ISSN 1990-3413, Astrophysical Bulletin, 2014, Vol. 69, No. 2, pp. 141–159. c Pleiades Publishing, Ltd., 2014. Original Russian Text c D.I. Solovyov, O.V. Verkhodanov, 2014, published in Astrofizicheskij Byulleten, 2014, Vol. 69, No. 2, pp. 150–169. Radio and Optical Identification of Giant Radio Galaxies from NVSS Radio Survey D. I. Solovyov 1* and O. V. Verkhodanov 2** 1 St. Petersburg Branch of the Special Astrophysical Observatory, Russian Academy of Sciences, St. Petersburg, 196140 Russia 2 Special Astrophysical Observatory, Russian Academy of Sciences, Nizhnii Arkhyz, 369167 Russia Received August 12, 2013; in final form, November 25, 2013 Abstract—We investigate giant radio galaxy candidates that were selected based on the components cataloged as separate sources in the NVSS survey. The radio and optical identification is done for fifty radio galaxies using the CATS, NED, and SkyView databases. DOI: 10.1134/S1990341314020023 Key words: galaxies: active—radio continuum: galaxies—submillimeter: galaxies 1. INTRODUCTION Giant radio galaxies (GRG) are among the largest objects in the Universe observed in the radio range. Their sizes are about 1 Mpc or larger and are com- parable to the dimensions of galaxy clusters. We only know about 150 giant radio galaxies with flux den- sities above 150 mJy at the frequency of 1.4 GHz. GRGs typically belong to the FR II morphological type [1] and are identified in the optics with giant elliptical galaxies and quasars. GRGs are much less common than the conven- tional radio galaxies which complicates their statis- tical study. Several teams [2–11] investigate them. This way, Jamrozy et al. [9] have noted that since the GRG sizes are comparable with the sizes of galaxy groups or even larger, they can have a significant impact on the ambient medium. They are therefore treated as objects playing an important role in the formation of the large-scale structure of Universe. The view on the GRG formation mechanism is not unanimous. There is a theory according to which such large sizes of GRGs can be explained by the effect produced by the orientation of galaxies, when the maximum value of the projection perpendicular to the observer’s line of sight is reached. However, the GRG observations with the 100-m Effelsberg Radio Telescope do not confirm this hypothesis [3]. The team of Schoenmakers et al. [3] explains the emergence of GRGs as a result of evolution in the ambient medium of radiation from the oldest sources * E-mail: [email protected]** E-mail: [email protected]belonging to the radio galaxy group, with relatively powerful cores. Komberg and Pashchenko [12] have shown that the size of a giant radio source may also be determined by the presence of a group of radio-loud nuclei, which will eventually evolve into GRGs. In our previous paper [13] we have used the NVSS (NRAO VLA Sky Survey) catalog [14] for the initial search of large galaxies. The survey covers 82% of the celestial sphere (the entire sky north of 40 ◦ in declination) and has a sufficiently high angular res- olution. The NVSS survey catalog contains approx- imately 1.81 million discrete objects at the frequency of 1.4 GHz. The flux density limit for a resolvable dis- crete source in the NVSS is 2.5 mJy. For the objects with surface brightness of less than 15 mJy, the high- est resolution accuracy is estimated at 1 . The GRG candidates in our list possess higher flux densities. We have selected 55 giant radio galaxy candidates from the catalog, 30 of which have a distinct FR II morphological type and 25 are the FR I-type radio sources. The distribution of objects on the celestial sphere is shown in Fig. 1. The search for these GRG candidates was per- formed using a custom-developed automatic proce- dure, having the aim of selecting the sources of a comparatively large size (larger than 4 ) from the NVSS survey catalog classified in the NVSS lists as several (two or more) independent sources. The algorithm is based on the analysis of the angular sep- aration between the centers of the objects, the sizes of the major axes of radio source component candidates, and the angle between the directions of major axes of the examined pair of objects. We have selected some 141
Radio and Optical Identification of Giant Radio Galaxiesfrom NVSS Radio Survey
D. I. Solovyov1* and O. V. Verkhodanov2**
1St. Petersburg Branch of the Special Astrophysical Observatory, Russian Academy of Sciences,St. Petersburg, 196140 Russia
2Special Astrophysical Observatory, Russian Academy of Sciences, Nizhnii Arkhyz, 369167 RussiaReceived August 12, 2013; in final form, November 25, 2013
Abstract—We investigate giant radio galaxy candidates that were selected based on the componentscataloged as separate sources in the NVSS survey. The radio and optical identification is done for fiftyradio galaxies using the CATS, NED, and SkyView databases.
Giant radio galaxies (GRG) are among the largestobjects in the Universe observed in the radio range.Their sizes are about 1 Mpc or larger and are com-parable to the dimensions of galaxy clusters. We onlyknow about 150 giant radio galaxies with flux den-sities above 150 mJy at the frequency of 1.4 GHz.GRGs typically belong to the FR II morphologicaltype [1] and are identified in the optics with giantelliptical galaxies and quasars.
GRGs are much less common than the conven-tional radio galaxies which complicates their statis-tical study. Several teams [2–11] investigate them.This way, Jamrozy et al. [9] have noted that since theGRG sizes are comparable with the sizes of galaxygroups or even larger, they can have a significantimpact on the ambient medium. They are thereforetreated as objects playing an important role in theformation of the large-scale structure of Universe.
The view on the GRG formation mechanism isnot unanimous. There is a theory according to whichsuch large sizes of GRGs can be explained by theeffect produced by the orientation of galaxies, whenthe maximum value of the projection perpendicular tothe observer’s line of sight is reached. However, theGRG observations with the 100-m Effelsberg RadioTelescope do not confirm this hypothesis [3].
The team of Schoenmakers et al. [3] explains theemergence of GRGs as a result of evolution in theambient medium of radiation from the oldest sources
belonging to the radio galaxy group, with relativelypowerful cores. Komberg and Pashchenko [12] haveshown that the size of a giant radio source may alsobe determined by the presence of a group of radio-loudnuclei, which will eventually evolve into GRGs.
In our previous paper [13] we have used the NVSS(NRAO VLA Sky Survey) catalog [14] for the initialsearch of large galaxies. The survey covers 82% ofthe celestial sphere (the entire sky north of 40◦ indeclination) and has a sufficiently high angular res-olution. The NVSS survey catalog contains approx-imately 1.81 million discrete objects at the frequencyof 1.4 GHz. The flux density limit for a resolvable dis-crete source in the NVSS is 2.5 mJy. For the objectswith surface brightness of less than 15 mJy, the high-est resolution accuracy is estimated at 1′′. The GRGcandidates in our list possess higher flux densities.We have selected 55 giant radio galaxy candidatesfrom the catalog, 30 of which have a distinct FR IImorphological type and 25 are the FR I-type radiosources. The distribution of objects on the celestialsphere is shown in Fig. 1.
The search for these GRG candidates was per-formed using a custom-developed automatic proce-dure, having the aim of selecting the sources of acomparatively large size (larger than 4′) from theNVSS survey catalog classified in the NVSS listsas several (two or more) independent sources. Thealgorithm is based on the analysis of the angular sep-aration between the centers of the objects, the sizes ofthe major axes of radio source component candidates,and the angle between the directions of major axes ofthe examined pair of objects. We have selected some
141
142 SOLOVYOV, VERKHODANOV
Fig. 1. Positions of the discovered FR I (top) and FR II-type galaxies (below) on the celestial sphere in galacticcoordinates. The figure shows the galactic equator andthe prime meridian.
relatively weak in terms of the integral flux densitycomponents of the searched objects (Si � 100 mJy),which were not included in the GRG catalogs of otherauthors. We did not set a limit on the linear size ofradio sources, only using their angular sizes. Hence,we shall further call the selected objects as large radiogalaxies (LRG), implying that their angular size islarger than 4′. Note that 5 of 55 radio sources wereexcluded from the studied list, as they are the H IIregions (2 identifications with the H II catalogs) ortheir candidates, having ragged structures and lo-cated near the Galactic plane.
In this paper we continue to investigate the dis-covered LRGs and present below the radio and opticalidentifications of the objects from our list, conductedwith the aid of catalogs covering other frequencyranges. The main goal of this work is to build andexplore a selection of objects with large angular sizesbut not included in the published GRG lists. Onthe one hand, it will increase the extent of a sparsesample of such radio galaxies, and on the other handit will allow to isolate such regions on the maps ofthe cosmic microwave background which may becausing the further distortion of the signal on thescales of 5–10′ [15–18]. Apart for the contribution to
the cosmic microwave background (CMB), the GRGregions may also exhibit the Sunyaev–Zel’dovich ef-fect [19].
2. IDENTIFICATION
The 2MASS survey [20, 21] (the K-band) wasused as the infrared object database. The DSS wasused as the main catalog in the optical range. TheCATS database1 [22, 23] was used for the radioidentification. For individual radio galaxies we alsogive the identifications with the objects from the firstradio astronomical catalogs: the Cambridge 3C, 4Cand Parkes (PKS) catalogs, if such have been de-tected. Calculating the spectral indices, we used thecross-identification results in the CATS databasewith the identification window sized 180′′×180′′.To remove the random radio objects of the field ina given box, we used the data analysis techniquesimilar to that described in [24, 25]. The methodimplies the application of a joint data analysis in thecoordinate data and spectral spaces to find probableidentifications of specific radio sources at differentradio frequencies. For these purposes we used thespg code [26] of the continuous data processingsystem at the RATAN-600. Describing the S(ν)spectra for the subsequent calculation of spectralindices, we applied the parametrization of S(ν) bylog S(ν) = A + Bx + Cf(x), where S is the fluxdensity in Jansky (Jy), x is the logarithm of fre-quency ν in MHz, and f(x) is one of the followingfunctions: exp(−x), exp x, or x2. The results ofidentification and approximation of the spectra forthe FR I and FR II-type objects are shown in thetable. The table columns give: (1) the name in theIAU standard, including the source coordinates andcomponent coordinates; (2) the object type, accord-ing to the Fonarev–Riley classification; the casesof uncertain and transition types are designated asFR I/II; (3) flux density S1.4 in mJy at the frequencyof 1.4 GHz, integral flux densities are given for thecomponents, and their sum for the entire radio galaxy;(4) angular size in arcminutes at the 2 mJy isophotelevel and linear size in Mpc in the presence of a knownredshift; (5) the presence of identification in the IR (I),optical (O) and X-ray (X) ranges; (6) spectroscopicredshift according to the NED; (7) approximationdependence of the continuous spectrum for the in-tegral flux density. Among the main radio catalogsof the CATS database used in constructing theLRG spectra, let us note lists from [14, 27–44].
1http://cats.sao.ru
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LRGs detected via the component axis comparison method
Name TypeS1.4, Size,
XIO z SpectrummJy arcmin/Mpc
(1) (2) (3) (4) (5) (6) (7)
J 000041.4+121445 FR II 247.7 10.1/– – 0.422− 0.000x− 0.039ex
J 225321.7+162014 FR II 183.7 9.4/– IO 2.410− 0.944x
J 225319.7+162226 96.0
J 225323.7+161801 87.7
J 231600.3–282359 FR II 301.6 10.2/2.2 O 0.2293 1.976− 0.783x
J 231555.2–282640 152.4
J 231605.4–282118 149.2
J 235721.0+475238 FR I 396.9 10.6/0.55 O 0.0436 1.856− 0.671x
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2.1. Comments on Individual Sources.FR I and FR I/II-Types
This section gives comments to the sources ofFR I-type and the complex FR I/II-type. Figures 2and 3 demonstrate the images from the NVSS surveyand their radio spectra constructed according to theresults of identification in the CATS database.
J 005744.4+302156. The type FR I radio sourcewith a characteristic brightness drop from the centerto the edges of the structure and a contrast radio jet.It is identified in the optics with the elliptical galaxyNGC 315 with the apparent magnitude of 11 .m2. Theradio source is present on the Planck mission map at100 GHz.
J 010725.4+322439. The type FR I radio sourcewith the characteristic radio brightness drop from thecenter to the edges of the structure; multiple warpingof the radio structure is observed. It is cataloged as3C 31 and 4C +32.05. The host galaxy is NGC 383(12 .m14). The structural features can also be seen onthe Planck mission map at the frequency of 100 GHzand on the map of the cosmic microwave background(Fig. 4).
J 011306.9–172028. The type FR I radio sourcehaving a structure resembling the “S” shape, wherethree enhanced radio brightness regions can beidentified: one in the center and two symmetricallyfrom the center, arranged almost in parallel to eachother. The object is identified with the 2MASX galaxyJ 01130721–1720241.
J 022033.5+365943. An FR I/II-type radio sourcehaving a complex asymmetric structure with promi-nent areas closer to the center. The host galaxy isMCG +06-06-021 (B = 15m).
J 065122.5+193713. A radio galaxy of an unusualshape with extended radio components stretched inone direction, in the beginning of which hot spotsare observed. It is identified with the 2MASX sourceJ 06513590+1935513 (V = 15 .m5).
J 073331.1+574133. A radio galaxy with a promi-nent center and broad radio components. It is identi-fied with MCG +10-11-077 (about 16m). The Planckmission map at 100 GHz in the source region revealsa local minimum in the distribution of detected radi-ation, while the cosmic microwave radiation map inthis area yields a local positive peak (Fig. 5).
J 083533.9–015100. An FR I-type radio galaxywith a prominent center and two symmetrically lo-cated broad radio components. It is identified with theNGC 2616 galaxy (apparent magnitude 12 .m7) andcataloged as PKS 0833–016.
J 084507.2–334711. An elongated radio galaxywith a smooth buildup of radio brightness to thecenter. It is identified with NGC 2663 (apparentmagnitude 10 .m9). The radio source is cataloged as
PKS 0843–336. The radio source is present on thePlanck mission map at 100 GHz.
J 122045.0+055204. An FR I-type radio sourcehaving a complex structure composed of many brightspots. In the optical range it is identified with a weakdiffuse object r = 21 .m3 (SDSS). No radio identifica-tion in the CATS database with the data from othercatalogs.
J 124159.1+323217. An FR I-type radio galaxy inthe shape of a complex elongated structure with aprominent central region. The radio image follows thestructure of the galaxy in the optics. It is identifiedwith the NGC 4631 object (apparent magnitude 9m).In the vicinity of the radio galaxy with the radius of 6′,about 400 SDSS catalog galaxies are located.
J 125310.7–103115. A type-FR I radio sourcewith a radio brightness drop towards the edges of thestructure, characteristic for this morphological type.It is identified with NGC 4760 (apparent magnitude11 .m6) and cataloged as PKS 1250–102.
J 132345.8+313402. An FR I-type radio source ofa symmetric dumbbell shape nevertheless revealing aradio brightness increase towards the center of thestructure. It is identified with NGC 5127 (apparentmagnitude of 12 .m5). In the vicinity of the radio galaxywith the radius of 6′, about 400 SDSS catalog galax-ies are located.
J 140955.9+173243. An FR I-type radio sourceelongated along one line. It is identified with the ellip-tical galaxy NGC 5490 (also known as NGC 5490A,UGC 9058, MCG +03-36-65, ZWG 103.95,PGC 50558). The apparent magnitude is 12 .m0.About 500 SDSS catalog galaxies are located in the6′-vicinity of the radio galaxy.
J 154901.7–321747. An FR II-type radio galaxyhaving a dumbbell shape typical for its class exceptfor the presence of another smaller extended structurecrossing the center at an angle and with a decreasingradio brightness distribution like in FR I. It can beattributed to a particular type of “X.” Cataloged asPKS 1545–321.
J 170502.0–244602. A radio galaxy of a complexshape with a prominent center and two extendedsources. It is identified with the 2MASX objectJ 17050125–2445099. The radio source is present onthe Planck mission map at the frequency of 100 GHz.
J 175643.3–263829. An extended radio galaxywith an almost homogeneous distribution of radiobrightness.
J 195230.9–011711. An FR I-type radio sourcehaving a nearly uniform radio brightness distributionthroughout the structure with a slightly outstandingcore and radio components. Cataloged as 3CR 403.1,4C –01.51 and PKS 1949–014. It is identified witha 2MASS galaxy (Ks = 12 .m2). The radio source is
present on the Planck mission map at the frequencyof 100 GHz.
J 210138.4–280158. An FR I-type radio sourcewith a strongly warped structure in the radio rangewith two prominent spots located symmetrically op-posite each other from the center. It is identified withNGC 6998 (apparent magnitude 14 .m2) and cata-loged as PKS 2058–282.
J 223115.9+392501. An FR I-type radio galaxyhaving an asymmetric structure with a fragmentationinto separate areas with distance from the center. It isidentified with the source UGC 12064 (14 .m5).
J 224548.5+394113. A dumbbell-shaped radiogalaxy with poorly resolved radio components. Itis identified with the Seyfert galaxy of 16 .m6 andcataloged as 3C 452 and 4C +39.71.
J 235721.0+475238. An FR I-type radio galaxywith the radio components converging at a slightangle. Belongs to the CGPG 2354.9+4736 group ofgalaxies.
2.2. Comments on Individual Sources.FR II-Type
The following is a commentary to the type FR IIsources from the list. Figures 6 and 7 show the im-ages from the NVSS survey and their radio spectraconstructed according to the results of identificationin the CATS database.
J 000041.4+121445. An FR II-type radio galaxywith a small angle between the radio components. No
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Frequency, MHz
Flu
x de
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, Jy
Fig. 3. Continuous radio spectra of the FR I and FR I/II-type LRGs from the results of identification in the CATS. The scalealong the axes is logarithmic.
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Fig. 4. The area centered on the J 010725.4+322439radio galaxy on the Planck space mission maps.Left: the observational data at the frequency of 100 GHz.Right: the cosmic microwave background data. The areasize is 30′×30′. The right ascension is along the x-axis,and declination is along the y-axis. The position of theradio galaxy is circled.
identifications were found in the optical, X-ray, andinfrared ranges.
J 001748.5–222256. A rather symmetricalFR II-type radio galaxy with a slight radio brightnessdecrease towards the center, cataloged asPKS 0015–226. A possible candidate for the identifi-cation in the optical and IR ranges (Fig. 8) is 2MASXJ 00174780–2223195 (B = 20 .m41).
J 005108.0–202818. An FR II-type radio galaxywith a slightly prominent lower radio component. Itis identified with the 2MASX object J 00510710–2028248 (B = 16 .m6).
J 005331.6+403059. An FR II-type radio galaxy ofa standard dumbbell shape with a poorly identifiablecenter. It is identified with a Seyfert galaxy 2MASXJ 00533165+4031255 (V = 18 .m8). An X-ray sourceRXS J005327.0+403101 is located next to the galaxy.
J 011203.6+493004. An FR II-type radio galaxy ofa standard dumbbell shape with a prominent centerand radio component edges. It is identified with thequasar 3C 35 (4C +49.04). In the optical range it hasan apparent magnitude of 15 .m6.
J 015302.5+711559. A radio galaxy with a stronglyshifted center, identified with the object 8C 0149+710(a BL Lac-type object). In the optics it has an appar-ent magnitude of about 15 .m5.
J 015756.3+020950. A dumbbell-shaped radiogalaxy with a somewhat fragmented structure to-wards the center. A candidate for identification onthe DSS image is APMUKS B 015517.56+015518.5(B = 20 .m08).
J 031821.9+682932. An FR II-type radio galaxywith clearly separated radio components, one ofwhich is superior to the other in brightness. Thebrightest component hosts a perpendicularly po-sitioned small structure closer to the center. The
Fig. 5. The area centered on the radio galaxyJ 073331.1+574133 on the Planck space missionmaps. Left: the observational data at the frequencyof 100 GHz. The vicinity of radio source exhibits a localminimum. Right: the data of the cosmic microwavebackground. The vicinity of the object reveals a localmaximum. The area size is 30′×30′. The right ascensionis plotted along the x-axis, and declination is along they-axis. The position of the radio galaxy is circled.
object is identified with a Seyfert galaxy 2MASXJ 03181899+6829322.
J 071244.0–085019. An FR II-type radio galaxywith a characteristic radio brightness drop from theperiphery to the center of the structure. The 100 GHzPlanck mission map reveals a radiation minimum inthe region of the radio source (Fig. 9). It is identifiedwith the 2MASX galaxy J 07124386–0850176.
J 080244.1–095757. A radio source with a com-plex structure with two prominent radio compo-nents of different shapes and an unobservable core.An identification candidate is the 2MASX galaxyJ 08024016–0957504. It is cataloged asPKS 0800–098.
J 082128.4–301124. A dumbbell-shaped FR II-type radio galaxy with a weak radio brightness declinetowards the center of the structure. It is identifiedwith the 2MASX object J 08212682–3011030 andcataloged as PKS 0819–300.
J 091251.6+350929. An FR II-type radio galaxywith prominent radio components and the centerwhich is almost not luminous in the radio range.It is identified with one of the galaxies of the com-pact group of galaxies SDSS CGB 23048. About550 SDSS catalog galaxies are located in the6′-neighborhood of the radio galaxy.
J 102054.5+483044. A radio source which mostlikely represents interacting radio galaxies. It isidentified with the KPAIR object J 1020+4831 (apair of galaxies). Visually it looks like two extendedradio objects facing each other at a slight angle, withfading trails pointing in opposite directions. It is cat-aloged as 4C +48.29 and identified with the 2MASXgalaxy J 10205188+4831096 (17m). The region ofthe radio galaxy hosts an X-ray the source. The
6′-neighborhood of the object contains an increasednumber (about 570) of background SDSS galaxiesof 20m–22m, the redshift of z ∼ 0.06 is measured forsome of them.
J 111141.9–132417. An FR II-type radio galaxyFR II with a weak radio brightness decline towardsthe center and possessing a structure of an almostconstant width.
J 113538.0+390154. A radio galaxy representedby two distinct radio components. The 2′-vicinityof the object has an increased number (about 80)background SDSS galaxies 20m–22m, the redshift ofz = 0.15–0.17 is measured for some of them.
J 115909.1+582041. A radio galaxy of a milddumbbell shape. Faint structures depart in the op-posite directions from the radio components whichmay indicate the rotation of the radio galaxy. Probableidentification—CGCG 292-05 (B = 15 .m7).
J 123846.9+440949. An FR II-type radio galaxy ofa dumbbell shape. Probable identification is a galaxyof 19 .m2 in the g-band.
J 142554.6–080401. An FR II-type radio galaxywith clearly pronounced radio components and alacking center.
J 172331.0–352542. A weak FR II-type radiosource.
J 182708.3–124020. Two radio components withvirtually unnoticeable relations between them. The
X-ray and optical ranges are void, while the infraredreveals an object in the center, possibly associatedwith the radio galaxy. The region of the radio sourceincludes a pair of galaxies CGMW 3-2209. Thesource was selected to the catalog of the H II regioncandidates as G 18.9–0.5. The radio source is presenton the Planck mission map at 100 GHz.
J 184133.3–015251. A typical FR II-type radiogalaxy with radio brightness decreasing from theedges of the structure towards the center. The sourcewas selected to the catalog of the supernova remnantcandidates.
J 185528.6–071613. An FR II-type radio galaxywith a characteristic structure. One of the radio com-ponents is somewhat brighter than the other.
J 191918.2+514208. An FR II-type radio galaxywith a brightness center which is shifted with regardto the center of the radio components towards oneof them; there is a small structure not far from thiscenter, located at an angle to the main radio galaxy.The radio components have different brightnesses.The 100 GHz Planck mission map in the region of theradio source reveals a radiation minimum (Fig. 11).
J 194348.3–354651. An FR II-type radio galaxywith a poorly identifiable center and radio compo-nents of different brightness. It is identified with a2MASX galaxy J 19434935–3546460 (B ∼17m) andcataloged as PKS 1940–358.
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Frequency, MHz
Flu
x de
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, Jy
Fig. 7. Continuous radio spectra of FR II-type LRGs based on the identification results in the CATS. The scale of the axes islogarithmic.
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Fig. 7. (Contd.)
J 202339.8+170350. An FR II-type radio galaxywith radio components asymmetric in brightness.The radio source is cataloged as 4C +16.68 andPKS 2021+16. The identification candidate is the2MASX galaxy J 20233698+1702409. The radiogalaxy region contains an X-ray source.
J 213208.6+342057. A FR II-type radio galaxy ofa standard dumbbell shape with a poorly identifi-able center. It is identified with the 2MASX galaxyJ 21320953+3420448.
J 223536.0+373523. A symmetrical FR II-typeradio galaxy. The center of the radio galaxy includesfaint diffuse objects on the DSS and 2MASS map.The radio source is present on the Planck missionmap at 100 GHz (Fig. 13).
J 225321.7+162014. A faint FR II-type radiogalaxy with radio components located at a small angleto each other. It is identified with a 2MASX galaxyJ 22532268+1620056.
J 231600.3–282359. An FR II-type radio galaxywith outstanding radio components and a bright
central point source. It is identified with the object2dFGRS TGS266Z204 (B ∼ 18 .m6).
3. CONCLUSIONWe have performed identification of radio galaxies
selected by comparing the axes of the “unrelated”NVSS catalog sources with the separation of over 4′.The resulting list was divided into two subsamples ofFR I-type (21 sources) and FR II-type (29 sources)objects. Identification of radio galaxies was performedusing the tools of the CATS, NED2 and SkyView3
databases. The objects from the FR I list are, as arule, located closer and have identifications in theoptical range in the DSS survey images more oftenthan the FR II list sources. If we consider the lack ofidentification or the weakness of the optical candidate,the FR II-type LRGs from our list are on the averagelocated further than the FR I-type LRGs and havelarger linear dimensions.
RADIO AND OPTICAL IDENTIFICATION OF GIANT RADIO GALAXIES 157
Fig. 8. A candidate for the identification of theJ 001748.5–222256 radio galaxy—the 2MASX galaxyJ 00174780–2223195. The isolines are plotted on theDSS image according to the NVSS data. The candidateis marked with an arrow. The image size is 6′×6′.
Fig. 9. The area centered on the radio galaxy J 071244.0–085019 on the Planck space mission maps. A local min-imum is located in the vicinity of the radio source. Thedata are at the frequency of 100 GHz. The area size is30′×30′. The right ascension is plotted along the x-axis,and declination is along the y-axis. The position of theradio galaxy is circled.
Fig. 10. A candidate for the identification of theJ 080244.1–095757 radio galaxy—the 2MASX galaxyJ 08024016–0957504. The isolines are plotted on theDSS image according to the NVSS data. The candidateis marked with an arrow. The image size is 6′×6′.
Fig. 11. The area centered on the radio galaxyJ 191918.2+514208 on the Planck space mission maps. Alocal minimum is located in the vicinity of the radio source.The data are at the frequency of 100 GHz. The area size is30′×30′. The right ascension is plotted along the x-axis,and declination is along the y-axis. The position of theradio galaxy is circled.
Fig. 12. A candidate for the identification of theJ 202339.8+170350 radio galaxy—the 2MASX galaxyJ 20233698+ 1702409. The isolines are plotted on theDSS image according to the NVSS data. The candidateis marked with an arrow. The image size is 9′×9′.
Fig. 13. The area centered on the radio galaxyJ 223536.0+373523 on the Planck space mission maps. Alocal minimum is located in the vicinity of the radio source.The data are at the frequency of 100 GHz. The area sizeis 30′×30′. The right ascension is plotted along the x-axis, and declination is along the y-axis. The position ofthe radio galaxy is circled.
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Giant linear dimensions exceeding 1 Mpc wereconfirmed for a part of radio galaxies with knownredshifts (see the table):
J 005331.6+403059, J 011203.6+493004,
J 031821.9+682932, J 091251.6+350929,
J 154901.7–321747, J 231600.3–282359.Seven more objects have d > 0.5 Mpc. Note also thatthe FR II-type objects dominate by number amongthe giant radio sources in our list.
A radio galaxy J 154901.7–321747 (PKS 1545–321) of the mixed type, designated as “X,” wasdiscovered among the selected radio sources. Ap-parently, it is the result of merging of two activegalactic nuclei. Virtually all the galaxies possess asteep continuous spectrum built on integral data. Thepresence of the corresponding source for the objectsof the list was checked on the 100 GHz Planckspace experiment map. We can expect to see here themost contrasting Sunyaev–Zel’dovich effect in theshape of the minimum in the CMB distribution [45].Within the detailed study of the effect for the LRGs,component separation has to be done and signalfrequency distribution has to be studied. During thevisual examination of ten objects of our list we havefound two effects: (1) the presence of a maximum onthe map at the frequency of 100 GHz in the regionof radio galaxies J 005744.4+302156, J 084507.2–334711, J 170502.0–244602, J 195230.9–011711(FR I-type), as well as J 182708.3–124020 andJ 223536.0+373523 (FR II-type); (2) the source co-ordinates fall into the local minimum region in themicrowave map of radio galaxies J 073331.1+574133(FR I) and J 071244.0–085019, J 082128.4–301124,J 191918.2+514208 (FR II). Although the statisticsis small, note that the maximum on the microwavemaps centered in the source region is detected morefrequently than the minimum zone for the first type ofgalaxies, while the minimum, on the contrary, is morecommon than the maximum for the second type ofgalaxies.
Our following paper will investigate the distribu-tion of the microwave background at different fre-quencies of the Planck mission for all the list objectsand the known cataloged GRGs.
ACKNOWLEDGMENTS
The authors thank the referee for the useful com-ments that allowed to improve the text. Our studymade use of the NED (NASA/IPAC ExtragalacticDatabase, which is operated by the Jet PropulsionLaboratory, California Institute of Technology, undercontract with the National Aeronautics and Space
Administration) and the SkyView Virtual Observa-tory. The authors also used the CATS database ofradio astronomy catalogs [23, 46] and the FADPSradio astronomy data (http://sed.sao.ru/∼vo//fadps_e.html) processing system [47, 48]. Weused the data of the open Planck experiment archiveof the European Space Agency (the Planck LegacyArchive at http://www.sciops.esa.int). For theanalysis of the Planck mission maps, we usedthe GLESP package (http://www.glesp..nbi.dk) [49, 50]. This study was supported by theRFBR grant (project No. 13-02-00027-a).
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