Upload
others
View
1
Download
0
Embed Size (px)
Citation preview
RevealingtheoriginofextraplanarmolecularcloudsinarampressurestrippedgalaxythroughtheALMA
BumhyunLee&AereeChungDepartmentofAstronomy,YonseiUniversity,SouthKorea
East-AsiaALMAScienceWorkshop2017-Korea,November27-29,2017
Credit:ESO/B.Tafreshi(twanight.org)
Galaxyevolutioninclusterenvironment
Red
Blue
Density
Low High
• Elliptical&S0galaxies:90%intheclusterenvironment
2
Hoggetal.2004
• Clusterpopulation:passiveandred
Field Cluster
Rampressurestripping
✓ ICM(theintraclustermedium)–ISM(theinterstellarmedium)
Rampressurestripping(RPS,Gunn&Gott1972)rampressure>restoringforce→gasisstripped→red&passivegalaxy?
✓ HIgasstripping(e.g.Cayatteetal.1990;Chungetal.2007,2009)✓ Starformationquenching(Koopmann&Kenney2004a,b)
3
Moleculargas→adirectingredientforstarformation
Q.Whethermoleculargasisstripped/disturbedbytherampressure
Q.Whetherclusteraredeficientinmoleculargas(Starketal.1986,Kenny&Young1989vs.Fumagallietal.2009,Bosellietal.2014)
NGC4396
NGC4654
Chungetal.2009
Moleculargasunderstrongrampressure
4
SMAobservationsinordertoinvestigatedetailedCOproperties
12CO(2-1):blue,SMA,Lee&Chungetal.201712CO(2-1):green,IRAM30m,Vollmeretal.2008HI:red,Chungetal.2009D25intheopticalimage,RC3TheICMwinddirection:blackarrows
Virgocluster(16Mpc),threespiralsinactiveRPS
UsingSMA12CO(2-1)data,✓ 12COmorphology→highlyasymmetricanddisturbed→closelyrelatedtotheHImorphology
Lee&Chungetal.2017,MNRAS,446,1382
▶Strong rampressurecanaffectpropertiesofmoleculargas(evenwithinafewkpcofstellardisk)
ExtraplanarCOgasinNGC4522
5
• Activerampressurestrippingstage• Only25%ofexpectedHIgasmass• 40%oftotalHIgas(green)intheextraplanar• 25%oftotalCOgas(whitecontour)inthe
extraplanar• ExtraplanarCOgas&extarplanarHαpatches(Kenneyetal.2004;Vollmeretal.2008;Chungetal.2009)
✓ Aninterestingcase,asthenearestexampleamongonlythefewgalaxiesfoundwithextraplanarmoleculargas
✓ Moleculargaspropertiesandstarformationactivitiesinside&outsidethediskwiththefollow-upALMAobservations
ScientificquestionsintheALMAobservations
6
Q1.Whatarepropertiesofextraplanarmolecularclouds?(e.g.mass,linewidths,velocityfield,12/13COlineratio)
Q2.CanthemoleculargasgetstrippedbyrampressureduetotheICM?Ifso,isitstrippedascloudorisitre-crumpledafterstripping?Inaddition,canthemoleculargasbenewlyformedfromstrippedatomicgasoutsidethestellardisk?Q3.HowefficientlydostarsforminaRPSgalaxy?✓ Arelationbetweenthemoleculargassurfacedensityandthe
starformationrate(i.e.theKennicutt-Schmidtlaw)atsub-kpcscale
TheALMAobservations(Cycle3,PI:Lee,B)
7 Credit:ALMA(ESO/NAOJ/NRAO),B.Tafreshi
Using12marray,• January12,2016,12CO,46antennas• January19,2016,13CO,43antennas
Inband3andband6(MultiCOlines),• 12CO(1-0);115.271GHz• 13CO(1-0);110.201GHz• 12CO(2-1);230.538GHz
Intworegions,• onearoundthecenterofNGC4522• Onecenteredonthepeakofthe
extraplanarCOgas
On-sourcetime:• 12CO(1-0):0.9hrs,13CO(1-0):4.6hrs• 12CO(2-1):0.3hrs
Intotalobservationtime:~5.8hrs
FOV:~50arcsec(band3)~25arcsec(band6)
TheALMAdataofNGC4522
8
✓ Extraplanarcloudsdetectedinboth12COand13CO(C,D,E,G)
✓ Thefirstreportforextraplanar13COdetectioninaRPSgalaxy,usingALMA→importantdatatoconstraintheoriginofextraplanarcloudsandtheirphysicalstates
Leeetal.inprep.
3.03”X2.34” 3.14”X2.31”
12CO(1-0)intensitymap 13CO(1-0)intensitymap 12CO(1-0)velocityfieldmap
F
TheALMAdataofNGC4522
9
Leeetal.inprep.
3.03”X2.34” 3.14”X2.31”
12CO(1-0)intensitymap 13CO(1-0)intensitymap 12CO(1-0)velocityfieldmap
F
Lineratioof12CO&13CO
10
Arrow:theICMwinddirectionEllipse:theopticaldisk
✓ Meanlineratioofextraplanarclouds:~11.1(i.e.comparabletothelineratioofthemaindisk:~10.8)
✓ UGC12914/5interactingsystem:~50inthetidalbridge(cf.~15inthecenterofUGC12915)
▶Theexternalpressure:rampressure?(Alataloetal.2015)
✓ Lineratiogradientinextraplanarclouds(C,D,E,G;easttowest)
✓ Lowineast→highinwest
▶DiffuseCOgasisstripped?(Alataloetal.2015)
12CO/13CO(1-0)ratiomap
Twopotentialoriginsofextraplanarclouds
11
1.MoleculargasformationfromstrippedHIgas
2.Strippingmoleculargas
ascloudORreassemble(Sivanandametal.2010)
✓ Rampressure>restoringforceformolecularcloudsinthestellardisk
→strippingmolecularclouds(Leeetal.2017)
Leeetal.inprep.
✓ Consideringvarioustimescales(e.g.GMCformationtimescale(30Myr),strippingtimescale(100Myr))(Vollmeretal.2006;Crowl&Kenney2008)
✓ Thecombinationoftwopotentialorigins?
Twopotentialoriginsofextraplanarclouds
12 Leeetal.inprep.
✓ 13COdetection→ahintfortheoriginoftheextraplanarmoleculargas?
13C13C13C13C
Marigo2006
TheKennicutt-Schmidt(KS)relationofNGC4522
13
Bluesolidline:gasdepletiontime(=1/SFE)
1)Sub-linearrelation(slope:0.76)ontheKSplot✓ Inefficientstarformationactivityduetoinjectingturbulenceintomoleculargasby
rampressureAlataloetal.2015,Leeetal.2017,Shettyetal.2013Leeetal.inprep.
TheKennicutt-Schmidt(KS)relationofNGC4522
14
Bluesolidline:gasdepletiontime(=1/SFE)
Leeetal.inprep.
Summary
15
Jachymetal.2014
IC3418
Kenneyetal.2014
Ebelingetal.2014
Recentstudiesformanyjellyfishgalaxies
✓ Thefirstreportfor13COdetectionoutsidethemaindiskoftheRPSgalaxythankstohigh-sensitivityofALMA
✓ Extraplanarmolecularcloudsareaccelerated(40km/sblueshifted)towardVirgocluster
✓ Lineratiogradient,east(low)towest(high)inextraplanarclouds,diffuseCOgasisstripped?
✓ Twopotentialoriginsofextraplanarclouds,butextraplanr13CO→extraplanrmolecularcloudsarestrippedbyrampressure
✓ Sub-linearslopeintheKSplotandrelativelylonggasdepletiontimeinextraplanarmolecularclouds
ThisALMAdatawillgiveanopportunitytobetterunderstandthefateofISMandstarformationactivityintheextraplanarspace
Thankyou