Stacking)Analysis)of)CO)spectra)a5er)the)velocity)axis)normaliza;on.��Kana$Matsui�Nario$Kuno�NRO �

������INTRODUCTION�������

The$recovery$of$CO$emission$from$the$HI<gas$dominated$region$by$stacking$CO$

spectra$a5er)re=normalizing)the)CO)velocity)axis)so$that$v=0$corresponds$to$the$local$mean$HI$velocity$(Scuruba$et$al.$2011,ApJ,142,37)�

Recovering)the)weak)13CO)emissions)

using)the)12CO)velocity)field�

��������DATA����������Sample$galaxy$should$have$12CO$and$13CO$mapping$data$�NGC3627��12CO$map$from$Kuno$et$al.$(2007,PASJ,59,117)$and$13CO$map$from$Watanabe$et$al.$(2011,MNRAS,411,1409),$both$are$obtained$with$Nobeyama$45<m$telescope.�

��������RESULTS����������������SUMMARY���������We$invesZgated$the$validaZon$of$the$method$of$stacking$analysis$of$13CO$spectra$a[er$the$velocity$axis$normalizaZons$with$the$informaZon$of$the$velocity$field$of$12CO$using$the$12CO$and$13CO$maps$of$NGC3627.$

�Different$features$in$each$region$$different$reasons?$$Interarm$region:$high$raZo$of$FWHM$$Bar$region:$high$raZo$of$Tpeak$

�We$obtained$consistent$values$of$the$integrated$intensity$calculated$from$the$just<stacked$spectra$with$that$from$the$V<shi[<stacked$spectra.$

�With)this)method)and)mul;=CO)observa;on)with)FOREST,)we)can)

es;mate)the)more)realis;c)value)of)gas)mass)of)13CO=diffuse)region)

and)total)gas)mass)of)galaxies)with)observing);me)necessary)for)

obtaining)12CO)map.)

Figure$1,$Images$of$NGC3627.$From$le[$to$right,$K<band$image$(2MASS),$12CO$integrated$intensity$map$(Kuno$et$al.$2007)$and$13CO$integrated$intensity$map$(Watanabe$et$al.$2011).$

�Validate$this$method$!!!$

1)$CalculaZng$moment<1$from$12CO$cube$fits.�

2)$Shi[ing$velocity$axis$of$each$13CO$spectrum$according$to$the$moment<1$value$of$corresponding$pixel$in$12CO$map.�

�������ANALYSIS��������

3)$Summing$up$all$spectra$of$the$region$interested$in.�

We$divide$the$galaxy$into$the$arm,$interarm,$bar,$bar<end,$central$and$off<set$regions$referring$to$Watanabe$et$al.$(2011)$(see$figure$2).�

Figure$2,$Le[:$profile$map$of$12CO$(Kuno$et$al.$2007),$right:$profile$map$of$13CO$(Watanabe$et$al.$2011).$The$area$in$each$color$corresponds$to$purple:$arm,$yellow:$interarm,$green:$bar,$blue:$bar<ends,$red:$central$and$orange:$offset$regions,$respecZvely.$

Widely)accepted)and)used)molecular)gas)tracer:)12CO) $The$strongest$known$extragalacZc$molecular$line$

However…$opZcally$thick$line,$just$the$surface$of$the$clouds…$Total$emission$of$12CO$depends$primarily$on$the$#$of$clouds$

AssumpZon:$all$clouds$are$the$same$(T,$ρ)$and$virialized.$

$Mass$of$molecular$clouds.�Ideally,)op;cally=thin)lines)like)13CO)or)C18O)are)beTer)tracers...)

But$they$are$5<20$Zmes$or$>~20$Zmes$weaker$than$12CO…�

Applying)this)method…�

Arm�

Interarm�

Bar�

Bar=end�

Center�

Offset�

12CO� 13CO)� 12CO,)V=shi5� 13CO,)V=shi5�

Arm� Interarm� Bar� Bar=end� Center� Offset�

Tpeak� 13.3$±$0.8� 17.6$±$2.1� 25.3)±)4.0� 12.2$±$0.8� 20.6$±$2.9� 11.3$±$2.1�FWHM� 0.95$±$0.28�1.88)±)0.67�0.89$±$0.19�1.05$±$0.31�0.93$±$0.12�1.42$±$0.68�ICO� 13.0$±$0.4� 25.8)±)1.1� 27.7)±)2.4� 12.9$±$0.5� 16.9$±$0.9� 14.1$±$1.7�

Figure$3,$Resulted$spectra.$From$le[$to$right,$the$stacked$spectra$of$12CO$w/o$velocity$shi[$(Tmb),$13CO$w/o$velocity$shi[$(Ta*),$12CO$w/$velocity$shi[$(Tmb),$and$13CO$w/$velocity$shi[$(Ta*).$From$top$to$boqom,$the$spectra$of$arm,$interarm,$bar,$bar<end,$center$and$offset$region$defined$in$figure$2.$

We$show$the$resulted$spectra$in$figure$3$and$summarized$basic$results$of$obtained$spectra$in$table$1.�

�The$12CO<to<13CO$raZo$of$peak$temperature,$FWHM$and$integrated$intensity$of$stacked$spectra$of$each$region$are$shown$in$table$2.$�

�We$could$successfully$detect$the$13CO$emissions$of$interarm$and$bar$regions$by$stacking$analysis$a[er$the$velocity$axis$normalizaZon$!!�

�The)ra;o)of)integrated)intensi;es)of)Interarm)and)bar)regions)are)high)

(higher)T12/T13)in)the)bars)while)higher)FWHM12/FWHM13)in)the)interarms).)�

12CO)w/o)V=shi5� 13CO)w/o)V=shi5� 12CO)w/)V=shi5� 13CO)w/)V=shi5�

Arm� 157$±$19$mK$(S/N=8)$29.8)±)0.8)K)km/s)(37))

375$km/s,$200$km/s$

13.7$±$3.1$mK(4)$2.11)±)0.25)K)km/s)(9))

320$km/s,$160$km/s$

254$±$10$mK$(10)$28.5)±)0.4)K)km/s)(70))

325$km/s,$95$km/s$

19.1$±$0.8$mK$(24)$2.19)±)0.07)K)km/s)(33))

375$km/s,$200$km/s$

Interarm� 103$±$22$mK$(5)$21.4)±)0.9)K)km/s)(23))

380$km/s,$350$km/s$

6.87$±$2.55$mK(3)$1.05)±)0.20)K)km/s)(5))

300$km/s,$260$km/s$

145$±$16$mK$(9)$20.3)±)0.6)K)km/s)(32))

320$km/s,$150$km/s$

8.23$±$0.39$mK$(21)$0.787)±)0.026)K)km/s(30))

220$km/s,$80$km/s$

Bar� 276$±$34$mK$(8)$45.2)±)1.6)K)km/s)(29))

410$km/s,$280$km/s$

8.29$±$1.81$mK(5)$1.43)±)0.18)K)km/s)(8))

500$km/s,$420$km/s$

340$±$28$mK$(12)$44.7±1.1)K)km/s)(41))

300$km/s,$125$km/s$

13.5$±$1.8$mK$(7)$1.61)±)0.13)K)km/s)(12))

260$km/s,$140$km/s$

Bar=end� 243$±$27$mK$(9)$46.7)±)1.3)K)km/s)(36))

455$km/s,$95,135$km/s$

20.8$±$2.5$mK(8)$3.84)±)0.26)K)km/s)(15))

540$km/s,$120,80$km/s$

421$±$18$mK$(22)$46.7)±)0.6)K)km/s)(70))

260$km/s,$105$km/s$

34.5$±$1.6$mK$(20)$3.61)±)0.13)K)km/s)(32))

220$km/s,$100$km/s$

Center� 367$±$36$mK$(10)$68.7)±)1.6)K)km/s)(43))

390$km/s,$230$km/s$

22.3$±$4.5$mK(5)$4.10)±)0.45)K)km/s)(10))

400$km/s,$200$km/s$

376$±$34$mK$(11)$70.5)±)1.6)K)km/s)(45))

440$km/s,$205$km/s$

18.2$±$2.0$mK$(9)$4.16)±)0.19)K)km/s)(20))

540$km/s,$220$km/s$

Offset� 319$±$35$mK$(9)$20.8)±)0.9)K)km/s)(22))

145$km/s,$75$km/s$

28.7$±$4.4$mK(7)$1.55)±)0.21)K)km/s)(7))

120$km/s,$60$km/s$

244$±$29$mK$(9)$20.6)±)0.9)K)km/s)(23))

180$km/s,$85$km/s$

21.7$±$3.0$mK$(7)$1.46)±)0.16)K)km/s)(9))

140$km/s,$60$km/s$

Table$1,$Summary$of$the$stacking$analysis.$In$each$box,$from$top$to$boqom,$peak$temperature$(Tpeak$in$Tmb),$integrated$intensity$(ICO),$the$full$width$of$the$emission$lines$and$the$full$width$half$maximum$(FWHM).$The$value$in$parenthesis$are$the$signal<to<noise$raZo$(S/N).$

Table$2,$$The$12CO<to<13CO$raZo$of$peak$temperature,$FWHM$and$integrated$intensity$of$each$region.$

�Integrated$intensity$of$spectra$obtained$with$the$velocity$shi[$procedure$almost$could$recover$that$of$just<stacked$spectra.�

Validated)this)method)!!�

�With$this$method,$we$successfully$detected$the$13CO$emission$from$the$interarm$and$bar$regions$where$the$S/Ns$of$the$lines$are$too$low$for$the$detecZon$when$the$just<stacked$spectra$were$used.$

�The$12CO<to13CO$raZo$of$integrated$intensiZes$in$the$interarm$and$bar$regions$are$high.$

������������CO��������