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Start Over Author "Asfandiyarov, I." Publication Type Magazines
5 results on '"Asfandiyarov, I."'

1. Results of WEBT, VLBA and RXTE monitoring of 3C 279during 2006–2007*

Author

Larionov, V. M., Jorstad, S. G., Marscher, A. P., Raiteri, C. M., Villata, M., Agudo, I., Aller, M. F., Arkharov, A. A., Asfandiyarov, I. M., Bach, U., Bachev, R., Berdyugin, A., Böttcher, M., Buemi, C. S., Calcidese, P., Carosati, D., Charlot, P., Chen, W.-P., Di Paola, A., Dolci, M., Dogru, S., Doroshenko, V. T., Efimov, Yu. S., Erdem, A., Frasca, A., Fuhrmann, L., Giommi, P., Glowienka, L., Gupta, A. C., Gurwell, M. A., Hagen-Thorn, V. A., Hsiao, W.-S., Ibrahimov, M. A., Jordan, B., Kamada, M., Konstantinova, T. S., Kopatskaya, E. N., Kovalev, Y. Y., Kovalev, Y. A., Kurtanidze, O. M., Lähteenmäki, A., Lanteri, L., Larionova, L. V., Leto, P., Le Campion, P., Lee, C.-U., Lindfors, E., Marilli, E., McHardy, I., Mingaliev, M. G., Nazarov, S. V., Nieppola, E., Nilsson, K., Ohlert, J., Pasanen, M., Porter, D., Pursimo, T., Ros, J. A., Sadakane, K., Sadun, A. C., Sergeev, S. G., Smith, N., Strigachev, A., Sumitomo, N., Takalo, L. O., Tanaka, K., Trigilio, C., Umana, G., Ungerechts, H., Volvach, A., Yuan, W., Larionov, V. M., Jorstad, S. G., Marscher, A. P., Raiteri, C. M., Villata, M., Agudo, I., Aller, M. F., Arkharov, A. A., Asfandiyarov, I. M., Bach, U., Bachev, R., Berdyugin, A., Böttcher, M., Buemi, C. S., Calcidese, P., Carosati, D., Charlot, P., Chen, W.-P., Di Paola, A., Dolci, M., Dogru, S., Doroshenko, V. T., Efimov, Yu. S., Erdem, A., Frasca, A., Fuhrmann, L., Giommi, P., Glowienka, L., Gupta, A. C., Gurwell, M. A., Hagen-Thorn, V. A., Hsiao, W.-S., Ibrahimov, M. A., Jordan, B., Kamada, M., Konstantinova, T. S., Kopatskaya, E. N., Kovalev, Y. Y., Kovalev, Y. A., Kurtanidze, O. M., Lähteenmäki, A., Lanteri, L., Larionova, L. V., Leto, P., Le Campion, P., Lee, C.-U., Lindfors, E., Marilli, E., McHardy, I., Mingaliev, M. G., Nazarov, S. V., Nieppola, E., Nilsson, K., Ohlert, J., Pasanen, M., Porter, D., Pursimo, T., Ros, J. A., Sadakane, K., Sadun, A. C., Sergeev, S. G., Smith, N., Strigachev, A., Sumitomo, N., Takalo, L. O., Tanaka, K., Trigilio, C., Umana, G., Ungerechts, H., Volvach, A., and Yuan, W.

Abstract

Context. The quasar 3C 279is among the most extreme blazars in terms of luminosity and variability of flux at all wavebands. Its variations in flux and polarization are quite complex and therefore require intensive monitoring observations at multiple wavebands to characterise and interpret the observed changes.

Published
2008
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2. COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses*

Author

Vuissoz, C., Courbin, F., Sluse, D., Meylan, G., Ibrahimov, M., Asfandiyarov, I., Stoops, E., Eigenbrod, A., Le Guillou, L., van Winckel, H., Magain, P., Vuissoz, C., Courbin, F., Sluse, D., Meylan, G., Ibrahimov, M., Asfandiyarov, I., Stoops, E., Eigenbrod, A., Le Guillou, L., van Winckel, H., and Magain, P.

Abstract

Aims.Our aim is to measure the time delay between the two gravitationally lensed images of the zqso= 1.547 quasar SDSS J1650+4251, in order to estimate the Hubble constant H0.

Published
2007
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3. The WEBT BL LacertaeCampaign 2001 and its extension

Author

Villata, M., Raiteri, C. M., Kurtanidze, O. M., Nikolashvili, M. G., Ibrahimov, M. A., Papadakis, I. E., Tosti, G., Hroch, F., Takalo, L. O., Sillanpää, A., Hagen-Thorn, V. A., Larionov, V. M., Schwartz, R. D., Basler, J., Brown, L. F., Balonek, T. J., Benítez, E., Ramírez, A., Sadun, A. C., Boltwood, P., Carini, M. T., Barnaby, D., Coloma, J. M., Ros, J. A., Dai, B. Z., Xie, G. Z., Mattox, J. R., Rodriguez, D., Asfandiyarov, I. M., Atkerson, A., Beem, J. L., Bloom, S. D., Chanturiya, S. M., Ciprini, S., Crapanzano, S., de Diego, J. A., Efimova, N. V., Gardiol, D., Guerra, J. C., Kahharov, B. B., Kapanadze, B. Z., Karttunen, H., Kato, T., Kimeridze, G. N., Kudryavtseva, N. A., Lainela, M., Lanteri, L., Larionova, E. G., Maesano, M., Marchili, N., Massone, G., Monroe, T., Montagni, F., Nesci, R., Nilsson, K., Noble, J. C., Nucciarelli, G., Ostorero, L., Papamastorakis, J., Pasanen, M., Peters, C. S., Pursimo, T., Reig, P., Ryle, W., Sclavi, S., Sigua, L. A., Uemura, M., Wills, W., Villata, M., Raiteri, C. M., Kurtanidze, O. M., Nikolashvili, M. G., Ibrahimov, M. A., Papadakis, I. E., Tosti, G., Hroch, F., Takalo, L. O., Sillanpää, A., Hagen-Thorn, V. A., Larionov, V. M., Schwartz, R. D., Basler, J., Brown, L. F., Balonek, T. J., Benítez, E., Ramírez, A., Sadun, A. C., Boltwood, P., Carini, M. T., Barnaby, D., Coloma, J. M., Ros, J. A., Dai, B. Z., Xie, G. Z., Mattox, J. R., Rodriguez, D., Asfandiyarov, I. M., Atkerson, A., Beem, J. L., Bloom, S. D., Chanturiya, S. M., Ciprini, S., Crapanzano, S., de Diego, J. A., Efimova, N. V., Gardiol, D., Guerra, J. C., Kahharov, B. B., Kapanadze, B. Z., Karttunen, H., Kato, T., Kimeridze, G. N., Kudryavtseva, N. A., Lainela, M., Lanteri, L., Larionova, E. G., Maesano, M., Marchili, N., Massone, G., Monroe, T., Montagni, F., Nesci, R., Nilsson, K., Noble, J. C., Nucciarelli, G., Ostorero, L., Papamastorakis, J., Pasanen, M., Peters, C. S., Pursimo, T., Reig, P., Ryle, W., Sclavi, S., Sigua, L. A., Uemura, M., and Wills, W.

Abstract

BL Lacertaehas been the target of four observing campaigns by the Whole Earth Blazar Telescope (WEBT) collaboration. In this paper we present ${\it UBVRI}$light curves obtained by the WEBT from 1994 to 2002, including the last, extended BL Lac 2001 campaign. A total of about 7500 optical observations performed by 31 telescopes from Japan to Mexico have been collected, to be added to the ~$15\,600$observations of the BL Lac Campaign 2000. All these data allow one to follow the source optical emission behaviour with unprecedented detail. The analysis of the colour indices reveals that the flux variability can be interpreted in terms of two components: longer-term variations occurring on a few-day time scale appear as mildly-chromatic events, while a strong bluer-when-brighter chromatism characterizes very fast (intraday) flares. By decoupling the two components, we quantify the degree of chromatism inferring that longer-term flux changes imply moving along a ~$ 0.1$bluer-when-brighter slope in the $B-R$versus Rplane; a steeper slope of ~$ 0.4$would distinguish the shorter-term variations. This means that, when considering the long-term trend, the B-band flux level is related to the R-band one according to a power law of index ~$ 1.1$. Doppler factor variations on a “convex" spectrum could be the mechanism accounting for both the long-term variations and their slight chromatism.

Published
2004
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5. COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses⋆⋆⋆

Author

Courbin, F., Chantry, V., Revaz, Y., Sluse, D., Faure, C., Tewes, M., Eulaers, E., Koleva, M., Asfandiyarov, I., Dye, S., Magain, P., van Winckel, H., Coles, J., Saha, P., Ibrahimov, M., and Meylan, G.

Abstract

We present accurate time delays for the quadruply imaged quasar HE 0435-1223. The delays were measured from 575 independent photometric points obtained in the R-band between January 2004 and March 2010. With seven years of data, we clearly show that quasar image A is affected by strong microlensing variations and that the time delays are best expressed relative to quasar image B. We measured ΔtBC= 7.8  ±  0.8 days, ΔtBD=  −6.5  ±  0.7 days and ΔtCD=  −14.3  ±  0.8 days. We spacially deconvolved HST NICMOS2 F160W images to derive accurate astrometry of the quasar images and to infer the light profile of the lensing galaxy. We combined these images with a stellar population fitting of a deep VLT spectrum of the lensing galaxy to estimate the baryonic fraction, fb, in the Einstein radius. We measured fb= 0.65-0.10+0.13if the lensing galaxy has a Salpeter IMF and fb= 0.45-0.07+0.04if it has a Kroupa IMF. The spectrum also allowed us to estimate the velocity dispersion of the lensing galaxy, σap= 222  ±  34 km s-1. We used fband σapto constrain an analytical model of the lensing galaxy composed of an Hernquist plus generalized NFW profile. We solved the Jeans equations numerically for the model and explored the parameter space under the additional requirement that the model must predict the correct astrometry for the quasar images. Given the current error bars on fband σap, we did not constrain H0yet with high accuracy, i.e., we found a broad range of models with χ2< 1. However, narrowing this range is possible, provided a better velocity dispersion measurement becomes available. In addition, increasing the depth of the current HST imaging data of HE 0435-1223 will allow us to combine ourconstraints with lens reconstruction techniques that make use of the full Einstein ring that is visible in this object.

Published
2011
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