Recent Results from VERITAS AGN Observations

Benbow, W.

doi:10.22323/1.395.0794

Cited by 3 publications

(1 citation statement)

References 12 publications

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“…(VERITAS observed TXS 0506+056 in 2016-2017; that is, prior to IC170922A, with no detection.) Both MAGIC and VERITAS, together with multiwavelength partners, perform unbiased monitoring observations to study the long term behavior of TXS 0506+056 [85,86]. Open questions include the object's nature (FSRQ vs BL Lac [87]) and its duty cycle, which is an important ingredient to derive the coincidence probability between the different messengers.…”

Section: Txs 0506+056-neutrino Blazar?mentioning

confidence: 99%

High-Energy Alerts in the Multi-Messenger Era

Dorner

Mostafá

Satalecka³

2021

Universe

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The observation of electromagnetic counterparts to both high energy neutrinos and gravitational waves marked the beginning of a new era in astrophysics. The multi-messenger approach allows us to gain new insights into the most energetic events in the Universe such as gamma-ray bursts, supernovas, and black hole mergers. Real-time multi-messenger alerts are the key component of the observational strategies to unravel the transient signals expected from astrophysical sources. Focusing on the high-energy regime, we present a historical perspective of multi-messenger observations, the detectors and observational techniques used to study them, the status of the multi-messenger alerts and the most significant results, together with an overview of the future prospects in the field.

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Section: Txs 0506+056-neutrino Blazar?mentioning

confidence: 99%

High-Energy Alerts in the Multi-Messenger Era

Dorner

Mostafá

Satalecka³

2021

Universe

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Comparison Between TeV and Non-TeV Fermi-detected BL Lacertae Objects

Liang,

Zeng,

Chen

et al. 2023

PASP

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In this paper, we compiled a sample of 410 Fermi-detected BL Lacs, including 42 TeV-detected BL Lacs (TBLs) and 368 non-TeV-detected BL Lacs (non-TBLs) with corresponding mid-infrared (mid-IR), TeV and Fermi γ-ray data, and calculated some important parameters including monochromatic luminosities (mid-IR, GeV and TeV bands) and mid-IR spectral indices. Based on those parameters, we discussed the relationship between the mid-IR and the TeV bands and that between the mid-IR and the GeV bands. Main conclusions are drawn as follows: (1) In the color–color and color–magnitude diagrams, our sample forms a WISE-Gamma Strip in the [3.4]–[4.6]–[12] μm color–color diagram, and TBLs occupy the brighter region than the non-TBLs for the similar color-index in the color-magnititue diagram; (2) The mid-IR luminosity of the TBLs is on average higher than that of non-TBLs, while the average mid-IR spectral index of TBLs is smaller than the non-TBLs, suggesting that TBLs are brighter and hold a more flat spectrum than do the non-TBLs in the mid-IR band. Besides, HBLs have a more flat mid-IR spectrum than LBLs and IBLs; (3) The mid-IR luminosity is positively correlated with the GeV luminosity and the intrinsic TeV luminosity. A positive correlation exists between the mid-IR spectral index and the observed TeV spectral index, which is consistent with the expectations of the synchrotron self-Compton mechanism. We suggest that the HBLs with extreme relativistic electrons might scatter the mid-IR photons up to the TeV band.

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GeV Variability Properties of TeV Blazars Detected by Fermi-LAT

Wang,

Xiao,

Fan

et al. 2024

ApJS

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Variability is a prominent observational feature of blazars. The high-energy radiation mechanism of jets has always been important but is still unclear. In this work, we performed a detailed analysis using Fermi-LAT data across 15 yr and obtained GeV light-curve information for 78 TeV blazars detected by Fermi. We provided annual GeV fluxes and corresponding spectral indices for the 78 TeV blazars and thorough monthly GeV fluxes for a subsample of 41 bright blazars. Our results suggest a strong correlation between the γ-ray photon index and log L γ for the flat spectrum radio quasars (FSRQs) and high-energy peaked BL Lacs. Fourteen sources in our sample show significant GeV outbursts/flares above the relatively stable, low-flux light curve, with six of them showing a clear sharp peak profile in their 5 day binned light curves. We quantified the variability utilizing the fractional variability parameter F var, and found that the flux of the FSRQs showed significantly stronger variability than that of the BL Lacs. The 41 bright blazars in this work are best fit by a log-normal flux distribution. We checked the spectral behavior and found 11 out of the 14 sources show a bluer-when-brighter trend, suggesting this spectral behavior for these TeV blazars at the GeV band arises from the mechanism in which the synchrotron-self Compton process dominates the GeV emission. Our research offers a systematic analysis of the GeV variability properties of TeV blazars and serves as a helpful resource for further associated blazar studies.

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Recent Results from VERITAS AGN Observations

Cited by 3 publications

References 12 publications

High-Energy Alerts in the Multi-Messenger Era

High-Energy Alerts in the Multi-Messenger Era

Comparison Between TeV and Non-TeV Fermi-detected BL Lacertae Objects

GeV Variability Properties of TeV Blazars Detected by Fermi-LAT

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