"Made in Britain": Black Britishness al femminile

Giommi, Francesca

doi:10.3280/mm2011-002010

Cited by 3 publications

(8 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…By superimposing the spectrum from the radiation zone with α rad = -1/3 and the steep spectrum from the acceleration zone that can be explained by the acceleration mechanisms, we can obtain the low frequency flat radio spectrum with spectral indices(α LF , for ν < ν break ) of α LF ≈ 0.2 for FSRQs and α LF ≈ 0.08 for BL Lacs. This result is consistent with the statistical average value of 0.1 that presented by Giommi et al (2012) which suggests that our model can explain the low frequency flat radio spectrum self-consistently.…”

Section: Discussionsupporting

confidence: 92%

“…As the spectral index of the steep radio spectrum in the acceleration zone is the same as the steep radio spectrum in the radiation zone, we can study it through the observed radio spectrum. Giommi et al (2012) study the low and high frequency radio spectrum with power law to estimate their spectral indices of 105 blazars. The average value of the high frequency spectral indices (α HF , for ν > ν break ) of FSRQs and BL Lacs are α HF = 0.73 ± 0.04 and α HF = 0.51 ± 0.07, respectively.…”

Section: Discussionmentioning

confidence: 99%

“…On the other hand, there are some blazars that do not have significant break in the radio spectrum (e.g., see the SEDs of J0006-0623, J0102+5824, J0433+0521 in Planck Collaboration et al 2011). Statistically, the distributions of low frequency spectral indices are similar for FSRQs and BL Lacs with α∼-0.1, which mean that the flat radio spectrum is a common property for both types of blazars (Planck Collaboration et al 2011;Giommi et al 2012).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

An explanation about the flat radio spectrum for Mrk 421

Xue,

Wang

2020

Preprint

View full text Add to dashboard Cite

It is well known that the flat radio spectrum is a common property in the spectral energy distribution of blazars. Although the one-zone leptonic models are generally successful in explaining the multi-wave band emission, they are problematic in reproducing the radio spectrum. In the study of Mrk 421, one-zone models suggest that in order to avoid overproducing the radio flux, the minimum electron Lorentz factor should be larger than a few hundred at least, even considering the synchrotron self-absorption effect. This result suggests that the model predicted spectral index in the radio band of Mrk 421 should be -1/3. On the basis of this result, by assuming there is a neglected region that will also contribute the radio emission and its electron energy index is naturally originate from the simplest first-order Fermi acceleration mechanism, we can get a superimposed flat radio spectrum. In this paper, a two-zone model is proposed to reproduce the quiescent state spectral energy distribution of Mrk 421. In addition to taking into account the emission from a conventional radiation zone, we further consider the emission from the acceleration zone in which particles are accelerated at a shock front. With the present model, our fitting result suggests that the low frequency flat radio spectrum of Mrk 421 might be explained as a superposition of the synchrotron emission from acceleration zone and radiation zone.

show abstract

Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

An explanation about the flat radio spectrum for Mrk 421

Xue,

Wang

2020

Preprint

View full text Add to dashboard Cite

show abstract

“…Several LSP blazars are not detected in the X-ray band, as the X-ray emission of this type of objects is weak and their flux may easily be below the sensitivity of currently available observations. For similar reasons, HSPs with relatively high ν peak values might not be de-Radio/Fermi Catalogs X-ray Catalogs NVSS (Condon et al, 1998) XMMSL Dr2 Clean (Saxton et al, 2008) FIRST (White et al, 1997;Helfand et al, 2015) 3XMM Dr8 (Watson et al, 2009) SUMSS V2.1 (Manch et al, 2003) RASS 2RXS (Boller et al, 2016) CRATES (Healey et al, 2007) WGACAT2 (White et al, 2000) Fermi 4FGL (The Fermi-LAT collaboration, 2019) Swift 1SXPS (Evans et al, 2014) Fermi 3FHL (The Fermi-LAT collaboration, 2017) SDS82 (Brandt and Giommi, 2019 in preparation) Fermi 3FGL (Acero et al, 2015) Einstein IPC (Harris et al, 1990) 1BIGB SED (Arsioli et al, 2018) Einstein IPC slew survey (Munz, 1992) MST-9Y (Campana et al, 2018) BMW-HRI (Panzera et al, 2003) FermiMeV (Principe et al, 2018) Chandra (Evans et al, 2010) 2AGILE (Bulgarelli et al, 2019) Swift OUSXB (Giommi et al, 2019) Swift OUSXG (Giommi et al, 2019 in preparation) Blazar/Pulsar/GRB/Quasar Catalogs Cluster of galaxies Catalogs 5BZCat (Massaro et al, 2015) ZW CLUSTERS (Zwicky et al, 1968) 3HSP (Chang et al, 2019) PLANCK SZ2 (Planck Collaboration, 2016) ATNF PULSAR (Manchester et al, 2005) ABELL (Abell et al, 1989) Fermi 2PSR (The Fermi-LAT Collaboration, 2013) MCXC (Piffaretti et al, 2011) Fermi GRB (Ajello et al, 2019) SDSS WHL (Wen et al, 2009) Million Quasar (Flesch, 2015) SW XCS (Liu et al, 2015) VO conesearch in this step is set to same as the input radius, same as in the first phase. The GALEX data then are converted to monochromatic fluxes and de-reddened using Fitzpatrick (1999) extinction rule.…”

Section: Workflowmentioning

confidence: 99%

The Open Universe VOU-Blazars tool

Chang

Brandt

Giommi

2020

Astronomy and Computing

View full text Add to dashboard Cite

Context: Blazars are a remarkable type of Active Galactic Nuclei (AGN) that are playing an important and rapidly growing role in today's multi-frequency and multi-messenger astrophysics. In the past several years, blazars have been discovered in relatively large numbers in radio, microwave, X-ray and γ-ray surveys, and more recently have been associated to high-energy astrophysical neutrinos and possibly to ultra-high energy cosmic rays. Blazars are expected to dominate the high-energy extragalactic sky that will soon be surveyed by the new generation of very high-energy γ-ray observatories such as CTA. In parallel to the discovery of many blazars at all frequencies, the technological evolution, together with the increasing adoption of open data policies, is causing an exponential growth of astronomical data that is freely available through the network of Virtual Observatories (VO) and the web in general, providing an unprecedented potential for multi-wavelength and multi-messenger data analysis.Product: We present VOU-Blazars, a tool developed within the Open Universe initiative that has been designed to facilitate the discovery of blazars and build their spectral energy distributions (SED) using public multi-wavelength photometric and spectral data that are accessible through VO services. The tool is available as source code, as a Docker container, and as a web-based service accessible within the Open Universe portal * .Methods: VOU-Blazars implements a heuristic approach based on the well known SED that differentiate blazars from other astronomical sources. The VOU-Blazars outputs are flux tables, bibliographic references, sky plots and SEDs.Results: This paper describes the working mechanism of the tool, gives details of the catalogues and on-line services that are used to produce the output, and gives some examples of usage. VOU-Blazars has been extensively tested during the selection of new high-energy peaked (HSP) blazars recently published in the 3HSP catalog, and has been used to search for blazar counterparts of Fermi 3FHL, Fermi 4FGL, AGILE γ-ray sources, and of IceCube astrophysical neutrinos.

show abstract

“…Therefore, the multi-frequency data are quasisimultaneous but not really simultaneous. Very recently, Giommi et al (2011) built the SEDs for 105 blazars with the simultaneous Planck, Swift, Fermi, and ground-based data. The data of the 105 blazars are obtained between 2009 Dec. and 2010 Oct., which were all collected in one day or several days, and the multi-frequency data are really simultaneous.…”

Section: Introductionmentioning

confidence: 99%

The estimate of emission region locations of {\it Fermi} FSRQs

Yan,

Zeng,

Zhang

2012

Preprint

View full text Add to dashboard Cite

We study the locations of emission regions through modelling the quasi-simultaneous multi-frequency spectral energy distributions of 21 Fermi flat spectrum radio quasars (FSRQs) in the frame of a multicomponent one-zone leptonic model. In our calculations, we take the detailed broad line region (BLR) structure into account and discuss the effect of the uncertainty of the BLR structure on constraining the location of the emission regions for each FSQR, meanwhile we also include both the internal and external absorptions. Our results indicate that (1) the contribution of external Compton-BLR component is important to γ-ray emission, and the energy density of external target photon fields depends on the location of the emission region, which can be derived through reproducing the observed γ-ray emission, and (2) the emission regions of FSRQs with relative low accretion disk luminosity lie in the region of 7.9 × 10 16 -1.3 × 10 18 cm (300 -4300 Schwarzschild radii) from central black hole, and for FSRQs with high accretion disk luminosity, the emission regions locate in the larger region of 2.6 × 10 17 -4.2 × 10 18 cm (300 -5600 Schwarzschild radii).

show abstract

"Made in Britain": Black Britishness al femminile

Cited by 3 publications

References 0 publications

An explanation about the flat radio spectrum for Mrk 421

An explanation about the flat radio spectrum for Mrk 421

The Open Universe VOU-Blazars tool

The estimate of emission region locations of {\it Fermi} FSRQs

Contact Info

Product

Resources

About