PoS(IX EVN Symposium)096 http://pos.sissa.it/ esearch School (IMPRS) for 8 GHz). Most of GPS . 1 ver, we found a number ce. ∼ dates (24 of them are highly multaneous multi-frequency 1– e. We use publicly available data the Golden Age for uency ( jet – quasar does not hold. These y. Most of GPS galaxies are charac- nd higher observed peak frequency ynchrotron model of a homogeneous cale components of GPS sources to be rces. Among them we found 121 core 9, 53121 Bonn, oNet R113CT 2003 5058187. Y. Y. Kovalev is a Re- naya 84/32, 117997 Moscow, atory, California Institute of Technology, under contract n Foundation for Basic Research (projects 01-02-16812, cooperative agreement with Associated Universities, Inc. s research has made use of the NASA/IPAC Extragalactic e VLBA is a facility of the National Science Foundation 2 , 1 EVN Symposium was partly supported by funding from the th ive Commons Attribution-NonCommercial-ShareAlike Licen and Yuri Y. Kovalev ∗ 2 , 1 K. Sokolovsky is supported by the International Max Planck R 6 GHz). This is in good agreement with previous results. Howe . 10 mG. 3 (ksokolov,ykovalev)@mpifr-bonn.mpg.de ∼ ∼ quasars are characterized by “core-jet”-type morphology a ( probable), 16 sources have complex parsec-scale morpholog We investigate the sample of 213 GPS sources selected fromto si characterize parsec-scale structure ofdominated the sources, selected sou 76 Compact Symmetric Object (CSO) candi terized by CSO-type morphology and lower observed peak freq 22 GHz observations obtained with RATAN–600 radio telescop of sources for which the general relation CSO – galaxy, core- B sources deserve detailed investigation. Assumingcloud simple we s estimate characteristic magnetic field in parsec-s Acknowledgments. ∗ Copyright owned by the author(s) under the terms of the Creat Max-Planck-Institute für Radioastronomie, Auf dem Hügel 6 Astro Space Center, Lebedev Physical Institute, Profsoyuz c The 9th European VLBI Network Symposiumand on EVN The Users role Meeting of VLBISeptember in 23-26, 2008 Bologna, 1 E-mail: 2 operated by the National Radio Astronomy Observatory under 05-02-17377, 08-02-00545). Database (NED) which is operatedwith by the the Jet National Propulsion Aeronautics Labor and Space Administration. Th RATAN–600 observations were partly supported by the Russia European Community’s sixth Framework Programmesearch under Fellow Radi of the Alexander von Humboldt Foundation. Thi Radio and ; his participation in the 9 Kirill V. Sokolovsky Parsec-scale properties of GHz-Peaked Spectrum sources from 2.3 and 8.6 GHz VLBI surveys PoS(IX EVN Symposium)096 1.4 1.4 1.4 2 2 1.2 1.2 1.2 possible CSO | | 1 1 1 1.5 1.5 highly probable CSO Core-Jet/Naked Core 0.8 0.8 0.8 097. Red points on . component 2component 2 αα 0 [GHz] 0 1 1 - - ν 0.6 0.6 0.6 =

z 10 log 0.4 0.4 0.4 (c) 8.6 GHz VLBA image component 1component 1 αα 0.5 0.5 | | 0.2 0.2 0.2 represent literature data. 0 0 0 LBI components of CSO candidates. ces with different optical identification 0 0 -0.2 -0.2 -0.2 8 8 6 6 4 4 2 2 0 0 8 6 4 2 0 8 6 4 2 0 5 0 12 12 10 10 14 12 10 14 12 10 45 40 35 30 25 20 15 10 NN N (b) Difference between spectral indices of components 2 1 1.4 1.4 1.4 (b) Radio spectrum 0.5 1.2 1.2 1.2 galaxies quasars empty fields 1 1 1 0 0.8 0.8 0.8 [GHz] 0 -0.5 ν 0.6 0.6 0.6 2.3-8.6 GHz

α 10 140 – new GPS galaxy with CSO morphology at log 0.4 0.4 0.4 -1 − 0.2 0.2 0.2 -1.5 0 0 0 (a) 2.3 GHz VLBA image -2 -0.2 -0.2 -0.2 (a) Spectral indices of individual components 5 0 25 20 15 10 30 5 0 8 6 4 2 0 5 0 12 10 25 20 15 10 25 20 15 10 N N Figure 1: Distributions of 2.3–8.6 GHz spectral indices of V the pannel (b) denote RATAN–600 observations, green points and parsec-scale radio structure. Figure 3: Observed peak frequency distribution for GPS sour Parsec-scale properties of GPS sources Figure 2: PKS 1555 PoS(IX EVN Symposium)096 ∼ DIFMAP ] e measurements we can estimate er observed peak frequency ( elected sources which have two ptions, that CSOs are associated and 3) sources with complex pc- o three groups: 1) “core-jet/naked s with two dominating components ed on Fig. 2. ucted the spectral indices (between s was taken from [9] and from the AN–600 sample [7]. After a visual ing simple synchrotron model (e.g., LBA (RDV, [2], [4]) project to char- bable CSO candidates”. Example of on of difference between the spectral g. 1b. Since two mini-lobes of a CSO PS quasars. This is in good agreement J, 136, 580 a for all CSO candidates using he pc-scale components of GPS sources observed peak frequency for GPS sources scale morphology are presented on Fig. 3. ] 3 PoS(IX EVN Symposium)086 arXiv:0901.1064 http://lacerta.gsfc.nasa.gov/vlbi/images , we selected 24 sources with spectral index difference 2 6 GHz). . 3 ∼ 2.3 and 8.6 GHz VLBI data from the VLBA Calibrator Survey ([3] 1 arXiv:0806.0167 ] α 10 mG. ν ∼ ∼ arXiv:0812.4615 ν B [ Information about the optical identification for the source To further distinguish between true CSO and core-jet source S By combining the single-dish spectrum with VLBI angular siz Compilation of publicly available VLBI data at We use publicly available 2 1 8 GHz) then core-jet sources ( . [8] Stanghellini C. et al., A&A, 377,[9] 377 Véron-Cetty, M.-P. and Véron, P. 2006, A&A, 455, 773 [5] Shepherd M.C. 1997, ASPC, 125, 77 [6] Slysh V.I. 1963, Nature, 199, 682 [7] Sokolovsky K.V. et al. 2009, AN, 330, 199 [ [1] Marscher, A.P. 1983, ApJ, 264, 296 [2] Petrov L. et al., in press [ [3] Petrov L., Kovalev Fomalont Y.Y., E.B., Gordon[4] D. 2008, Pushkarev A A.B., Kovalev this Y.Y. proceedings a newly identified GPS galaxy associated with a CSO is present NASA/IPAC Extragalactic Database. We found,with with GPS a galaxies few and core-jet exce sources arewith associated previous with results G (e.g., [8]). The distributions of the GPS sources associated with1 CSO are characterized by the low between two pc-scale components less than 0.5 as “highly pro with different optical counterparts and with different pc- and references therein) and the Research andacterize Development pc-scale – V properties of 213inspection GPS of sources the from VLBI the images RAT core” we have sources, divided 2) the possible sources in Compactscale t morphology. Symmetric Objects (CSO) (a core and a jet feature), wepackage have modeled [5] the visibility with dat two circularcomponents detected Gaussian at components. both 2.3 and We 8.62.3 have GHz and images s 8.6 and GHz) constr for eachindices component of (Fig. two 1a). components The of distributi these sourcesare is expected presented to on have Fi close spectral indices the magnetic field in pc-scale components[6], of [1]). a We radio estimate source the us characteristic magnetic field in t to be Parsec-scale properties of GPS sources References