Ten new BL Lacertae objects discovered by an efficient X-ray/radio/optical technique

Schachter, J. F.; Stocke, John T.; Perlman, Eric S.; Elvis, M.; Remillard, Ron; Granados, Arno; Luu, Jane; Huchra, J. P.; Humphreys, R. M.; Urry, C. Megan; Wallin, John F.

doi:10.1086/172942

Cited by 105 publications

(92 citation statements)

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“…In order to avoid pile-up effects in the energy spectrum, the core pixels in the image were not used and the extraction region was chosen to be an annulus (e.g. Giommi et al 2006) (Elvis et al 1992;Schachter et al 1993;Perlman et al 1996;Wolter et al 1998;Raiteri et al 1998;Urry et al 2000;Cheung et al 2003;Giroletti et al 2004;Perlman et al 2005). A simple synchrotron self Compton model (see text) is also shown (solid curve).…”

Section: Swift and Atom Observations And Resultsmentioning

confidence: 99%

Discovery of VHE γ-rays from the distant BL Lacertae 1ES 0347-121

Aharonian¹,

Akhperjanian²,

Almeida³

et al. 2007

A&A

112

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Aims. Our aim is to study the production mechanism for very-high-energy (VHE; >100 GeV) γ-rays in distant active galactic nuclei (AGN) and use the observed VHE spectrum to derive limits on the Extragalactic Background Light (EBL). We also want to determine physical quantities through the modeling of the object's broad-band spectral energy distribution (SED). Methods. VHE observations (∼25 h live time) of the BL Lac 1ES 0347-121 (redshift z = 0.188) were conducted with the High Energy Stereoscopic System (HESS) between August and December 2006. Contemporaneous X-ray and UV/optical observations from the SWIFT satellite are used to interpret the SED of the source in terms of a synchrotron self Compton (SSC) model.Results. An excess of 327 events, corresponding to a statistical significance of 10.1 standard deviations, is detected from 1ES 0347-121. Its photon spectrum, ranging from ∼250 GeV to ∼3 TeV, is well described by a power law with a photon index of Γ = 3.10 ± 0.23 stat ± 0.10 sys . The integral flux above 250 GeV corresponds to ∼2% of the flux of the Crab Nebula above the same threshold. No VHE flux variability is detected within the data set. Conclusions. Constraints on the EBL density at optical to near-infrared wavelengths derived from the photon spectrum of 1ES 0347-121 are close to the strongest limits derived previously. The strong EBL limits confirm earlier findings, that the EBL density in the near-infrared is close to the lower limits from source counts. This implies that the universe is more transparent to VHE γ-rays than previously believed. An SSC model provides a reasonable description of the contemporaneous SED.

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Section: Swift and Atom Observations And Resultsmentioning

confidence: 99%

Discovery of VHE γ-rays from the distant BL Lacertae 1ES 0347-121

Aharonian¹,

Akhperjanian²,

Almeida³

et al. 2007

A&A

112

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“…These very high-significance data sets yield excellent quality spectra that are crucial for an unambiguous identification of the EBL absorption pattern. For 1ES 0229+200 (z = 0.14, Schachter et al 1993), H 2356−309 (z = 0.165, Jones et al 2009), 1ES 1101−232 (z = 0.186, Remillard et al 1989, and 1ES 0347−121 (z = 0.188, Woo et al 2005), the data are identical to those used in HESS2013. The blazar 1ES 0414+009 (z = 0.287, Halpern et al 1991) is also added to the sample.…”

Section: Blazar Samplementioning

confidence: 99%

Measurement of the EBL spectral energy distribution using the VHE γ-ray spectra of H.E.S.S. blazars

Abdalla¹,

Abramowski²,

Aharonian³

et al. 2017

A&A

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Very high-energy γ rays (VHE, E 100 GeV) propagating over cosmological distances can interact with the low-energy photons of the extragalactic background light (EBL) and produce electron-positron pairs. The transparency of the Universe to VHE γ rays is then directly related to the spectral energy distribution (SED) of the EBL. The observation of features in the VHE energy spectra of extragalactic sources allows the EBL to be measured, which otherwise is very difficult. An EBL model-independent measurement of the EBL SED with the H.E.S.S. array of Cherenkov telescopes is presented. It was obtained by extracting the EBL absorption signal from the reanalysis of high-quality spectra of blazars. From H.E.S.S. data alone the EBL signature is detected at a significance of 9.5σ, and the intensity of the EBL obtained in different spectral bands is presented together with the associated γ-ray horizon.

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“…The HBL object, 1ES 1959+650 (z = 0.047) was first detected in radio band with NARO Green Bank 91 m telescope (Becker et al 1991;Gregory & Condon 1991) and later in X-ray (Schachter et al 1993) using Imaging Proportional counter (IPC) on board Einstein Observatory. TeV emission from this source was first observed by Utah Seven Telescope Array collaboration with total significance of 3.9σ above 600 GeV (Nishiyama 1999).…”

Section: Introductionmentioning

confidence: 99%

Broadband study of blazar 1ES 1959+650 during flaring state in 2016

Patel

Shukla

Chitnis

et al. 2018

A&A

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Aims. The nearby TeV blazar 1ES 1959+650 (z=0.047) was reported to be in flaring state during June -July 2016 by Fermi-LAT, FACT, MAGIC and VERITAS collaborations. We studied the spectral energy distributions (SEDs) in different states of the flare during MJD 57530 -57589 using simultaneous multiwaveband data to understand the possible broadband emission scenario during the flare. Methods. The UV/optical and X-ray data from UVOT and XRT respectively on board Swift and high energy γ-ray data from Fermi-LAT are used to generate multiwaveband lightcurves as well as to obtain high flux states and quiescent state SEDs. The correlation and lag between different energy bands is quantified using discrete correlation function. The synchrotron self Compton (SSC) model was used to reproduce the observed SEDs during flaring and quiescent states of the source. Results. A decent correlation is seen between X-ray and high energy γ-ray fluxes. The spectral hardening with increase in the flux is seen in X-ray band. The powerlaw index vs flux plot in γ-ray band indicates the different emission regions for 0.1 -3 GeV and 3-300 GeV energy photons. Two zone SSC model satisfactorily fits the observed broadband SEDs. The inner zone is mainly responsible for producing synchrotron peak and high energy γ-ray part of the SED in all states. The second zone is mainly required to produce less variable optical/UV and low energy γ-ray emission. Conclusions. Conventional single zone SSC model does not satisfactorily explain broadband emission during observation period considered. There is an indication of two emission zones in the jet which are responsible for producing broadband emission from optical to high energy γ-rays.

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Ten new BL Lacertae objects discovered by an efficient X-ray/radio/optical technique

Cited by 105 publications

References 0 publications

Discovery of VHE γ-rays from the distant BL Lacertae 1ES 0347-121

Discovery of VHE γ-rays from the distant BL Lacertae 1ES 0347-121

Measurement of the EBL spectral energy distribution using the VHE γ-ray spectra of H.E.S.S. blazars

Broadband study of blazar 1ES 1959+650 during flaring state in 2016

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