Pinpointing the location of the gamma-ray emitting region in the FSRQ 4C+01.28

Abstract

The FSRQ 4C+01.28 is a bright and highly variable radio and $\gamma$-ray emitter. We aim to pinpoint the location of the $\gamma$-ray emitting region within its jet in order to derive strong constraints on $\gamma$-ray emission models for blazar jets. We use radio and $\gamma$-ray data obtained with ALMA, OVRO, SMA and Fermi/LAT to study the cross-correlation between $\gamma$-ray and multi-frequency radio light curves. Moreover, we employ VLBA observations at 43 GHz over a period of around nine years to study the parsec-scale jet kinematics. To pinpoint the location of the $\gamma$-ray emitting region, we use a model in which outbursts shown in the $\gamma$-ray and radio light curves are produced when moving jet components pass through the $\gamma$-ray emitting and the radio core regions. We find two bright and compact newly ejected jet components that are likely associated with a high activity period visible in the $\gamma$-ray and radio light curves. The kinematic analysis of the VLBA observations leads to a maximum apparent jet speed of ${\beta }_{app}=19\pm 10$ and an upper limit on the viewing angle of $\varphi$ < 4 deg. We determine the power law indices that are characterizing the jet geometry, brightness temperature distribution, and core shift to be $l=0.974\pm 0.098$, $s=-3.31\pm 0.31$, and $k_r=1.09\pm 0.17$, which are in agreement with a conical jet in equipartition. A cross-correlation analysis shows that the radio light curves follow the $\gamma$-ray light curve. We pinpoint the location of the $\gamma$-ray emitting region with respect to the jet base to the range of $2.6\mathrm{pc}\le d_{\gamma }\le 20\mathrm{pc}$. Our derived observational limits places the location of $\gamma$-ray production in 4C+01.28 beyond the expected extent of the broad-line region (BLR) and therefore challenges blazar-emission models that rely on inverse Compton up-scattering of seed photons from the BLR.

References in corpus (37)

• The Large Area Telescope on the Fermi Gamma-ray Space Telescope Mission
• Reverberation Measurements for 17 Quasars and the Size-Mass-Luminosity Relations in Active Galactic Nuclei
• Polarimetric Observations of 15 Active Galactic Nuclei at High Frequencies: Jet Kinematics from Bimonthly Monitoring with the Very Long Baseline Array
• On Uncertainties in Cross-Correlation Lags and the Reality of Wavelength-Dependent Continuum Lags in Active Galactic Nuclei
• Blazars in the Fermi Era: The OVRO 40-m Telescope Monitoring Program
• MOJAVE: Monitoring of Jets in Active Galactic Nuclei with VLBA Experiments. VI. Kinematics Analysis of a Complete Sample of Blazar Jets
• Canonical high power blazars
• Bright AGN Source List from the First Three Months of the Fermi Large Area Telescope All-Sky Survey
• Sub-milliarcsecond Imaging of Quasars and Active Galactic Nuclei. IV. Fine Scale Structure
• MAGIC discovery of VHE Emission from the FSRQ PKS 1222+21
• Constraining Emission Models of Luminous Blazar Sources
• Kinematics of Parsec-Scale Jets of Gamma-Ray Blazars at 43~GHz within the VLBA-BU-BLAZAR Program
• MOJAVE: Monitoring of Jets in AGN with VLBA Experiments - I. First-Epoch 15 GHz Linear Polarization Images
• MOJAVE. XVII. Jet Kinematics and Parent Population Properties of Relativistically Beamed Radio-Loud Blazars
• Jet opening angles and gamma-ray brightness of AGN
• On the Reliability of Cross Correlation Function Lag Determinations in Active Galactic Nuclei
• Multi-Epoch VLBA Observations of EGRET-Detected Quasars and BL Lac Objects: Connection between Superluminal Ejections and Gamma-Ray Flares in Blazars
• Detection of significant cm to sub-mm band radio and gamma-ray correlated variability in Fermi bright blazars
• Time-correlation between the radio and gamma-ray activity in blazars and the production site of the gamma-ray emission
• MOJAVE: Monitoring of Jets in Active Galactic Nuclei with VLBA Experiments. XI. Spectral distributions
• Kinematics of Parsec-Scale Jets of Gamma-Ray Bright Blazars at 43 GHz during Ten Years of the VLBA-BU-BLAZAR Program
• Long-Term X-ray Spectral Variability in Seyfert 1 Galaxies
• On the origin of gamma rays in Fermi blazars: beyond the broad line region
• A transition from parabolic to conical shape as a common effect in nearby AGN jets
• MOJAVE: XVIII. Kinematics and Inner Jet Evolution of Bright Radio-Loud Active Galaxies
• Radio Jet-Ambient Medium Interactions on Parsec Scales in the Blazar 1055+018
• The Twin--Jet System in NGC 1052: VLBI-Scrutiny of the Obscuring Torus
• Through The Ring Of Fire: $\gamma$-Ray Variability In Blazars By A Moving Plasmoid Passing A Local Source Of Seed Photons
• "Orphan" $\gamma$-ray Flares and Stationary Sheaths of Blazar Jets
• A decade of joint MOJAVE-Fermi AGN monitoring: localisation of the gamma-ray emission region
• Modelling the AGN broad line region using single-epoch spectra II. Nearby AGN
• Maximum Brightness Temperature of an Incoherent Synchrotron Source : Inverse Compton Limit - a Misnomer
• Dual-high-frequency VLBI study of blazar-jet brightness-temperature gradients and collimation profiles
• The size of BLRs of low luminous Active Galactic Nuclei
• MOJAVE -- XXII. Brightness temperature distributions and geometric profiles along parsec-scale AGN jets
• Gamma-ray flares and broadband spectral study of PKS 0402-362
• Imprint of "Local Opacity" Effect in Gamma-Ray Spectrum of Blazar Jet