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$high.$
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