The 0.1-100 keV spectrum and variability of Mrk 421 in a high state

Malizia, A.; Capalbi, M.; Fiore, F.; Giommi, P.; Gandolfi, G.; Tesseri, A.; Antonelli, L. A.; Butler, R. C.; Celidonio, G.; Coletta, Alessandro; Ciolo, L. di; Müller, J.; Piro, L.; Rebecchi, S.; Ricci, Davide; Ricci, R.; Smith, Mike; Torroni, V.

doi:10.1046/j.1365-8711.2000.03106.x

Cited by 25 publications

(10 citation statements)

References 19 publications

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“…We observed and detected Mkn 421 with the INTEGRAL instruments IBIS/ISGRI, JEM-X and OMC during a high state that followed the detection of a powerful TeV energy outburst (Cortina & Holder 2013) that was likely subsiding during our observation. The X-ray flux is among the highest previously recorded for this object by INTEGRAL itself and other satellites (Malizia et al 2000;Donnarumma et al 2009;Abdo et al 2011). The optical state is also very bright, with few precedents (Tosti et al 1998).…”

Section: Discussionmentioning

confidence: 69%

“…This synchrotron self-Compton component peaks at very high energies, making this blazar a strong TeV emitter, although the TeV spectrum is often heavily suppressed by the Klein-Nishina effect (Maraschi et al 1999;Fossati et al 2008;Mankuzhiyil et al 2011). Mkn 421 was the target of many multiwavelength campaigns involving high energy satellites, Cherenkov telescopes and ground-based optical and radio facilities (Takahashi et al 1996;Maraschi et al 1999;Malizia et al 2000;Fossati et al 2000a,b;Brinkmann et al 2001;Albert et al 2007a;Lichti et al 2008;Fossati et al 2008;Donnarumma et al 2009;Acciari et al 2009;Ushio et al 2009;Tramacere et al 2009;Horan et al 2009;Aleksić et al 2010;Isobe et al 2010;Abdo et al 2011;Acciari et al 2011;Barres de Almeida 2011;Aleksić et al 2012;Shukla et al 2012). The variations at X-ray and TeV frequencies are often very well correlated with no measurable delay (Maraschi et al 1999), but complex intra-day X-ray variability is present (e.g.…”

Section: Introductionmentioning

confidence: 99%

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An active state of the BL Lacertae object Markarian 421 detected by INTEGRAL in April 2013

Pian¹,

Türler²,

Fiocchi³

et al. 2014

A&A

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Aims. Multiwavelength variability of blazars offers indirect, but very effective, insight into their powerful engines and on the mechanisms through which energy is propagated from the centre down the jet. The BL Lac object Mkn 421 is a TeV emitter, a bright blazar at all wavelengths, and therefore an excellent target for variability studies. Methods. We activated INTEGRAL observations of Mkn 421 in an active state on 16-21 April 2013, and complemented them with Fermi-LAT data. Results. We obtained well sampled optical, soft, and hard X-ray light curves that show the presence of two flares and time-resolved spectra in the 3.5-60 keV (JEM-X and IBIS/ISGRI) and 0.1-100 GeV (Fermi-LAT) ranges. The average flux in the 20-100 keV range is 9.1 × 10 −11 erg s −1 cm −2 (∼4.5 mCrab) and the nuclear average apparent magnitude, corrected for Galactic extinction, is V 12.2. In the time-resolved X-ray spectra, which are described by broken power laws and, marginally better, by log-parabolic laws, we see a hardening that correlates with flux increase, as expected in refreshed energy injections in a population of electrons that later cool via synchrotron radiation. The hardness ratios between the JEM-X fluxes in two different bands and between the JEM-X and IBIS/ISGRI fluxes confirm this trend. During the observation, the variability level increases monotonically from the optical to the hard X-rays, while the large LAT errors do not allow a significant assessment of the MeV-GeV variability. The cross-correlation analysis during the onset of the most prominent flare suggests a monotonically increasing delay of the lower frequency emission with respect to that at higher frequency, with a maximum time-lag of about 70 min, that is however not well constrained. The spectral energy distributions from the optical to the TeV domain were compared to homogeneous models of blazar emission based on synchrotron radiation and synchrotron self-Compton scattering. They represent a satisfactory description, except in the state corresponding to the LAT softest spectrum and highest flux. Conclusions. Multiwavelength variability of Mkn 421 can be very complex, with patterns changing from epoch to epoch down to intra-day timescales, depending on the emission state. This makes accurate monitoring of this source during bright hard X-ray states necessary and calls for the elaboration of multicomponent, multizone, time-dependent models.

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Section: Discussionmentioning

confidence: 69%

Section: Introductionmentioning

confidence: 99%

An active state of the BL Lacertae object Markarian 421 detected by INTEGRAL in April 2013

Pian¹,

Türler²,

Fiocchi³

et al. 2014

A&A

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“…3 and 4 in Kirk et al 1998). The loop path has been frequently reported in X-rays (e.g., Sembay et al 1993;Takahashi et al 1996;Kataoka et al 1999;Zhang et al 1999Zhang et al , 2002Malizia et al 2000;Ravasio et al 2004) and, in one case, in the infrared (Gear et al 1986). In the optical regime, Xilouris et al (2006) have reported a similar pattern, and Wu et al (2007a) showed a clockwise loop with the nightly means of magnitudes and colors.…”

Section: Color Evolution During Flaresmentioning

confidence: 74%

SIMULTANEOUSB′V′R′ MONITORING OF BL LACERTAE OBJECT S5 0716+714 AND DETECTION OF INTER-BAND TIME DELAY

Böttcher

et al. 2012

The Astronomical Journal

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We present the results of our optical monitoring of the BL Lac object S5 0716+714 on seven nights in 2006 December. The monitoring was carried out simultaneously at three optical wavelengths with a novel photometric system. The object did not show large-amplitude internight variations during this period. Intranight variations were observed on four nights and probably on one more. Strong bluer-when-brighter chromatism was detected on both intranight and internight timescales. The intranight variation amplitude decreases in the wavelength sequence of B ′ , R ′ , and V ′ . Cross correlation analyses revealed that the variability at the B ′ and V ′ bands lead that at the R ′ band by about 30 minutes on one night.

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“…In other regime like gamma-ray and X-ray, the loop path has been reported frequently (e.g. Sembay et al 1993;Takahashi et al 1996;Malizia et al 2000;Albani et al 2007;Kataoka et al 2010;Zhang et al 1999;Zhang et al 2002).…”

Section: Color Behavior and Spectral Hysteresismentioning

confidence: 99%

Simultaneous optical monitoring of BL Lacertae object S5 0716+714 with high temporal resolution

Man¹,

Zhang²,

Wu³

et al. 2016

Mon. Not. R. Astron. Soc.

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We have monitored the BL Lacertae object S5 0716+714 simultaneously in the B, R and I bands on three nights in November 2014. The average time resolution is quite high (73s, 34s, 58s for the filters B, R and I), which can help us trace the profile of the variation and search for the short inter-band time delay. Intra-day variability was about 0.1 mag on the first two nights and more than 0.3 mag on the third. A bluerwhen-brighter color behavior was found. An clear loop path can be seen on the colormagnitude diagram of the third night, revealing possible time delays between variations at high and low energies. It is the first time that the intra-day spectral hysteresis loop has been found so obviously in the optical band. We used the interpolated crosscorrelation function method to further confirm the time delay and calculated the values of lag between light curves at different wavelengths on each night. On the third night, variations in the R and B bands is approximately 1.5 minutes lagging behind the I band. Such optical time delay is probably due to the interplay of different processes of electrons in the jet of the blazar.

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The 0.1-100 keV spectrum and variability of Mrk 421 in a high state

Cited by 25 publications

References 19 publications

An active state of the BL Lacertae object Markarian 421 detected by INTEGRAL in April 2013

An active state of the BL Lacertae object Markarian 421 detected by INTEGRAL in April 2013

SIMULTANEOUSB′V′R′ MONITORING OF BL LACERTAE OBJECT S5 0716+714 AND DETECTION OF INTER-BAND TIME DELAY

Simultaneous optical monitoring of BL Lacertae object S5 0716+714 with high temporal resolution

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