NEW HIGH-z FERMI BL LACS WITH THE PHOTOMETRIC DROPOUT TECHNIQUE

Kaur, A.; Rau, A.; Ajello, M.; Greiner, J.; Hartmann, D. H.; Paliya, Vaidehi S.; Domínguez, A.; Bolmer, J.; Schady, P.

doi:10.3847/1538-4357/834/1/41

Cited by 25 publications

(40 citation statements)

References 54 publications

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“…Padovani et al 2003;Antón & Browne 2005;Raiteri & Capetti 2016) and high power -high ν S peak (e.g. Padovani, Giommi, & Rau 2012;Kaur et al 2017Kaur et al , 2018 regions of parameter space.…”

Section: Txs 0506+056 As a "Blazar Sequence" Outliermentioning

confidence: 99%

TXS 0506+056, the first cosmic neutrino source, is not a BL Lac

Padovani

Oikonomou

Πετροπούλου

et al. 2019

Monthly Notices of the Royal Astronomical Society: Letters

167

146

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We present evidence that TXS 0506+056, the first plausible non-stellar neutrino source, despite appearances, is not a blazar of the BL Lac type but is instead a masquerading BL Lac, i.e., intrinsically a flat-spectrum radio quasar with hidden broad lines and a standard accretion disk. This re-classification is based on: (1) its radio and O ii luminosities; (2) its emission line ratios; (3) its Eddington ratio. We also point out that the synchrotron peak frequency of TXS 0506+056 is more than two orders of magnitude larger than expected by the so-called "blazar sequence", a scenario which has been assumed by some theoretical models predicting neutrino (and cosmic-ray) emission from blazars. Finally, we comment on the theoretical implications this reclassification has on the location of the γ-ray emitting region and our understanding of neutrino emission in blazars.

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Section: Txs 0506+056 As a "Blazar Sequence" Outliermentioning

confidence: 99%

TXS 0506+056, the first cosmic neutrino source, is not a BL Lac

Padovani

Oikonomou

Πετροπούλου

et al. 2019

Monthly Notices of the Royal Astronomical Society: Letters

167

146

View full text Add to dashboard Cite

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“…First, there are very few objects in our sample beyond redshift 3, and without γ-ray detection that poses difficulty in accurately measuring their IC peak luminosity and hence CD. Second, only a minor fraction of our sample are BL Lac objects, which are typically low-CD sources (e.g., Tavecchio et al 2010), and it is possible that such objects could be located at high redshifts (see, e.g., Kaur et al 2017). In our future work, we will try to address these shortcomings by considering more BL Lac sources and γ-ray detected high-redshift blazars (Ackermann et al 2017).…”

Section: Blazar Evolution Scenariomentioning

confidence: 99%

“…Connecting these findings with those discussed above, we can conclude that the accretion disk plays a major role in controlling the observed properties of powerful blazars, and this supports the claim that the blazar sequence has a physical origin (see also, Ghisellini et al 2017). However, it may be worth revisiting this hypothesis by including a large sample of BL Lac objects, especially high-redshift ones (see, e.g., Kaur et al 2017). …”

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confidence: 99%

General Physical Properties of CGRaBS Blazars

Paliya

Marcotulli

Ajello

et al. 2017

ApJ

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We present the results of a multi-frequency, time-averaged analysis of blazars included in the Candidate Gamma-ray Blazar Survey catalog. Our sample consists of 324 γ-ray detected (γ-ray loud) and 191 non γ-ray detected (γ-ray quiet) blazars, and we consider all the data up to 2016 April 1. We find that both the γ-ray loud and the γ-ray quiet blazar populations occupy similar regions in the WISE color-color diagram, and in the radio and X-ray bands γ-ray loud sources are brighter. A simple one-zone synchrotron inverse-Compton emission model is applied to derive the physical properties of both populations. We find that the central black hole mass and the accretion disk luminosity (L disk ) computed from the modeling of the optical-UV emission with a Shakura-Sunyaev disk reasonably matches with that estimated from the optical spectroscopic emission-line information. A significantly larger Doppler boosting in the γ-ray loud blazars is noted, and their jets are more radiatively efficient. On the other hand, the γ-ray quiet objects are more MeV-peaked, thus could be potential targets for next-generation MeV missions. Our results confirm the earlier findings about the accretion-jet connection in blazars; however, many of the γ-ray quiet blazars tend to deviate from the recent claim that the jet power exceeds L disk in blazars. A broadband study, considering a larger set of γ-ray quiet objects and also including BL Lacs, will be needed to confirm/reject this hypothesis and also to verify the evolution of the powerful high-redshift blazars into their low-power nearby counterparts.

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“…In this work, we focus on the high-z source 4FGL J2146.5-1344, found by Kaur et al (2017) to be at z =1.34 using the photometric redshift technique. With the goal of identifying the nature of this source, we collected data from optical, UV and X-ray facilities.…”

Section: Introductionmentioning

confidence: 99%

“…TARGET SELECTION 4FGL J2146.5-1344 (J2146 from here on) is an HSP BL Lac first detected in the 1FGL catalog and then subsequently reported in all Fermi-LAT catalogs (Nolan et al 2012;Acero et al 2015;The Fermi-LAT collaboration 2019). Found to be a high-z source (z =1.34) by Kaur et al 2017 as a part of the photometric campaign for BL Lacs begun by Rau, A. et al 2012, J2146 exhibits a synchrotron peak frequency of ∼10 16 Hz, a luminosity in excess of ∼10 47 erg s −1 , and a very hard γ-ray spectrum with photon index ∼1.6. The considerable emission at 100 GeV ) also makes it a powerful tool to probe EBL, since at z=1.34 the universe is already opaque to the propagation of E ∼ 100 GeV photons (optical depth, τ >1.3; Domínguez et al 2011).…”

Section: Introductionmentioning

confidence: 99%

NuSTAR Observations and Multiwavelength Modeling of the High-redshift BL Lacertae Object 4FGL J2146.5-1344

Rajagopal¹,

Marcotulli²,

Ajello³

et al. 2020

ApJ

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High synchrotron peak (HSP; ν pk sy > 10 15 Hz) BL Lacs are some of the most extreme accelerators in the Universe. Those found at high redshifts (z > 1) challenge our understanding of blazar evolution models and are crucial for cosmological measurements of the Extragalactic Background Light. In this paper, we study a high-z BL Lac, 4FGL J2146.5-1344, detected to be at z=1.34 using the photometric dropout technique. We collected multi-wavelength data for this source from optical up to γ-rays, in order to study its spectral energy distribution (SED). In particular, this source was observed for the first time with NuSTAR, which accurately measures the synchrotron emission of this blazar up to 50 keV. Despite being classified as an HSP BL Lac object, the modeling of the SED reveals that this source likely belongs to the "masquerading BL Lac" class, which comprises of FSRQs appearing as disguised BL Lac objects.

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NEW HIGH-z FERMI BL LACS WITH THE PHOTOMETRIC DROPOUT TECHNIQUE

Cited by 25 publications

References 54 publications

TXS 0506+056, the first cosmic neutrino source, is not a BL Lac

TXS 0506+056, the first cosmic neutrino source, is not a BL Lac

General Physical Properties of CGRaBS Blazars

NuSTAR Observations and Multiwavelength Modeling of the High-redshift BL Lacertae Object 4FGL J2146.5-1344

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