Annotation of the results obtained in 2023
We continued to develop the RCSEDv2 catalog and web service for data visualization and access. The functionality of our main spectral analysis tool, NBursts, was significantly expanded by simultaneously modeling the absorption and emission components of galaxy and active nucleus spectra. These modifications were implemented into our spectral analysis pipeline. Additionally, a new set of medium spectral resolution (R=8000) stellar population models based on the X-Shooter Spectral Library (Verro et al. 2022) was added. All new spectral modeling results in the new modes and with the new population models are available on the project's website: https://rcsed2-dev.voxastro.org. The website's functionality was also expanded, including a) the ability to download search results in CSV and FITS formats; b) improved language for search queries, allowing the composition of conditions involving arbitrary sets of mathematical operations on available table columns; c) an internal converter from galaxy names to coordinates was added, reducing dependency on external services and improving RCSEDv2 stability. Additionally, we established the interface for the Virtual Observatory to access the RCSEDv2 database via the TAP protocol: https://dc.voxastro.org/. We conducted extensive work on standardizing available photometric data for galaxies from surveys such as VHS, VIKING, UHS, UKIDSS, DES, DELVE, Legacy Survey, SDSS, VST Atlas, KIDS, PanSTARRS. By gathering photometry from various sources for the same galaxies, we calculated conversion formulas for integrated and aperture magnitudes to the standard SDSS system. This work is a critical component of the photometric aspect of RCSEDv2 and is actively used in creating a catalog of active galactic nuclei for the upcoming 4MOST ChANGES spectroscopic survey. A detailed description of the work is published in the article by Toptun, Chilingarian, Grishin, Katkov titled "Color Transformations of Photometric Measurements of Galaxies in Optical and Near-Infrared Wide-Field Imaging Surveys," published in PASP. The photometric data conversion formulas are presented as an interactive web calculator on the website: https://colors.voxastro.org/. The observational campaign aimed at obtaining higher spectral resolution spectra than SDSS for refining estimates of intermediate-mass black hole masses continues in the study of intermediate-mass black holes (IMBHs). As of November 2023, over 150 spectra of unique objects were obtained using telescopes such as Magellan, Keck, SALT, and the KGO. A re-analysis of the acquired spectra was conducted using an improved methodology for analyzing emission lines, which allows the avoidance of the rotational contribution from the galaxy disk to the broad components of Balmer lines (BLR) - the main indicator of black hole masses. We demonstrated that transitioning from the massive part of the "black hole mass - stellar spheroid velocity dispersion" dependence to the regime of lower masses increases the dispersion of values. A systematic deviation toward larger stellar velocity dispersions is observed. This likely indicates the absence of a tight connection between the processes of black hole and spheroid growth in the low-mass regime, unlike the massive part of the dependence where the growth of black holes and spheroids occurred through mergers. The growth of bulges/pseudobulges could occur through secular evolution mechanisms, which do not necessarily lead to the feeding and growth of central black holes. Additionally, bulges themselves may have different properties; for example, more compact bulges may result in a greater dispersion of stellar velocities. During 2023, the Chandra orbital observatory observed seven candidates for black holes with masses less than a million solar masses as part of our program. Based on X-ray data, a fundamental plane of activity was constructed for the candidate sample, linking X-ray luminosity, radio luminosity (using archival data from VLASS and FIRST surveys), and our estimates of black hole masses. Despite a significant scatter in measurements, we found that the fundamental plane is traced even in the low-mass regime. In the frame of study on IMBHs, two students, Vladimir Goradzhanov and Victoria Toptun, as part of the research team, excellently defended their theses under the supervision of Igor Chilingarian at the astronomy department of the Physics Faculty of Moscow State University. Using light curve data from the Zwicky Transient Facility Forced Photometry and the Asteroid Terrestrial-impact Last Alert System, we study the optical variability of black holes with masses below 1 million solar masses. We discovered a correlation between optical variability and X-ray luminosity, which disappears at low X-ray luminosities, which is most likely due not to the absence of optical variability, but to the impossibility of its statistically significant detection against the background of errors. Light curves after additional processing steps and the results of analysis of the optical spectra of the studied galaxies are presented in the form of a website http://lc-dev.voxastro.org/valc.html. To study the unique object we discovered, J1631+24, with a binary black hole, one of which is IMBH, we requested and accepted observations at the James Webb Space Telescope (JWST) with the IFU NIRSpec instrument in May 2023. In 2023, a spectrum was obtained with the COS spectrograph on the Space Telescope. Hubble (HST), which made it possible to detect in this galaxy broad components in the UV lines Ly_alpha, CIV, HeII, CIII], indicating the presence of high ionization in the near nuclear region caused by one or two accretion disks. Also in January 2023, an IR spectrum was obtained at the Keck telescope with DEIMOS, where high ionization lines [FeX], [FeXI], and [CaV] were also detected. The RCSEDv2 catalog allows us to solve a wide range of scientific problems. In particular, the redshift data available in the RCSEDv2 catalog allowed us to select a sample of giant low-brightness galaxies and, for the first time, estimate their volume density of gLSBs, which turned to be 4.04*10^-5 Mpc^-3. This corresponds to approximately 12,700 such objects in the entire sky up to redshift 0.1 and shows that giant low surface brightness galaxies are not as rare as previously thought, and also the feasibility of large-scale searches for such systems to further study their evolution and origin scenarios on a statistically significant sample. This will allow us to improve our understanding of the evolution of disk galaxies in general. We published an article in the MNRAS (Afanasiev et al. 2023) about a rare type of galaxy: “KDG64: a large dwarf spheroidal or a small ultra-diffuse satellite of Messier 81”, where spectrophotometric analysis was first used to describe the integral spectrum of a dwarf spheroidal galaxy (dSph) and demonstrated its effectiveness at a very low signal-to-noise ratio SNR~3, thanks to which it was possible to measure the parameters of the dark halo of this galaxy and even compare different possible dark matter density profiles. We published a paper in ApJS about recalibrating the UVES-POP library of stellar spectra “New Generation Stellar Spectral Libraries in the Optical and Near-Infrared I: The Recalibrated UVES-POP Library for Stellar Population Synthesis”. The library contains spectra of about 400 stars of different spectral classes at different stages of evolution and with different chemical compositions. The work done made it possible to improve the quality of calibration of spectra by fluxes up to 1-2% for most spectra. We also calculated the atmospheric parameters of most of the stars in the library using the numerical minimization method we developed and estimated their masses and ages. The results obtained have wide application for the analysis of stellar populations of galaxies and extragalactic globular clusters. Thus, in the same paper, using processed spectra, we estimated the velocity dispersions of the stellar populations of two ultra-compact dwarf galaxies UCD 320 and UCD 330.

 

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Annotation of the results obtained in 2022
During the incomplete 7 months of the project, our scientific team prepared applications, which subsequently obtained observational time at three space observatories: the Hubble Space Telescope and the XMM-Newton X-ray Observatory. Hubble Space Telescope, the Chandra and XMM-Newton X-ray observatories. Observational time was also obtained at a number of the largest telescopes in the world: Keck, Gemini, ESO VLT, etc. On all these programs our team has already started to receive the first data and to carry out their analysis. As for the preparation of publications, the stated plan of three articles submitted for publication was exceeded exactly in two times: during the reporting period, 6 articles were submitted to the journals from Q1, two of which at the time of writing this report were either accepted for publication or have already been published. We carried out a systematic search for giant low-surface-brightness galaxies in the data of the HSC SSP deep photometric sky survey. We selected galaxies with redshifts available in RCSEDv2 or other databases not exceeding 0.1. As a result of this search, a sample of 37 giant low surface brightness galaxies and 5 more high-brightness giant disk galaxies was identified. This corresponds to a volume density of 4.04×10−5 Mpc−3 for giant low surface brightness galaxies, which gives an estimate of about 12,700 such galaxies in the entire sky. The resulting volume density of giant low surface brightness galaxies is in good agreement with the results of EAGLE cosmological simulations. From a study of the evolutionary history of giant low surface brightness model galaxies, it follows that they experienced mergers (especially major mergers) more often than medium-sized disk galaxies, although cases without mergers are also possible. On the one hand, this provides more evidence in favor of formation scenarios with mergers, on the other hand, it confirms the conclusion made in our earlier works that the class of giant low surface brightness galaxies is heterogeneous, and various scenarios of their formation are possible. The publication of this paper has been submitted to MNRAS Letters. A study was made of two interacting M51-type galaxies with a clear spiral structure and a low-mass companion near the end of the spiral branch: Arp58 and Arp68. As a result of the analysis of spectral long-slit data, profiles of the metallicity kinematics of the ionized gas were obtained, which showed the presence of strong non-circular motions of the gas in both systems. Estimates of gas metallicity indicate that the gas metallicity in Arp58 is higher than in Arp68, which has too low metallicity even for its lower luminosity, this may be due to Arp68 being in the void. It was concluded that despite the different masses and environments, both galaxies are at the same stage of interaction with the satellite. The results of this study are published in MNRAS The UVES-POP stellar spectra library has been completed (the paper has been sent to the journal ApJS, Borisov et al. 2022). This library contains about 400 spectra of high spectral resolution stars (original R=80000) of different spectral classes (fully covering the Hertzsprung-Russell diagram) in a large wavelength range (from 320 to 1025 nm). At the web-site of the project sl.voxastro.org one can find the updated spectra in two spectral resolutions (R=20000 and R=80000), the available photometry in a wide range of filters, different additional information and the results of stellar atmospheres simulation by the PHOENIX models. On its basis, we plan to create a new generation of stellar population models for the analysis of galaxy spectra. We have finished working on a paper presenting the analysis of kinematics and stellar population of a dwarf galaxy KDG64 (M81 satellite), where we managed to determine the dark matter halo mass and constrain the evolutionary scenarios for this object. We also put KDG64 in a perspective relative to a few dozen other dwarf satellite galaxies. The paper is submitted to MNRAS and is currently being revised following a referee report. A program of observations of intermediate-mass black holes on the Hubble Space Telescope has been prepared and approved. The program includes the observation of 86 objects from a sample created using optical selection of AGN features and data from X-ray archives. This project will yield sizes, luminosities, and stellar populations of a statistically significant sample of hosts, and probe whether the MBH-Mbulge scaling relation holds in the low-mass regime and central low-mass black holes do indeed co-evolve with host galaxy spheroids. Observations will be carried out in the near-UV/optical range using HST WFC3 in the form of a SNAP program. ​​Also, to confirm candidates for black holes of intermediate mass, an application for observations of 23 objects on the Chandra Space Telescope has been approved. Observations of four objects from this list have already been carried out, and two of them have shown significant emission in the X-ray range, which confirms the presence of an active nucleus and a black hole of intermediate mass in these galaxies. The 4MOST ChANGES catalog was produced in collaboration with the Universidad Católica de Chile. On the basis of the DELVE, VHS, VIKING, and CatWISE photometric catalogs in the optical and infrared, an input catalog for virtually the entire southern sky, containing over 300 million objects, validated with observations on the 6.5-m telescopes MMT and Magellan was assembled. As part of the work on the RCSEDv2 photometric catalog, the various photometric data used in it were translated to the standard SDSS ugriz filter system in the optical range and the UKIRT YJHK in the infrared. For this purpose, the formulas for translating the stellar magnitudes for the DECaLS, MzLS, BOSS, DES, DELVE, VST Atlas, KIDS, VIKING, and VHS surveys and back were derived. The results were implemented in the form of a publicly available website with a stellar magnitude calculator https://colors.voxastro.org/ and codes in Python and IDL. The results resulted in a paper, "Color Transformations of Photometric Measurements of Galaxies in Optical and Near-Infrared Wide-Field Imaging Surveys," sent to Publications of the Astronomical Society of the Pacific in early December 2022. The association of three compact satellites with their host gLSBs has been confirmed by spectrograph data from the EFOSC2 spectrograph of low surface brightness (gLSB) giant galaxy candidates and their satellite candidates. This unexpected juxtaposition of two of the rarest types of galaxies indicates the possible formation of a giant galaxy disk by tidal sniping of the smaller galaxy by the central giant galaxy. During the reporting period, an analysis of the processed data obtained on the 2.5-meter telescope of the GAISH MSU (TDS instrument) for the supposed double black hole J1631+24 confirmed the presence of two broad components in the resolved lines, which is a confirmation of the duality of the central black hole.

 

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