The blazar content in the<i>Swift</i>-BAT hard X-ray sky

Maselli, A.; Cusumano, G.; Massaro, E.; Parola, V. La; Segreto, A.; Sbarufatti, B.

doi:10.1051/0004-6361/201014331

Cited by 11 publications

(9 citation statements)

References 23 publications

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“…The Roma‐BZCAT (Massaro et al 2011a) gives the X‐ray flux in the 0.1–2.4 keV band F X in units of 10 −12 erg cm −2 s −1 , while the radio flux density at 1.4 GHz S 1.4 is in mJy. Following Maselli et al (2010a), to express this ratio in a convenient non‐dimensional number, we multiplied the radio flux density by a bandwidth Δν, assumed equal to 1 GHz, and the value of the ratio was opportunely multiplied by a scale factor; for the Roma‐BZCAT data we have In this way, the value of the X‐ray to radio flux ratio equal to 10 −11 erg cm −2 s −1 Jy −1 corresponds to Φ XR = 1. We found that for well‐established L sources the values of Φ XR are smaller than 0.1, while for the H objects they are higher than 1.…”

Section: Bl L Ac Colours and Classificationmentioning

confidence: 99%

The colours of BL Lac objects: a new approach to their classification

Massaro¹,

Nesci²,

Piranomonte³

2012

Monthly Notices of the Royal Astronomical Society

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We selected a sample of 437 BL Lac objects, taken from the RomaBZCat catalogue, for which spectroscopic information and SDSS photometry is available. We propose a new classification of BL Lacs in which the sources' type is not defined only on the basis of the peak frequency of the synchrotron component in their Spectral Energy Distribution (types L and H), but also on the relevance of this component with respect to the brightness of the host galaxy (types N and G, for nuclear or galaxy dominated sources). We found that the SDSS colour index u-r=1.4 is a good separator between these two types. We used multiband colour-colour plots to study the properties of the BL Lac classes and found that in the X-ray to radio flux ratio vs u-r plot most of the N (blue) sources are located in a rather narrow strip, while the G-sources (red) are spread in a large area, and most of them are located in galaxy clusters or interacting systems, suggesting that their X-ray emission is not from a genuine BL Lac nucleus but it is related to their environment. Of the about 135 sources detected in the gamma-rays by Fermi-GST, nearly all belong to the N-type, indicating that only this type of sources should be considered as genuine BL Lac nuclei. The J-H, H-K plot of sources detected in the 2MASS catalogue is consistent with that of the "bona fide" BL Lac objects, independently of their N or G classification from the optical indices, indicating the existence in G-type sources of a K-band excess possibly due to a steep, low frequency peaked emission which deserves further investigations. We propose to use these colour plots as a further tool for searching candidate counterparts of newly discovered high-energy sources.Comment: 11 pages, 7 figures. Submitted 29/08/2011 to MNRAS, first referee report received 31/10/2011, accepted 21/02/201

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Section: Bl L Ac Colours and Classificationmentioning

confidence: 99%

The colours of BL Lac objects: a new approach to their classification

Massaro¹,

Nesci²,

Piranomonte³

2012

Monthly Notices of the Royal Astronomical Society

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“…We find 74 more sources, the largest fraction of which are blazars (16 BZB, 18 BZQ, and 9 BZU), followed by other AGNs (among which is the well known FR I radiogalaxy M87), the starburst galaxy NGC 253, and a few pulsars; 14 sources are unidentified. We note that, according to Maselli et al (2010), the number of spurious correspondences for such a low σ T value is ∼20%.…”

Section: Properties Of the Resulting Samples Of Sourcesmentioning

confidence: 82%

“…In the effort of increasing the list of objects emitting both in the BAT and in the LAT energy ranges we consider the adoption of a lower significance threshold. Taking into account the results obtained by Maselli et al (2010) in the cross-correlation of the BZCAT Blazar Catalogue (Massaro et al 2009) with the 39-month 15-150 keV BAT map (Cusumano et al 2010a) we adopt σ ⋆ T = 3. From their analysis, carried out at |b| > 10 • , Maselli et al (2010) found that the adoption of σ ⋆ T follows in a fraction of ∼ 3% of related spurious associations; this value is presumably underestimated at |b| < 10 • due to the higher density of sources.…”

Section: Correspondences Of 1fgl Sources With the 54-month Hard X-ray...mentioning

confidence: 99%

The populations of hard X-ray andγ-ray sources: a correlation study and new possible identifications

Maselli

Cusumano²,

Massaro³

et al. 2011

A&A

Self Cite

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Aims. We present the results of our analysis devoted to researching Galactic and extragalactic sources emitting in the energy bands surveyed by both the Swift-BAT and the Fermi-LAT telescopes. Methods. We cross-correlated the Fermi-LAT 1-year point source catalogue (1FGL) of gamma-ray sources and the second Palermo BAT catalogue (2PBC) of hard X-ray sources, establishing a correspondence between sources when their error boxes overlap. With dedicated software for reducing BAT data, we also extracted the value of the detection significance σ in the BAT 15-150 keV all-sky map in the direction of the 1FGL sources and took those above the threshold σ T = 3 into account. Results. We obtain 62 firm correspondences by cross-correlating the 1FGL and 2PBC catalogues and verifying the agreement between the identified counterparts. The number of objects emitting in both the hard X-ray and the γ-ray energy bands rises to 104 (∼7% of all the 1FGL objects) when considering all the sources with a detection significance down to σ T . This group of objects is made of 82 extragalactic sources, the largest number of which are blazars, 15 Galactic sources, and seven unidentified objects. We discuss the blazar content of the collected 1FGL-2PBC sources and compare their redshift distribution with that of the whole blazar population as reported in the second edition of the BZCAT blazar catalogue. We describe in greater detail the properties of two unidentified sources at low Galactic latitude, 1FGL J0137.8+5814 and 1FGL J2056.7+4938, and support their classification as blazars after the analysis of their broad-band spectral energy distribution.

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“…It was detected by the Fermi/LAT with a 5σ significance (Acero et al 2015). It is also a strong X-ray AGN observed by Swift with a flux of 3.22 ×10 at 0.1−2.4 keV (Maselli et al 2010). The optical image shows signs of post-merger with unusual distribution of dust .…”

Section: +315 (J2203+3145)mentioning

confidence: 98%

The Most Compact Bright Radio-loud AGNs. II. VLBA Observations of 10 Sources at 43 and 86 GHz

Cheng¹,

An²,

Hong³

et al. 2018

ApJS

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Radio-loud active galactic nuclei (AGNs), hosting powerful relativistic jet outflows, provide an excellent laboratory for studying jet physics. Very long baseline interferometry (VLBI) enables high-resolution imaging on milli-arcsecond (mas) and sub-mas scales, making it a powerful tool to explore the inner jet structure, shedding light on the formation, acceleration and collimation of AGN jets. In this paper, we present Very Long Baseline Array (VLBA) observations of ten radio-loud AGNs at 43 and 86 GHz, which were selected from the Planck catalogue of compact sources and are among the brightest in published VLBI images at and below 15 GHz. The image noise levels in our observations are typically 0.3 mJy beam at 43 and 86 GHz, respectively. Compared with the VLBI data observed at lower frequencies from the literature, our observations with higher resolution (the highest resolution up to 0.07 mas at 86 GHz and 0.18 mas at 43 GHz) and at higher frequencies detected new jet components at sub-parsec scales, offering valuable data for studies of the physical properties of innermost jets. These include compactness factor of the radio structure (the ratio of core flux density to total flux density), and core brightness temperature (T b ). In all these sources, the compact core accounts for a significant -2 -fraction (> 60%) of the total flux density. Their correlated flux density at the longest baselines is higher than 0.16 Jy. The compactness of these sources make them good phase calibrators of mm-wavelength ground-based and space VLBI.

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The blazar content in theSwift-BAT hard X-ray sky

Cited by 11 publications

References 23 publications

The colours of BL Lac objects: a new approach to their classification

The colours of BL Lac objects: a new approach to their classification

The populations of hard X-ray andγ-ray sources: a correlation study and new possible identifications

The Most Compact Bright Radio-loud AGNs. II. VLBA Observations of 10 Sources at 43 and 86 GHz

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