Investigation of the correlation patterns and the Compton dominance variability of Mrk 421 in 2017

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Investigation of the correlation patterns and the Compton dominance variability of Mrk 421 in 2017. / MAGIC Collaboration.

In: ASTRONOMY & ASTROPHYSICS, Vol. 655, A89, 01.11.2021.

Research output: Contribution to journal › Article › peer-review

BibTeX

@article{83b4bef1a4a745368308fed16619c011,

title = "Investigation of the correlation patterns and the Compton dominance variability of Mrk 421 in 2017",

abstract = "We present a detailed characterisation and theoretical interpretation of the broadband emission of the paradigmatic TeV blazar Mrk 421, with special focus on the multi-band flux correlations. The dataset has been collected through an extensive multiwavelength campaign organised between 2016 December and 2017 June. The instruments involved are MAGIC, FACT, Fermi-LAT, Swift, GASP-WEBT, OVRO, Medicina and Mets{\"a}hovi. Additionally, four deep exposures (several hours long) with simultaneous MAGIC and NuSTAR observations allowed a precise measurement of the falling segments of the two spectral components. The very-high-energy (VHE; E > 100 GeV) gamma rays and X-rays are positively correlated at zero time lag, but the strength and characteristics of the correlation change substantially across the various energy bands probed. The VHE versus X-ray fluxes follow different patterns, partly due to substantial changes in the Compton dominance during a few days without a simultaneous increase in the X-ray flux (i.e. orphan gamma-ray activity). Studying the broadband spectral energy distribution (SED) during the days including NuSTAR observations, we show that these changes can be explained within a one-zone leptonic model with a blob that increases its size over time. Our multi-band correlation study also hints at an anti-correlation between UV/optical and X-ray at a significance higher than 3 sigmas. A VHE flare observed on 2017 February 4 shows gamma-ray variability on multi-hour timescales, with a factor 10 increase in the TeV flux but only a moderate increase in the keV flux. The related broadband SED is better described by a two-zone leptonic scenario rather than by a one-zone scenario. We find that the flare can be produced by the appearance of a compact second blob populated by high energetic electrons spanning a narrow range of Lorentz factors.",

keywords = "Astrophysics - High Energy Astrophysical Phenomena, Radiation mechanisms: non-thermal, Galaxies: active, BL Lacertae objects: individual: Mrk 421, SWIFT OBSERVATIONS, radiation mechanisms: non-thermal, BL-LACERTAE, LARGE-AREA TELESCOPE, RAY LIGHT CURVES, ELECTRON ACCELERATION, PARTICLE-ACCELERATION, LOG-PARABOLIC SPECTRA, ACTIVE GALACTIC NUCLEI, galaxies: active, X-RAY, MULTIWAVELENGTH OBSERVATIONS",

author = "{MAGIC Collaboration} and Acciari, {V. A.} and S. Ansoldi and Antonelli, {L. A.} and {Arbet Engels}, A. and M. Artero and K. Asano and A. Babi{\'c} and A. Baquero and {Barres De Almeida}, U. and Barrio, {J. A.} and I. Batkovi{\'c} and {Becerra Gonz{\'a}lez}, J. and W. Bednarek and L. Bellizzi and E. Bernardini and M. Bernardos and A. Berti and J. Besenrieder and W. Bhattacharyya and C. Bigongiari and O. Blanch and {\v Z}. Bo{\v s}njak and G. Busetto and R. Carosi and G. Ceribella and M. Cerruti and Y. Chai and A. Chilingarian and S. Cikota and Colak, {S. M.} and E. Colombo and Contreras, {J. L.} and J. Cortina and S. Covino and G. D{\textquoteright}amico and Gupta, {A. C.} and Larionov, {V. M.} and Grishina, {T. S.} and Hagen-thorn, {V. A.} and Kopatskaya, {E. N.} and Larionova, {E. G.} and Larionova, {L. V.} and Morozova, {D. A.} and Nikiforova, {A. A.} and Savchenko, {S. S.} and Troitskiy, {I. S.} and Troitskaya, {Y. V.} and Vasilyev, {A. A.} and Merkulova, {O. A.} and Jorstad, {S. G.}",

year = "2021",

month = nov,

day = "1",

doi = "10.1051/0004-6361/202141004",

language = "English",

volume = "655",

journal = "ASTRONOMY & ASTROPHYSICS",

issn = "0004-6361",

publisher = "EDP Sciences",

}

RIS

TY - JOUR

T1 - Investigation of the correlation patterns and the Compton dominance variability of Mrk 421 in 2017

AU - MAGIC Collaboration

AU - Acciari, V. A.

AU - Ansoldi, S.

AU - Antonelli, L. A.

AU - Arbet Engels, A.

AU - Artero, M.

AU - Asano, K.

AU - Babić, A.

AU - Baquero, A.

AU - Barres De Almeida, U.

AU - Barrio, J. A.

AU - Batković, I.

AU - Becerra González, J.

AU - Bednarek, W.

AU - Bellizzi, L.

AU - Bernardini, E.

AU - Bernardos, M.

AU - Berti, A.

AU - Besenrieder, J.

AU - Bhattacharyya, W.

AU - Bigongiari, C.

AU - Blanch, O.

AU - Bošnjak, Ž.

AU - Busetto, G.

AU - Carosi, R.

AU - Ceribella, G.

AU - Cerruti, M.

AU - Chai, Y.

AU - Chilingarian, A.

AU - Cikota, S.

AU - Colak, S. M.

AU - Colombo, E.

AU - Contreras, J. L.

AU - Cortina, J.

AU - Covino, S.

AU - D’amico, G.

AU - Gupta, A. C.

AU - Larionov, V. M.

AU - Grishina, T. S.

AU - Hagen-thorn, V. A.

AU - Kopatskaya, E. N.

AU - Larionova, E. G.

AU - Larionova, L. V.

AU - Morozova, D. A.

AU - Nikiforova, A. A.

AU - Savchenko, S. S.

AU - Troitskiy, I. S.

AU - Troitskaya, Y. V.

AU - Vasilyev, A. A.

AU - Merkulova, O. A.

AU - Jorstad, S. G.

PY - 2021/11/1

Y1 - 2021/11/1

N2 - We present a detailed characterisation and theoretical interpretation of the broadband emission of the paradigmatic TeV blazar Mrk 421, with special focus on the multi-band flux correlations. The dataset has been collected through an extensive multiwavelength campaign organised between 2016 December and 2017 June. The instruments involved are MAGIC, FACT, Fermi-LAT, Swift, GASP-WEBT, OVRO, Medicina and Metsähovi. Additionally, four deep exposures (several hours long) with simultaneous MAGIC and NuSTAR observations allowed a precise measurement of the falling segments of the two spectral components. The very-high-energy (VHE; E > 100 GeV) gamma rays and X-rays are positively correlated at zero time lag, but the strength and characteristics of the correlation change substantially across the various energy bands probed. The VHE versus X-ray fluxes follow different patterns, partly due to substantial changes in the Compton dominance during a few days without a simultaneous increase in the X-ray flux (i.e. orphan gamma-ray activity). Studying the broadband spectral energy distribution (SED) during the days including NuSTAR observations, we show that these changes can be explained within a one-zone leptonic model with a blob that increases its size over time. Our multi-band correlation study also hints at an anti-correlation between UV/optical and X-ray at a significance higher than 3 sigmas. A VHE flare observed on 2017 February 4 shows gamma-ray variability on multi-hour timescales, with a factor 10 increase in the TeV flux but only a moderate increase in the keV flux. The related broadband SED is better described by a two-zone leptonic scenario rather than by a one-zone scenario. We find that the flare can be produced by the appearance of a compact second blob populated by high energetic electrons spanning a narrow range of Lorentz factors.

AB - We present a detailed characterisation and theoretical interpretation of the broadband emission of the paradigmatic TeV blazar Mrk 421, with special focus on the multi-band flux correlations. The dataset has been collected through an extensive multiwavelength campaign organised between 2016 December and 2017 June. The instruments involved are MAGIC, FACT, Fermi-LAT, Swift, GASP-WEBT, OVRO, Medicina and Metsähovi. Additionally, four deep exposures (several hours long) with simultaneous MAGIC and NuSTAR observations allowed a precise measurement of the falling segments of the two spectral components. The very-high-energy (VHE; E > 100 GeV) gamma rays and X-rays are positively correlated at zero time lag, but the strength and characteristics of the correlation change substantially across the various energy bands probed. The VHE versus X-ray fluxes follow different patterns, partly due to substantial changes in the Compton dominance during a few days without a simultaneous increase in the X-ray flux (i.e. orphan gamma-ray activity). Studying the broadband spectral energy distribution (SED) during the days including NuSTAR observations, we show that these changes can be explained within a one-zone leptonic model with a blob that increases its size over time. Our multi-band correlation study also hints at an anti-correlation between UV/optical and X-ray at a significance higher than 3 sigmas. A VHE flare observed on 2017 February 4 shows gamma-ray variability on multi-hour timescales, with a factor 10 increase in the TeV flux but only a moderate increase in the keV flux. The related broadband SED is better described by a two-zone leptonic scenario rather than by a one-zone scenario. We find that the flare can be produced by the appearance of a compact second blob populated by high energetic electrons spanning a narrow range of Lorentz factors.

KW - Astrophysics - High Energy Astrophysical Phenomena

KW - Radiation mechanisms: non-thermal

KW - Galaxies: active

KW - BL Lacertae objects: individual: Mrk 421

KW - SWIFT OBSERVATIONS

KW - radiation mechanisms: non-thermal

KW - BL-LACERTAE

KW - LARGE-AREA TELESCOPE

KW - RAY LIGHT CURVES

KW - ELECTRON ACCELERATION

KW - PARTICLE-ACCELERATION

KW - LOG-PARABOLIC SPECTRA

KW - ACTIVE GALACTIC NUCLEI

KW - galaxies: active

KW - X-RAY

KW - MULTIWAVELENGTH OBSERVATIONS

UR - http://www.scopus.com/inward/record.url?scp=85121042376&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/54c78f29-1c94-3970-9c33-958142ed2806/

U2 - 10.1051/0004-6361/202141004

DO - 10.1051/0004-6361/202141004

M3 - Article

VL - 655

JO - ASTRONOMY & ASTROPHYSICS

JF - ASTRONOMY & ASTROPHYSICS

SN - 0004-6361

M1 - A89

ER -

ID: 85052720