Ultra-High Energy Cosmic Rays Detected by Auger and AGASA:Corrections for Galactic Magnetic Field Deflections, Source Populations, and Arguments for Multiple-Components
AAstronomy & Astrophysics manuscript no. nagar˙aanda c (cid:13)
ESO 2018October 30, 2018
Ultra-High Energy Cosmic Rays Detected by Auger and AGASA:
Corrections for Galactic Magnetic Field Deflections, Source Populations, andArguments for Multiple-Components
Neil M. Nagar and Javier Matulich Astronomy Department, Universidad de Concepci´on, Concepci´on, Chilee-mail: [email protected],[email protected]
Received June 16, 2009; accepted December 5, 2009
ABSTRACT
Context.
The origin and composition of Ultra-High Energy Cosmic Ray Events (UHECRs) are under debate. Possible sources include ActiveGalactic Nuclei - selected by various criteria - and extragalactic magnetars.
Aims.
We aim to improve constraints on the source population(s) and compositions of UHECRs by accounting for UHECR deflections withinexisting Galactic magnetic field models (GMFs).
Methods.
We used Monte Carlo simulations for UHECRs detected by the Pierre Auger Observatory and AGASA, to determine the UHECRtrajectories within the galaxy and their outside-the-Galaxy arrival directions. The simulations, which used UHECR compositions from protonsto Iron and seven models of the ordered GMF, accounted for uncertainties in the GMF and a turbulent magnetic field component. The trajectoriesand outside-the-Galaxy arrival directions were compared with Galactic and extragalactic sources.
Results.
For a given proton or light UHECR, the multiple potential outside-the-Galaxy arrival directions within a given GMF model are notvery di ff erent, allowing meaningful constraints on source populations. The correlation between a subset of UHECRs and nearby extendedradiogalaxies (Nagar & Matulich 2008) remains valid, even strengthened, within several GMF models. Both the nearest radiogalaxy Cen A,and the nearest radio-extended BL Lac, CGCG 413 − / or microquasars. For heavier UHECRs, the multiplepotential outside-the-Galaxy arrival directions of any given UHECR are highly scattered but still allow meaningful constraints. It is possible,but unlikely, that all UHECRs originate in the nearby radiogalaxy Cen A. Conclusions.
Nearby radiogalaxies remain a strong potential source of a significant subset of UHECRs. For light UHECRs about a third ofUHECRs can be “matched” to nearby galaxies with extended radio jets. The remaining UHECRs could also be explained as originating inextended radiogalaxies if one has at least one of: a large UHECR mean free path, a high cluster and / or intergalactic magnetic field, a heavycomposition for two-thirds of the detected UHECRs. If extended radiogalaxies are, or trace, UHECR sources, the most consistent models forthe ordered GMF are the BS-S and BS-A models; the GMF models of Sun et al. 2008 are acceptable if a dipole component is added. Key words. interstellar-medium: Cosmic Rays – interstellar-medium: Magnetic Fields – Galaxies: Active – Galaxies: jets;
1. Introduction
Ultra-High Energy Cosmic Rays (UHECRs) are protons orfully ionized nuclei with energies greater than about 10 eV (10 EeV). On entering the earth’s atmosphere they pro-duce a shower of secondary particles and excite atmosphericmolecules. The detection of both e ff ects from the ground al-lows a precise measurement of both the initial energy andthe arrival direction of the UHECR above the earth’s at-mosphere e.g. AGASA (Takeda et al., 1999) and the PierreAuger Observatory (Pierre Auger Collaboration et al., 2004).The resultant positional accuracy of the earth-arrival direction, Send o ff print requests to : Neil M. Nagar now better than a degree, allows correlations with astronomi-cal sources in order to determine the source population(s) ofUHECRs - a long held mystery. Exploiting the full potentialof the earth-arrival directions nevertheless requires taking intoaccount deflections su ff ered due to Galactic and extragalacticmagnetic fields.Suspected sources of ultra high energy cosmic rays includepowerful active galaxies, magnetars, core collapse Supernovae(SN II), and gamma rays bursts (for reviews and lecturessee Hillas (1999); Kachelriess (2008) and references therein).Specifically, an origin in nearby radiogalaxies and BL Lacs haslong been predicted (Rachen & Biermann, 1993; Romero etal., 1996). More exotic explanations include dark matter anhi- a r X i v : . [ a s t r o - ph . H E ] D ec Nagar & Matulich: UHECRs: Galactic Magnetic Field Deflections lation and evaporation of micro black holes. The main energyloss for a UHECR propagating over cosmological distances isexpected to be pion-production triggered by interaction with aCMB photon, the so called Greisen Zatsepin Kuzmin (GZK)e ff ect (Greisen, 1966; Zatsepin & Kuzmin, 1966). The pre-dicted energy loss (around 30%) and mean free path of theUHECR ( ∼ ◦ ; of these, 27 have energies above 56 EeV and have been re-ported in Pierre Auger Collaboration et al. (2007, 2008, here-after PA07, PA08). The origins of the latter 27 UHECRs, to-gether with 11 UHECRs detected by AGASA at energies above56 EeV (Hayashida et al., 2000) are the focus of this paper.The PAO has since detected additional UHECRs (The PierreAuger Collaboration et al., 2009a,b, hereafter PA09a, PA09b)but detailed positions and energies are not yet published. Inthis work we use “UHECR” to refer to UHECRs with energyabove 56 EeV unless explicitly mentioned otherwise. The com-positions of the detected UHECRs are still under debate (e.g.PA09a; PA09b; Matthews, 2007; Hooper & Taylor, 2009) withevidence for a mix of protons and heavy nuclei at the high-est energies. There has been recent doubt about the measuredenergies of the UHECRs detected by PAO and AGASA. ThePAO team have lowered their previous reported energies bya small percentage (PA09a, PA09b) and there have been sug-gestions that energies reported by AGASA should be loweredby up to 30%. To avoid confusion we report our results sepa-rately for PAO and AGASA UHECRs. Several other UHECRobservatories, e.g. Haverah Park and Fly’s Eye, have detected asignificant number of UHECRs: given that the GMF deflectioncalculations and source matching in this work require accurateenergies ( (cid:46) (cid:46) ◦ ) we do not includetheir results in our analysis.The arrival directions of the 27 UHECRs detected by PAOare not isotropic at a 99% significance level (PA07, PA08,PA09a, PA09b). Several correlations, or lack thereof, with ex-tragalactic sources have been suggested: AGNs from the cata-log of V´eron-Cetty & V´eron (PA07, PA08), hard X-ray selectedAGNs (George et al., 2008), nearby extended radiogalaxies(Nagar & Matulich, 2008), nearby spiral galaxies (Ghisellini etal., 2008), local volume galaxies (Cuesta & Prada, 2009) andlarge scale structure (Ryu et al., 2009).Galactic and extragalactic magnetic fields deflect cosmicrays via the Lorentz force even at energies above 56 EeV. If theextragalactic field is unordered over large scales the expecteddeflections for these energies are only a few degrees (e.g.Harari et al., 2002; Dolag et al., 2004). An ordered GalacticMagnetic Field (GMF) can, however, produce significant de-flections (e.g. Takami & Sato, 2008) especially on trajectorieswhich pass close to the Galactic plane and / or for heavy com-position UHECRs.The line of sight integrated GMF of the Galaxy has beenmeasured in various directions via e.g. the rotation measures of pulsars and extragalactic radio sources, and polarization ofstarlight or radio synchrotron emission (e.g. Heiles, 1996;Brown et al., 2007; Noutsos et al., 2008; Sun et al., 2008;Han, 2009; Beck, 2009). Additionally, local magnetic fieldscan be measured accurately via Zeeman splitting of emissionlines. For a given line of sight, the rotation measure traces theintegrated parallel component of the GMF while a UHECRis deflected by the perpendicular component of the GMF. Aglobal model of the ordered GMF is thus required to trans-fer information from rotation measures into information usefulfor UHECR deflections. Several models have been presentedfor ordered magnetic fields in the Galaxy. These typically con-sider one or more of the following: a toroidal type field in andnear the galaxy disk, a toroidal field in the halo, and a poloidalfield which reproduces the vertical component seen in the Solarneighbourhood and the Galactic center. Models for the orderedcomponent of the magnetic field are discussed in the next sec-tion, and recent comprehensive reviews can be found in Han(2008) and Beck (2008). Studies of the global magnetic fieldof other galaxies has greatly facilitated the refinement of mod-els of the Galactic GMF (see Beck, 2008, 2009, for a review),even though there is significant variation between galaxies inboth the ordered and turbulent GMF, especially among thosewith high star formation rates.In this article, we expand the work of Nagar & Matulich(2008) in two directions: first we use Monte Carlo simulationsto derive UHECR trajectories within the Galaxy and corre-sponding outside-the-Galaxy arrival directions for all PAO andAGASA UHECRs. The simulations, run for six UHECR com-positions - from protons to iron - and seven GMF models, in-clude uncertainties in the GMF and a turbulent magnetic fieldcomponent. We then compare the UHECR trajectories withinthe galaxy and their outside-the-Galaxy arrival directions withvarious Galactic and extragalactic sources, and discuss the im-plications of the results. The individual steps followed in thiswork have been addressed previously by various authors ref-erenced here and in the next section. The new facet of thiswork is that we combine all of the above steps within thesame Monte Carlo simulation, in order to model the trajecto-ries of the PAO and AGASA UHECRs with energies greaterthan 56 EeV within a large number of ordered GMF modelsand UHECR compositions. Sec. 2 introduces the magnetic fieldmodels and describes the Monte Carlo simulations, Sec. 3 sum-marizes the sources of the data used, and Sec. 4 describes theprinciple results obtained. Finally, Sec. 5 contains a brief dis-cussion and the conclusions of our study. Distances to galaxiesare calculated using a Hubble constant of 72 km s − Mpc − ,except for relatively nearby galaxies for which we use distancesas referenced.
2. Magnetic Fields and Monte Carlo Simulations
We consider seven ordered magnetic field models for ourGalaxy (for recent reviews of Galactic and extragalactic or-dered magnetic fields see Beck, 2008; Han, 2008; Beck, 2009).Four of these models, the so called BS-S, BS-A, AS-S, andAS-A have been used previously by several authors. Here, thefirst two alphabets signify a (bi-)symmetric (BS) or asymmet- agar & Matulich: UHECRs: Galactic Magnetic Field Deflections 3 ric (AS) configuration w.r.t. a transformation between θ and θ + π , where θ is the cylindrical azimuthal angle in the Galacticplane. The last alphabet signifies whether the field reverses di-rection (A) or not (B) in passing from above the Galactic planeto below the Galactic plane. Given the evidence for a vertical( z ) component of the GMF, both in the Galactic center and inthe Solar vicinity, a dipole field model is usually added to thetoroidal field above. Detailed descriptions and discussions ofthese GMFs can be found in Stanev (1997); Beck (2001); Han(2002); Tinyakov & Tkachev (2002); Prouza & ˇSm´ıda (2003);Brown et al. (2007); Kachelrieß et al. (2007); Men et al. (2008);Takami & Sato (2008); Han (2009). For these four models, weuse the equations and their related normalizations strictly fol-lowing Takami & Sato (2008), and always include the dipolefield component as specified in Takami & Sato (2008).Sun et al. (2008, hereafter S08) have recently presentedthree new variations of the above GMF models - AS-S + RING,AS-S + ARM and a modified BS-S - tailored to best fit observa-tions of Galactic synchrotron emission and its polarization, androtation measures of pulsars. For brevity we sometimes refer tothese three models as ASS + R, ASS + A, and BSS(S) in the textand tables. Sun et al. (2008) find that the first two models pro-vide the best fit to current radio observations. These two mod-els use the basic configuration of the AS-S model, but introducefield reversals in a specified ring or arm, respectively. The mod-ified BS-S model is based on the traditional BS-S model butwith di ff erent parameters and normalizations. The three newmodels presented by S08 also include a toroidal halo field asinitially presented in Prouza & ˇSm´ıda (2003), but do not in-clude a dipole magnetic field component. We use these threemodels and their related halo field as described in S08 with onlyone di ff erence: in the AS-S + ARM model we directly use thelog spiral arm morphology described in Wainscoat et al. (1992)without correcting for their shape near the solar neighbour-hood as in S08, who used the correction suggested in Taylor& Cordes (1993). We do not expect significant changes in theUHECR trajectories due to this small change in the morphol-ogy of the spiral arms. Sun et al. (2008) assumed that there isno ordered dipole field component in the Galaxy GMF, argu-ing that the vertical ( z ) component of the local magnetic fieldis a turbulent component. Since the parametric form and nor-malizations of the S08 models were derived via fits to radioobservations, it is not strictly correct to add a dipole field to themodels. Nevertheless, for illustrative purposes (and out of cu-riosity) we also performed simulations of the S08 GMF modelsincluding the dipole field component as specified in Takami &Sato (2008). We refer to these results as the Sun et al. (2008)GMFs plus dipole.We simulated UHECR trajectories for six di ff erent UHECRcompositions: protons, He + , O + , Al + , Ca + , and Fe + .Once chosen, a composition was maintained fixed during thefull trajectory within the galaxy: i.e. we do not consider photo-dissociation-produced composition changes to a UHECR dur-ing its Galactic trajectory. UHECR trajectories were simulatedby firing an anti-particle with the corresponding UHECR mass,(anti)charge, and energy from the Earth in the earth-arrival di-rection of the UHECR and following its trajectory - includingdeflections in the magnetic field - in steps of 10 pc. The simu- lations were carried out until the anti-particle left a sphere withdiameter 40 kpc centered on the Galactic center. The Galacticcoordinate pair ( l , b ) derived from the final position and veloc-ity of the anti-particle in the simulation is equivalent to the ar-rival direction of the UHECR before it entered the Galaxy, andwe refer to this direction as the ‘outside-the-Galaxy’ arrival di-rection, to distinguish it from the ‘earth-arrival’ direction mea-sured by the observatory.Each UHECR’s trajectory within each GMF model wassimulated fifty times using a Monte Carlo approach: introduc-ing uncertainties in the ordered magnetic field and a randomturbulent magnetic field component. In more detail, in each10 pc simulation step we (a) computed the 3-vector repre-senting the Cartesian coordinates of the ordered magnetic fieldfrom the relevant model. For the AS-S, AS-A, BS-S, and BS-A models this was the sum of the cylindrical (disk) field andthe dipole field. For the AS-S + ARM, AS-S + RING, and BS-S model of S08 this was the sum of the disk and halo fields(with or without the dipole field as described above); (b) addeda Gaussian-distributed random error in each component of theordered magnetic field, i.e. a change in both magnitude and di-rection of the ordered field. This was done by adding to the3-vector of the previous step a 3-vector whose each componentwas a random number derived from a Gaussian distributionwith mean = σ = ff erent normalization parameters: the maximumturbulent magnetic field strength in each Cartesian componentwas taken to be ± µ G, and the probability of a turbulent fieldbeing present was taken to be 1% in the halo of the galaxy, 20%in the disk of the galaxy (Galactic radius less then 20 kpc andGalactic height less than 1.5 kpc) and 80% in the spiral armsof the Galaxy - where we used the spiral arm definition fromWainscoat et al. (1992), spiral arm thickness 0.75 kpc in thedisk (i.e. coordinate r ), and half-height 0.5 kpc (coordinate z ).We therefore generated a random number to determine whethera turbulent field was required to be added following the prob-abilities above. If so, we generated a 3-vector in which eachcomponent was a random number uniformly distributed be-tween ± µ G. This was added to the magnetic field 3-vector inthe previous step in order to derive the total magnetic field usedin the deflection calculation of this step. This turbulent fieldwas then kept constant for the next 50 pc (i.e. an additional fivesimulation steps), the expected scale length of turbulent field inthe Galaxy (Prouza & ˇSm´ıda, 2003; Beck, 2008). Note that theturbulent field used here is relatively large in comparison withcurrent measurements of the turbulent field in the Galaxy (S08)and other galaxies (Beck, 2009).In summary, within each GMF model we derived 50outside-the-Galaxy arrival directions for each UHECR of a spe-cific composition, or a total of 300 outside-the-Galaxy arrivaldirections for each UHECR over all six compositions mod-elled.
Nagar & Matulich: UHECRs: Galactic Magnetic Field Deflections
3. Data
Positions and energies of the 27 UHECRs detected by the PAOwith energies ≥
56 EeV were taken from PA08; we have notmade the small energy corrections to these UHECRs as laterreported by the PAO (PAO09b). Positions and energies of theUHECRs detected by AGASA with energies ≥
56 EeV weretaken from Hayashida et al. (2000) which is an updation ofthe data listed in Takeda et al. (1999). For AGASA UHECRs,we lowered the energies reported in Takeda et al. (1999) by30%: this resulted in 11 UHECRs with energy above 56 EeV.In this work we use ‘AGASA UHECRs’ to refer to only these11 UHECRs unless explicitly stated otherwise.Our catalogs of astronomical sources were drawn from var-ious publications and web-based source lists, and chosen to berepresentative of previously suspected or posited Galactic andextragalactic sources of UHECRs. In all cases, we attemptedto select the most comprehensive catalog available. Sourcelists for galaxies, galaxy clusters, GRBs, Galactic supernovaremnants, and extragalactic radio supernova are described inNagar & Matulich (2008). As in Nagar & Matulich (2008), inthe case of radiogalaxies and radio sources we used severalsurveys and catalogs, including NVSS (Condon et al., 1998),SUMMS (Bock et al., 1999), and NED. The list of extragalac-tic jets is based on that compiled by Liu & Zhang (2002); tothis list we added data on the galaxies as given in NED, andre-measured the total flux and total extent of the radio emissionfrom NVSS and SUMMS maps or from the list of DRAGNscompiled by P. Leahy . The DRAGNs list is a subset of the3CRR sources (Laing et al., 1983) which have one or all ofradio-emitting jets, lobes, and hotspots. The total extent of theradio emission therefore includes both radio jets and any ra-dio lobes. This extent is typically referred to as the LargestAngular Size (LAS) or Largest Linear Size (LLS). In the caseof double sided jet or lobe sources, we added the LLS of thetwo jets and lobes as scalars instead of vectors in order to dis-count the e ff ects of jet and lobe bending. Nagar & Matulich(2008) listed the 10 radiogalaxies in the field of view of PAOwith D ≤
75 Mpc and LLS ≥
180 kpc. To this we added all other(northern) radiogalaxies satisfying the same criteria: NGC 315(D = = = =
907 kpc), NGC 1275 (D = =
468 kpc),NGC 5127 (D = =
230 kpc), and CGCG 514-050 (D =
72 Mpc; LLS =
506 kpc). Together, these 15 galaxies,form our sample of all nearby (D ≤
75 Mpc) extended (LLS ≥
180 kpc) radiogalaxies. In the case of nearby galaxies, wealso used the HIPASS catalog (Meyer et al., 2004; Wong etal., 2006) as used by Ghisellini et al. (2008) in their study ofthe correlation between UHECR arrival directions and nearbygalaxies. Additionally, we used the revised Third ReferenceCatalog of Bright Galaxies (Corwin et al., 1994) to select asample of nearby elliptical galaxies.In this work we have considered several new sourcecatalogs: Galactic Soft Gamma-Ray Repeaters (SGRs) andGalactic Anamolous X-ray Pulsars (AXPs) were taken fromWoods & Thompson (2006) and updated with the online list http: // / atlas / dragns.html maintained by the McGill pulsar group . As of June 2009, thislist includes six SGRs (two of which are candidates) and 10AXPs (one of which is a candidate). These SGRs and AXPsare believed to be high magnetic field radio pulsars or “mag-netars”. Of the total of 16 SGRs and AXPs, 14 are close to theplane of the Galaxy, and two are in the SMC and LMC.Confirmed Galactic microquasars were taken from the listin Paredes (2005), and candidate micro-quasars from Combiet al. (2008). Various gamma-ray catalogs have been used:the BeppoSAX catalog of GRB and X-ray afterglows (dePasquale et al., 2006), the BeppoSAX complete catalogue ofGRBs (Vetere et al., 2007), Gamma-ray Blazars in northern sky(Sowards-Emmerd et al., 2003), Blazar counterparts for 3EGsources (Sowards-Emmerd et al., 2004), Gamma-ray Blazarcandidates (Sowards-Emmerd et al., 2005), Sources detectedby ISGRI (Bodaghee et al., 2007), and the Third EGRET cata-log (Hartman et al., 1999). We also used the HESS (Hofmann,2005) catalog of 54 Gamma-ray sources between 100 GeV and100 TeV as obtained from the HESS online catalog in June2009 .
4. Results
We performed several Monte Carlo test runs varying the mag-nitudes of the error of the ordered field and the maximum tur-bulent field strength. Here we present and discuss the results ofsimulations which used a Gaussian-distributed (mean = σ =
50% of the value of the Cartesian GMF component) errorin each Cartesian component of the ordered GMF, and a tur-bulent magnetic field uniformly distributed between ± µ G ineach Cartesian component of the magnetic field, with details asdescribed in Sec. 2. We note that for the simulated GMF error,using 25%–100% instead of 50% as described above does notsignificantly change the trajectories in the case of anti-protons.The relative deflections su ff ered by the UHECR from the or-dered field and turbulent field components can thus be roughlyjudged by comparing the average and r.m.s. of the deflectionangles corresponding to the fifty outside-the-Galaxy arrival di-rections for each UHECR within each GMF model.We used the following distance limits between a singleoutside-the-Galaxy arrival direction and an extragalactic astro-nomical object in order to be considered a “match”: 2.5 ◦ for H,3 ◦ for He, 6 ◦ for O, 9 ◦ for Al, 12 ◦ for Ca, and 15 ◦ for Fe. Thesesemi-arbitrary values were chosen considering a constant addi-tive error of 2 ◦ - to account for e.g. the error in determining thearrival direction of the UHECR - plus a composition-weightederror of 0.5 times the charge of the UHECR which roughly ac-counts for errors in the deflection calculations and deflectionsby intergalactic magnetic fields but avoids too large “matchradii” for heavy nuclei. To match an astronomical source witha UHECR we require that at least 4 of the 50 outside-the-Galaxy arrival directions are ‘matched’ by the above criterion;this ≥
8% match probability was chosen as it implies roughlythat a match cannot be ruled out at better than a 2 σ level withinthe simulation parameters. http: // / pulsar / magnetar / main.html http: // / hfm / HESS / pages / home / sources / agar & Matulich: UHECRs: Galactic Magnetic Field Deflections 5 Graphical representations of our simulation results areshown in Figures 1 to 5. Coordinates of the arrival directions ofthe UHECRs detected by PAO (blue for UHECRs with energy ≥
75 EeV and green for UHECRs with energy between 56 and75 EeV) and AGASA (red) are shown as open circles of (ar-bitrary) radius 3.5 ◦ . The outside-the-Galaxy arrival directionsof the UHECRs are plotted with small colored dots (50 perUHECR, each representing the result of one Monte Carlo sim-ulation). Figures 1 and 3 appear in the printed version of thismanuscript while Figures 2, 4, and 5 are available in the elec-tronic version only. The outside-the-Galaxy arrival directionswere plotted in the order red, green, blue, and yellow. Whenone of these colors is not seen for a UHECR, it lies below oneof the following colors in the sequence above. For example, thepairs BS-S (red), BS-A (blue) and AS-S (green), AS-A (yel-low) have the same deflection for positive values of Galacticlatitude ( b ). To avoid overcrowding, results for the three mod-els of S08 are shown separately from the other four models.Figures 1 to 5 include the positions of all galaxies with ra-dio jets from the catalog of Liu & Zhang (2002) within 500 kpcand the 16 confirmed and candidate SGRs and AXPs in theGalaxy (Woods & Thompson, 2006). As in Nagar & Matulich(2008) - but with di ff erent cuto ff s - we have divided the galax-ies with radio jets into three redshift bins: “nearby” (D ≤
75 Mpc; red circular symbols), “intermediate” (75 Mpc < D ≤
200 Mpc; blue circular symbols), and “distant” (200 Mpc < D ≤
500 Mpc; black circular symbols). In all redshift bins, we dis-tinguish between galaxies with radio structures more extendedthan 180 kpc (“extended”; solid symbols) and those with radiostructures less extended than 180 kpc (“compact”; open sym-bols). Filled triangles are used for Galactic magnetars: red forSGRs and blue for AXPs. Of the 16 magnetars, two are in theLMC and SMC and the others are close to the plane of theGalaxy.
Columns 5 to 7 of Tables 1 and 2, present the results of the de-flection simulations for proton UHECRs within the BS-A GMFmodel. Tabular results for other models are not shown for spacereasons and can be requested from the authors. The first fourcolumns of the tables identify the UHECR by an index num-ber, its arrival direction in Galactic coordinates, and its energy.Then, for each UHECR composition simulated, we list the av-erage and r.m.s. of the deflection angles corresponding to the50 outside-the-Galaxy arrival directions of each UHECR, fol-lowed by the nearby extended radiogalaxy which best matchesthe fifty outside-the-Galaxy arrival directions (see the previoussection for a definition of a match). A nearby extended radio-galaxy is only listed if more than four of the 50 outside-the-Galaxy arrival directions are matched. For proton UHECRs, theaverage deflection and its r.m.s. for each UHECR are both typ-ically 1 ◦ –5 ◦ though values greater than 30 ◦ are seen for a fewUHECRs whose trajectories pass close to the Galactic planeand / or Galactic center.We emphasize four important results of the proton-UHECRtrajectory simulations: (a) even after considering errors in the model GMF and adding a relatively strong turbulent mag-netic field component, the outside-the-Galaxy arrival directionsof the majority of proton-UHECRs are typically su ffi cientlyconcentrated to allow meaningful comparisons with Galacticand extragalactic sources; (b) for a given proton-UHECR, theoutside-the-Galaxy arrival directions are typically significantlydi ff erent for di ff erent GMF models. An assumption of thesource population therefore allows constraints on competingmodels of the ordered GMF; (c) almost all UHECRs withGalactic latitude − ◦ < b < ◦ have trajectories which passclose to or cross the Galactic plane within certain GMF mod-els, especially those which include an ordered dipole field;(d) as discussed in detail in Sec. 4.5, the match betweenproton-UHECRs and nearby extended radiogalaxies (Nagar &Matulich, 2008) is maintained in most GMF models, and sig-nificantly strengthened in some GMF models. With increasingly heavy UHECR compositions, the increaseddeflections su ff ered by the UHECRs tend to scatter their out-of-Galaxy arrival directions over larger regions of the sky.Figure 3, which compares the deflections su ff ered by UHECRsin four models for di ff erent UHECR compositions, empha-sizes the importance of UHECR composition for source iden-tification. The simulation in this figure does not include aMonte Carlo approach: i.e. we did not consider GMF uncer-tainties or turbulent magnetic fields. We remark on several in-teresting features in Figure 3, especially for compositions nearOxygen: (a) the three PAO UHECRs near l = ◦ , b = − ◦ move close to the radiogalaxy 3C120 for a UHECR compo-sition of Oxygen; (b) the twin mystery PAO UHECRs near l = ◦ , b = − ◦ move toward the Galactic plane in thecase of light compositions, and then toward the Cen A concen-tration of radiogalaxies for an Oxygen composition. (c) severalUHECRs move toward the extended radiogalaxies NGC 315and NGC 383 (near position l = ◦ , b = − ◦ ) for composi-tions near Oxygen.A summary of the results of our Monte Carlo simulationsfor heavy-nuclei UHECRs within the BS-A GMF model can befound in Tables 1 and 2. Graphical representations for Oxygenand Iron UHECRs within the BS-S, BS-A, AS-S, and AS-Amodels are presented in Figures 4 and 5. As expected, both theaverage and the r.m.s. of the deflection angles corresponding tothe 50 outside-the-Galaxy arrival directions for each UHECRincrease with increasing UHECR mass (Tables 1 and 2). Forcompositions up to around Oxygen, the 50 outside-the-Galaxyarrival directions corresponding to each UHECR are typicallystill identifiably together on the sky - allowing potential sourcesearches (Figure 4). For compositions close to and higher thanCa, the fifty outside-the-Galaxy arrival directions correspond-ing to each UHECR are typically scattered over most of the sky.However, even in the case of Iron UHECRs (Figure 5) a con-centration can still be seen in the region of the SuperGalacticplane near to and north of Cen A. Nagar & Matulich: UHECRs: Galactic Magnetic Field Deflections
The concentration of UHECRs in the Cen A region has drawna lot of attention since its first report by the PAO team. OurMonte Carlo simulations can be used to test whether Cen A isthe dominant, or only, source of UHECRs. The results of thesetests are shown in Table 3 for UHECRs detected by PAO andTable 4 for UHECRs detected by AGASA. In these tables, thefirst column for each composition reports the fraction of thetotal (1350 for PAO and 550 for AGASA) outside-the-Galaxyarrival directions which fall within three 20 ◦ circles centered onthe Cen A nucleus and its northern and southern radio lobes.The second column for each composition shows the numberof UHECRs (of the total of 27 for PAO and 11 for AGASA),for which at least one of the fifty outside-the-Galaxy arrivaldirections falls in the 20 ◦ circles described above.Within our simulation parameters, it is possible but unlikelythat Cen A is the source of all PAO-detected UHECRs: for pro-ton UHECRs one third or less of the total outside-the-Galaxyarrival directions are within the 20 ◦ circles around Cen A inany GMF model, and almost two thirds of PAO UHECRs donot have even one outside-the-Galaxy arrival direction withinthe above area. For heavier compositions a smaller fraction oftotal outside-the-Galaxy arrival directions are within the 20 ◦ circles around Cen A but a larger fraction of PAO UHECRs, al-most 100% for Ca and Fe, have at least one outside-the-Galaxyarrival direction which falls within the Cen A circles. The lat-ter result is due to the large scatter of the outside-the-Galaxy ar-rival directions of any given heavy composition UHECR. In thecase of AGASA UHECRs, the fraction of outside-the-Galaxyarrival directions which fall within the Cen A circles is verysmall for all compositions, though for heavy UHECR composi-tions, a large fraction or all UHECRs have at least one outside-the-Galaxy arrival direction falling within the Cen A circles.If we consider all 300 outside-the-Galaxy arrival directionscorresponding to each UHECR (6 compositions, 50 outside-the-Galaxy arrival directions per composition) then withinthe models AS-S, AS-A, BS-S and BS-A, all PAO-detectedUHECRs have at least one outside-the-Galaxy arrival directionwhich falls within the 20 ◦ circles around Cen A. In the Sun etal. 2008 models a few (two to six) PAO UHECRs do not sat-isfy the above criterion. For the AGASA-detected UHECRs,for the AS-S and AS-A models all UHECRs have at least oneoutside-the-Galaxy arrival direction which falls within the 20 ◦ circles around Cen A for some one composition, while in theother models between two and eight UHECRs do not satisfythis criterion. As Nagar & Matulich (2008) have pointed out, the area aroundCen A hosts the highest density of nearby extended radiogalax-ies. We repeated the analysis of the previous section, but using abox around all nearby extended radiogalaxies in this area. Forsimplicity we used the following limits for the box: Galacticlongitude between 240 ◦ and 360 ◦ and Galactic latitude be-tween − ◦ and 70 ◦ (the “RG box”). The results are listed in sub-columns 3 and 4 for each composition in Table 3 for PAOUHECRs and Table 4 for UHECRs detected by AGASA.As expected the match statistics are better than in the caseof only the 20 ◦ circles around Cen A and its radio lobes. The“RG box” contains between a quarter and a half of all outside-the-Galaxy arrival directions for any one given composition.For light UHECRs at least half of all PAO-detected UHECRshave at least one outside-the-Galaxy arrival direction whichfalls in the RG box. For Ca and Fe compositions all UHECRssatisfy this criteria. In the case of AGASA UHECRs heavycompositions are required to provide a good match betweenthe UHECRs and the RG box.If we consider all 300 outside-the-Galaxy arrival directionscorresponding to each UHECR then within the models AS-S,AS-A, BS-S and BS-A, all PAO and AGASA UHECRs haveat least one outside-the-Galaxy arrival direction which fallswithin the RG box. In the Sun et al. models a few (two to four)AGASA-detected UHECRs do not satisfy the above criterion. Nagar & Matulich (2008) have previously argued that the ar-rival directions of a subset of PAO-detected UHECRs are cor-related with the directions of nearby extended radiogalaxies. Adistance of less than 3.5 ◦ was found between the radio struc-tures of six extended radiogalaxies (of the 10 “visible” to thePAO) and 8 UHECRs detected by PAO. Considering the fullsky, we have a total of 15 nearby (D <
75 Mpc) galaxies withextended ( >
180 kpc) radio structures, with the new galax-ies listed in Sec. 3, to be compared to 38 UHECRs. Addingthe AGASA-detected events, adds two new matches to earth-arrival directions of UHECRs: an AGASA event with originalreported energy E =
120 EeV matched to NGC 7626 (which isalso matched to a PAO-detected UHECR) and a match betweenan AGASA event with original reported energy E =
68 EeVwith CGCG 514 −
050 (this event does not appear in the fig-ures as its 30% reduced energy is below our UHECR cuto ff of 56 EeV). The correlation between nearby extended radio-galaxies and UHECRs detected by PAO and AGASA thereforeremains highly statistically significant even before consider-ing deflections by the GMF. We remark that the Supergalacticplane in the Cen A region passes close to the Galactic longi-tudes where the deflection produced by an ordered GMF withazimuthal symmetry is minimal (e.g. Takami & Sato, 2008). Itmay be this fortuitous coincidence which allowed us to findseveral UHECR events “matched” to nearby extended radiogalaxies in Nagar & Matulich (2008).Including deflections of UHECRs by the GMF main-tains, and in some models increases, the correlation betweenUHECRs and nearby extended radiogalaxies. Table 5, in itsfirst four columns, lists the statistics of matches betweenUHECRs and our sample of 15 nearby extended radiogalax-ies for all compositions and models simulated. The BS-S andBS-A models clearly result in the best match between nearbyextended radiogalaxies and UHECRs. For proton UHECRs thematches are few: in part due to using a rather strict match agar & Matulich: UHECRs: Galactic Magnetic Field Deflections 7 criterion of 2.5 ◦ . At heavy compositions a large fraction ofUHECRs are matched to nearby extended radiogalaxies.For proton-UHECRs, of the seven models tested the BS-S and BS-A models maintain the high correlation betweenUHECRs and radiogalaxies in the Cen A region (Figs. 1 to 5).Accounting for deflections within the BS-S and BS-A mod-els lead to a higher concentration of UHECRs around Cen A(the UHECR detected toward Cen B is now also deflected upto Cen A) and the radiogalaxy WKK 4432. Applying deflec-tions from the models of S08 do not result in good matchesbetween UHECRs and radiogalaxies in this region, thoughadding a dipole field to these models significantly improvesthe matches. In the case of the three matched events nearNGC 7626, CGCG 413 −
019 and CGCG 514 −
050 (see Nagar& Matulich, 2008), all of BS-S, BS-A, and AS-S are acceptablefor UHECR-radiogalaxy matches; however, the S08 models -with or without a dipole component - do not provide consis-tently good matches.For many other UHECRs in Figures 1 to 5 we do notsee obvious matches between the earth-arrival direction ofUHECRs and nearby or intermediate (red and blue symbols)galaxies with radio jets. However, accounting for deflectionsby the GMF suggests several new potential matches betweenproton-UHECRs and extended radio jets. Some interesting po-tential matches between galaxies with distance <
200 Mpc andjet structures larger than 180 kpc are worth specifically not-ing: (a) we see possible matches between NGC 1275 and twoAGASA-detected UHECRs; (b) CGCG 403 − −
309 and 1ES 0347 − ff er-ences of several tens of degrees between the out-of-Galaxy andearth arrival directions. Recent results on UHECR compositionfrom the Auger collaboration make this scenario likely (PA09a;PA09b).Given the small sample size of known UHECRs it is dif-ficult to evaluate how including UHECR deflections in theGMF e ff ects the correlation between UHECRs and nearbymassive spiral galaxies (Ghisellini et al., 2008); this is bestleft for later analysis with a larger number of UHECRs. Ourcomparisons of UHECR outside-the-Galaxy arrival directionswith the DRAGN sample, and with the several catalogs of Gamma-Ray sources also revealed individually interesting co-incidences. However, their statistical significance is di ffi cult toevaluate and we do not discuss them here. Given the match between a subset of UHECRs and nearby ex-tended radio galaxies, it is relevant to test whether the potentialassociation comes directly from the presence of extended ra-dio emission or from some underlying material associated withmassive elliptical galaxies, for e.g. luminous or dark matterconcentrations. As a preliminary test, we have used the RC3catalog (Corwin et al., 1994) to extract all nearby (D ≤
75 Mpc)elliptical galaxies. From this subset we identified all nearbyRC3 ellipticals with extended radio jets and lobes, obtaininga list of 11 galaxies which includes all of our 15 nearby ex-tended radio galaxies except NGC1275, Cen B, WKK 4552,and CGCG 514-050. The limits in RC3 parameters for this sub-set of ellipticals are: distance D ≤
75 Mpc, morphological type − ≤ T ≤ −
2, apparent B-band magnitude 7 . ≤ m B ≤ . − . ≤ m B ≤ − .
9, and size1 . ≤ D ≤ .
42, 0 . ≤ R ≤ .
2, 1 . ≤ D ≤ .
45. Wethen selected a control sample of all RC3 ellipticals withoutextended radio jets and lobes which satisfied the above limitsin RC3 measured parameters. This resulted in a control sampleof 183 “radio-compact” ellipticals. Histograms comparing thedistribution of distance, absolute magnitude, size, and angularseparation from Cen A, of the two samples are shown in Fig. 6.The two samples are reasonably well matched with a small ten-dency for the radio-extended ellipticals to have slightly higherabsolute magnitudes and to be slightly closer to Cen A on av-erage.A comparison of the statistics of matches of the two ellipti-cal samples to the outside-the-Galaxy arrival directions of PAOUHECRs is shown in Table 5. When normalized for the numberof galaxies in each sample, the matches between UHECRs andextended radiogalaxies is significantly higher than in the caseof radio-compact ellipticals. This di ff erence is most extreme inthe BS-S and BS-A models. Very few UHECRs have been detected by PAO and AGASAin the region within 10 ◦ of the Galactic plane. Accounting fordeflections in the GMF, however, results in several “Galacticplane crossing UHECRs” in most GMF models. In particular,the BS-S and AS-S models, and the models of S08 with or with-out a dipole component, serve to move the arrival directions ofseveral UHECRs at − < b < +
14, a good match is obtained in all models ex-
Nagar & Matulich: UHECRs: Galactic Magnetic Field Deflections cept the S08 models without a dipole component. In the case ofSGR 1627-41, AS-S and AS-A model deflections lead to a con-nection to the mysterious close pair of events detected by PAO.Several UHECR trajectories also pass close to confirmed orcandidate Galactic microquasars, and HESS-detected Galacticsources (e.g. Vela X and Vela Junior). Of course, fine tuning ofthe normalizations of the model permit closer matches; giventhe many free parameters (not least the uncertain distances tothese Galactic sources, and the mass of the UHECR). We thusdo not attempt a detailed study of the coincidences, but merelynote that some UHECRs potentially cross the Galactic planenear candidate UHECR sources.
5. Discussion & Concluding Remarks
The UHECR deflection simulations presented here, and the de-rived outside-the-Galaxy arrival directions of UHECRs, high-light several interesting points. For light (proton or Helium)UHECRs, the relatively small dispersions in the outside-the-Galaxy arrival directions for a specific UHECR and GMFmodel confirm that tantalizing insights into the source pop-ulation of UHECRs can be gained with a small sample ofUHECRs. While heavy composition UHECRs su ff er deflec-tions of several tens of degrees the concentration of outside-the-Galaxy arrival directions in the quadrant containing theSuperGalactic plane near Cen A also allows source populationconstraints. Conversely, picking one or a few UHECR sourcepopulations permits an evaluation of competing models of theordered GMF.For light compositions, the trajectories of several UHECRspass close to or through the Galactic plane within several GMFmodels. Interestingly, several pass relatively close to SGRs,AXPs, and / or microquasars in the Galaxy. Ghisellini et al.(2008) have argued that magnetars in nearby galaxies could beresponsible for the PAO detected UHECRs. The integrated fluxof HI emission from our galaxy is greater than the summedintegrated HI fluxes of all massive spirals in the HIPASS sur-vey considered by Ghisellini et al. (2008). If UHECRs origi-nate in magnetars in steady state - rather than in formation -then it would not be surprising to detect some magnetar-relatedUHECR events in the Galaxy.In Nagar & Matulich (2008) we claimed a correlation be-tween nearby galaxies with extended radio jets and the earth-arrival direction of a subset of UHECRs. By fortuitous chancethese matched pairs lie along the lines of Galactic longitudewhich su ff er the minimum deflection by axisymmetric orderedGalactic magnetic fields. The correlation is strengthened withthe results presented here. Accounting for deflections by BS-S and BS-A GMFs do not significantly change the previouslyclaimed matches in the case of proton UHECRs. Rather, us-ing the BS-S model actually concentrates proton UHECRscloser to the nucleus of Cen A, and also results in severalnew UHECR-radiogalaxy matches. The models of S08, witha dipole GMF component added, also maintain the previousmatched pairs. Both the nearest radiogalaxy and the near-est radio-extended BL Lac are potentially sources of multipleUHECRs. It is possible but unlikely that all UHECRs origi-nate in Cen A. In the best case, i.e. choosing the most conve- nient global GMF model for any given match, about 30% ofUHECRs outside the range − ◦ < b < ◦ could be matched toa galaxy with extended radio jets or an extragalactic Gamma-ray source in the case of proton only UHECRs. For heavy com-position or varied composition UHECRs we cannot rule outthe possibility that all UHECRs originate in nearby galaxieswith extended radio jets. We particularly noted several interest-ing and new matches between UHECRs and radiogalaxies forcompositions near Oxygen.A remaining question is whether the correlation betweenradiogalaxies and UHECRs depends directly on the presence ofextended radio jets and lobes or whether both trace an under-lying source population. We have briefly addressed this issuein a comparative test of nearby ellipticals with and without ex-tended radio structure: there is a strong indication that, withinthe BS-S and BS-A models of the GMF, the correlation withnearby extended radiogalaxies is directly related to the radiojets rather than to an underlying source population traced bymassive elliptical galaxies.If radiogalaxies, or sources traced by radiogalaxies, are re-sponsible for a subset of UHECRs, a BS-S or BS-A model forthe GMF is supported towards the Cen A region, i.e. the north-ern hemisphere of the fourth quadrant. The BS-S model (butnot the BS-A) also allows a match between some UHECRs andGalactic plane sources. The models of S08 are consistent withboth of the above only after we added a dipole field component(see Sect.2 for why this is dipole addition is not necessarily aself-consistent step).Finally, we remark that this work identifies the subset ofUHECRs which can be matched to extended radiogalaxies us-ing a light composition (H or He) for UHECRs, and thosewhich require a medium to heavy composition (e.g. Table 1).The relative ratio of proton to heavy composition UHECRsthen roughly agree with the composition mix suggested byPA09a and PA09b. It would be interesting to verify if the X max distributions of these two UHECR sub-samples confirm thiscomposition di ff erence. Acknowledgements.
We acknowledge funding from ALMA 3016013,ALMA 3107015, ALMA 3108022, Fondecyt 1080324, BASAL PFB-06 / / IPAC Extragalactic Database (NED) whichis operated by the Jet Propulsion Laboratory, California Institute ofTechnology, under contract with the National Aeronautics and SpaceAdministration.
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JETP, 4, 78 T A B LE R E S U LT S O F T H E M ON TE C A R L O S I M U L A T I ON SF O R P AOUH E CR S AND T H E B S - AG M F M OD EL E v e n tl b E n e r gy HH e OA l C a F e d i s t r m s m a t c hd i s t r m s m a t c hd i s t r m s m a t c hd i s t r m s m a t c hd i s t r m s m a t c hd i s t r m s m a t c h 015 . . . . . — . . — . . — . . — . . N ( ) . . N ( ) - . . . . . — . . — . . — . . N ( ) . . I ( ) . . I ( ) - . . . . . — . . N ( ) . . — . . N ( ) . . I ( ) . . N ( ) - . - . . . . — . . — . . — . . — . . N ( ) . . — - . . . . . — . . — . . N ( ) . . N ( ) . . N ( ) . . N ( ) - . - . . . . — . . — . . — . . N ( ) . . — . . N ( ) . - . . . . — . . — . . — . . — . . — . . — - . . . . . N ( ) . . N ( ) . . I ( ) . . N ( ) . . N ( ) . . W ( ) . - . . . . — . . — . . — . . — . . — . . N ( ) . - . . . . — . . — . . — . . — . . — . . — - . - . . . . — . . — . . — . . — . . — . . — - . - . . . . — . . — . . N ( ) . . — . . — . . — - . - . . . . — . . — . . — . . — . . N ( ) . . — - . . . . . — . . N ( ) . . N ( ) . . I ( ) . . I ( ) . . I ( ) . - . . . . N ( ) . . — . . — . . N ( ) . . — . . — - . - . . . . — . . — . . — . . — . . — . . — - . . . . . N ( ) . . N ( ) . . N ( ) . . I ( ) . . N ( ) . . N ( ) - . . . . . — . . — . . — . . N ( ) . . N ( ) . . N ( ) . - . . . . — . . — . . — . . — . . N ( ) . . — - . . . . . N ( ) . . N ( ) . . N ( ) . . N ( ) . . N ( ) . . I ( ) - . . . . . — . . — . . I ( ) . . I ( ) . . N ( ) . . N ( ) - . - . . . . — . . — . . — . . — . . — . . — - . . . . . W ( ) . . W ( ) . . N ( ) . . — . . N ( ) . . N ( ) . - . . . . — . . — . . — . . — . . — . . N ( ) - . . . . . — . . — . . — . . — . . N ( ) . . N ( ) - . . . . . — . . — . . — . . N ( ) . . I ( ) . . N ( ) - . - . . . . — . . — . . — . . — . . — . . — N o t e . — T h i s t a b l e s u mm a r i ze s t h e r e s u lt s o f ou r M on t e C a r l o s i m u l a ti on s f o r eac h P AO - d e t ec t e d UH E CR w it h i n t h e B S - A m od e l o f t h e G a l ac ti c M a gn e ti c F i e l d . T h e fi r s t f ou r c o l u m n ss p ec i f y a UH E CR i nd e xnu m b e r , t h ea rr i v a l d i r ec ti on a tt h e ob s e r v a t o r y i n G a l ac ti cc oo r d i n a t e s , a nd t h ee n e r gy i n E e V u s e d f o r t h e UH E CR . T h e r e m a i n i ng c o l u m n ss u mm a r i ze t h e r e s u lt s f o r t h e s i x c o m po s iti on s f o r UH E CR ss i m u l a t e d . F o r eac h c o m po s iti on w e li s tt h ea v e r a g e ( fi r s t c o l u m n f o r eac h c o m po s iti on ) a nd r . m . s . ( s ec ond c o l u m no f eac h c o m po s iti on ) o f t h e e fl ec ti on a ng l e s , c o rr e s pond i ng t o t h e fi f t y M on t e C a r l o s i m u l a ti on s . T h e d e fl ec ti on a ng l e i s t h ea ngu l a r d i s t a n ce b e t w ee n t h eea r t h - a rr i v a l d i r ec ti on a nd t h e ou t s i d e - t h e - G a l a xy a rr i v a l d i r ec ti on . I n t h e t h i r d c o l u m n f o r eac h c o m po s iti on w e li s tt h e n ea r by e x t e nd e d r a d i og a l a xy w h i c hb e s t m a t c h e s t h e t s i d e - t h e - G a l a xy a rr i v a l d i r ec ti on s o f t h e UH E CR a nd , i np a r e n t h e s i s , t h e nu m b e r o f ou t s i d e - t h e - G a l a xy a rr i v a l d i r ec ti on s m a t c h e d t o t h i s n ea r by e x t e nd e d r a d i og a l a xy ( m a x i m u m ) . T A B LE R E S U LT S O F T H E M ON TE C A R L O S I M U L A T I ON SF O R AGA S AUH E CR S AND T H E B S - AG M F M OD EL E v e n tl b E n e r gy HH e OA l C a F e d i s t r m s m a t c hd i s t r m s m a t c hd i s t r m s m a t c hd i s t r m s m a t c hd i s t r m s m a t c hd i s t r m s m a t c h 063 . . . . . — . . — . . — . . N ( ) . . N ( ) . . N ( ) . . . . . — . . — . . — . . N ( ) . . N ( ) . . N ( ) . . . . . — . . — . . — . . N ( ) . . N ( ) . . N ( ) . . . . . — . . — . . N ( ) . . N ( ) . . N ( ) . . N ( ) . - . . . . — . . — . . — . . — . . — . . N ( ) . . . . . — . . — . . — . . N ( ) . . N ( ) . . N ( ) . . . . . — . . — . . — . . N ( ) . . N ( ) . . N ( ) . - . . . . — . . — . . — . . — . . N ( ) . . — . - . . . . — . . — . . N ( ) . . N ( ) . . N ( ) . . N ( ) . - . . . . N ( ) . . N ( ) . . — . . . . — . . — . - . . . . — . . — . . — . . — . . — . . — N o t e . — C o l u m n s a r ea s i n T a b l e t f o r t h e AGA S A - d e t ec t e d UH E CR s agar & Matulich: UHECRs: Galactic Magnetic Field Deflections 13 T A B LE P AO - UH E CR M A T C H E S T O C E N A AND T H E R AD I OGA L AXY C ON C E N T R A T I ONN E A R C E N A HOA l C a F e C e n A R G B ox C e n A R G B ox C e n A R G B ox C e n A R G B ox C e n A R G B ox M od e l F r ac M a t c h F r ac M a t c h F r ac M a t c h F r ac M a t c h F r ac M a t c h F r ac M a t c h F r ac M a t c h F r ac M a t c h F r ac M a t c h F r ac M a t c h B S - S . . . . . . . . . . A S - S . . . . . . . . . . B S - A . . . . . . . . . . A S - A . . . . . . . . . . A SS + R . . . . . . . . . . A SS + A . . . . . . . . . . B S - S ( S ) . . . . . . . . . . N o t e . — T h i s t a b l e s u mm a r i ze s t h e s t a ti s ti c s o f t h e m a t c h e s b e t w ee n UH E CR s d e t ec t e dby t h e P i e rr e A ug e r O b s e r v a t o r y a nd s e l ec t e d a r ea s a r ound C e n A a nd a nd a r ound t h ec on ce n t r a ti ono f e x t e nd e d r a d i og a l a x i e s . C o l u m n s a r e : ( ) G M F m od e l; ( ) fr ac ti ono f t h e t o t a l ( ) ou t s i d e - t h e - g a l a xy a rr i v a l d i r ec ti on s w h i c h f a ll w it h i n a d i s t a n ce o f ◦ o f C e n A a nd it s e x t e nd e d r a d i o l ob e s i n t h eca s e o f p r o t on UH E CR s ; ( ) nu m b e r o f UH E CR s ( o f t h e t o t a l o f ) w h i c hh a v ea tl ea s t on e o f t h e i r fi f t you t s i d e - t h e - g a l a xy a rr i v a l d i r ec ti on s w it h i n20 ◦ o f C e n A a nd it s e x t e nd e d r a d i o l ob e s i n t h eca s e o f p r o t on UH E CR s ; ( ) fr ac ti ono f t h e t o t a l ( ) ou t s i d e - t h e - g a l a xy a rr i v a l d i r ec ti on s w h i c h f a ll w it h i n t h e ‘ R a d i og a l a xybox ’ w it h li m it s i n G a l ac ti cc oo r d i n a t e s ◦ ≥ l ≤ ◦ a nd − ◦ ≥ b ≤ ◦ ; ( ) nu m b e r o f UH E CR s ( o f t h e t o t a l o f ) w h i c hh a v ea tl ea s t on e o f t h e i r fi f t you t s i d e - t h e - g a l a xy a rr i v a l d i r ec ti on s w it h i n t h e ‘ R a d i og a l a xybox ’ d e s c r i b e d a bov e ; ( t o21 ) a s i n c o l u m n s t o5bu t f o r h ea v i e r c o m po s iti on s a s l a b e ll e d . T A B LE AGA S A - UH E CR M A T C H E S T O C E N A AND T H E R AD I OGA L AXY C ON C E N T R A T I ONN E A R C E N A HOA l C a F e C e n A R G B ox C e n A R G B ox C e n A R G B ox C e n A R G B ox C e n A R G B ox M od e l F r ac M a t c h F r ac M a t c h F r ac M a t c h F r ac M a t c h F r ac M a t c h F r ac M a t c h F r ac M a t c h F r ac M a t c h F r ac M a t c h F r ac M a t c h B S - S . . . . . . . . . . A S - S . . . . . . . . . . B S - A . . . . . . . . . . A S - A . . . . . . . . . . A SS + R . . . . . . . . . . A SS + A . . . . . . . . . . B SS ( S ) . . . . . . . . . . N o t e . — C o l u m n s a r ea s i n T a b l e , bu t f o r UH E CR s d e t ec t e dby AGA S A . I n t h i s t a b l e w e r e po r t UH E CR e v e n t s c o rr e s pond i ng t o550ou t s i d e - t h e - G a l a xy a rr i v a l d i r ec ti on s ov e r a ll s i x c o m po s iti on s . agar & Matulich: UHECRs: Galactic Magnetic Field Deflections 15 T ABLE ATCHES BETWEEN
PAO-UHECR S & N EARBY E LLIPTICAL S AMPLES
RG Extended RC3 Extended RC3 Non-extendedC Model Match Frac. Match Frac. Match Frac.BSS 4 7.4 3 9.4 9 1.2ASS 0 0.3 0 0.1 12 1.3BSA 5 7.1 4 8.8 8 1.2H ASA 1 0.1 1 0.1 13 1.4ASS+R 1 1.2 0 0.1 10 1.3ASS+A 2 1.3 0 0.1 9 1.2BSS(S) 2 1.7 0 0.0 9 1.3BSS 5 5.6 5 7.3 13 1.8ASS 2 1.5 1 1.0 9 1.2BSA 5 7.5 5 9.5 11 1.6He ASA 1 0.5 1 0.7 11 1.5ASS+R 5 4.7 2 3.5 6 1.1ASS+A 3 2.3 0 0.2 5 0.8BSS(S) 1 1.1 0 0.3 7 0.9BSS 10 10.7 10 13.1 18 3.6ASS 1 5.1 1 6.1 6 2.4BSA 7 8.5 7 11.0 15 3.6O ASA 1 2.4 1 3.2 5 2.3ASS+R 2 5.9 2 5.5 10 2.6ASS+A 3 6.3 3 6.5 9 2.5BSS(S) 2 3.9 2 3.5 10 2.1BSS 11 13.3 11 17.0 25 4.8ASS 2 8.8 1 10.2 9 3.9BSA 8 10.7 8 13.3 19 4.9Al ASA 1 5.1 1 5.2 10 3.9ASS+R 4 8.7 4 9.2 20 3.7ASS+A 1 6.3 0 5.6 11 3.7BSS(S) 0 5.1 0 3.5 10 3.0BSS 15 24.5 14 29.8 19 5.7ASS 4 16.2 4 19.6 16 4.8BSA 12 18.2 12 22.4 20 5.4Ca ASA 2 8.7 1 8.9 10 4.6ASS+R 4 9.7 4 11.3 19 4.6ASS+A 3 10.0 3 9.7 16 4.6BSS(S) 0 8.1 0 6.0 13 4.3BSS 18 31.2 17 37.8 22 5.9ASS 7 20.6 7 23.5 19 5.6BSA 14 24.9 14 29.2 23 5.9Fe ASA 5 15.9 4 16.1 14 5.5ASS+R 6 13.8 6 14.6 23 5.7ASS+A 2 12.3 1 11.2 17 5.3BSS(S) 5 13.1 2 10.1 19 5.3Note. — This table summarizes the match statistics between UHECRs de-tected by the Pierre Auger Observatory and three samples of ellipticals at D ≤
75 Mpc: all 15 nearby extended (LLS ≥
180 kpc) radiogalaxies (columns 3and 4), all ellipticals from the RC3 catalog with extended (LLS ≥
180 kpc)radio structure (columns 5 and 6) and a matched sample of ellipticals fromthe RC3 catalog without extended radio structure (columns 7 and 8; see text).Columns 1 and 2 list the UHECR composition and GMF model. The twocolumns for each sample of ellipticals list the number of UHECRs (of thetotal of 27) which can be matched (see text) to some member of the sample,and the fraction of the total (1350) Monte Carlo points which fall within thematch distance-limit of the sample’s galaxies.
Fig. 1.
A comparison of the earth-arrival directions of all UHECRs with energies above 56 EeV detected by PAO (blue forUHECRs with energy ≥
75 EeV and green for UHECRs with energy between 56 and 75 EeV ) and AGASA (red open circlesof radius 3.5 ◦ ) with the estimated outside-the-Galaxy arrival directions of the same UHECRs (small colored dots) for our MonteCarlo simulations of the BS-S (red), AS-S (green), BS-A (blue), and AS-A (yellow) GMFs using a proton composition for theUHECRs. The colored circular symbols mark the positions of galaxies with radio jets at D ≤
75 Mpc (red), 75 Mpc < D ≤
200 Mpc (blue), and 200 Mpc < D ≤
500 Mpc (black). In all redshift bins, filled circular symbols are used for galaxies with radiostructures more extended than 180 kpc, and open circular symbols for galaxies with radio structures less extended than 180 kpc.Galactic SGRs (red triangles) and AXPs (blue triangles) are also plotted. The Supergalactic plane is marked by the dashed line.In this and following figures we use an Aito ff -Hammer (equi-area) projection in Galactic coordinates. agar & Matulich: UHECRs: Galactic Magnetic Field Deflections 17 Fig. 2.
Same as Fig. 1 for the three new models proposed by S08: AS-S + RING (small red dots), AS-S + ARM (small green dots),and BS-S (small blue dots). Here, as in S08, no ordered dipole field component was used.
Fig. 3.
A comparison of the measured earth-arrival directions of all UHECRs with energies above 56 EeV detected by PAO andAGASA (blue, green, and red open circles with radius 3.5 ◦ as in Fig.1) with the estimated outside-the-Galaxy arrival directionsof the same UHECR (crosses) within the BS-S model for UHECR compositions of protons (red), He (green), Oxygen (blue),Aluminum (yellow), and Calcium and Iron (black). The first three compositions of the same UHECR are connected with bluelines while the heavier compositions are not connected to avoid overcrowding. Other symbols and names in the figure are thesame as in Fig. 1. agar & Matulich: UHECRs: Galactic Magnetic Field Deflections 19 Fig. 4.
Same as Fig. 1 but for a UHECR composition of Oxygen.
Fig. 5.
Same as Fig. 1 but for a UHECR composition of Iron. agar & Matulich: UHECRs: Galactic Magnetic Field Deflections 21
Fig. 6.
Histograms of Morphological Type, Distance, Absolute B magnitude and distance from Cen A for the two samples of D ≤≤