126 research outputs found

    Optical monitoring of the z=4.40 quasar Q 2203+292

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    We report Cousins R-band monitoring of the high-redshift (z=4.40) radio quiet quasar Q 2203+292 from May 1999 to October 2007. The quasar shows maximum peak-to-peak light curve amplitude of ~0.3 mag during the time of our monitoring, and ~0.9 mag when combined with older literature data. The rms of a fit to the light curve with a constant is 0.08 mag and 0.2 mag, respectively. The detected changes are at ~3-sigma level. The quasar was in a stable state during the recent years and it might have undergone a brightening event in the past. The structure function analysis concluded that the object shows variability properties similar to those of the lower redshift quasars. We set a lower limit to the Q 2203+292 broad line region mass of 0.3-0.4 M_odot. Narrow-band imaging search for redshifted Ly_alpha from other emission line objects at the same redshift shows no emission line objects in the quasar vicinity.Comment: 9 pages, 8 figures, accepted for publication in MNRA

    WET SCRUBBER COLUMN FOR AIR DETRITIATION

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    This paper evaluates detritiation of air contaminated with tritium in the for

    Dissecting the long-term emission behaviour of the BL Lac object Mrk 421

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    We report on long-term multiwavelengthmonitoring of blazar Mrk 421 by the GLAST-AGILE Support Program of the Whole Earth Blazar Telescope (GASP-WEBT) collaboration and Steward Observatory, and by the Swift and Fermi satellites. We study the source behaviour in the period 2007–2015, characterized by several extreme flares. The ratio between the optical, X-ray and γ -ray fluxes is very variable. The γ -ray flux variations show a fair correlation with the optical ones starting from 2012.We analyse spectropolarimetric data and find wavelengthdependence of the polarization degree (P), which is compatible with the presence of the host galaxy, and no wavelength dependence of the electric vector polarization angle (EVPA). Optical polarimetry shows a lack of simple correlation between P and flux and wide rotations of the EVPA.We build broad-band spectral energy distributions with simultaneous near-infrared and optical data from the GASP-WEBT and ultraviolet and X-ray data from the Swift satellite. They show strong variability in both flux and X-ray spectral shape and suggest a shift of the synchrotron peak up to a factor of ∼50 in frequency. The interpretation of the flux and spectral variability is compatible with jet models including at least two emitting regions that can change their orientation with respect to the line of sight.http://10.0.4.69/mnras/stx2185Accepted manuscrip

    A new activity phase of the blazar 3C 454.3. Multifrequency observations by the WEBT and XMM-Newton in 2007-2008

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    We present and analyse the WEBT multifrequency observations of 3C 454.3 in the 2007-2008 observing season, including XMM-Newton observations and near-IR spectroscopic monitoring, and compare the recent emission behaviour with the past one. In the optical band we observed a multi-peak outburst in July-August 2007, and other faster events in November 2007 - February 2008. During these outburst phases, several episodes of intranight variability were detected. A mm outburst was observed starting from mid 2007, whose rising phase was contemporaneous to the optical brightening. A slower flux increase also affected the higher radio frequencies, the flux enhancement disappearing below 8 GHz. The analysis of the optical-radio correlation and time delays, as well as the behaviour of the mm light curve, confirm our previous predictions, suggesting that changes in the jet orientation likely occurred in the last few years. The historical multiwavelength behaviour indicates that a significant variation in the viewing angle may have happened around year 2000. Colour analysis reveals a complex spectral behaviour, which is due to the interplay of different emission components. All the near-IR spectra show a prominent Halpha emission line, whose flux appears nearly constant. The analysis of the XMM-Newton data indicates a correlation between the UV excess and the soft-X-ray excess, which may represent the head and the tail of the big blue bump, respectively. The X-ray flux correlates with the optical flux, suggesting that in the inverse-Compton process either the seed photons are synchrotron photons at IR-optical frequencies or the relativistic electrons are those that produce the optical synchrotron emission. The X-ray radiation would thus be produced in the jet region from where the IR-optical emission comes.Comment: 10 pages, 12 figures (7 included in the text, 5 in GIF format), accepted for publication in A&

    Comparative analysis of anxiety-depressive spectrum disorders in patients with rheumatic diseases

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    Research objective - comparative analysis of incidence and structure of anxiety-depressive spectrum disorders (ADD) in patients with various rheumatic diseases (RD). Materials and methods. 613 patients with RD were enrolled in the study: 180 with a reliable diagnosis of systemic lupus erythematosus (SLE), 128 with rheumatoid arthritis (RA), 110 with systemic sclerosis (SSc), 115 with Behcet's disease (BD), 80 with primary Sjögren's syndrome (pSS). Female prevailed in all groups (95% of patients with pSS, 88,2% - SSc, 87,2% - RA, 85,5% of SLE) except BD patients (70% male). The mean age was 42.3±1.54 years and was lower in patients with BD (33.3±0.98 years) and SLE (34.6±0.93 years) compared to patients with SSc (49.9±2.47 years), RA (47.4±0.99 years) and pSS (46.2±2.3 years). The mean RD duration was 130,0±8,65 months and was more at BD - 148,5±10,4 months, pSS - 141,6±8,92 months, RA - 138,4±10,1months, and less at SLE - 134,9±8,8 months and SSc - 87,0±5,04 months. The mean SLE activity index SLEDAI was 9,13±0,63 points (high), RA (DAS28) - 5,26±0,17 points (high), BD (BDCAF) - 3,79±0,2 points (moderate) and SSc by G. Valentini - 1,1±0,20 points (moderate). Glucocorticoids took 100% of patients with pSS, 91,1% - SLE, 90% - SSc, 87% - BD and 67,2% - RA patients; conventional disease modifying anti-rheumatic drugs (cDMARDs) took 90% of patients with SSc, 84% - BD, 79,6% - RA, 68% - pSS, 40,6% - SLE. Biologic DMARDs took 32% of patients with RA, 17,4% - BD, 7,3% - SSc and 7,2% - SLE. Mental disorders were diagnosed by psychiatrist as a result of screening by the hospital anxiety and depression scale (HADS) and in semi-structured interview in accordance with the ICD-10/ DSM-IV. The severity of depression was evaluated by Montgomery-Asberg Depression Rating Scale (MADRS) and anxiety - by Hamilton Anxiety Rating Scale (HAM-A). Projective psychological methods were used for cognitive impairment detection. Results. Screening of depressive disorders (HADS-D≥8) was positive in 180 (29,4%) patients with RD, including 74 (41%) patients with SLE, 38 (35%) - SSc, 29 (23%) - RA, 23 (20%) - BD and 16 (20%) - pSS; anxiety disorders (HADS-A≥8) - in 272 (44,4%) patients, including 66 (52%) patients with RA, 40 (50%) - pSS, 77 (43%) - SLE, 45 (41%) - SSc and 44 (38%) - BD. In accordance with the ICD-10/ DSM-IV depressive disorders have been identified in 389 (63%) patients, including 94 (73%) patients with RA, 71 (64,5%) - SSc, 69 (60%) - BD, 90 (50%) - SLE and 39 (49%) - pSS; anxiety disorders - in 377 (61,5%) patients, including 20 (25%) patients with pSS, 44 (24,5%) - SLE, 29 (23%) - RA, 20 (17%) - BD and 7 (6,4%) - SSc. Conclusion. Anxiety-depressive spectrum disorders are typical for most patients with RA, SLE, SSc, pSS and BD. ADDs diagnosis in RD patients with the use of the HADS did not reveal a significant proportion. To obtain objective data on the frequency and structure of ADDs, psychopathological and clinical psychological diagnosis is necessary

    WEBT and XMM-Newton observations of 3C 454.3 during the post-outburst phase. Detection of the little and big blue bumps

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    The blazar 3C 454.3 underwent an unprecedented optical outburst in spring 2005. This was first followed by a mm and then by a cm radio outburst, which peaked in February 2006. We report on follow-up observations by the WEBT to study the multiwavelength emission in the post-outburst phase. XMM-Newton observations on July and December 2006 added information on the X-ray and UV fluxes. The source was in a faint state. The radio flux at the higher frequencies showed a fast decreasing trend, which represents the tail of the big radio outburst. It was followed by a quiescent state, common at all radio frequencies. In contrast, moderate activity characterized the NIR and optical light curves, with a progressive increase of the variability amplitude with increasing wavelength. We ascribe this redder-when-brighter behaviour to the presence of a "little blue bump" due to line emission from the broad line region, which is clearly visible in the source SED during faint states. Moreover, the data from the XMM-Newton OM reveal a rise of the SED in the UV, suggesting the existence of a "big blue bump" due to thermal emission from the accretion disc. The X-ray spectra are well fitted with a power-law model with photoelectric absorption, possibly larger than the Galactic one. However, the comparison with previous X-ray observations would imply that the amount of absorbing matter is variable. Alternatively, the intrinsic X-ray spectrum presents a curvature, which may depend on the X-ray brightness. In this case, two scenarios are possible.Comment: 9 pages, 7 figures, accepted for publication in A&

    WEBT multiwavelength monitoring and XMM-Newton observations of BL Lacertae in 2007-2008. Unveiling different emission components

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    In 2007-2008 we carried out a new multiwavelength campaign of the Whole Earth Blazar Telescope (WEBT) on BL Lacertae, involving three pointings by the XMM-Newton satellite, to study its emission properties. The source was monitored in the optical-to-radio bands by 37 telescopes. The brightness level was relatively low. Some episodes of very fast variability were detected in the optical bands. The X-ray spectra are well fitted by a power law with photon index of about 2 and photoelectric absorption exceeding the Galactic value. However, when taking into account the presence of a molecular cloud on the line of sight, the data are best fitted by a double power law, implying a concave X-ray spectrum. The spectral energy distributions (SEDs) built with simultaneous radio-to-X-ray data at the epochs of the XMM-Newton observations suggest that the peak of the synchrotron emission lies in the near-IR band, and show a prominent UV excess, besides a slight soft-X-ray excess. A comparison with the SEDs corresponding to previous observations with X-ray satellites shows that the X-ray spectrum is extremely variable. We ascribe the UV excess to thermal emission from the accretion disc, and the other broad-band spectral features to the presence of two synchrotron components, with their related SSC emission. We fit the thermal emission with a black body law and the non-thermal components by means of a helical jet model. The fit indicates a disc temperature greater than 20000 K and a luminosity greater than 6 x 10^44 erg/s.Comment: 11 pages, 7 figures, accepted for publication in A&

    Radio-to-UV monitoring of AO 0235+164 by the WEBT and Swift during the 2006--2007 outburst

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    The blazar AO 0235+164 was claimed to show a quasi-periodic behaviour in the radio and optical bands. Moreover, an extra emission component contributing to the UV and soft X-ray flux was detected, whose nature is not yet clear. A predicted optical outburst was observed in late 2006/early 2007. We here present the radio-to-optical WEBT light curves during the outburst, together with UV data acquired by Swift in the same period. We found the optical outburst to be as strong as the big outbursts of the past: starting from late September 2006, a brightness increase of 5 mag led to the outburst peak in February 19-21, 2007. We also observed an outburst at mm and then at cm wavelengths, with an increasing time delay going toward lower frequencies during the rising phase. Cross-correlation analysis indicates that the 1 mm and 37 GHz flux variations lagged behind the R-band ones by about 3 weeks and 2 months, respectively. These short time delays suggest that the corresponding jet emitting regions are only slightly separated and/or misaligned. In contrast, during the outburst decreasing phase the flux faded contemporaneously at all cm wavelengths. This abrupt change in the emission behaviour may suggest the presence of some shutdown mechanism of intrinsic or geometric nature. The behaviour of the UV flux closely follows the optical and near-IR one. By separating the synchrotron and extra component contributions to the UV flux, we found that they correlate, which suggests that the two emissions have a common origin.Comment: 9 pages, 7 figures, in press for Astronomy and Astrophysic
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