The 5th edition of the Roma-BZCAT Multifrequency Catalogue of Blazars is
available in a printed version and online at the ASDC website
(http://www.asdc.asi.it/bzcat); it is also in the NED database. It presents
several relevant changes with respect to the past editions which are briefly
described in this paper.Comment: 5 pages, 3 figures. Accepted for publication in Astrophysics and
  Space Scienc

Giommi, Paolo

Leto, Cristina

Marchegiani, Paolo

Maselli, Alessandro

Massaro, Enrico

Perri, Matteo

Piranomonte, Silvia

English

arXiv

E. Massaro

A. Maselli

C. Leto

P. Marchegiani

M. Perri

P. Giommi

S. Piranomonte

Crossref

Astrophysics and Space Science

The 5th edition of the Roma-BZCAT. A short presentation

The 5th edition of the Roma-BZCAT Multifrequency Catalogue of Blazars is available in a printed version and online at the ASDC website (http://www.asdc.asi.it/bzcat); it is also in the NED database. It presents several relevant changes with respect to the past editions which are briefly described in this paper

Massaro, E.

MASELLI, Alessandro

Leto, C.

Marchegiani, P.

PERRI, Matteo

Giommi, P.

PIRANOMONTE, Silvia

OA@INAF - Istituto Nazionale di Astrofisica

2015Publication Year2020-07-07T14:40:25ZAcceptance in OA@INAFThe 5th edition of the Roma-BZCAT. A short presentationTitleMassaro, E.; MASELLI, Alessandro; Leto, C.; Marchegiani, P.; PERRI, Matteo; et al.Authors10.1007/s10509-015-2254-2DOIhttp://hdl.handle.net/20.500.12386/26376HandleASTROPHYSICS AND SPACE SCIENCEJournal357NumberarXiv:1502.07755v1  [astro-ph.HE]  26 Feb 2015The 5th edition of the Roma-BZCAT. A short presentationE. Massaro1,2 • A. Maselli3 • C. Leto4 •P. Marchegiani5 • M. Perri4,6 • P. Giommi4 •S. Piranomonte6Abstract The 5th edition of the Roma-BZCAT Mul-tifrequency Catalogue of Blazars is available in aprinted version and online at the ASDC website(http://www.asdc.asi.it/bzcat); it is also in the NEDdatabase. It presents several relevant changes with re-spect to the past editions which are briefly described inthis paper.Keywords sample article;1 IntroductionThe work on the Roma-BZCAT (Massaro et al. 2009),which is a list of carefully checked blazars, started moreE. Massaro1INAF, Istituto di Astrofisica e Planetologia Spaziali, Roma,Italy2In Unam Sapientiam, Roma, ItalyA. Maselli3INAF, Istituto di Astrofisica Spaziale e Fisica Cosmica,Palermo, ItalyC. Leto4ASI Science Data Center, Roma, ItalyP. Marchegiani5School of Physics, University of the Witwatersrand, Johannes-burg Wits, 2050, South AfricaM. Perri4ASI Science Data Center, Roma, Italy6Osservatorio Astronomico di Roma, INAF, MonteporzioCatone, ItalyP. Giommi4ASI Science Data Center, Roma, ItalyS. Piranomonte6Osservatorio Astronomico di Roma, INAF, MonteporzioCatone, Italythan 10 years ago. It was originally conceived for de-veloping a complete database from catalogue and liter-ature data for the identification of counterparts to highenergy sources. The Fermi-LAT collaboration, in fact,used it at this purpose in various γ-ray source cata-logues, like 1FGL (Abdo et al. 2010a), 1LAC (FermiLAT AGN Catalog, Abdo et al. 2010b) and the sub-sequent 2FGL (Nolan et al. 2012) and 2LAC (Ack-ermann et al. 2011). However, considering that thesources reported in the catalogue were divided into afew classes having a remarkable homogeneity, it wasalso successfully applied in new blazar researches andprovided powerful selection criteria for surveys in otherelectromagnetic bands.The Roma-BZCAT is now at the 5th Edition (Mas-saro et al. 2014) which contains coordinates and multi-frequency data of 3561 sources, about 30% more thanin the 1st edition, either confirmed blazars or exhibit-ing characteristics close to this type of sources. Withrespect to the previous editions, this new edition hasrelevant changes in the sources’ classification and has anew format for the notes in the tables. We emphasizethat all the sources in the Roma-BZCAT have a detec-tion in the radio band. Moreover, a complete spectro-scopic information is published and could be accessedby us for all of them, with the exception of BL Laccandidates. Consequently, peculiar sources as the socalled “radio quiet BL Lacs”, which are reported insome other catalogues, are not included here becauseof possible contamination with hot stars and other ex-tragalactic objects.In this paper we summarize the major changes withrespect to the previous editions and give some indica-tions on the use of the online version. For a more com-plete description we address to the catalogue printedversion (Massaro et al. 2014).2Fig. 1 Hammer-Aitoff projection in galactic coordinates of the sky distribution of blazars in the 5th Edition of the Roma-BZCAT. The dots’ colours correspond to the following sources’ types: BL Lacs and candidates (red), BZGs (yellow), FSRQs(blue), blazars of uncertain classification (green) [from Massaro et al. 2014].2 Types of blazars and source namingTraditionally, blazars come in two main flavors: BL Lacobjects and Flat Spectrum Radio Quasars (FSRQ), de-pending on the width and strength of the emission linesin their optical spectrum. Variability and other un-certainties, however, raised the problem of an accurateblazar definition, an issue that is still open. Since thefirst edition, therefore, we divided blazars into thesetwo main classes, originally named as BZB and BZQ,respectively. It was clear, however, that there is a frac-tion of Active Galactic Nuclei (AGN) exhibiting blazarproperties mixed to other features which make difficultthe classification in the two previous types. Thus thesesources were included in the Roma-BZCAT as blazars ofuncertain type or BZU, together with sources with datatoo poor for a safe classification. New studies of theblazar population properties, also based on the resultsof high energy observations (Massaro, Nesci and Pira-nomonte 2012), suggested us the definition of the newclass of BZG blazars (or blazar candidates), whose mul-tifrequency emission exhibits some properties of blazarsbut appears dominated by the host galaxy contributionin the optical-UV. It is not clear if BZG objects, whichare characterized by redshift values generally lower than0.3, are all genuine blazars, for instance in a rather qui-escent state considering the high variability that theycan present, or are moderately bright AGNs whose non-thermal emission does not present evidence for relativis-tic beaming, or again misclassified sources. Only veryaccurate observational investigations of these sourcescan provide more stringent criteria for a better classifi-cation.In the 5th Edition we use similar denomination ofblazars adopted in the previous editions. Each blazaris identified by a code, with 5BZ for all blazars, a fourthletter that specifies the type, followed by the truncatedequatorial coordinates (J2000). We introduced the edi-tion number before the letters BZ to avoid possible con-fusion due to the fact that several sources changed theirold names because of the new adopted classification.The codes are:• 5BZB: BL Lac objects, used for AGNs with a fea-tureless optical spectrum, or having only absorptionlines of galaxian origin and weak and narrow emissionlines;• 5BZG: sources, usually reported as BL Lac objectsin the literature, but having a spectral energy dis-tribution (SED) with a significant dominance of thegalaxian emission over the nuclear one;• 5BZQ: Flat Spectrum Radio Quasars, with an opti-cal spectrum showing broad emission lines and dom-inant blazar characteristics;• 5BZU: blazars of Uncertain type, adopted for asmall number of sources having peculiar characteris-tics but also exhibiting blazar activity: for instance,occasional presence/absence of broad spectral linesor other features, transition objects between a radiogalaxy and a BL Lac, galaxies hosting a low luminos-ity blazar Nucleus, etc.3The 5th edition contains 1151 BZB sources, 92 ofwhich are reported as candidates because we could notfind their optical spectra in the literature, 1909 BZQsources, 274 BZG sources and 227 BZU objects.3 Multifrequency dataFor each source, in addition to the J2000 coordinatesmostly derived from VLBI (Titov & Malkin 2009; Titovet al. 2011; Petrov & Taylor 2011), WISE and opticaldatabases like SDSS, the following data are also given:– the apparent magnitude R from USNO B1 or r fromSDSS DR10, or in other bandpasses when these dataare not available;– radio flux density from NVSS (Condon et al. 1998) orFIRST (White et al. 1997) at 1.4 GHz or at 0.843 GHzfrom SUMSS (Mauch et al. 2003) when the former onesare not available;– radio flux density at 4.85 GHz from GB6 (Gregory etal. 1996) or PMN (Wright et al. 1994), for a few othersources other bands are used as specified by notes;– microwave flux density, mostly at 143 GHz, fromPLANCK (Planck Compact Source Catalogue PublicRelease 1, Planck Collaboration, 2013) catalogues;– the 0.1–2.4 keV X-ray flux from ROSAT archive orSwift-XRT catalogues, in other cases as specified bynotes;– hard X-ray flux (15–150 keV) from Palermo BAT Cat-alogue (Cusumano et al. 2010), in other cases as spec-ified by notes;– γ-ray flux from 1FGL or 2FGL catalogues;– the redshift.When data for the considered band were not foundin catalogues or in the literature a sign - is reported,while a sign + indicates that some data are availablebut an additional analysis is necessary to be insertedin the catalogue. In the latter case the correspondingnote gives information on the instrument archive wheredata can be recovered.4 On-line version and scientific toolsThe on-line version of the Roma-BZCAT provides ac-cess to useful tools developed at ASDC that can be eas-ily accessed by clicking on the Data Explorer button.For instance it is possible to build sky maps of cata-logued sources in the region surrounding the selectedblazar or retrieve optical and radio images at differentsize scale. A large series of catalogues in many elec-tromagnetic bands is available and all major databasescan be accessed in a transparent way, including bibli-ographical services. A useful tool is the ASDC SEDFig. 2 The spectral energy distribution of the very wellstudied BL Lac object OJ 287/5BZB J0854+2006 obtainedby means of the ASDC tool. Used symbols are described inthe on-line page.builder: the user can obtain time resolved SEDs of aselected source (see Fig. 2) from a collection of avail-able data and possibly add his own dataset. Then, hecan also calculate some emission models by means of asynchrotron self-Compton code. Finally, the user canevaluate the spectral parameters of the sources for in-vestigating the expected fluxes in other bands accordingto different criteria.5 ConclusionThe Roma-BZCAT is likely the most complete list ofblazars, useful for identifying the counterparts to high-energy sources and for investigating the populations ofextragalactic sources in other frequency bands such asin the microwaves or in the far and mid infrared. More-over, it provides a large database of SEDs for differenttypes of blazars useful for studying radiation mecha-nisms and relativistic beaming effects.The completeness of the catalogue is an open issue,because the sky coverage of the used surveys is not uni-form. In the past editions we noticed that the num-ber of blazars in the Northern sky was higher than inthe Southern part. This situation is partially changedwith the new large surveys, like AT20G (Massardi et al.2011), as shown by the declination distributions of BLLac objects and FSRQs reported in Fig. 3. The N-Sasymmetry is well apparent for the former sources whilethe latter ones does not show any significant effect. Thisdifference is due to the fact that many BL Lac objectsclassified as HBL (High frequency peaked BL Lac, seePadovani and Giommi 1995) have radio flux densities at1.4 GHz lower than about 50 mJy and are not detected4Fig. 3 The Declination distributions of BL Lac objects(upper panel) and of Flat Spectrum Radio Quasars (lowerpanel) in the Roma-BZCAT.in the surveys of the Southern sky, while only a verysmall fraction of FSRQs have flux densities lower thanthis value. Moreover, one has to consider that a rele-vant number of new discovered BL Lacs was identifiedusing spectroscopic observations available in the SDSS,and that a similar facility is not present in the southernsky observatories. We expect that the combination ofradio and optical data with other multifrequency sur-veys, as for example with the mid-infrared colours fromthe AllWISE catalogue (Cutri et al. 2013), as recentlyproposed by Massaro et al. (2011, 2013) and D’Abruscoet al. (2012, 2013), will increase the efficiency for dis-covering new HBL objects.Users who will make use of the Roma-BZCAT (5thEdition) in a publication, are kindly requested to ac-knowledge the source of the information by referencingthe present paper or the book which gives a full descrip-tion of the catalogue.Acknowledgements This work started when one ofthe authors (E.M.) was at the Università di Roma LaSapienza. We made large use of the Sloan Digital SkySurvey (SDSS), the NED database and other astronom-ical catalogues distributed in digital form (Vizier andSimbad) at Centre de Dates astronomiques de Stras-bourg (CDS) at the Louis Pasteur University. Thiswork has made use of the Palermo BAT Catalogue anddatabase operated at INAF-IASF Palermo. Spectrafrom the Final Release of 6dFGS have been used inour blazar diagnostics.The use of the online version of the Roma-BZCATand the scientific tools developed at the ASI ScienceData Center (with the supervision of Paolo Giommi)were fundamental for the catalogue revision. We aretherefore grateful to the ASDC technical staff for theexcellent work carried out to support the on-line versionof the Roma-BZCAT.P.M. acknowledges support from the DST/NRFSKA post-graduate bursary initiative. This work hasbeen partially supported by research funds of Univer-sità di Roma La Sapienza and by the ASI grant toINAF to support the scientific activities of the ASDC.5ReferencesAbdo, A.A., Ackermann, M., Ajello, M. et al.: Astrophys.J. Suppl. Ser., 188, 405 (2010a)Abdo, A.A., Ackermann, M, Ajello, M.. et al.: Astro-phys. J., 715, 429 (2010b)Ackermann, M., Ajello, M., Allafort, A. et al.: Astro-phys. J., 743, 171 (2011)Condon, J.J., Cotton, W.D., Greisen, E.W. et al.: As-tron. J., 115, 1693 (1998)Cusumano, G., La Parola, V., Segreto, A. et al.: Astron.Astrophys., 524, A64 (2010)Cutri, R.M., Wright, E.L., Conrow, T. et al.: VizieR On-line Data Catalog, II/328 (2013)D’Abrusco, R., Massaro, F., Ajello, M. et al.: Astrophys. J.,748, 68 (2012)D’Abrusco, R., Massaro, F., Paggi, A. et al.: Astrophys. J.Suppl. Ser., 206, 12 (2013)Gregory, P.C., Scott, W.K., Douglas, K., Condon, J.J.: As-trophys. J. Suppl. Ser., 103, 427 (1996)Massardi, M., Ekers, R.D., Murphy, T. et al.: Mon. Not. R.Astron. 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