A SEARCH for SPECTRAL HYSTERESIS and ENERGY-DEPENDENT TIME LAGS from X-RAY and TeV GAMMA-RAY OBSERVATIONS of Mrk 421

A. U. Abeysekara, S. Archambault, A. Archer, W. Benbow, R. Bird, M. Buchovecky, J. H. Buckley, V. Bugaev, J. V. Cardenzana, M. Cerruti, X. Chen, L. Ciupik, M. P. Connolly, W. Cui, J. D. Eisch, A. Falcone, Q. Feng, J. P. Finley, H. Fleischhack, A. FlindersL. Fortson, A. Furniss, S. Griffin, M. H N Hakansson, D. Hanna, O. Hervet, J. Holder, T. B. Humensky, P. Kaaret, P. Kar, M. Kertzman, D. Kieda, M. Krause, S. Kumar, M. J. Lang, G. Maier, S. McArthur, A. McCann, K. Meagher, P. Moriarty, R. Mukherjee, D. Nieto, S. O R A Ong, A. N. Otte, N. Park, V. Pelassa, M. Pohl, A. Popkow, E. Pueschel, K. Ragan, P. T. Reynolds, G. T. Richards, E. Roache, I. Sadeh, M. Santander, G. H. Sembroski, K. Shahinyan, D. Staszak, I. Telezhinsky, J. V. Tucci, J. Tyler, S. P. Wakely, A. Weinstein, A. Wilhelm, D. A. Williams, M. L. Ahnen, S. Ansoldi, L. A. Antonelli, P. Antoranz, C. Arcaro, A. Babic, B. Banerjee, P. Bangale, U. Barres De Almeida, J. A. Barrio, J. Becerra González, W. Bednarek, E. Bernardini, A. Berti, B. Biasuzzi, A. Biland, O. Blanch, S. Bonnefoy, G. Bonnoli, F. Borracci, T. Bretz, R. Carosi, A. Carosi, A. Chatterjee, P. Colin, E. Colombo, J. L. Contreras, J. Cortina, S. Covino, P. Cumani, P. Da Vela, F. Dazzi, A. De Angelis, B. De Lotto, E. De Ona Wilhelmi, F. Di Pierro, M. Doert, A. Domínguez, D. Dominis Prester, D. Dorner, M. Doro, S. Einecke, D. Eisenacher Glawion, D. Elsaesser, M. Engelkemeier, V. Fallah Ramazani, A. Fernández-Barral, D. Fidalgo, M. V. Fonseca, L. Font, C. Fruck, D. Galindo, R. J García López, M. Garczarczyk, M. Gaug, P. Giammaria, N. Godinović, D. Gora, D. Guberman, D. Hadasch, A. Hahn, T. Hassan, M. Hayashida, J. Herrera, J. Hose, D. Hrupec, G. Hughes, W. Idec, K. Kodani, Y. Konno, H. Kubo, J. Kushida, D. Lelas, E. Lindfors, S. Lombardi, F. Longo, M. López, R. López-Coto, P. Majumdar, M. Makariev, K. Mallot, G. Maneva, M. Manganaro, K. Mannheim, L. Maraschi, B. Marcote, M. Mariotti, M. Martínez, D. Mazin, U. Menzel, R. Mirzoyan, A. Moralejo, E. Moretti, D. Nakajima, V. Neustroev, A. Niedzwiecki, M. Nievas Rosillo, K. Nilsson, K. Nishijima, K. Noda, L. Nogués, M. Nöthe, S. Paiano, J. Palacio, M. Palatiello, D. Paneque, R. Paoletti, J. M. Paredes, X. Paredes-Fortuny, G. Pedaletti, M. Peresano, L. Perri, M. Persic, J. Poutanen, P. G Prada Moroni, E. Prandini, I. Puljak, J. R. Garcia, I. Reichardt, W. Rhode, M. Ribó, J. Rico, T. Saito, K. Satalecka, S. Schroeder, T. Schweizer, S. N. Shore, A. Sillanp, J. Sitarek, I. Snidaric, D. Sobczynska, A. Stamerra, M. Strzys, T. Surić, L. Takalo, F. Tavecchio, P. Temnikov, T. Terzić, D. Tescaro, M. Teshima, D. F. Torres, N. Torres-Albà, T. Toyama, A. Treves, G. Vanzo, M. Vazquez Acosta, I. Vovk, J. E. Ward, M. Will, M. H. Wu, R. Zanin, T. Hovatta, I. De La Calle Perez, P. S. Smith, E. Racero, M. Baloković

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Blazars are variable emitters across all wavelengths over a wide range of timescales, from months down to minutes. It is therefore essential to observe blazars simultaneously at different wavelengths, especially in the X-ray and gamma-ray bands, where the broadband spectral energy distributions usually peak. In this work, we report on three "target-of-opportunity" observations of Mrk 421, one of the brightest TeV blazars, triggered by a strong flaring event at TeV energies in 2014. These observations feature long, continuous, and simultaneous exposures with XMM-Newton (covering the X-ray and optical/ultraviolet bands) and VERITAS (covering the TeV gamma-ray band), along with contemporaneous observations from other gamma-ray facilities (MAGIC and Fermi-Large Area Telescope) and a number of radio and optical facilities. Although neither rapid flares nor significant X-ray/TeV correlation are detected, these observations reveal subtle changes in the X-ray spectrum of the source over the course of a few days. We search the simultaneous X-ray and TeV data for spectral hysteresis patterns and time delays, which could provide insight into the emission mechanisms and the source properties (e.g., the radius of the emitting region, the strength of the magnetic field, and related timescales). The observed broadband spectra are consistent with a one-zone synchrotron self-Compton model. We find that the power spectral density distribution at 4 ×10-4 Hz from the X-ray data can be described by a power-law model with an index value between 1.2 and 1.8, and do not find evidence for a steepening of the power spectral index (often associated with a characteristic length scale) compared to the previously reported values at lower frequencies.

Original languageEnglish (US)
Article number2
JournalAstrophysical Journal
Volume834
Issue number1
DOIs
StatePublished - Jan 1 2017

Fingerprint

blazars
x rays
gamma rays
coverings
broadband
wavelength
timescale
XMM-Newton telescope
spectral energy distribution
hysteresis
wavelengths
newton
flares
energy
density distribution
synchrotrons
power law
emitters
time lag
telescopes

Keywords

  • BL Lacertae objects: individual (Markarian 421)
  • galaxies: active
  • gamma rays: general
  • radiation mechanisms: non-thermal

Cite this

Abeysekara, A. U., Archambault, S., Archer, A., Benbow, W., Bird, R., Buchovecky, M., ... Baloković, M. (2017). A SEARCH for SPECTRAL HYSTERESIS and ENERGY-DEPENDENT TIME LAGS from X-RAY and TeV GAMMA-RAY OBSERVATIONS of Mrk 421. Astrophysical Journal, 834(1), [2]. https://doi.org/10.3847/1538-4357/834/1/2

A SEARCH for SPECTRAL HYSTERESIS and ENERGY-DEPENDENT TIME LAGS from X-RAY and TeV GAMMA-RAY OBSERVATIONS of Mrk 421. / Abeysekara, A. U.; Archambault, S.; Archer, A.; Benbow, W.; Bird, R.; Buchovecky, M.; Buckley, J. H.; Bugaev, V.; Cardenzana, J. V.; Cerruti, M.; Chen, X.; Ciupik, L.; Connolly, M. P.; Cui, W.; Eisch, J. D.; Falcone, A.; Feng, Q.; Finley, J. P.; Fleischhack, H.; Flinders, A.; Fortson, L.; Furniss, A.; Griffin, S.; Hakansson, M. H N; Hanna, D.; Hervet, O.; Holder, J.; Humensky, T. B.; Kaaret, P.; Kar, P.; Kertzman, M.; Kieda, D.; Krause, M.; Kumar, S.; Lang, M. J.; Maier, G.; McArthur, S.; McCann, A.; Meagher, K.; Moriarty, P.; Mukherjee, R.; Nieto, D.; Ong, S. O R A; Otte, A. N.; Park, N.; Pelassa, V.; Pohl, M.; Popkow, A.; Pueschel, E.; Ragan, K.; Reynolds, P. T.; Richards, G. T.; Roache, E.; Sadeh, I.; Santander, M.; Sembroski, G. H.; Shahinyan, K.; Staszak, D.; Telezhinsky, I.; Tucci, J. V.; Tyler, J.; Wakely, S. P.; Weinstein, A.; Wilhelm, A.; Williams, D. A.; Ahnen, M. L.; Ansoldi, S.; Antonelli, L. A.; Antoranz, P.; Arcaro, C.; Babic, A.; Banerjee, B.; Bangale, P.; Almeida, U. Barres De; Barrio, J. A.; González, J. Becerra; Bednarek, W.; Bernardini, E.; Berti, A.; Biasuzzi, B.; Biland, A.; Blanch, O.; Bonnefoy, S.; Bonnoli, G.; Borracci, F.; Bretz, T.; Carosi, R.; Carosi, A.; Chatterjee, A.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; Cumani, P.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Lotto, B.; De Ona Wilhelmi, E.; Di Pierro, F.; Doert, M.; Domínguez, A.; Prester, D. Dominis; Dorner, D.; Doro, M.; Einecke, S.; Glawion, D. Eisenacher; Elsaesser, D.; Engelkemeier, M.; Ramazani, V. Fallah; Fernández-Barral, A.; Fidalgo, D.; Fonseca, M. V.; Font, L.; Fruck, C.; Galindo, D.; López, R. J García; Garczarczyk, M.; Gaug, M.; Giammaria, P.; Godinović, N.; Gora, D.; Guberman, D.; Hadasch, D.; Hahn, A.; Hassan, T.; Hayashida, M.; Herrera, J.; Hose, J.; Hrupec, D.; Hughes, G.; Idec, W.; Kodani, K.; Konno, Y.; Kubo, H.; Kushida, J.; Lelas, D.; Lindfors, E.; Lombardi, S.; Longo, F.; López, M.; López-Coto, R.; Majumdar, P.; Makariev, M.; Mallot, K.; Maneva, G.; Manganaro, M.; Mannheim, K.; Maraschi, L.; Marcote, B.; Mariotti, M.; Martínez, M.; Mazin, D.; Menzel, U.; Mirzoyan, R.; Moralejo, A.; Moretti, E.; Nakajima, D.; Neustroev, V.; Niedzwiecki, A.; Rosillo, M. Nievas; Nilsson, K.; Nishijima, K.; Noda, K.; Nogués, L.; Nöthe, M.; Paiano, S.; Palacio, J.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Paredes-Fortuny, X.; Pedaletti, G.; Peresano, M.; Perri, L.; Persic, M.; Poutanen, J.; Moroni, P. G Prada; Prandini, E.; Puljak, I.; Garcia, J. R.; Reichardt, I.; Rhode, W.; Ribó, M.; Rico, J.; Saito, T.; Satalecka, K.; Schroeder, S.; Schweizer, T.; Shore, S. N.; Sillanp, A.; Sitarek, J.; Snidaric, I.; Sobczynska, D.; Stamerra, A.; Strzys, M.; Surić, T.; Takalo, L.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Torres, D. F.; Torres-Albà, N.; Toyama, T.; Treves, A.; Vanzo, G.; Acosta, M. Vazquez; Vovk, I.; Ward, J. E.; Will, M.; Wu, M. H.; Zanin, R.; Hovatta, T.; De La Calle Perez, I.; Smith, P. S.; Racero, E.; Baloković, M.

In: Astrophysical Journal, Vol. 834, No. 1, 2, 01.01.2017.

Research output: Contribution to journalArticle

Abeysekara, AU, Archambault, S, Archer, A, Benbow, W, Bird, R, Buchovecky, M, Buckley, JH, Bugaev, V, Cardenzana, JV, Cerruti, M, Chen, X, Ciupik, L, Connolly, MP, Cui, W, Eisch, JD, Falcone, A, Feng, Q, Finley, JP, Fleischhack, H, Flinders, A, Fortson, L, Furniss, A, Griffin, S, Hakansson, MHN, Hanna, D, Hervet, O, Holder, J, Humensky, TB, Kaaret, P, Kar, P, Kertzman, M, Kieda, D, Krause, M, Kumar, S, Lang, MJ, Maier, G, McArthur, S, McCann, A, Meagher, K, Moriarty, P, Mukherjee, R, Nieto, D, Ong, SORA, Otte, AN, Park, N, Pelassa, V, Pohl, M, Popkow, A, Pueschel, E, Ragan, K, Reynolds, PT, Richards, GT, Roache, E, Sadeh, I, Santander, M, Sembroski, GH, Shahinyan, K, Staszak, D, Telezhinsky, I, Tucci, JV, Tyler, J, Wakely, SP, Weinstein, A, Wilhelm, A, Williams, DA, Ahnen, ML, Ansoldi, S, Antonelli, LA, Antoranz, P, Arcaro, C, Babic, A, Banerjee, B, Bangale, P, Almeida, UBD, Barrio, JA, González, JB, Bednarek, W, Bernardini, E, Berti, A, Biasuzzi, B, Biland, A, Blanch, O, Bonnefoy, S, Bonnoli, G, Borracci, F, Bretz, T, Carosi, R, Carosi, A, Chatterjee, A, Colin, P, Colombo, E, Contreras, JL, Cortina, J, Covino, S, Cumani, P, Da Vela, P, Dazzi, F, De Angelis, A, De Lotto, B, De Ona Wilhelmi, E, Di Pierro, F, Doert, M, Domínguez, A, Prester, DD, Dorner, D, Doro, M, Einecke, S, Glawion, DE, Elsaesser, D, Engelkemeier, M, Ramazani, VF, Fernández-Barral, A, Fidalgo, D, Fonseca, MV, Font, L, Fruck, C, Galindo, D, López, RJG, Garczarczyk, M, Gaug, M, Giammaria, P, Godinović, N, Gora, D, Guberman, D, Hadasch, D, Hahn, A, Hassan, T, Hayashida, M, Herrera, J, Hose, J, Hrupec, D, Hughes, G, Idec, W, Kodani, K, Konno, Y, Kubo, H, Kushida, J, Lelas, D, Lindfors, E, Lombardi, S, Longo, F, López, M, López-Coto, R, Majumdar, P, Makariev, M, Mallot, K, Maneva, G, Manganaro, M, Mannheim, K, Maraschi, L, Marcote, B, Mariotti, M, Martínez, M, Mazin, D, Menzel, U, Mirzoyan, R, Moralejo, A, Moretti, E, Nakajima, D, Neustroev, V, Niedzwiecki, A, Rosillo, MN, Nilsson, K, Nishijima, K, Noda, K, Nogués, L, Nöthe, M, Paiano, S, Palacio, J, Palatiello, M, Paneque, D, Paoletti, R, Paredes, JM, Paredes-Fortuny, X, Pedaletti, G, Peresano, M, Perri, L, Persic, M, Poutanen, J, Moroni, PGP, Prandini, E, Puljak, I, Garcia, JR, Reichardt, I, Rhode, W, Ribó, M, Rico, J, Saito, T, Satalecka, K, Schroeder, S, Schweizer, T, Shore, SN, Sillanp, A, Sitarek, J, Snidaric, I, Sobczynska, D, Stamerra, A, Strzys, M, Surić, T, Takalo, L, Tavecchio, F, Temnikov, P, Terzić, T, Tescaro, D, Teshima, M, Torres, DF, Torres-Albà, N, Toyama, T, Treves, A, Vanzo, G, Acosta, MV, Vovk, I, Ward, JE, Will, M, Wu, MH, Zanin, R, Hovatta, T, De La Calle Perez, I, Smith, PS, Racero, E & Baloković, M 2017, 'A SEARCH for SPECTRAL HYSTERESIS and ENERGY-DEPENDENT TIME LAGS from X-RAY and TeV GAMMA-RAY OBSERVATIONS of Mrk 421', Astrophysical Journal, vol. 834, no. 1, 2. https://doi.org/10.3847/1538-4357/834/1/2
Abeysekara, A. U. ; Archambault, S. ; Archer, A. ; Benbow, W. ; Bird, R. ; Buchovecky, M. ; Buckley, J. H. ; Bugaev, V. ; Cardenzana, J. V. ; Cerruti, M. ; Chen, X. ; Ciupik, L. ; Connolly, M. P. ; Cui, W. ; Eisch, J. D. ; Falcone, A. ; Feng, Q. ; Finley, J. P. ; Fleischhack, H. ; Flinders, A. ; Fortson, L. ; Furniss, A. ; Griffin, S. ; Hakansson, M. H N ; Hanna, D. ; Hervet, O. ; Holder, J. ; Humensky, T. B. ; Kaaret, P. ; Kar, P. ; Kertzman, M. ; Kieda, D. ; Krause, M. ; Kumar, S. ; Lang, M. J. ; Maier, G. ; McArthur, S. ; McCann, A. ; Meagher, K. ; Moriarty, P. ; Mukherjee, R. ; Nieto, D. ; Ong, S. O R A ; Otte, A. N. ; Park, N. ; Pelassa, V. ; Pohl, M. ; Popkow, A. ; Pueschel, E. ; Ragan, K. ; Reynolds, P. T. ; Richards, G. T. ; Roache, E. ; Sadeh, I. ; Santander, M. ; Sembroski, G. H. ; Shahinyan, K. ; Staszak, D. ; Telezhinsky, I. ; Tucci, J. V. ; Tyler, J. ; Wakely, S. P. ; Weinstein, A. ; Wilhelm, A. ; Williams, D. A. ; Ahnen, M. L. ; Ansoldi, S. ; Antonelli, L. A. ; Antoranz, P. ; Arcaro, C. ; Babic, A. ; Banerjee, B. ; Bangale, P. ; Almeida, U. Barres De ; Barrio, J. A. ; González, J. Becerra ; Bednarek, W. ; Bernardini, E. ; Berti, A. ; Biasuzzi, B. ; Biland, A. ; Blanch, O. ; Bonnefoy, S. ; Bonnoli, G. ; Borracci, F. ; Bretz, T. ; Carosi, R. ; Carosi, A. ; Chatterjee, A. ; Colin, P. ; Colombo, E. ; Contreras, J. L. ; Cortina, J. ; Covino, S. ; Cumani, P. ; Da Vela, P. ; Dazzi, F. ; De Angelis, A. ; De Lotto, B. ; De Ona Wilhelmi, E. ; Di Pierro, F. ; Doert, M. ; Domínguez, A. ; Prester, D. Dominis ; Dorner, D. ; Doro, M. ; Einecke, S. ; Glawion, D. Eisenacher ; Elsaesser, D. ; Engelkemeier, M. ; Ramazani, V. Fallah ; Fernández-Barral, A. ; Fidalgo, D. ; Fonseca, M. V. ; Font, L. ; Fruck, C. ; Galindo, D. ; López, R. J García ; Garczarczyk, M. ; Gaug, M. ; Giammaria, P. ; Godinović, N. ; Gora, D. ; Guberman, D. ; Hadasch, D. ; Hahn, A. ; Hassan, T. ; Hayashida, M. ; Herrera, J. ; Hose, J. ; Hrupec, D. ; Hughes, G. ; Idec, W. ; Kodani, K. ; Konno, Y. ; Kubo, H. ; Kushida, J. ; Lelas, D. ; Lindfors, E. ; Lombardi, S. ; Longo, F. ; López, M. ; López-Coto, R. ; Majumdar, P. ; Makariev, M. ; Mallot, K. ; Maneva, G. ; Manganaro, M. ; Mannheim, K. ; Maraschi, L. ; Marcote, B. ; Mariotti, M. ; Martínez, M. ; Mazin, D. ; Menzel, U. ; Mirzoyan, R. ; Moralejo, A. ; Moretti, E. ; Nakajima, D. ; Neustroev, V. ; Niedzwiecki, A. ; Rosillo, M. Nievas ; Nilsson, K. ; Nishijima, K. ; Noda, K. ; Nogués, L. ; Nöthe, M. ; Paiano, S. ; Palacio, J. ; Palatiello, M. ; Paneque, D. ; Paoletti, R. ; Paredes, J. M. ; Paredes-Fortuny, X. ; Pedaletti, G. ; Peresano, M. ; Perri, L. ; Persic, M. ; Poutanen, J. ; Moroni, P. G Prada ; Prandini, E. ; Puljak, I. ; Garcia, J. R. ; Reichardt, I. ; Rhode, W. ; Ribó, M. ; Rico, J. ; Saito, T. ; Satalecka, K. ; Schroeder, S. ; Schweizer, T. ; Shore, S. N. ; Sillanp, A. ; Sitarek, J. ; Snidaric, I. ; Sobczynska, D. ; Stamerra, A. ; Strzys, M. ; Surić, T. ; Takalo, L. ; Tavecchio, F. ; Temnikov, P. ; Terzić, T. ; Tescaro, D. ; Teshima, M. ; Torres, D. F. ; Torres-Albà, N. ; Toyama, T. ; Treves, A. ; Vanzo, G. ; Acosta, M. Vazquez ; Vovk, I. ; Ward, J. E. ; Will, M. ; Wu, M. H. ; Zanin, R. ; Hovatta, T. ; De La Calle Perez, I. ; Smith, P. S. ; Racero, E. ; Baloković, M. / A SEARCH for SPECTRAL HYSTERESIS and ENERGY-DEPENDENT TIME LAGS from X-RAY and TeV GAMMA-RAY OBSERVATIONS of Mrk 421. In: Astrophysical Journal. 2017 ; Vol. 834, No. 1.
@article{473dbdf0e4c44fedb25d05f5e2d31147,
title = "A SEARCH for SPECTRAL HYSTERESIS and ENERGY-DEPENDENT TIME LAGS from X-RAY and TeV GAMMA-RAY OBSERVATIONS of Mrk 421",
abstract = "Blazars are variable emitters across all wavelengths over a wide range of timescales, from months down to minutes. It is therefore essential to observe blazars simultaneously at different wavelengths, especially in the X-ray and gamma-ray bands, where the broadband spectral energy distributions usually peak. In this work, we report on three {"}target-of-opportunity{"} observations of Mrk 421, one of the brightest TeV blazars, triggered by a strong flaring event at TeV energies in 2014. These observations feature long, continuous, and simultaneous exposures with XMM-Newton (covering the X-ray and optical/ultraviolet bands) and VERITAS (covering the TeV gamma-ray band), along with contemporaneous observations from other gamma-ray facilities (MAGIC and Fermi-Large Area Telescope) and a number of radio and optical facilities. Although neither rapid flares nor significant X-ray/TeV correlation are detected, these observations reveal subtle changes in the X-ray spectrum of the source over the course of a few days. We search the simultaneous X-ray and TeV data for spectral hysteresis patterns and time delays, which could provide insight into the emission mechanisms and the source properties (e.g., the radius of the emitting region, the strength of the magnetic field, and related timescales). The observed broadband spectra are consistent with a one-zone synchrotron self-Compton model. We find that the power spectral density distribution at 4 ×10-4 Hz from the X-ray data can be described by a power-law model with an index value between 1.2 and 1.8, and do not find evidence for a steepening of the power spectral index (often associated with a characteristic length scale) compared to the previously reported values at lower frequencies.",
keywords = "BL Lacertae objects: individual (Markarian 421), galaxies: active, gamma rays: general, radiation mechanisms: non-thermal",
author = "Abeysekara, {A. U.} and S. Archambault and A. Archer and W. Benbow and R. Bird and M. Buchovecky and Buckley, {J. H.} and V. Bugaev and Cardenzana, {J. V.} and M. Cerruti and X. Chen and L. Ciupik and Connolly, {M. P.} and W. Cui and Eisch, {J. D.} and A. Falcone and Q. Feng and Finley, {J. P.} and H. Fleischhack and A. Flinders and L. Fortson and A. Furniss and S. Griffin and Hakansson, {M. H N} and D. Hanna and O. Hervet and J. Holder and Humensky, {T. B.} and P. Kaaret and P. Kar and M. Kertzman and D. Kieda and M. Krause and S. Kumar and Lang, {M. J.} and G. Maier and S. McArthur and A. McCann and K. Meagher and P. Moriarty and R. Mukherjee and D. Nieto and Ong, {S. O R A} and Otte, {A. N.} and N. Park and V. Pelassa and M. Pohl and A. Popkow and E. Pueschel and K. Ragan and Reynolds, {P. T.} and Richards, {G. T.} and E. Roache and I. Sadeh and M. Santander and Sembroski, {G. H.} and K. Shahinyan and D. Staszak and I. Telezhinsky and Tucci, {J. V.} and J. Tyler and Wakely, {S. P.} and A. Weinstein and A. Wilhelm and Williams, {D. A.} and Ahnen, {M. L.} and S. Ansoldi and Antonelli, {L. A.} and P. Antoranz and C. Arcaro and A. Babic and B. Banerjee and P. Bangale and Almeida, {U. Barres De} and Barrio, {J. A.} and Gonz{\'a}lez, {J. Becerra} and W. Bednarek and E. Bernardini and A. Berti and B. Biasuzzi and A. Biland and O. Blanch and S. Bonnefoy and G. Bonnoli and F. Borracci and T. Bretz and R. Carosi and A. Carosi and A. Chatterjee 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 {De Ona Wilhelmi}, E. and {Di Pierro}, F. and M. Doert and A. Dom{\'i}nguez and Prester, {D. Dominis} and D. Dorner and M. Doro and S. Einecke and Glawion, {D. Eisenacher} and D. Elsaesser and M. Engelkemeier and Ramazani, {V. Fallah} and A. Fern{\'a}ndez-Barral and D. Fidalgo and Fonseca, {M. V.} and L. Font and C. Fruck and D. Galindo and L{\'o}pez, {R. J Garc{\'i}a} and M. Garczarczyk and M. Gaug and P. Giammaria and N. Godinović and D. Gora and D. Guberman and D. Hadasch and A. Hahn and T. Hassan and M. Hayashida and J. Herrera and J. Hose and D. Hrupec and G. Hughes and W. Idec and K. Kodani and Y. Konno and H. Kubo and J. Kushida and D. Lelas and E. Lindfors and S. Lombardi and F. Longo and M. L{\'o}pez and R. L{\'o}pez-Coto and P. Majumdar and M. Makariev and K. Mallot and G. Maneva and M. Manganaro and K. Mannheim and L. Maraschi and B. Marcote and M. Mariotti and M. Mart{\'i}nez and D. Mazin and U. Menzel and R. Mirzoyan and A. Moralejo and E. Moretti and D. Nakajima and V. Neustroev and A. Niedzwiecki and Rosillo, {M. Nievas} and K. Nilsson and K. Nishijima and K. Noda and L. Nogu{\'e}s and M. N{\"o}the and S. Paiano and J. Palacio and M. Palatiello and D. Paneque and R. Paoletti and Paredes, {J. M.} and X. Paredes-Fortuny and G. Pedaletti and M. Peresano and L. Perri and M. Persic and J. Poutanen and Moroni, {P. G Prada} and E. Prandini and I. Puljak and Garcia, {J. R.} and I. Reichardt and W. Rhode and M. Rib{\'o} and J. Rico and T. Saito and K. Satalecka and S. Schroeder and T. Schweizer and Shore, {S. N.} and A. Sillanp and J. Sitarek and I. Snidaric and D. Sobczynska and A. Stamerra and M. Strzys and T. Surić and L. Takalo and F. Tavecchio and P. Temnikov and T. Terzić and D. Tescaro and M. Teshima and Torres, {D. F.} and N. Torres-Alb{\`a} and T. Toyama and A. Treves and G. Vanzo and Acosta, {M. Vazquez} and I. Vovk and Ward, {J. E.} and M. Will and Wu, {M. H.} and R. Zanin and T. Hovatta and {De La Calle Perez}, I. and Smith, {P. S.} and E. Racero and M. Baloković",
year = "2017",
month = "1",
day = "1",
doi = "10.3847/1538-4357/834/1/2",
language = "English (US)",
volume = "834",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "1",

}

TY - JOUR

T1 - A SEARCH for SPECTRAL HYSTERESIS and ENERGY-DEPENDENT TIME LAGS from X-RAY and TeV GAMMA-RAY OBSERVATIONS of Mrk 421

AU - Abeysekara, A. U.

AU - Archambault, S.

AU - Archer, A.

AU - Benbow, W.

AU - Bird, R.

AU - Buchovecky, M.

AU - Buckley, J. H.

AU - Bugaev, V.

AU - Cardenzana, J. V.

AU - Cerruti, M.

AU - Chen, X.

AU - Ciupik, L.

AU - Connolly, M. P.

AU - Cui, W.

AU - Eisch, J. D.

AU - Falcone, A.

AU - Feng, Q.

AU - Finley, J. P.

AU - Fleischhack, H.

AU - Flinders, A.

AU - Fortson, L.

AU - Furniss, A.

AU - Griffin, S.

AU - Hakansson, M. H N

AU - Hanna, D.

AU - Hervet, O.

AU - Holder, J.

AU - Humensky, T. B.

AU - Kaaret, P.

AU - Kar, P.

AU - Kertzman, M.

AU - Kieda, D.

AU - Krause, M.

AU - Kumar, S.

AU - Lang, M. J.

AU - Maier, G.

AU - McArthur, S.

AU - McCann, A.

AU - Meagher, K.

AU - Moriarty, P.

AU - Mukherjee, R.

AU - Nieto, D.

AU - Ong, S. O R A

AU - Otte, A. N.

AU - Park, N.

AU - Pelassa, V.

AU - Pohl, M.

AU - Popkow, A.

AU - Pueschel, E.

AU - Ragan, K.

AU - Reynolds, P. T.

AU - Richards, G. T.

AU - Roache, E.

AU - Sadeh, I.

AU - Santander, M.

AU - Sembroski, G. H.

AU - Shahinyan, K.

AU - Staszak, D.

AU - Telezhinsky, I.

AU - Tucci, J. V.

AU - Tyler, J.

AU - Wakely, S. P.

AU - Weinstein, A.

AU - Wilhelm, A.

AU - Williams, D. A.

AU - Ahnen, M. L.

AU - Ansoldi, S.

AU - Antonelli, L. A.

AU - Antoranz, P.

AU - Arcaro, C.

AU - Babic, A.

AU - Banerjee, B.

AU - Bangale, P.

AU - Almeida, U. Barres De

AU - Barrio, J. A.

AU - González, J. Becerra

AU - Bednarek, W.

AU - Bernardini, E.

AU - Berti, A.

AU - Biasuzzi, B.

AU - Biland, A.

AU - Blanch, O.

AU - Bonnefoy, S.

AU - Bonnoli, G.

AU - Borracci, F.

AU - Bretz, T.

AU - Carosi, R.

AU - Carosi, A.

AU - Chatterjee, A.

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 - De Ona Wilhelmi, E.

AU - Di Pierro, F.

AU - Doert, M.

AU - Domínguez, A.

AU - Prester, D. Dominis

AU - Dorner, D.

AU - Doro, M.

AU - Einecke, S.

AU - Glawion, D. Eisenacher

AU - Elsaesser, D.

AU - Engelkemeier, M.

AU - Ramazani, V. Fallah

AU - Fernández-Barral, A.

AU - Fidalgo, D.

AU - Fonseca, M. V.

AU - Font, L.

AU - Fruck, C.

AU - Galindo, D.

AU - López, R. J García

AU - Garczarczyk, M.

AU - Gaug, M.

AU - Giammaria, P.

AU - Godinović, N.

AU - Gora, D.

AU - Guberman, D.

AU - Hadasch, D.

AU - Hahn, A.

AU - Hassan, T.

AU - Hayashida, M.

AU - Herrera, J.

AU - Hose, J.

AU - Hrupec, D.

AU - Hughes, G.

AU - Idec, W.

AU - Kodani, K.

AU - Konno, Y.

AU - Kubo, H.

AU - Kushida, J.

AU - Lelas, D.

AU - Lindfors, E.

AU - Lombardi, S.

AU - Longo, F.

AU - López, M.

AU - López-Coto, R.

AU - Majumdar, P.

AU - Makariev, M.

AU - Mallot, K.

AU - Maneva, G.

AU - Manganaro, M.

AU - Mannheim, K.

AU - Maraschi, L.

AU - Marcote, B.

AU - Mariotti, M.

AU - Martínez, M.

AU - Mazin, D.

AU - Menzel, U.

AU - Mirzoyan, R.

AU - Moralejo, A.

AU - Moretti, E.

AU - Nakajima, D.

AU - Neustroev, V.

AU - Niedzwiecki, A.

AU - Rosillo, M. Nievas

AU - Nilsson, K.

AU - Nishijima, K.

AU - Noda, K.

AU - Nogués, L.

AU - Nöthe, M.

AU - Paiano, S.

AU - Palacio, J.

AU - Palatiello, M.

AU - Paneque, D.

AU - Paoletti, R.

AU - Paredes, J. M.

AU - Paredes-Fortuny, X.

AU - Pedaletti, G.

AU - Peresano, M.

AU - Perri, L.

AU - Persic, M.

AU - Poutanen, J.

AU - Moroni, P. G Prada

AU - Prandini, E.

AU - Puljak, I.

AU - Garcia, J. R.

AU - Reichardt, I.

AU - Rhode, W.

AU - Ribó, M.

AU - Rico, J.

AU - Saito, T.

AU - Satalecka, K.

AU - Schroeder, S.

AU - Schweizer, T.

AU - Shore, S. N.

AU - Sillanp, A.

AU - Sitarek, J.

AU - Snidaric, I.

AU - Sobczynska, D.

AU - Stamerra, A.

AU - Strzys, M.

AU - Surić, T.

AU - Takalo, L.

AU - Tavecchio, F.

AU - Temnikov, P.

AU - Terzić, T.

AU - Tescaro, D.

AU - Teshima, M.

AU - Torres, D. F.

AU - Torres-Albà, N.

AU - Toyama, T.

AU - Treves, A.

AU - Vanzo, G.

AU - Acosta, M. Vazquez

AU - Vovk, I.

AU - Ward, J. E.

AU - Will, M.

AU - Wu, M. H.

AU - Zanin, R.

AU - Hovatta, T.

AU - De La Calle Perez, I.

AU - Smith, P. S.

AU - Racero, E.

AU - Baloković, M.

PY - 2017/1/1

Y1 - 2017/1/1

N2 - Blazars are variable emitters across all wavelengths over a wide range of timescales, from months down to minutes. It is therefore essential to observe blazars simultaneously at different wavelengths, especially in the X-ray and gamma-ray bands, where the broadband spectral energy distributions usually peak. In this work, we report on three "target-of-opportunity" observations of Mrk 421, one of the brightest TeV blazars, triggered by a strong flaring event at TeV energies in 2014. These observations feature long, continuous, and simultaneous exposures with XMM-Newton (covering the X-ray and optical/ultraviolet bands) and VERITAS (covering the TeV gamma-ray band), along with contemporaneous observations from other gamma-ray facilities (MAGIC and Fermi-Large Area Telescope) and a number of radio and optical facilities. Although neither rapid flares nor significant X-ray/TeV correlation are detected, these observations reveal subtle changes in the X-ray spectrum of the source over the course of a few days. We search the simultaneous X-ray and TeV data for spectral hysteresis patterns and time delays, which could provide insight into the emission mechanisms and the source properties (e.g., the radius of the emitting region, the strength of the magnetic field, and related timescales). The observed broadband spectra are consistent with a one-zone synchrotron self-Compton model. We find that the power spectral density distribution at 4 ×10-4 Hz from the X-ray data can be described by a power-law model with an index value between 1.2 and 1.8, and do not find evidence for a steepening of the power spectral index (often associated with a characteristic length scale) compared to the previously reported values at lower frequencies.

AB - Blazars are variable emitters across all wavelengths over a wide range of timescales, from months down to minutes. It is therefore essential to observe blazars simultaneously at different wavelengths, especially in the X-ray and gamma-ray bands, where the broadband spectral energy distributions usually peak. In this work, we report on three "target-of-opportunity" observations of Mrk 421, one of the brightest TeV blazars, triggered by a strong flaring event at TeV energies in 2014. These observations feature long, continuous, and simultaneous exposures with XMM-Newton (covering the X-ray and optical/ultraviolet bands) and VERITAS (covering the TeV gamma-ray band), along with contemporaneous observations from other gamma-ray facilities (MAGIC and Fermi-Large Area Telescope) and a number of radio and optical facilities. Although neither rapid flares nor significant X-ray/TeV correlation are detected, these observations reveal subtle changes in the X-ray spectrum of the source over the course of a few days. We search the simultaneous X-ray and TeV data for spectral hysteresis patterns and time delays, which could provide insight into the emission mechanisms and the source properties (e.g., the radius of the emitting region, the strength of the magnetic field, and related timescales). The observed broadband spectra are consistent with a one-zone synchrotron self-Compton model. We find that the power spectral density distribution at 4 ×10-4 Hz from the X-ray data can be described by a power-law model with an index value between 1.2 and 1.8, and do not find evidence for a steepening of the power spectral index (often associated with a characteristic length scale) compared to the previously reported values at lower frequencies.

KW - BL Lacertae objects: individual (Markarian 421)

KW - galaxies: active

KW - gamma rays: general

KW - radiation mechanisms: non-thermal

UR - http://www.scopus.com/inward/record.url?scp=85010190196&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85010190196&partnerID=8YFLogxK

U2 - 10.3847/1538-4357/834/1/2

DO - 10.3847/1538-4357/834/1/2

M3 - Article

AN - SCOPUS:85010190196

VL - 834

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1

M1 - 2

ER -