Con lusions

Figure4.16: Photometri mainsequen eturnopointdistan esalongde lination

fortheOrphan stream. Ourdata point (blue ir le)is basedonthe theoreti al

iso hronefor a

10 .0 Gyr

^old^stellar^population^with

[ F e/H] = −1.63

^. ^The^other

values orrespond to Belokurov et al. (2007b) (green triangles), Newberg et al.

(2010)(orangediamonds)andCaseyetal.(2013a)( yanstar).

Gyr(limited bytheformationtime oftherststars)or in

∆[ F e/H] = ^+0.72 _−0.82 dex

(limitedbytheminimummetalli ityavailableinthesetoftheoreti aliso hrones)

fortheageandmetalli ityoftheemployedtheoreti aliso hronesmeetthis

toler-an e riterion. For theOrphanstream, ourdistan e measurement antoleratea

relativevariationof

∆ d rel = ^+0.24

−0.05

^,^whi
h ^translates^into

∆ M = ^+0.60 _−0.11

^. ^Variations

∆ t = ^+3.2 _−1.3

^Gyr ^or ⁱⁿ

∆[ F e/H] = ^+0.83 _−0.49 dex

(same limitations as above) for the ageandmetalli ityofthetheoreti aliso hronesrespe tthis requirement.

thiswayourmethodbypassestheneedfornearby ontrol-eldsthat anbeused

tosubtra tareferen eforegroundfrom thetargetCMDs.

Usingaset oftheoreti aliso hrones(Marigoet al.2008;Girardi etal.2010),

we have al ulated the distan es to dierent regions of the Sagittarius stream

(faintandbrightbran hesinboththenorthernandsouthernarms)andobtained

resultsin good agreementwith previous work (Belokurovet al.2006b; Koposov

etal.2012,2013;Slateretal.2013)(seeFigure4.7).

Wedete twhatseemstobethe ontinuationofthenorthern-leadingarminto

theSouthernhemisphere;wendthatitsdistan esareinex ellentagreementwith

thepredi tions by themodels in Peñarrubia et al. (2010) and Law &Majewski

(2010b),whilethetraje toryseemstobelo atedathigherde linations. Wealso

nd eviden e for a nearby bran h of the northern-trailing arm at RA

> 160 ^o

Boththedistan esand thefootprintontheskyarein good agreementwiththe

predi tionsfromthemodels,andare omparabletoworkbyCorrentietal.(2010).

Itisalso ompatiblewithbeingthe ontinuationofGeminiarm( laimedaspart

ofa northern-trailingwrap in Belokurov et al.(2014))ifit turnsor broadens to

higherlatitudesasitevolveswestwards,but itdoesnotfollowthesame distan e

trend as bran h C (Belokurov et al. 2006b). The nal interpretation of these

dierentoverdensitiesinthe ontextoftheSgrstreamwillrequirekinemati data

andaphotometri onne tionbetweentheknownandthetemptativelyasso iated

regions.

We have also used age and metalli ity measurements from previous work

(Martelletal.2002;Harris1996;Caseyetal.2013a),to al ulatedistan estothe

Pal5streamandtheOrphanstream. Thesedistan esareingoodagreementwith

theresultsintheliterature(Grillmair&Dionatos2006a;Vivas&Zinn2006;

Be-lokurovetal.2007b;Newbergetal.2010;Caseyetal.2013a),attestingtogether

withtheresultsfromtheSgrstreamforpreviouslyknownregionsofthestream

therobustness anda ura yofthe ross- orrelation.

The methods presented in this paper open the possibility of using deeper

existing pen il-beam surveys (maybe originally aimed for extragala ti studies)

tomeasure a uratedistan es (orages or metalli ities,providedthat two ofthe

threeparametersareknown)tostreams,globular lustersordwarfgalaxies. The

existen eofthesepen il-beamsurveysortheredu edrequirementsofprospe tive

ones,allowformore ompletemapsoftheGala ti halosubstru tureatredu ed

observational osts.

A sear h for stellar tidal debris

of defun t dwarf galaxies

around globular lusters in the

inner Gala ti halo

Authors

JulioA.Carballo-Bello,AntonioSollima,DavidMartínez-Delgado,Bereni e

Pila-Díez,RyanLeaman,JürgenFliri,Ri ardoR.Muñoz,Jesús M.Corral-Santana

Abstra t

Inthehierar hi alformations enario in whi h theouterhalo of theMilkyWay

is the result of the ontinuous a retion of low-mass galaxies, a fra tion of the

Gala ti globular lustersystemmighthaveoriginatedinandbeena retedwith

already extin t dwarf galaxies. In this ontext, we expe t that the remnants

of these progenitor galaxies might be still populating the surroundings of those

a retedglobulars. Inthiswork, wepresentwide-eldphotometryofasampleof

23globular lustersintheGala to entri distan erange

10 ≤ R G ≤ 40

^kp
,^whi
h

weusetosear hforremnantsoftheirhypotheti alprogenitorsystems. Ourdeep

photometryrevealsthepresen eofunderlyingstellarpopulationsalongthe

line-of-sightofabouthalfoftheglobularsin ludedinoursample. Amongthedete tions

lying in the footprintof theSagittarius tidal stream, whi h we identify via the

omparison with its orbit derived from numeri al simulations, only Whiting1

andNGC7492seemtobeinmersedinthatremnantata ompatiblehelio entri

distan e. Wealso onrmtheexisten eofasubja entMain-Sequen efeaturein

thesurroundingsofNGC1851. Atentativedete tionofthevastHer ules-Aquila

loudisunveiledintheba kgroundofNGC7006.

Publishedin MNRASVolume445,2971(2014)

Preprintin arXiv:1409.7390[astro-ph.GA℄

5.1 Introdu tion

Theformationoftheouterregionsofdis galaxiesinthe ontextofthe urrently

mosta epted osmologi al model,namely Lambda ColdDarkMatter (

Λ

CDM, Peebles 1974),tookpla e viathe hierar hi ala retionofminor stellarsystems,

similartothenowadaysGala ti satellitedwarfgalaxies(Fontetal.2011b).

Nu-meri al simulationsbased onthis model and fo used in our Galaxy(Bullo k &

Johnston2005;Cooperet al.2010;Fontet al.2011a;Gómezet al.2013)predi t

thattheGala ti halomightbepopulated bystellarremnants,vestiges of these

a retion events. An important observational eort hasbeen made to validate

this theoreti alwork bydete ting stellar tidal streamsin thehalo ofthe Milky

Way.

Therst satellitedwarfgalaxy dis overed that is urrentlyin thepro ess of

being a reted is the Sagittarius dwarf spheroidal (Sgr dSph; e.g. Ibata et al.

1994; Bonifa io et al. 2004; Bellazzini et al. 2006b; Siegel et al. 2007) whi h is

followinganalmostpolarorbitaroundtheGalaxy. Thedestru tionofthisminor

systemhasgeneratedthelargestandmost omplexhalosubstru tureobservedso

far(Majewskietal.2003;Martínez-Delgadoetal.2004a;Belokurovetal.2006b;

Koposov et al. 2012), whi h has allowed for aninvestigation of themass

distri-bution - potential - of the Milky Way by re onstru ting its orbit from diverse

spe tros opi and photometri datasets(e.g. Law &Majewski2010b;

Peñarru-biaet al. 2010). However, there arestill signi ant aspe ts ofthis substru ture

pendingforasatisfa toryexplanation,liketheexisten eofabifur ationintotwo

parallelstreams onits northernse tion (Fellhauer et al. 2006;Peñarrubia et al.

2011).

Far from beingtheonly dete tedtidaldebris, wide-skysurveys as theSloan

DigitalSky Surveyand theTwo Mi ronAll Sky Survey(SDSS and 2MASS

re-spe tively; York et al.2000; Skrutskieet al. 2006), have revealed theexisten e

ofsubstru tures su h as theMono eros ring(Newberget al. 2002; Yanny et al.

2003;Ro ha-Pinto et al.2003;Connet al.2005, 2007;Juri¢et al.2008; Sollima

etal.2011),diversestreamssu hastheOrphan(Grillmair2006a;Belokurovetal.

2007b; Sales et al.2008; Newberget al. 2010), Aquarius (Williamset al. 2011),

Cetus(Newbergetal.2009)andVirgo(Duauetal.2006),andtheover-densities

ofHer ules-Aquila(Belokurovet al.2007a; Simionet al.2014)andVirgo(Juri¢

etal.2008;Martínez-Delgadoetal.2007;Bona aetal.2012b)asthebest-studied

examples. Inaddition,minormergersandfaintsubstru tureshavebeenobserved

in spiralgalaxies in theLo al Universe (e.g. Ibata et al.2001a, 2007;

Martínez-Delgado et al. 2008; M Conna hie et al. 2009; Martínez-Delgado et al. 2010b),

showingthat ourGalaxyisnotunusualinthisrespe t.

Theglobular luster (GC)population ofa givengalaxy ontainsvaluable

in-formationabouttheformationpro ess ofits host galaxy. Eviden efor separate

populationsofGCsintheMilkyWayandothergalaxieshavebeensteadily

a u-mulating,andit isinterpretedas eviden ethat supports thehierar hi algalaxy

formations enario(Zinn1993;Leamanetal.2013;Tonini2013). Intheirseminal

paper Searle & Zinn (1978) showed that while GCs in the inner Gala ti halo

(atdistan es

< 8

^kp
) ^showâ ^lear^radialâbundan
e^gradient,^GCs ⁱⁿ ^theôuter

halo do not follow this trend. In terms of the relation between the horizontal

bran h (HB) type and metalli ity found for GCs (and assuming the age as the

se ondparameter),Zinn(1993) lassied globularsintoold halo andyoung halo

lusters, where the latterwould orrespond to the a reted fra tion of Gala ti

GCs. Simulations suggest that whereas the outer halo lusters (

R G ≥

¹⁵^kp
)

were probably formed in small fragments subsequently a reted by the Galaxy

(withthe mostmassiveGCs su h as Omega Centauri and M54 as the possible

remnant ores of thedisrupted progenitor; van den Bergh &Ma key 2004), an

inner omponentoftheMilkyWayhalo(andpossiblyafra tionofthehaloGCs)

mayhaveformedinsitu (e.g. Zolotovetal.2009). Are entanalysisofthe

rel-ative ages for55 lusters al ulatedfrom theturn-o magnitude (Marín-Fran h

etal.2009;VandenBergetal.2013)showedthattheGCsage-metalli ityrelation

isbifu artedintotwo distin tgroups. Interestingly, thesestudies ndthatmost

of the outer halo GCs belong to the bran h hara terized by the steeper

age-metalli ityrelation although GCs belonging to bothbran hes over omparable

ageranges.

Among the MilkyWay satellites, Fornax and the ore of the SgrdSph host

a population of 5 and 4 (at least) GCs respe tively (Ibata et al. 1997; Strader

et al. 2003),suggesting that a reted low-mass systems mighthave ontributed

with their own globulars to the Gala ti GC system. The fra tion of a reted

Gala ti lusters estimated by Forbes & Bridges (2010) represents 1/4 of the

entire Gala ti GCsystem,when onsidering parameters su h asage-metalli ity

relations, retrograde orbits and HB morphologies. A higher fra tion of

∼ 50%

ofa retedGCs wasestimated byLeamanetal.(2013),whi h isalso onsistent

withtheestimated fra tion ofa reted halo starsforthe Galaxy(Zolotovet al.

2009;Cooperet al.2013). Inthis ontext,weexpe t partoftheMilkyWayGC

populationtobeasso iatedwithsomeofthetidalstreamsthatpopulatetheouter

halo,similar towhathasbeenobservedin M31,where thelo ationoftheouter

GCsystem oin ideswiththestreamsobservedaroundthatgalaxy(Ma keyetal.

2010,2013). Ifthese GCs were formedin subsequentlya reted stellarsystems,

theymightbestillsurrounded bythetidal streamsgenerated bythedisruption

oftheirprogenitor satellites.

Thepossibleasso iationofGala ti GCswiththestellartidalstreamofSgrhas

beenextensively onsideredintheliteratureusingdierentmethodsanddatasets

(e.g. Dines u et al. 2000; Bellazzini et al. 2002; Martínez-Delgado et al. 2002;

Palma et al. 2002a; Forbeset al. 2004; Martínez-Delgado et al. 2004a; Carraro

2009; Forbes & Bridges 2010). Bellazzini et al. (2003) found that, among the

Gala ti globulars in the distan e range

10 ≤ R G ≤ 40

^kp
, ^there ^are ^at ^least

18GCs ompatible bothin position and kinemati s withthe orbitproposed for

thatdSphgalaxybyIbata etal.(1997). Morere ently,(Law&Majewski2010a,

hereafterL10)alsoinvestigatedtheasso iationof64 Gala ti GCs withtheSgr

stream as predi ted by Law & Majewski (2010b). In that ase, 9 GCs were

suggested as systems formed in the interior of theSgr dSph, latter a reted by

theMilkyWay.

Thesear hforGala ti GCsasso iatedwiththeotherpossiblemajora retion

event, the Mono eros ring, has been ompli ated by the un ertainty about the

originanddynami alhistoryofthatstellarstru tureandtheunknownlo ationof

itstentativeprogenitorgalaxy. Dierentformations enarioshavebeenproposed

forthestellar ring, from thea retion by theMilky Wayof a dwarf ompanion

system(Helmietal.2003;Martinetal.2004;Martínez-Delgadoetal.2005;

Peñar-rubiaetal.2005;Sollimaetal.2011)tothedistortionordete tionofmoredistant

Gala ti omponents(Momanyetal.2004;López-Corredoira2006;Momanyetal.

2006; Hammersley& López-Corredoira 2011). Regardingthe hypotheti al

pro-genitora reteddwarf galaxy,the ontroversial CanisMajorstellarover-density

inthe dire tion

( ℓ, b) = (240 ^◦ , −8 ^◦ )

∼

⁷^kp^from ^the^Sun^has^been^proposed

asitsremnantnu leus(Martinetal.2004;Dines uetal.2005;Martínez-Delgado

etal.2005;Bellazzinietal.2006b)butitsoriginhasalsobeenthesubje tof

de-bateduringthelastyears(Momanyetal.2004;Moitinhoetal.2006;Mateuetal.

2009). Nonetheless, several low-latitude GCs have been proposed as members

oftheMono eros progenitor galaxyGCsystemin ludingNGC1851, NGC1904,

NGC4590and Rup106 (Martin et al.2004; Forbes& Bridges2010), NGC2298

(Craneetal. 2003;Frin haboy etal.2004; Martinet al.2004; Forbes&Bridges

2010)andNGC7078(Martinet al.2004).

Inthiswork,weexplorethepossibilityof thepresen eofstellarremnantsof

a reteddwarfgalaxiesaroundasampleofGCsintheinnerGala ti halo,whi h

have beenextensively onsidered as tra ers of thehierar hi alformation of the

MilkyWayhalo. Withthatpurpose, wepresentwide-eld deepphotometryofa

statisti allysigni antsampleof lustersandoftheareasurroundingthem.

5.2 Observations and data redu tion

5.2.1 Sample sele tion and observations

Theresultspresentedhere arepart of a systemati surveyof stellartidal debris

around GCs of the Gala ti halo, based on photometri observations of these

systems with wide-eld ameras at dierent intermediate-size teles opesduring

thelast10years. Preliminary resultsof thissurveywerepresentedin

Martínez-Delgadoet al.(2002), Martínez-Delgado et al.(2004a)and Carballo-Belloet al.

(2012). In this work, we have fo used on lusters lying in the distan e range

≤ R G ≤

⁴⁰^kp^(only⁹ ^Gala
ti^GCs ^are^found^beyond^that ^distan
e),^whi
h

mightin ludethesuggestedtransitionregionbetweena retedandin-situformed

Gala ti stellar halo (

R G ∼

¹⁵²⁰^kp ^Carollo êt âl. ^2007). ^Tô ^minimize ^the

presen e of dis stars whi h ould severely ae t our photometry, we ex luded

fromtheinitialsampleallthose lustersatlowGala ti latitude(

|b| ≤ 20 ^◦

⁾^with

theex eption of NGC2298 and Rup106, globularswhose properties suggest an

Table5.1: SampleofGala ti GCs: positionaldata,tidalradiiandmetalli ities(Harris

2010;Carballo-Belloetal.2012).

Cluster

ℓ( ^◦

⁾ ^b(

^◦

⁾

d _⊙

^(kp
)

R G

^(kp
)

r t

^(ar
min) ^[Fe/H℄

Whiting 1 161.2 -60.7 30.1 34.5 3.2 -0.70

NGC1261 270.5 -52.1 16.3 18.1 10.9 -1.27

NGC1851 244.5 -35.0 12.1 16.6 11.6 -1.18

NGC1904 227.2 -29.3 12.9 18.8 11.3 -1.60

NGC2298 245.6 -16.0 10.8 15.8 10.1 -1.92

NGC4147 252.8 77.2 19.3 21.4 6.6 -1.80

Rup106 300.8 11.6 21.2 18.5 9.0 -1.68

NGC4590 299.6 36.0 10.3 10.2 21.4 -2.23

NGC5024 332.9 79.7 17.9 18.4 18.0 -2.10

NGC5053 335.7 78.9 17.4 17.8 13.1 -2.27

NGC5272 42.2 78.7 10.2 12.0 25.4 -1.50

AM4 320.3 33.5 32.2 27.8 3.3 -1.30

NGC5466 42.2 73.6 16.0 16.3 23.4 -1.98

NGC5634 342.2 49.3 25.2 21.2 9.6 -1.88

NGC5694 331.1 30.4 35.0 29.4 4.7 -1.98

NGC5824 332.6 22.1 32.1 25.9 5.7 -1.91

Pal5 0.8 45.9 23.2 18.6 21.1 -1.41

NGC6229 73.6 40.3 30.5 29.8 3.8 -1.47

Pal15 18.8 24.3 45.1 38.4 5.6 -2.07

NGC6864 20.3 -25.7 20.9 14.7 6.8 -1.29

NGC7006 63.8 -19.4 41.2 38.5 5.7 -1.52

NGC7078 65.0 -27.3 10.4 10.4 17.5 -2.37

NGC7492 53.4 -63.5 26.3 25.3 9.2 -1.78

externalorigin(Craneetal.2003;Forbes&Bridges2010;Dotteretal.2011). We

havealsoex ludedNGC6715,Terzan7,Arp2andTerzan8be ausetheirlo ation

hasalready beenestablished within the main body of the Sgr dSph (Bellazzini

etal.2003,2008)andPal12,whi hhaspreviouslybeenasso iatedto itsstream

(Dines uetal.2000;Martínez-Delgadoetal.2002). Followingthese riteria,our

nalsample is omposed of23 ofthese systems. Itrepresentsa half oftheGCs

inthe onsideredGala to entri distan erangeand the3/4 of the lustersthat

mat h ourlatitude riteria.

Table5.1in ludestheposition,distan eandotherrelevantinformationofour

GCsample. Thepositionsand[Fe/H℄estimatesaretakenfromtheHarris(2010)

atalogue.TidalradiiaretakenfromCarballo-Belloetal.(2012),wherestru tural

parametersfortheseglobularswerederivedusingthesamephotometri database

presentedinthispaper,withtheex eptionofthe lustersWhiting1,AM4,Pal15

andNGC7006notin ludedinthatworkandforwhi htheyhavebeenestimated

using a similar pro edure as the des ribed in Carballo-Belloet al. (2012). The

radialdensityprolesforthese4 GCs havebeenobtained in ludinginformation

fortheinner regionofthe lustersfrom theliterature(Harris 1991;Trager etal.

1995;Carraroet al.2007;Carraro2009).

Oursurveystrategywasbasedonobtainingdeepphotometri observationsin

a wide eld of view (FOV) around the lusters, whi h allows us to explore for

thersttimetheirexternalregions,poorlyrepresentedin shallower photometri

data. Inthis ase,themaintra ersofthetidaldebrisofthesepossibleprogenitor

systemsaremain-sequen e(MS)stars23magnitudesfainter thantheMS

turn-o(TO)of theoldstellarpopulation. Giventhelowlevelsofsurfa e-brightness

for known tidal streams (

µ V >

³⁰^mag^ar
se

⁻²

^, Martínez-Delgado et al. 2001;

Majewskiet al.2003),very deep olour-magnitudediagrams(CMDs)areneeded

to get enough statisti of MS-TO starsin theexplored area. In addition, good

seeing onditions are essentialto undertakea reliable de ontamination of

ba k-groundgalaxiesintheCMD,whi hwouldotherwiseae tthedete tionofaMS

feature asso iated to an underlying stellar population in the blue region of the

diagramatfaintermagnitudes(e.g. seeFigures5.2and5.7).

ObservationshavebeenperformedusingtheWideFieldCamera(WFC)mounted

attheIsaa Newton teles ope(INT),establishedatEl RoquedelosMu ha hos

ObservatoryontheislandofLaPalma(CanaryIslands)andtheWideField

Im-ager(WFI)attheMPG/ESO2.2mteles ope,attheLaSillaObservatory(Chile).

TheWFCprovides,with4CCDswithapixelsizeof0.333ar se pixel

−1

,atotal

F W HM < 1 ^′′

^. ^Daily^sky-atsând^bias^wereôbtainedândûsed^for^biasând

at-eld orre tionbymeansofredu tionroutinesbasedonirafstandardtasks.

AsetofLandolt(1992)standardstarswereobservedduringtheruns,atdierent

airmassrangesto allowa pre ise alibrationofthenalphotometri atalogs.

Table 5.2: Coordinates, exposure times, mean seeing and datesof the observational

ampaignsinwhi htheGCswereobserved. Servi emodeobservationsaredenotedby

(s)

ClusterRA(2000)DEC(2000)t

exp B

^(s)^t

exp R/r

^(s)^seeing()^Instrument^Obs. ^run^date

×

⁹⁰⁰ ⁶

×

⁶⁰⁰ ^0.9 ^WFI 2009/11/08-12

5.2.2 Photometry and ompleteness test

PSF photometry was obtained using daophot ii/allstar (Stetson 1987) Our

nal atalogs only ontains obje tswith

|

^SHARP

| ≤

^0.4, ^redu
ing^the^pollution

in the CMDs by ba kground galaxies and allowing us to dete t the MS of the

tentative underlying streams in the region of the diagram dominated by these

non-stellar obje ts. Theaperture orre tionof our magnitudes were performed

usingbrightstellar-shaped obje tsin theouter regionsof theeld,farfrom the

GC,with

σ <

^0.1. ^With ^these^riteria, ^we^had ^a^good^sample ^of^bright^stars ^to

omparethe PSF tting from allstar with theaperturephotometry obtained

withdaophotii/phot. Thetypi al orre tionsarebelow0.2mag. To estimate

themagnitudeofourstarsoutsidetheatmosphere,weusedtheextin tion

oe- ients omputedforea hobservatory:

A ^B = 0 .22

^and

A ^r = 0 .07

^magnitudes ^per

airmass unit for the Roque de losMu ha hosObservatory and

A ^B = 0 .19

^and

A ^R = 0 .06

^at^La^SillaObservatory.

Forthe alibrationoftheWFCphotometry,wehavesear hedforstarspresent

bothinourdataandinSDSS.Due tothedieren esbetweentheltersusedby

thissurveyandthose usedinourproje t,wetransformedtheSDSSmagnitudes

(

ugriz

⁾^to^theJohnson-Cousinssystem(

BR

⁾^using^Chonis^&^Gaskell⁽²⁰⁰⁸⁾

equa-tions(forstarsinthe olorrange0.08

< r − i <

^0.5^and^0.2

< g − r <

^1.4). ^The

brightestsubsampleof ommonstars(2030starsper hip)wasusedtoobtaina

orre tionfa tortoapplytoourobje tsandthatalsoa ountsforthedieren es

betweenthephotometri systems. Nosigni ant olortrendshavebeennoti ed

inthe omparisonbetweenBandRmagnitudesintheWFCandJohnson-Cousin

photometri system. For this reason we applied only a systemati shift. Mean

valuesforthese orre tionsarefoundtobe

C B

⁼^25.10

±

^0.08^and

C R

⁼^25.72

±

0.09. For theWFI data,wederivedtransformationsfrom the omparisonofthe

instrumental results for the Landolt (1992) standard stars observed and their

alibratedmagnitudes. Themeanvalues forthetransformation oe ientsare:

B Lan − B inst = 25 .09 ( ± 0.09 ) + 0.19 ( ± 0.23 ) (B − R) inst

^(5.1)

R Lan − R inst = 24 .57 ( ± 0.07 ) − 0.02 ( ± 0.02 ) (B − R) inst

^(5.2)

Inordertoestimatethe ompletenessofourphotometri atalogs inthe

sur-roundingareaofthe lusters,wehave onsideredseparatelythefurthest hipwith

respe ttothe luster entre. Wehavein ludedintheimagessyntheti starswith

magnitudesin therange

17 ≤ B, R ≤ 26

^and^olor

0 .5 < B − R < 1.5

^,^randomly

distributed throughout the hip. Thetotal number of syntheti stars added in

ea h of the frames was designed notto ex eed15

%

of thenumber of originally

In document Title: Structure and substructure in the stellar halo of the Milky Way (pagina 107-119)

10 .0 Gyr

[ F e/H] = −1.63

∆[ F e/H] = +0.72 −0.82 dex

∆ d rel = +0.24

−0.05

∆ M = +0.60 −0.11

∆ t = +3.2 −1.3

∆[ F e/H] = +0.83 −0.49 dex

> 160 o

10 ≤ R G ≤ 40

Λ

< 8

R G ≥

∼ 50%

10 ≤ R G ≤ 40

( ℓ, b) = (240 ◦ , −8 ◦ )

∼

≤ R G ≤

R G ∼

|b| ≤ 20 ◦

ℓ( ◦

◦

d ⊙

R G

r t

µ V >

−2

−1

×

×

×

B

×

R

F W HM < 1 ′′

(s)

exp B

exp R/r

×

×

×

×

×

×

s

×

×

×

×

s

×

×

s

×

×

×

×

×

×

×

×

×

×

×

×

×

×

s

×

×

×

×

×

×

×

×

×

×

×

∆[ F e/H] = ^+0.72 _−0.82 dex

∆ d rel = ^+0.24

∆ M = ^+0.60 _−0.11

∆ t = ^+3.2 _−1.3

∆[ F e/H] = ^+0.83 _−0.49 dex

> 160 ^o

( ℓ, b) = (240 ^◦ , −8 ^◦ )

|b| ≤ 20 ^◦

ℓ( ^◦

^◦

d _⊙

⁻²

F W HM < 1 ^′′

A ^B = 0 .22

A ^r = 0 .07

A ^B = 0 .19

A ^R = 0 .06