E. K. Majorova

Tessellated mapping of cosmic background radiation correlations and source distributions

We offer a method of correlations mapping on the full celestial sphere that allows to check the quality of reconstructed maps, their non-Gaussianity and conduct experiments in various frequency ranges. The method was evaluated on the WMAP data, both on the reconstructed maps and foreground components, and on the NRAO VLA Sky Survey (NVSS) data. We detected a significant shift in the correlation data of the dust component, which can be preconditioned by a more complex dust model than the one currently in use for component separation. While studying the NVSS correlation data, we demonstrated that the statistics of the coinciding spots in the microwave background and in the NVSS survey corresponds to the one expected in the ΛCDM model. This can testify for a chance coincidence of the spots in the NVSS and WMAP data in the CMB Cold Spot region. Our method is software-implemented in the GLESP package. PACS: 95.75.-z, 98.62.Ve, 98.70.Dk, 98.70.Vc, 98.80.-kWe offer a method of correlations mapping on the full celestial sphere that allows to check the quality of reconstructed maps, their non-Gaussianity and conduct experiments in various frequency ranges. The method was evaluated on the WMAP data, both on the reconstructed maps and foreground components, and on the NRAO VLA Sky Survey (NVSS) data. We detected a significant shift in the correlation data of the dust component, which can be preconditioned by a more complex dust model than the one currently in use for component separation. While studying the NVSS correlation data, we demonstrated that the statistics of the coinciding spots in the microwave background and in the NVSS survey corresponds to the one expected in the ΛCDM model. This can testify for a chance coincidence of the spots in the NVSS and WMAP data in the CMB Cold Spot region. Our method is software-implemented in the GLESP package.

RATAN-600 7.6-cm deep sky strip surveys at the declination of the SS433 source during the 1980–1999 period. Data reduction and the catalog of radio sources in the right-ascension interval 7h ≤ R.A. < 17h

We use two independent methods to reduce the data of the surveys made with RATAN600 radio telescope at 7.6 cm in 1988–1999 at the declination of the SS433 source. We also reprocess the data of the “Cold” survey (1980–1981). The resulting RCR (RATAN COLD REFINED) catalog contains the right ascensions and fluxes of objects identified with those of the NVSS catalog in the right-ascension interval 7 ≤ R.A. < 17. We obtain the spectra of the radio sources and determine their spectral indices at 3.94 and 0.5 GHz. The spectra are based on the data from all known catalogs available from the CATS, Vizier, and NED databases, and the flux estimates inferred from the maps of the VLSS and GB6 surveys. For 245 of the 550 objects of the RCR catalog the fluxes are known at two frequencies only: 3.94 GHz (RCR) and 1.4 GHz (NVSS). These are mostly sources with fluxes smaller than 30 mJy. About 65% of these sources have flat or inverse spectra (α > −0.5). We analyze the reliability of the results obtained for the entire list of objects and construct the histograms of the spectral indices and fluxes of the sources. Our main conclusion is that all 10–15 mJy objects found in the considered right-ascension interval were already included in the decimeter-wave catalogs.We use two independent methods to reduce the data of the surveys made with RATAN-600 radio telescope at 7.6 cm in 1988–1999 at the declination of the SS433 source. We also reprocess the data of the “Cold” survey (1980–1981). The resulting RCR (RATAN COLD REFINED) catalog contains the right ascensions and fluxes of objects identified with those of the NVSS catalog in the right-ascension interval 7h ≤ R.A. < 17h. We obtain the spectra of the radio sources and determine their spectral indices at 3.94 and 0.5 GHz. The spectra are based on the data from all known catalogs available from the CATS, Vizier, and NED databases, and the flux estimates inferred from the maps of the VLSS and GB6 surveys. For 245 of the 550 objects of the RCR catalog the fluxes are known at two frequencies only: 3.94 GHz (RCR) and 1.4 GHz (NVSS). These are mostly sources with fluxes smaller than 30mJy. About 65% of these sources have flat or inverse spectra (α > −0.5). We analyze the reliability of the results obtained for the entire list of objects and construct the histograms of the spectral indices and fluxes of the sources. Our main conclusion is that all 10–15 mJy objects found in the considered right-ascension interval were already included in the decimeter-wave catalogs.

Identification and properties of host galaxies of RCR radio sources

FIRST and NVSS radio maps are used to cross identify the radio sources of the RCR catalog, which is based on observational data obtained in several runs of the “Cold” survey, with the SDSS and DPOSS digital optical sky surveys and the 2MASS, LAS UKIDSS, and WISE infrared surveys. Digital images in various filters and the coadded gri-band SDSS images, red and infrared DPOSS images, JHK-band UKIDSS images, and JHK-band 2MASS images are analyzed for the sources with no optical candidates found in the above catalogs. Our choice of optical candidates was based on the data on the structure of the radio source, its photometry, and spectroscopy (where available). We found reliable identifications for 86% of the radio sources; possible counterparts for 8% of the sources, and failed to find any optical counterparts for 6% of the sources because their host objects proved to be fainter than the limiting magnitude of the corresponding surveys. A little over half of all the identifications proved to be galaxies; about one quarter were quasars, and the types of the remaining objects were difficult to determine because of their faintness. A relation between the luminosity and the radioloudness index was derived and used to estimate the 1.4 and 3.94 GHz luminosities for the sources with unknown redshifts. We found 3% and 60% of all the RCR radio sources to be FRI-type objects (L ≲ 1024 W/Hz at 1.4 GHz) and powerful FRII-type galaxies (L ≳ 1026.5 W/Hz), respectively, whereas the rest are sources including objects of the FRI, FRII, and mixed FRI-FRII types. Unlike quasars, galaxies show a trend of decreasing luminosity with decreasing flux density. Note that identification would be quite problematic without the software and resources of the virtual observatory.

Computation of the RATAN-600 radio telescope power beam pattern with allowance for diffraction effects in the southern-sector-with-flat-reflector mode

We report the results of computation of the power beam pattern (PB) of the RATAN-600 radio telescope operating in the Southern-sector-with-flat-reflector (South+flat) mode throughout the entire operating frequency range of the radio telescope with the allowance for diffraction effects in the space between the secondary, primary, and flat mirrors. We also computed the gain-phase field distributions at the mirror surfaces when operating in the South+flat mode and in single-sector observations at the close to horizon elevations. The width of the power beam pattern in the vertical direction is shown to decrease and the maximum of the diagram to shift towards lower elevations with increasing wavelength. When the radio telescope is operated in the South+flat mode the above two changes in the power beam pattern begin to show up at shorter wavelengths compared to the case of single-sector operation. The shift of the power beam pattern maximum is shown to depend on the height at which the antenna is mounted. The power beam pattern was computed both for the case of a focused antenna and for the case of the off-focus primary emitter. We report the results of the computation of the PB performed in terms of the Fresnel diffraction and geometrical optics approximations, and also based on the available experimental data. The diagrams computed using this technique agree well with the measured power beams.

Investigation of the RCR catalog sources in the millimeter and submillimeter ranges based on the Planck mission data

We have studied the regions of the microwave background radiation maps of the Planck experiment in the neighborhood of the RCR catalog radio sources. From the processed data for bright radio sources in the microwave range, we plotted the calibration curves which allow the brightness of the objects to be measured. For the first time, for 117 objects we obtained estimates of flux density at the millimeter and submillimeter waves, prepared the spectra, conducted identification, and gathered available information from databases. Faint microwave sources, difficult to clear out, additionally contribute to the secondary anisotropy at angular scales smaller than 7′.

On Possibility of Detection of Variable Sources Using the Data of "Cold" Surveys Carried Out on RATAN-600

In this study we attempt to assess the possibility of detection of variable sources using the data of the 7.6-cm wavelength surveys carried out on the RATAN-600 radio telescope in the period from 1980 through 1994. Objects selected according to certain criteria from the RCR catalog are used to construct the calibration curves and to estimate the accuracy of the resulting calibration curves and determine the r.m.s. errors for the measured source flux densities. To check the calibration sources for the presence of variable objects, quantitative estimates are performed for a number of parameters that characterize variability, in particular, for the long-term variability index V and the χ2 (chi-square) probability p. The long-term variability index was found to be positive for 14 out of approximately 80 calibration sources, possibly indicating that these sources are variable. The most likely candidate variables are the three sources with the χ2 probability p > 0.95. Five sources have χ2 probabilities in the 0.85 < p < 0.95 interval, and the remaining six in the 0.6 < p < 0.8 interval. Nine out of 14 objects are possibly variable in the optical range. The light curves and spectra are determined for possible variable sources and a number of “non-variable” objects. We plan to use the results of this study in our future searches for variable radio sources using the data of the “Cold” surveys.

The field of view and flux sensitivity of RATAN-600

The refined data on the diffraction scattering of RATAN-600 allowed the telescope field of view to be increased substantially at large elevations. Amethod, which can be used to reconstruct the parameters of the sources passing at angular distances fromthe beamaxis that are several dozen times greater than the half-power width of the beam, is analyzed. The knowledge about wide scattering of RATAN-600 allowed the noise from background radio sources at zenith to be reduced by one order of magnitude and flux sensitivity of the radio telescope to be increased by the same factor without resorting to two-dimensional mapping. Methods for cleaning one-dimensional records of the RZF survey are suggested that use model scans based on the data of the NVSS survey and MHAT filtering. The latter proved to be an especially efficient tool for suppressing sky noise and identifying sources in the central section of the survey. The flux sensitivity of RATAN-600 is estimated with new opportunities taken into account.

Study of the power beam pattern of RATAN-600 during the deep RZF survey (1998–2003)

This paper proposes a method for constructing an experimental power beam pattern (PB) of RATAN-600 based on the sample of NVSS sources observed in the process of a deep sky survey near local zenith. The data obtained from observations of radio sources at λ7.6 cm in nine bands of the survey (the 2002 and 2003 sets) are used to construct vertical PB of the telescope at rather large offsets from the central horizontal section of the PB (±36′). The experimental PBs obtained using different methods are compared and the root-mean-square deviations of the experimental PB from the corresponding computed PB are determined. The stability of the power beam pattern in its central part (±6′) during the RATAN-600 Zenith Field (RZF) survey (1998–2003) and the accuracies of the fluxes of the sources observed within the framework of this survey and included into the RZF catalog are estimated [1].

Search for variable sources using the data of Cold surveys in the right-ascension interval 2h ≤ RA ≤ 6h

We search for variable objects at 3.94 GHz in the 1988–1994 surveys within the right-ascension interval 2h ≤ RA ≤ 6h. In this study we continue to develop our technique for identifying variable radio sources in the Cold surveys. We identified a total of 195 radio sources in the available sky transit scans, and only 145 objects have their flux measured in two or more surveys. To check these radio sources for variability, we estimated the indices V of long-term variability, the relative variability amplitude Vχ, and the χ2 probability p. Among the 145 objects considered, 15 have positive long-term variability indices (V >0). Of these, five sources have χ2 probability p greater than 0.95. Three objects with p > 0.996 can be considered reliably variable sources, and two objects with probabilities 0.95 < p < 0.996 can be considered possibly variable sources. Eight objects prove to be reliably variable according to an analysis of our data combined with the flux measurements by other authors, performed within the framework of the 1980 survey. We draw the light curves for sources with positive long-term variability indices and perform optical identification of these objects.

Steep-spectrum sources of the RCR catalog in the millimeter and submillimeter ranges based on Planck data

We have investigated the regions of cosmic microwave background maps from the Planck experiment in the neighborhoods of radio sources from the RCR catalog. Based on the measurements of sources from the Planck catalog, we have constructed the calibration curves to determine the brightness of objects. For 34 steep-spectrum objects, for the first time we have estimated the flux densities at millimeter and submillimeter wavelengths, constructed the spectra, made identifications, and gathered information available in databases. Faint, difficult-to-clean, microwave sources make an additional contribution to the secondary anisotropy on angular scales <7′.