than in $\Lambda$CDM, which in turn can result in an earlier star formation and a nuclear activity in galaxies and can be detected and tested by, e.g., JWST. At $z=0$ the halo mass functions are hardly distinguishable from the standard $\Lambda$CDM, therefore the models with the bumpy spectra can be identified in observations by their excess in number of bright sources at high redshift only.Comment: 9 pages, 5 figures, submitted to MNRA