The Interpretation of Eclipse Light Curves in AM Her Type Systems

We have developed the code for modeling eclipse light curves in polars. The accretion stream model is described by two components: ballistic part defined by gravitational forces and dipole part where gas motions are controlled by the magnetic field. The geometry of the secondary is described by its Roche lobe. The orbital inclination i and mass ratio q = M2/M1 are supposed to be known. The technique was implemented for the analysis of eclipse light curve of the polar V808 Aur.Представлена программа моделирования фотометрических затмений в системах типа AM Her. Модель аккреционной струи описывается двумя составляющими: баллистической, определяемой силой притяжения компонентов, и дипольной, где движение газа управляется магнитным полем. Геометрия вторичного компонента описывается моделью полости Роша. Предполагается известное отношение масс компонентов q = M2/M1, наклон орбитальной плоскости i. Реализованный метод был применен к анализу кривой блеска затмения поляра V808 Aur

Market risks of financial sector and their impact on the regional institutions

The article considers the impact of components of market risk on its dynamics and structure of the Russian finance industry. It estimates change in the structure and in the number of financial institutions calculating market risk. It also identifies cause and effect link between the changes studied. The reasons of decline in the share of market risk in the general risks of the banking sector and a small growth of the market risk for the 2013-2014. Identifies the source and reasons for changes in the basic structure of the market risk and the built causal relationships change of market risk in the dynamics during the analyzed period. The article analyzes the market risk framework to determine the significance of market risk components in the domestic banking sector. Also referred to the importance of market risk for the medium and large banks that have built risk management policy and who are interested in the prediction of bank risks. In this article are revealed the causes of currency and stock market risk for the 2013-2014 and identified the relative growth of the two risks in the structure of the market risk for 2014. In addition, the article pointed out that throughout the analyzed period, interest rate risk and market risk in the structure of dominance has been defined

Market risks of financial sector and their impact on the regional institutions

The article considers the impact of components of market risk on its dynamics and structure of the Russian finance industry. It estimates change in the structure and in the number of financial institutions calculating market risk. It also identifies cause and effect link between the changes studied. The reasons of decline in the share of market risk in the general risks of the banking sector and a small growth of the market risk for the 2013-2014. Identifies the source and reasons for changes in the basic structure of the market risk and the built causal relationships change of market risk in the dynamics during the analyzed period. The article analyzes the market risk framework to determine the significance of market risk components in the domestic banking sector. Also referred to the importance of market risk for the medium and large banks that have built risk management policy and who are interested in the prediction of bank risks. In this article are revealed the causes of currency and stock market risk for the 2013-2014 and identified the relative growth of the two risks in the structure of the market risk for 2014. In addition, the article pointed out that throughout the analyzed period, interest rate risk and market risk in the structure of dominance has been defined

The TELPERION survey for distant [O iii] clouds around luminous and hibernating AGN

We present a narrow-band [O iii] imaging survey of 111 active galactic nucleus (AGN) hosts and 17 merging-galaxy systems, in search of distant extended emission-line regions (EELRs) around AGNs (either extant or faded). Our data reach deeper than detection from the broad-band SDSS data and cover a wider field than some early emission-line surveys used to study extended structure around AGNs. Spectroscopic follow-up confirms two new distant AGN-ionized clouds, in the merging systems NGC 235 and NGC 5514, projected at 26 and 75 kpc from the nuclei (respectively). We also recover the previously known region in NGC 7252. These results strengthen the connection between EELRs and tidal features; kinematically quiescent distant EELRs are virtually always photoionized tidal debris. We see them in ≈10 per cent of the galaxies in our sample with tidal tails. Energy budgets suggest that the AGN in NGC 5514 has faded by >3 times during the extra light traveltime ≈250 000 yr from the nucleus to the cloud and then to the observer; strong shock emission in outflows masks the optical signature of the AGN. For NGC 235 our data are consistent with but do not unequivocally require variation over ≈85 000 yr. In addition to these very distant ionized clouds, we find luminous and extensive line emission within four galaxies - IC 1481, ESO 362-G08, NGC 5514, and NGC 7679. Among these, IC 1481 shows apparent ionization cones, a rare combination with its LINER AGN spectrum. In NGC 5514, we measure a 7-kpc shell expanding at ≈370 km s-1 west of the nucleus. © 2022 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society

Search for and study of photometric variability in magnetic white dwarfs

© 2017, Pleiades Publishing, Ltd.We report the results of photometric observations of a number of magnetic white dwarfs in order to search for photometric variability in these stars. These V-band observations revealed significant variability in the classical highly magnetized white dwarf GRW+70◦8247 with a likely period from several days to several dozen days and a half-amplitude of about 0.m 04. Our observations also revealed the variability of the well-known white dwarf GD229. The half amplitude of its photometric variability is equal to about 0.m 005, and the likely period of this degenerate star lies in the 10–20 day interval. This variability is most likely due to the rotation of the stars considered.We also discuss the peculiarities of the photometric variability in a number of other white dwarfs. We present the updated “magnetic field–rotation period” diagram for the white dwarfs

WEAVE-StePS. A stellar population survey using WEAVE at WHT

The upcoming new generation of optical spectrographs on four-meter-class telescopes will provide valuable opportunities for forthcoming galaxy surveys through their huge multiplexing capabilities, excellent spectral resolution, and unprecedented wavelength coverage. WEAVE is a new wide-field spectroscopic facility mounted on the 4.2 m William Herschel Telescope in La Palma. WEAVE-StePS is one of the five extragalactic surveys that will use WEAVE during its first five years of operations. It will observe galaxies using WEAVE MOS (~950 fibres across a field of view of ~3 deg2 on the sky) in low-resolution mode (R~5000, spanning the wavelength range 3660-9590 AA). WEAVE-StePS will obtain high-quality spectra (S/N ~ 10 per AA at R~5000) for a magnitude-limited (I_AB = 20.5) sample of ~25,000 galaxies, the majority selected at z>=0.3. The survey goal is to provide precise spectral measurements in the crucial interval that bridges the gap between LEGA-C and SDSS data. The wide area coverage of ~25 deg2 will enable us to observe galaxies in a variety of environments. The ancillary data available in each observed field (including X-ray coverage, multi-narrow-band photometry and spectroscopic redshift information) will provide an environmental characterisation for each observed galaxy. This paper presents the science case of WEAVE-StePS, the fields to be observed, the parent catalogues used to define the target sample, and the observing strategy chosen after a forecast of the expected performance of the instrument for our typical targets. WEAVE-StePS will go back further in cosmic time than SDSS, extending its reach to encompass more than ~6 Gyr, nearly half of the age of the Universe. The spectral and redshift range covered by WEAVE-StePS will open a new observational window by continuously tracing the evolutionary path of galaxies in the largely unexplored intermediate-redshift range

Stellar metallicity from optical and UV spectral indices: Test case for WEAVE-StePS

Context. The upcoming generation of optical spectrographs on four meter-class telescopes, with their huge multiplexing capabilities, excellent spectral resolution, and unprecedented wavelength coverage, will provide high-quality spectra for thousands of galaxies. These data will allow us to examine of the stellar population properties at intermediate redshift, an epoch that remains unexplored by large and deep surveys. Aims. We assess our capability to retrieve the mean stellar metallicity in galaxies at different redshifts and signal-to-noise ratios (S/N), while simultaneously exploiting the ultraviolet (UV) and optical rest-frame wavelength coverage. Methods. The work is based on a comprehensive library of spectral templates of stellar populations, covering a wide range of age and metallicity values and built assuming various star formation histories, to cover an observable parameter space with diverse chemical enrichment histories and dust attenuation. We took into account possible observational errors, simulating realistic observations of a large sample of galaxies carried out with WEAVE at the William Herschel Telescope at different redshifts and S/N values. We measured all the available and reliable indices on the simulated spectra and on the comparison library. We then adopted a Bayesian approach to compare the two sets of measurements in order to obtain the probability distribution of stellar metallicity with an accurate estimate of the uncertainties. Results. The analysis of the spectral indices has shown how some mid-UV indices, such as BL3580 and Fe3619, can provide reliable constraints on stellar metallicity, along with optical indicators. The analysis of the mock observations has shown that even at S/N = 10, the metallicity can be derived within 0.3 dex, in particular, for stellar populations older than 2 Gyr. The S/N value plays a crucial role in the uncertainty of the estimated metallicity and so, the differences between S/N = 10 and S/N = 30 are quite large, with uncertainties of ~0.15 dex in the latter case. On the contrary, moving from S/N = 30 to S/N = 50, the improvement on the uncertainty of the metallicity measurements is almost negligible. Our results are in good agreement with other theoretical and observational works in the literature and show how the UV indicators, coupled with classic optical ones, can be advantageous in constraining metallicities. Conclusions. We demonstrate that a good accuracy can be reached on the spectroscopic measurements of the stellar metallicity of galaxies at intermediate redshift, even at low S/N, when a large number of indices can be employed, including some UV indices. This is very promising for the upcoming surveys carried out with new, highly multiplexed, large-field spectrographs, such as StePS at the WEAVE and 4MOST, which will provide spectra of thousands of galaxies covering large spectral ranges (between 3600 and 9000 Å in the observed frame) at relatively high S/N (>10 Å -1)F.R.D., A.I., M.L, S.Z., A.G., F.L.B. acknowledge financial support from grant 1.05.01.86.16 – Mainstream 2020. A.F.M. acknowledges support from RYC2021-031099-I and PID2021-123313NAI00 of MICIN/AEI/10.13039/501100011033/FEDER,UE. L.C. acknowledges financial support from Comunidad de Madrid under Atraccion de Talento grant 2018-T2/TIC-11612 and Spanish Ministerio de Ciencia e Innovacion MCIN/AEI/10.13039/501100011033 through grant PGC2018-093499-BI00. R.G.B. acknowledges financial support from the grants CEX2021-001131-S funded by MCIN/AEI/10.13039/501100011033 and to PID2019-109067-GB100. A.V. acknowledges support from grant PID2019-107427GB-C32 and PID2021-123313NA-I00 from the Spanish Ministry of Science, Innovation and Universities MCIU. This work has also been supported through the IAC project TRACES, which is partially supported through the state budget and the regional budget of the Consejería de Economía, Industria, Comercio y Conocimiento of the Canary Islands Autonomous Community. A.V. also acknowledges support from the ACIISI, Consejería de Economía, Conocimiento y Empleo del Gobierno de Canarias and the European Regional Development Fund (ERDF) under grant with reference ProID202101007

Retrieval of the physical parameters of galaxies from WEAVE-StePS-like data using machine learning

Context. The William Herschel Telescope Enhanced Area Velocity Explorer (WEAVE) is a new, massively multiplexing spectrograph that allows us to collect about one thousand spectra over a 3 square degree field in one observation. The WEAVE Stellar Population Survey (WEAVE-StePS) in the next 5 years will exploit this new instrument to obtain high-S/N spectra for a magnitude-limited (IAB = 20.5) sample of ∼25 000 galaxies at moderate redshifts (z ≥ 0.3), providing insights into galaxy evolution in this as yet unexplored redshift range. Aims. We aim to test novel techniques for retrieving the key physical parameters of galaxies from WEAVE-StePS spectra using both photometric and spectroscopic (spectral indices) information for a range of noise levels and redshift values. Methods. We simulated ∼105 000 galaxy spectra assuming star formation histories with an exponentially declining star formation rate, covering a wide range of ages, stellar metallicities, specific star formation rates (sSFRs), and dust extinction values. We considered three redshifts (i.e. z = 0.3, 0.55, and 0.7), covering the redshift range that WEAVE-StePS will observe. We then evaluated the ability of the random forest and K-nearest neighbour algorithms to correctly predict the average age, metallicity, sSFR, dust attenuation, and time since the bulk of formation, assuming no measurement errors. We also checked how much the predictive ability deteriorates for different noise levels, with S/NI,obs = 10, 20, and 30, and at different redshifts. Finally, the retrieved sSFR was used to classify galaxies as part of the blue cloud, green valley, or red sequence. Results. We find that both the random forest and K-nearest neighbour algorithms accurately estimate the mass-weighted ages, u-band-weighted ages, and metallicities with low bias. The dispersion varies from 0.08–0.16 dex for age and 0.11–0.25 dex for metallicity, depending on the redshift and noise level. For dust attenuation, we find a similarly low bias and dispersion. For the sSFR, we find a very good constraining power for star-forming galaxies, log sSFR ≳ −11, where the bias is ∼0.01 dex and the dispersion is ∼0.10 dex. However, for more quiescent galaxies, with log sSFR ≲ −11, we find a higher bias, ranging from 0.61 to 0.86 dex, and a higher dispersion, ∼0.4 dex, depending on the noise level and redshift. In general, we find that the random forest algorithm outperforms the K-nearest neighbours. Finally, we find that the classification of galaxies as members of the green valley is successful across the different redshifts and S/Ns. Conclusions. We demonstrate that machine learning algorithms can accurately estimate the physical parameters of simulated galaxies for a WEAVE-StePS-like dataset, even at relatively low S/NI, obs = 10 per Å spectra with available ancillary photometric information. A more traditional approach, Bayesian inference, yields comparable results. The main advantage of using a machine learning algorithm is that, once trained, it requires considerably less time than other methods

WEAVE-StePS: A stellar population survey using WEAVE at WHT

Context. The upcoming new generation of optical spectrographs on four-meter-class telescopes will provide valuable opportunities for forthcoming galaxy surveys through their huge multiplexing capabilities, excellent spectral resolution, and unprecedented wavelength coverage. Aims. WEAVE is a new wide-field spectroscopic facility mounted on the 4.2 m William Herschel Telescope in La Palma. WEAVE-StePS is one of the five extragalactic surveys that will use WEAVE during its first five years of operations. It will observe galaxies using WEAVE MOS (∼950 fibres distributed across a field of view of ∼3 square degrees on the sky) in low-resolution mode (R ∼ 5000, spanning the wavelength range 3660-9590 Å). Methods. WEAVE-StePS will obtain high-quality spectra (S/N ∼ 10 Å -1 at R ∼ 5000) for a magnitude-limited (IAB = 20.5) sample of ∼25 000 galaxies, the majority selected at z ≥ 0.3. The survey goal is to provide precise spectral measurements in the crucial interval that bridges the gap between LEGA-C and SDSS data. The wide area coverage of ∼25 square degrees will enable us to observe galaxies in a variety of environments. The ancillary data available in each of the observed fields (including X-ray coverage, multi-narrow-band photometry and spectroscopic redshift information) will provide an environmental characterisation for each observed galaxy. Results. This paper presents the science case of WEAVE-StePS, the fields to be observed, the parent catalogues used to define the target sample, and the observing strategy that was chosen after a forecast of the expected performance of the instrument for our typical targets. Conclusions. WEAVE-StePS will go back further in cosmic time than SDSS, extending its reach to encompass more than ∼6 Gyr. This is nearly half of the age of the Universe. The spectral and redshift range covered by WEAVE-StePS will open a new observational window by continuously tracing the evolutionary path of galaxies in the largely unexplored intermediate-redshift range

Market risks of financial sector and their impact on the regional institutions

The article considers the impact of components of market risk on its dynamics and structure of the Russian finance industry. It estimates change in the structure and in the number of financial institutions calculating market risk. It also identifies cause and effect link between the changes studied. The reasons of decline in the share of market risk in the general risks of the banking sector and a small growth of the market risk for the 2013-2014. Identifies the source and reasons for changes in the basic structure of the market risk and the built causal relationships change of market risk in the dynamics during the analyzed period. The article analyzes the market risk framework to determine the significance of market risk components in the domestic banking sector. Also referred to the importance of market risk for the medium and large banks that have built risk management policy and who are interested in the prediction of bank risks. In this article are revealed the causes of currency and stock market risk for the 2013-2014 and identified the relative growth of the two risks in the structure of the market risk for 2014. In addition, the article pointed out that throughout the analyzed period, interest rate risk and market risk in the structure of dominance has been defined