Detection of the blazar S4 0954+65 at very-high-energy with the MAGIC telescopes during an exceptionally high optical state

MAGIC Collaboration, Fermi-LAT Collaboration, Юлия Вячеславовна Троицкая

Research output

1 Citation (Scopus)

Abstract

Aims. The very high energy (VHE ≥ 100 GeV) -ray MAGIC observations of the blazar S4 0954+65, were triggered by an exceptionally high flux state of emission in the optical. This blazar has a disputed redshift of z = 0.368 or z ≥ 0.45 and an uncertain classification among blazar subclasses. The exceptional source state described here makes for an excellent opportunity to understand physical processes in the jet of S4 0954+65 and thus contribute to its classification. Methods. We investigated the multiwavelength (MWL) light curve and spectral energy distribution (SED) of the S4 0954+65 blazar during an enhanced state in February 2015 and have put it in context with possible emission scenarios. We collected photometric data in radio, optical, X-ray, and γ-ray. We studied both the optical polarization and the inner parsec-scale jet behavior with 43 GHz data. Results. Observations with the MAGIC telescopes led to the first detection of S4 0954+65 at VHE. Simultaneous data with Fermi-LAT at high energy γ-ray(HE, 100 MeV < E < 100 GeV) also show a period of increased activity. Imaging at 43 GHz reveals the emergence of a new feature in the radio jet in coincidence with the VHE flare. Simultaneous monitoring of the optical polarization angle reveals a rotation of approximately 100. Conclusions. The high emission state during the flare allows us to compile the simultaneous broadband SED and to characterize it in the scope of blazar jet emission models. The broadband spectrum can be modeled with an emission mechanism commonly invoked for flat spectrum radio quasars (FSRQs), that is, inverse Compton scattering on an external soft photon field from the dust torus, also known as external Compton. The light curve and SED phenomenology is consistent with an interpretation of a blob propagating through a helical structured magnetic field and eventually crossing a standing shock in the jet, a scenario typically applied to FSRQs and low-frequency peaked BL Lac objects (LBL).

Original languageEnglish
Article numberA30
JournalAstronomy and Astrophysics
Volume617
DOIs
Publication statusPublished - 1 Sep 2018

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telescopes
spectral energy distribution
radio
rays
radio spectra
optical polarization
energy
quasars
flares
light curve
polarization
broadband
phenomenology
dust
shock
scattering
detection
low frequencies
magnetic field
photons

Scopus subject areas

  • Astronomy and Astrophysics

Cite this

@article{5d200b89de0842fc8856d5761e344384,
title = "Detection of the blazar S4 0954+65 at very-high-energy with the MAGIC telescopes during an exceptionally high optical state",
abstract = "Aims. The very high energy (VHE ≥ 100 GeV) -ray MAGIC observations of the blazar S4 0954+65, were triggered by an exceptionally high flux state of emission in the optical. This blazar has a disputed redshift of z = 0.368 or z ≥ 0.45 and an uncertain classification among blazar subclasses. The exceptional source state described here makes for an excellent opportunity to understand physical processes in the jet of S4 0954+65 and thus contribute to its classification. Methods. We investigated the multiwavelength (MWL) light curve and spectral energy distribution (SED) of the S4 0954+65 blazar during an enhanced state in February 2015 and have put it in context with possible emission scenarios. We collected photometric data in radio, optical, X-ray, and γ-ray. We studied both the optical polarization and the inner parsec-scale jet behavior with 43 GHz data. Results. Observations with the MAGIC telescopes led to the first detection of S4 0954+65 at VHE. Simultaneous data with Fermi-LAT at high energy γ-ray(HE, 100 MeV < E < 100 GeV) also show a period of increased activity. Imaging at 43 GHz reveals the emergence of a new feature in the radio jet in coincidence with the VHE flare. Simultaneous monitoring of the optical polarization angle reveals a rotation of approximately 100. Conclusions. The high emission state during the flare allows us to compile the simultaneous broadband SED and to characterize it in the scope of blazar jet emission models. The broadband spectrum can be modeled with an emission mechanism commonly invoked for flat spectrum radio quasars (FSRQs), that is, inverse Compton scattering on an external soft photon field from the dust torus, also known as external Compton. The light curve and SED phenomenology is consistent with an interpretation of a blob propagating through a helical structured magnetic field and eventually crossing a standing shock in the jet, a scenario typically applied to FSRQs and low-frequency peaked BL Lac objects (LBL).",
keywords = "BL Lacertae objects: individual: S4 0954+65, Galaxies: active, Gamma rays: galaxies",
author = "{MAGIC Collaboration} and {Fermi-LAT Collaboration} and Ahnen, {M. L.} and S. Ansoldi and Antonelli, {L. A.} and C. Arcaro and D. Baack and A. Babić and B. Banerjee and P. Bangale and {Barres De Almeida}, U. and Barrio, {J. A.} and W. Bednarek and E. Bernardini and Berse, {R. Ch} and A. Berti and W. Bhattacharyya and A. Biland and O. Blanch and G. Bonnoli and R. Carosi and A. Carosi and G. Ceribella and A. Chatterjee and Colak, {S. M.} and P. Colin and E. Colombo and Contreras, {J. L.} and J. Cortina and S. Covino and P. Cumani and {Da Vela}, P. and F. Dazzi and {De Angelis}, A. and {De Lotto}, B. and M. Delfino and J. Delgado and {Di Pierro}, F. and A. Dom{\'i}nguez and {Dominis Prester}, D. and D. Dorner and M. Doro and S. Einecke and Jorstad, {S. G.} and Larionov, {V. M.} and Grishina, {T. S.} and Kopatskaya, {E. N.} and Larionova, {L. V.} and Morozova, {D. A.} and Savchenko, {S. S.} and Troitsky, {I. S.} and Vasilyev, {A. A.} and Троицкая, {Юлия Вячеславовна}",
year = "2018",
month = "9",
day = "1",
doi = "10.1051/0004-6361/201832624",
language = "English",
volume = "617",
journal = "ASTRONOMY & ASTROPHYSICS",
issn = "0004-6361",
publisher = "EDP Sciences",

}

TY - JOUR

T1 - Detection of the blazar S4 0954+65 at very-high-energy with the MAGIC telescopes during an exceptionally high optical state

AU - MAGIC Collaboration

AU - Fermi-LAT Collaboration

AU - Ahnen, M. L.

AU - Ansoldi, S.

AU - Antonelli, L. A.

AU - Arcaro, C.

AU - Baack, D.

AU - Babić, A.

AU - Banerjee, B.

AU - Bangale, P.

AU - Barres De Almeida, U.

AU - Barrio, J. A.

AU - Bednarek, W.

AU - Bernardini, E.

AU - Berse, R. Ch

AU - Berti, A.

AU - Bhattacharyya, W.

AU - Biland, A.

AU - Blanch, O.

AU - Bonnoli, G.

AU - Carosi, R.

AU - Carosi, A.

AU - Ceribella, G.

AU - Chatterjee, A.

AU - Colak, S. M.

AU - Colin, P.

AU - Colombo, E.

AU - Contreras, J. L.

AU - Cortina, J.

AU - Covino, S.

AU - Cumani, P.

AU - Da Vela, P.

AU - Dazzi, F.

AU - De Angelis, A.

AU - De Lotto, B.

AU - Delfino, M.

AU - Delgado, J.

AU - Di Pierro, F.

AU - Domínguez, A.

AU - Dominis Prester, D.

AU - Dorner, D.

AU - Doro, M.

AU - Einecke, S.

AU - Jorstad, S. G.

AU - Larionov, V. M.

AU - Grishina, T. S.

AU - Kopatskaya, E. N.

AU - Larionova, L. V.

AU - Morozova, D. A.

AU - Savchenko, S. S.

AU - Troitsky, I. S.

AU - Vasilyev, A. A.

AU - Троицкая, Юлия Вячеславовна

PY - 2018/9/1

Y1 - 2018/9/1

N2 - Aims. The very high energy (VHE ≥ 100 GeV) -ray MAGIC observations of the blazar S4 0954+65, were triggered by an exceptionally high flux state of emission in the optical. This blazar has a disputed redshift of z = 0.368 or z ≥ 0.45 and an uncertain classification among blazar subclasses. The exceptional source state described here makes for an excellent opportunity to understand physical processes in the jet of S4 0954+65 and thus contribute to its classification. Methods. We investigated the multiwavelength (MWL) light curve and spectral energy distribution (SED) of the S4 0954+65 blazar during an enhanced state in February 2015 and have put it in context with possible emission scenarios. We collected photometric data in radio, optical, X-ray, and γ-ray. We studied both the optical polarization and the inner parsec-scale jet behavior with 43 GHz data. Results. Observations with the MAGIC telescopes led to the first detection of S4 0954+65 at VHE. Simultaneous data with Fermi-LAT at high energy γ-ray(HE, 100 MeV < E < 100 GeV) also show a period of increased activity. Imaging at 43 GHz reveals the emergence of a new feature in the radio jet in coincidence with the VHE flare. Simultaneous monitoring of the optical polarization angle reveals a rotation of approximately 100. Conclusions. The high emission state during the flare allows us to compile the simultaneous broadband SED and to characterize it in the scope of blazar jet emission models. The broadband spectrum can be modeled with an emission mechanism commonly invoked for flat spectrum radio quasars (FSRQs), that is, inverse Compton scattering on an external soft photon field from the dust torus, also known as external Compton. The light curve and SED phenomenology is consistent with an interpretation of a blob propagating through a helical structured magnetic field and eventually crossing a standing shock in the jet, a scenario typically applied to FSRQs and low-frequency peaked BL Lac objects (LBL).

AB - Aims. The very high energy (VHE ≥ 100 GeV) -ray MAGIC observations of the blazar S4 0954+65, were triggered by an exceptionally high flux state of emission in the optical. This blazar has a disputed redshift of z = 0.368 or z ≥ 0.45 and an uncertain classification among blazar subclasses. The exceptional source state described here makes for an excellent opportunity to understand physical processes in the jet of S4 0954+65 and thus contribute to its classification. Methods. We investigated the multiwavelength (MWL) light curve and spectral energy distribution (SED) of the S4 0954+65 blazar during an enhanced state in February 2015 and have put it in context with possible emission scenarios. We collected photometric data in radio, optical, X-ray, and γ-ray. We studied both the optical polarization and the inner parsec-scale jet behavior with 43 GHz data. Results. Observations with the MAGIC telescopes led to the first detection of S4 0954+65 at VHE. Simultaneous data with Fermi-LAT at high energy γ-ray(HE, 100 MeV < E < 100 GeV) also show a period of increased activity. Imaging at 43 GHz reveals the emergence of a new feature in the radio jet in coincidence with the VHE flare. Simultaneous monitoring of the optical polarization angle reveals a rotation of approximately 100. Conclusions. The high emission state during the flare allows us to compile the simultaneous broadband SED and to characterize it in the scope of blazar jet emission models. The broadband spectrum can be modeled with an emission mechanism commonly invoked for flat spectrum radio quasars (FSRQs), that is, inverse Compton scattering on an external soft photon field from the dust torus, also known as external Compton. The light curve and SED phenomenology is consistent with an interpretation of a blob propagating through a helical structured magnetic field and eventually crossing a standing shock in the jet, a scenario typically applied to FSRQs and low-frequency peaked BL Lac objects (LBL).

KW - BL Lacertae objects: individual: S4 0954+65

KW - Galaxies: active

KW - Gamma rays: galaxies

UR - http://www.scopus.com/inward/record.url?scp=85053505295&partnerID=8YFLogxK

U2 - 10.1051/0004-6361/201832624

DO - 10.1051/0004-6361/201832624

M3 - Article

AN - SCOPUS:85053505295

VL - 617

JO - ASTRONOMY & ASTROPHYSICS

JF - ASTRONOMY & ASTROPHYSICS

SN - 0004-6361

M1 - A30

ER -