bulge asymmetries and dynamic evolution
TRANSCRIPT
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Bulge Asymmetries and Dynamic Evolution
The BAaDE Project
Loránt Sjouwerman (NRAO) Mark Claussen (NRAO) Isaiah Santistevan (UNM) Michael Stroh (UNM) This material is supported by the National Science Foundation under Grant number 1517970
Michael Rich (UCLA) Mark Morris (UCLA) Cameron Trapp (UNM)
Ylva Pihlström (UNM)
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TheBAaDEproject
Aim:TosignificantlyimprovemodelsofthedynamicsandstructureoftheGalac>cbulgeandtheinnerGalaxy.
• Usingradiodetectedpoint-massesprobingintoregionsnotreachablewith
op>calsurveys(-6<b°<6).
• Surveying~34,000starsforSiOmaseremissionusingVLAandALMA.– Directline-of-sightveloci>esobtainedfor20,000+stars
• UsingVLBAfordetailedorbitcharacteris>csinasubsampleofthesources.
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Mainresearchgoals(A)
1. Galac>cdynamicsanddetailedGalac>cstructure– LOSveloci>es+loca>on=>globaldynamicalmodel– Velocityrota>oncurves&velocitydispersions(fordynamicalmodels)
– Instabili>esandasymmetries
– High-velocitystars,aretheyanen>repopula>oninfluencedbythebar?
2. Sta>s>csofSiOmasersintheGalaxy– Detec>onsta>s>csasfunc>onsofMSXcolor,Galac>cloca>onandvelocity
– Comparisonwith2MASS,GLIMPSE,WISE,AKARI,etc.– Correla>onbetweendifferentmasertransi>onsintheshell
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OHandSiOmaserstars:IRASandMSX
• MasersinOH/IRstarshavepreviouslybeenusedforkinema>calstudiesoftheMilkyWay(e.g.,Habingetal.2006)– Only3000OHmaserstarsinMW
• IRAScolorspredic>veoffindingsourceswithcircumstellarmaterial.
• WorksalsoforMSX;incomparablecolorregionsthedetec>onrateofSiOmasersis50-90%.
VanderVeen&Habing1988Habing1996
Sjouwermanetal.2009,Messineoetal.2002.
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TheBAaDEproject
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VLAfrequencycoverage
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ExampleVLAspectra:(v=1,2,3andisotope29SiOv=0)
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ExampleVLAspectra:carbon
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ExampleALMAspectra:Dual(v=1,v=2)
ad3a-03988 SPEC 3.NOIFS.1No calibration applied and no bandpass applied
Vector averaged cross-power spectrum Several baselines averaged
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FREQ MHz85600 85800 86000 86200 86400 86600 86800 87000
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ad3a-04127 SPEC 4.NOIFS.1No calibration applied and no bandpass applied
Vector averaged cross-power spectrum Several baselines averagedM
illiA
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Jy
FREQ MHz85600 85800 86000 86200 86400 86600 86800 87000
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ExampleALMAspectra:Isotopes(29SiO),thermal
ad3a-04352 SPEC 5.NOIFS.1No calibration applied and no bandpass applied
Vector averaged cross-power spectrum Several baselines averaged
Am
pl J
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FREQ MHz85600 85800 86000 86200 86400 86600 86800 87000
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ad3a-04094 SPEC 4.NOIFS.1No calibration applied and no bandpass applied
Vector averaged cross-power spectrum Several baselines averaged
Am
pl J
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FREQ MHz85600 85800 86000 86200 86400 86600 86800 87000
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Dameetal.(2001)
• COdistribu>onalongb=0°,andtheBAaDEfirstsetofdetec>ons.
• Differentpopula>ons.
• Noncircularmo>ons.
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Aumer&Schönrich(2015)• Modelinginves>ga>ngthe“200km/sfeature”,tes>ngwithAPOGEEdata.
• Dynamicallycoolandyoungstarscapturedbythebar?
• Willbetestedbyobserva>onstonega>velongitudesandorbitaldetermina>onswiththeVLBA
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3. VLBIpropermo>onsofGalac>corbitsandstructureofindividualstars– Propermo>onsandperhapsorbitfamily,andparallaxdistanceswhenpossible
4. SiOmasercharacteris>csandstellarandcircumstellarproper>es– SiOmaserstellarproper>eslikemagnitude,color,variability,distance,age,
metallicityifpossible,SEDs– Correla>onwithmaserintensity
Mainresearchgoals(B)
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Summary
• Atthepointwherewearecollec>ngthebasicdata(VLA,ALMA)– SiOmasers/veloci>es– IRdata
• Preparingforfollow-upVLBAstudies– Calibratorsearches,pilotobserva>ons– Determiningsuitablesamples/keysources
• Firstdatarelease/paperearlySpring2016
• hqp://www.phys.unm.edu/~ylva/baade/
ThismaterialisbaseduponworksupportedbytheNaEonalScienceFoundaEonunderGrantNumber1517970.Anyopinions,findings,andconclusionsorrecommendaEonsexpressedinthismaterialarethoseoftheauthor(s)anddonotnecessarilyreflecttheviewsoftheNaEonalScienceFoundaEon.