The study of the origin and transport of water in the universe is an important part of the scientific program of the Millimetron space observatory. This will be made possible by observations conducted in single-dish mode using an onboard instrument-the high-resolution spectrometer (HRS). This instrument incorporates heterodyne array receivers operating within the range 0.5 -2.7 THz, comprising 3-pixel arrays of superconductor-insulator-superconductor mixers operating at frequencies below 1.3 THz and 7-pixel matrix receivers based on NbN HEB mixers observing above 1.3 THz. This article presents the current status of development for a mixers planned for use in the HRS instrument of the Millimetron space observatory.

The Millimetron Space Observatory will be equipped with the cryogenically cooled instrument for a Space-Earth Very Large Baseline Interferometry (S-E VLBI). It will be a multi-channel heterodyne receiver with 7mm, 3mm, 1.3mm and 0.8mm channels. The VLBI instrument will have a multi-frequency capability, provided by signal splitting in the input optics and by back-end functionalities. The optical design is shown in this report.

Cosmic objects with magnetic fields (quasars, radiogalaxies) are observed at redshifts z≥ 7 (Wang et al., 2021, Fan et al., 2023, Yang et al., 2024) and more (for instance, for z = 10.073± 0.002, Goulding et al., 2023) indicates the early creation of magnetic fields. The observations of the cosmic telescope JWST show that the first galaxies were formed at redshifts z≃ 15 – 20. We link the transformation of the low mass dark matter halos into galaxies with the creation of the first stars owing to the radiative cooling of partly ionized hydrogen at z≥ 10. The early formation of galaxies creates favourable conditions for high impact of the Compton scattering of the relic radiation photons and electrons on the electron temperature and leads to the partial separation of electrons and protons. Together with turbulent motions such separation stimulates creation of magnetic fields on a galactic scale. The same processes distort the primordial perturbations of the relic radiation what can be observed and confirmed in special simulations.

В работе рассмотрены научные и технические перспективы и возможные направления развития субтерагерцовой астрономии в Российской Федерации. Предложена концепция создания субтерагерцовых инструментов в виде универсальной компактной антенной решетки для размещения на территории России. На базе концепции такой антенной решетки возможна реализация нескольких космических проектов субтерагерцового диапазона нового поколения – космического интерферометра и телескопа, расположенного на поверхности Луны. Наземные антенные решетки смогут выступить в качестве поддержки режима интерферометра со сверхдлинной базой обсерватории «Миллиметрон».

The main technical solutions implemented in the Spektr-R observatory (RadioAstron) and the scientific results obtained during its orbital operation from 2011 through 2019 are reviewed. General characteristics and research objectives of the Millimetron (Spectrum-M) space observatory, a development of the Spectrum-R project in the submillimeter wavelength range, are outlined. The launch of Millimetron is scheduled for the early 2030s. Research programs of both projects are led by the Lebedev Physical Institute of the Russian Academy of Sciences.

For the numerical model in the range of redshifts 0 ⩽ z ⩽ 9 , we examined the properties and evolution of dark matter halos using a previously proposed method of compact analysis that allows separating the influence of random and regular factors on the main characteristics of the dark matter halo. In the investigated range of redshifts, a monotonic evolution of the average values of the basic parameters of small halo structures into a central massive object is observed through sequential hierarchical merging. These basic parameters include the circular velocity v_c , the parameter w_c = v_c/r , and the mass. In the range 3 ⩽ z ⩽ 9 , the parameters evolve slowly, while in the range 0 ⩽ z ⩽ 3 , they evolve rapidly. The evolution of the dark matter halos formed before reionization is characterized by a slow change in their average characteristics and the properties of the halo outskirts. The important role of early-formed massive structural elements is emphasized.

This paper addresses the scientific and technical prospects and potential directions for the development of subterahertz astronomy in the Russian Federation. The concept of creating subterahertz instruments in the form of a universal compact antenna array for placement on the territory of the Russian Federation is proposed. It is possible to implement several space projects in the subterahertz range using such an antenna array, including a space interferometer and a telescope on the surface of the Moon. Ground-based compact antenna arrays will be able to act as a support for the very long baseline interferometer mode of the Millimetron observatory.

An analysis of the absorption lines observed in the spectra of quasars makes it possible to study the evolution of the structure of the Universe up to redshifts z∼5. The observed clustering of C IV lines demonstrates the multiple birth of low-mass galaxies in separate structural elements—filaments and “pancakes.” This ensures their subsequent regular hierarchical merger in the central galaxy or group of galaxies. Remnants of the early “pancakes” are observed today as the Local Group, groups around the Andromeda and Centaurus galaxies, and other small groups of galaxies. In turn, the observed clustering of Lyman-alpha lines shows that starless dark matter (DM) halos are also formed in structural elements and their hierarchical clustering leads to the formation of massive starless dark matter halos of moderate density, which also appear in numerical models.

ABSTRACT A simple model of spherical dark matter haloes is proposed in terms of two structure functions. In the framework of this model, we analysed the properties of 450 000 simulated haloes with masses Mvir > 1011 M⊙. We compared the mean characteristics of simulated haloes with the corresponding characteristics of 641 galaxies and found that the basic characteristics of the two populations are similar but that their probability distribution functions are different. This disagreement may be caused by technical factors such as the halo identification algorithm, which does not reproduce the observed dark matter haloes correctly.

Галактики на больших красных смещениях ( z.≥9 ) в настоящий момент наблюдаются в ближнем (1.4-2 мкм), среднем инфракрасном (ИК) (5-28.8 мкм) и субмиллиметровом (500- 1000 мкм) диапазонах. Дальний ИК диапазон, несущий важную информацию о фундаментальных процессах в ранних галактиках, соответствующий среднему ИК диапазону в системе отсчета источника, скрыт от наблюдателя атмосферой Земли. Мы рассматриваем параметры излучения галактик на больших красных смещениях и возможность их обнаружения в дальнем ИК диапазоне при помощи гравитационного линзирования на массивных скоплениях галактик. Излучение, предположительно, возникает преимущественно в газе, ионизированном ультрафиолетовым (УФ) и рентгеновским излучением звезд и центральными сверхмассивными черными дырами (СМЧД) родительских галактик. Металличность газа родительских галактик находится в интервале -6≤[Z/H]≤-1, как следует из наблюдений далеких галактик на z≥9. Мы оцениваем спектральные особенности в дальнем ИК диапазоне и условия, при которых данные галактики могут быть обнаружены. Показано, что спектральные линии водорода Pf - α и Hm -α; , наряду с несколькими линиями металлов среднего ИК диапазона ([NeV] I7.6, [SIV] 10.5, [NeIII] 15.6, [NeV] 24.1, [OIV] 25.8 мкм и т.д.), могут быть достаточно яркими для обнаружения. За счет использования гравитационного линзирования на известных скоплениях галактик количество ожидаемых кандидатов на больших красных смещениях в дальнем ИК достаточно велико для проведения наблюдательной программы на космическом телескопе "Миллиметрон" в диапазоне длин волн 70-500 мкм.

A comparison of the virial parameters of galaxies and galaxy clusters (radius, density, and entropy function) in a wide range of masses, $${{10}^{6}} \leqslant {{M}_{{{\text{vir}}}}}{\text{/}}{{M}_{ \odot }} \leqslant {{10}^{{14}}}$$ , shows that these parameters are correlated and depend on the virial mass of an object in a regular way. For the observed galaxies and galaxy clusters the available estimates of virial parameters are quite close to each other and the values of reduced virial density Gρ are concentrated in a shallow interval $$0.5 \leqslant {{G}_{\rho }}{\text{/}}\langle {{G}_{\rho }}\rangle \leqslant 2$$ around its mean value. This “virial” paradox sharpen when compared with simulations, in which the number of such objects is very small, and for the majority of dark matter halos these densities are ~50–100 times smaller. Our theoretical analysis shows possible reasons for this discrepancy of observations and simulations, pointing out its connection with the spectrum of cosmological perturbations. After some refinement, the considered data can be used to constrain models of cosmological inflation. A number of accompanying questions is discussed.

The $$Ly_{\alpha}$$ forest observed in the spectra of quasars allows the evolution of the structure of the Universe and the properties of the ultraviolet (UV) background up to redshifts $${\sim}$$ 6 to be studied. An analysis of the properties of $${\sim}$$ 6000 $$Ly_{\alpha}$$ forest lines observed at redshifts $$4.5\geq z\geq 2$$ shows that this forest can be formed by the absorption of radiation from quasars by strongly ionized hydrogen concentrated in dark matter (DM) halos and the intergalactic medium. We propose a physical model of absorbers that allows the observed characteristics of absorption lines to be associated with the properties of DM halos and the surrounding UV background. We show that the Doppler parameter and the gas temperature are determined by the injection energy being released during hydrogen photoionization and depend only on the spectrum of the surrounding UV background. In contrast, the observed number density of neutral hydrogen depends both on the intensity and spectrum of the UV background and on the mass and density of the DM halos. Our analysis can be used to distinguish the limited population of DM halos observed as $$Ly_{\alpha}$$ lines among the set of all DM halos.

High-redshift galaxies (z ≳ 9) are currently observed in the near-infrared (1.4-2 μm), mid-infrared (IR) (5-28.8 μm), and submillimeter (500-1000 μm) ranges. The far IR band, which carries important information on fundamental processes in early galaxies corresponding to the mid-infrared range in the restframe is hidden from the observer by the earth’s atmosphere. We consider the parameters of the emission from galaxies at high redshifts and the possibility of observing them in the far IR using gravitational lensing on massive galactic clusters. The emission presumably arises predominantly in gas ionized by ultraviolet (UV) and X-ray emission of stars and the central supermassive black holes (SMBH) of host galaxy. The metallicity of the gas of the parent galaxies lies within an interval of -6 ≤ [Z/H] ≤ -1, as follows from observations of distant galaxies at (z ≳ 9). We estimate the spectral features in the far IR range and the conditions under which these galaxies can be detected. It is shown that the spectral lines Pf-α and Hm-α, along with several lines of metals in the mid IR range ([NeV] I7.6, [SIV] 10.5, [NeIII] 15.6, [NeV] 24.1, [OIV] 25.8 μm, etc.), can be sufficiently bright to be detected. With using gravitational lensing on known galactic clusters, the number of expected high-redshift candidates in the far IR is large enough to carry out a program of observations on the “Millimetron” Space Observatory in the 70-500 μm wavelength range.

We present the scientific program of the Spectr-M project aimed at the creation and operation of the Millimetron Space Observatory (MSO) planned for launch in the late 2020s. The unique technical capabilities of the observatory will enable broadband observations of astronomical objects from 50 μm to 10 mm wavelengths with a record sensitivity (up to ∼ 0.1 μJy) in the single-dish mode and with an unprecedented high angular resolution (∼ 0.1 μas) in the ground-space very long baseline interferometer (SVLBI) regime. The program addresses fundamental priority issues of astrophysics and physics in general that can be solved only with the MSO capabilities: 1) the study of physical processes in the early Universe up to redshifts z ∼ 2 × 10 6 through measuring μ -distortions of the cosmic microwave background (CMB) spectrum, and investigation of the structure and evolution of the Universe at redshifts z < 15 by measuring y -distortions of the CMB spectrum; 2) the investigation of the geometry of space-time around supermassive black holes (SMBHs) in the center of our Galaxy and M87 by imaging surrounding shadows, the study of plasma properties in the shadow formation regions, and the search for observational manifestations of wormholes; 3) the study of observational manifestations of the origin of life in the Universe — the search for water and biomarkers in the Galactic interstellar medium. Moreover, the technical capabilities of the MSO can help solve related problems, including the birth of the first galaxies and SMBHs ( z ≳ 10), alternative approaches to measuring the Hubble constant, the physics of SMBHs in ‘dusty’ galactic nuclei, the study of protoplanetary disks and water transport in them, and the study of ‘ocean worlds’ in the Solar System.

We propose a method of analyzing the absorption spectra of quasars that allows the physical parameters of absorbing clouds, absorbers, to be roughly estimated: their masses, sizes, and mean densities. An analysis of three representative catalogs of the Lyman-alpha ( $$Ly_{\alpha}$$ ) forest and metal absorption line systems confirms that these observations refer to two types of objects with different properties, each of which forms a one-parameter sequence. The parameters of the metal absorption line systems are consistent with the corresponding estimates of the parameters of galaxies. The parameters of the $$Ly_{\alpha}$$ forest differ significantly from the galactic ones, but are close to the parameters of a large number of halos presented in numerical models. Possible reasons for the emergence of two one-parameter systems of halos with different properties are discussed.

The prospects for observations of gravitationally lensed extragalactic sources in the far-infrared and submillimeter ranges of the electromagnetic spectrum by the planned space observatories with active cooling of the telescope mirror to cryogenic temperatures are considered. The possibility of solving topical cosmological and astrophysical problems related to the observations of gravitationally lensed sources is discussed. The number counts of lensed sources have been performed for various wavelengths in the range from 70 to 2000 µm. The redshift and magnification distributions of lensed sources and the mass distribution of lenses have been obtained. We have constructed model photometric sky maps for which the contribution from lensed sources has been calculated for the first time.

The luminosity of accreting magnetized neutron stars can largely exceed the Eddington value due to appearance of accretion columns. The height of the columns can be comparable to the neutron star radius. The columns produce the X-rays detected by the observer directly and illuminate the stellar surface, which reprocesses the X-rays and causes additional component of the observed flux. The geometry of the column and the illuminated part of the surface determine the radiation beaming. Curved space-time affects the angular flux distribution. We construct a simple model of the beam patterns formed by direct and reflected flux from the column. We take into account the possibility of appearance of accretion columns, whose height is comparable to the neutron star radius. We argue that depending on the compactness of the star, the flux from the column can be either strongly amplified due to gravitational lensing, or significantly reduced due to column eclipse by the star. The eclipses of high accretion columns result in specific features in pulse profiles. Their detection can put constraints on the neutron star radius. We speculate that column eclipses are observed in X-ray pulsar V 0332+53, leading us to the conclusion of large neutron star radius in this system (similar to 15 km if M similar to 1.4 M-circle dot). We point out that the beam pattern can be strongly affected by scattering in the accretion channel at high luminosity, which has to be taken into account in the models reproducing the pulse profiles.