Long term variability and correlation study of the blazar 3C 454.3 in radio, NIR and optical wavebands

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Long term variability and correlation study of the blazar 3C 454.3 in radio, NIR and optical wavebands. / Sarkar, A.; Chitnis, V.R.; Gupta, A.C.; Gaur, H.; Patel, S.R.; Wiita, P.J.; Volvach, A.E.; Tornikoski, Merja; Chamani Velasco, Wara; Enestam, Sissi; Lähteenmäki, Anne; Tammi, Joni; Vera Rodríguez, Rafael; Volvach, L.N.

In: Astrophysical Journal, Vol. 887, No. 2, 185, 20.12.2019.

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Sarkar, A., Chitnis, V. R., Gupta, A. C., Gaur, H., Patel, S. R., Wiita, P. J., ... Volvach, L. N. (2019). Long term variability and correlation study of the blazar 3C 454.3 in radio, NIR and optical wavebands. Astrophysical Journal, 887(2), [185]. https://doi.org/10.3847/1538-4357/ab5281

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@article{3c8577767a8c499a8346f0e36895c00a,
title = "Long term variability and correlation study of the blazar 3C 454.3 in radio, NIR and optical wavebands",
abstract = "We performed a long-term optical (B, V, R bands), infra-red (J and K bands) and radio band (15, 22, 37 GHz band) study on the flat spectrum radio quasar, 3C 454.3, using the data collected over a period of more than 8 years (MJD 54500–57500). The temporal variability, spectral properties and inter-waveband correlations were studied by dividing the available data into smaller segments with more regular sampling. This helped us constrain the size and the relative locations of the emission regions for different wavebands. Spectral analysis of the source revealed the interplay between the accretion disk and jet emission. The source predominantly showed a redder-when-brighter trend, though we observed a bluer-when-brighter trend at high flux levels which could be signatures of particle acceleration and radiative cooling. Significant correlations with near-zero lag were seen between various optical/infra-red bands, indicating that these emission regions are co-spatial. Correlations with a time lag of about 10–100 days are seen between optical/infra-red and radio bands indicating these emissions arise from different regions. We also observe the DCF peak lag change from year to year. We try to explain these differences using a curved jet model where the different emission regions have different viewing angles resulting in a frequency dependent Doppler factor. This variable Doppler factor model explains the variability timescales and the variation in DCF peak lag between the radio and optical emissions in different segments. Lags of 6-180 days are seen between emissions in various radio bands, indicating a core-shift effect.",
keywords = "galaxies: active, galaxies:jets, methods: observational, quasars: individual (3C 454.3), techniques: photometric",
author = "A. Sarkar and V.R. Chitnis and A.C. Gupta and H. Gaur and S.R. Patel and P.J. Wiita and A.E. Volvach and Merja Tornikoski and {Chamani Velasco}, Wara and Sissi Enestam and Anne L{\"a}hteenm{\"a}ki and Joni Tammi and {Vera Rodr{\'i}guez}, Rafael and L.N. Volvach",
year = "2019",
month = "12",
day = "20",
doi = "10.3847/1538-4357/ab5281",
language = "English",
volume = "887",
journal = "Astrophysical Journal",
issn = "0004-637X",
number = "2",

}

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TY - JOUR

T1 - Long term variability and correlation study of the blazar 3C 454.3 in radio, NIR and optical wavebands

AU - Sarkar, A.

AU - Chitnis, V.R.

AU - Gupta, A.C.

AU - Gaur, H.

AU - Patel, S.R.

AU - Wiita, P.J.

AU - Volvach, A.E.

AU - Tornikoski, Merja

AU - Chamani Velasco, Wara

AU - Enestam, Sissi

AU - Lähteenmäki, Anne

AU - Tammi, Joni

AU - Vera Rodríguez, Rafael

AU - Volvach, L.N.

PY - 2019/12/20

Y1 - 2019/12/20

N2 - We performed a long-term optical (B, V, R bands), infra-red (J and K bands) and radio band (15, 22, 37 GHz band) study on the flat spectrum radio quasar, 3C 454.3, using the data collected over a period of more than 8 years (MJD 54500–57500). The temporal variability, spectral properties and inter-waveband correlations were studied by dividing the available data into smaller segments with more regular sampling. This helped us constrain the size and the relative locations of the emission regions for different wavebands. Spectral analysis of the source revealed the interplay between the accretion disk and jet emission. The source predominantly showed a redder-when-brighter trend, though we observed a bluer-when-brighter trend at high flux levels which could be signatures of particle acceleration and radiative cooling. Significant correlations with near-zero lag were seen between various optical/infra-red bands, indicating that these emission regions are co-spatial. Correlations with a time lag of about 10–100 days are seen between optical/infra-red and radio bands indicating these emissions arise from different regions. We also observe the DCF peak lag change from year to year. We try to explain these differences using a curved jet model where the different emission regions have different viewing angles resulting in a frequency dependent Doppler factor. This variable Doppler factor model explains the variability timescales and the variation in DCF peak lag between the radio and optical emissions in different segments. Lags of 6-180 days are seen between emissions in various radio bands, indicating a core-shift effect.

AB - We performed a long-term optical (B, V, R bands), infra-red (J and K bands) and radio band (15, 22, 37 GHz band) study on the flat spectrum radio quasar, 3C 454.3, using the data collected over a period of more than 8 years (MJD 54500–57500). The temporal variability, spectral properties and inter-waveband correlations were studied by dividing the available data into smaller segments with more regular sampling. This helped us constrain the size and the relative locations of the emission regions for different wavebands. Spectral analysis of the source revealed the interplay between the accretion disk and jet emission. The source predominantly showed a redder-when-brighter trend, though we observed a bluer-when-brighter trend at high flux levels which could be signatures of particle acceleration and radiative cooling. Significant correlations with near-zero lag were seen between various optical/infra-red bands, indicating that these emission regions are co-spatial. Correlations with a time lag of about 10–100 days are seen between optical/infra-red and radio bands indicating these emissions arise from different regions. We also observe the DCF peak lag change from year to year. We try to explain these differences using a curved jet model where the different emission regions have different viewing angles resulting in a frequency dependent Doppler factor. This variable Doppler factor model explains the variability timescales and the variation in DCF peak lag between the radio and optical emissions in different segments. Lags of 6-180 days are seen between emissions in various radio bands, indicating a core-shift effect.

KW - galaxies: active

KW - galaxies:jets

KW - methods: observational

KW - quasars: individual (3C 454.3)

KW - techniques: photometric

U2 - 10.3847/1538-4357/ab5281

DO - 10.3847/1538-4357/ab5281

M3 - Article

VL - 887

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 2

M1 - 185

ER -

ID: 38244838