ISM@ST presentation of interests

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1. ISM@STScI January 22 2018 Caroline Bot RESEARCH: DUST EMISSION IN NEARBY GALAXIES FOREGROUND/BACKGROUND EMISSION ARCHIVAL DATA CDS ALADIN ASSOCIATE SCIENTIST EUROPEAN VIRTUAL OBSERVATORY (CURRENTLY ASTERICS) TEACHING FRENCH UNIVERSITIES COUNCIL, … ©Voutch Observatoire Astronomique de Strasbourg HI emission (Bruens et al. 2005) 500!m dust emission (HERITAGE)
2. 5 juillet 2016 Dust emission in nearby galaxies: a tracer of the interstellar medium mass and properties? Habilitation à Diriger les Recherches C. Bot Small Magellanic Cloud (SMC) Large Magellanic Cloud (LMC) HI emission (Bruens et al. 2005) 500!m dust emission (HERITAGE) mostly the Magellanic Clouds
3. Why study nearby
 galaxies? ❖ Look at a variety of environments ❖ evolution with metallicity ❖ impact of galaxies interactions, … ❖ External view, Global view ❖ Nearest neighbours: 
 Inventory of the different phases, dust contributors… LMC SMC M31 M51 @50kpc @60kpc @800kpc @8Mpc 1” 0.25pc 0.3pc 4pc 40pc 10” 2.5pc 3pc 40pc 400pc 1’ 15pc 17pc 200pc 2kpc
4. IR SED Mdust dust model Mgas gas to dust ratio metallicity does it scale? - dust growth - dust destruction Dust emission as a tracer of dust properties
5. In the Small Magellanic Cloud ✤ Bot et al. (2004): dust in the diffuse ISM in SMC is 30 times lower/gas than in solar neighbourgood ✤ more than metallicity -> dust destruction? ✤ Gordon et al. (2009): dust abundance in Magellanic tail is consistent with SMC origin Mgas/Mdust=1200±350
6. ✤ Gas-to-dust ratios in diffuse medium consistent with outer Magellanic Clouds Z Mgas/Mdust=380+250-130 Mgas/Mdust=1200+1600-420 Gordon et al. (2014), Roman-Duval et al. (2014) 
 w/ Herschel + Spitzer LMC SMC
7. IR SED Mdust dust model gas-to-dust ratio (e.g. from Z) Mgas other Mgas estimates 
 (XCO, virial, gamma-rays,…) consistent? dark gas 
 (H2 without CO,
 cold HI) Dust emission as a tracer of gas
8. H2 from dust 
 in the SMC ✤ Leroy et al. (2007): map of H2 from dust in the SMC from Spitzer data ✤ Rubio et al. 2004, Bot et al. 2007, Bot et al. 2010: Millimeter dust emission studies in the south-west regions of SMC ✤ in all SMC clouds: 
 Mmm(H2)>>Mvirial(H2) ✤ magnetic support? ✤ dynamics of CO clumps? ✤ how reliable is our 
 understanding of 
 dust emission? Mvirial Mvirial/MH2mm CO contours H2 from dust LABOCA 850µm, CO contours
9. ❖ Different models, different results? ❖ IRIS photometry at 100µm ❖ Excesses of observations wrt dust models ❖ 60-70µm excess ❖ sub-millimeter excess ❖ centimeter excess ❖ Contamination by foreground/background emission Jeremy Chastenet’s thesis My research in the last years: Issues with modeling dust in the Magellanic Clouds co-direction: K. Gordon
10. My research in the last years: Issues with modeling dust in the Magellanic Clouds ❖ Different models, different results? ❖ IRIS photometry at 100µm ❖ Excesses of observations wrt dust models ❖ 60-70µm excess ❖ sub-millimeter excess ❖ centimeter excess ❖ Contamination by foreground/background emission (probably linked…) Jeremy Chastenet’s thesis co-direction: K. Gordon
11. ✤ IRAS 100µm data is one of the most widely used in IR SEDs ✤ Latest version is called IRIS and was calibrated on DIRBE 
 (Miville-Deschenes & Lagache 2005) IRIS-DIRBE comparison ✤ Large scale comparison of DIRBE and IRIS at 100µm shows global agreement but significantly biased regions (Bot et al., still in prep.) Magellanic Clouds!
12. ✤ found an error on the DIRBE beam used previously ✤ systematic bias uncovered between 2 data releases (|β|> or < 50o) ✤ improvements on convolution kernels, edges of maps, use of healpix allsky format,… ✤ Missing step in processing IRIS-DIRBE comparison Bot et al., still in prep. ✤ significant improvement of the whole sky photometry
13. Millimeter-centimeter excess ✤ Israel et al. 2010, Bot et al. 2010: discovery of excess emission in the Magellanic Clouds at micro-wave wavelengths above dust+free-free+synchrotron ✤ very cold dust ruled out (needs to be 3K) ✤ DCD/TLS effects? anomalous (spinning) dust? ✤ Draine & Hensley 2012: magnetic dipole from magnetic nanoparticles?
14. mm-cm excess ✤ excess in LMC explained by CMB fluctuations & foreground emission ✤ significant excess remains in SMC ✤ need to do it with new Planck data calibration ✤ And what about other galaxies?? Potential thesis project With Planck… Planck collaboration 2011 (XVII) cm excess Hα contours
15. Background & Foregrounds ❖ By looking at low luminosity galaxies, we learn how important it is to care about the possible contaminants to dust emission ❖ unresolved/resolved stellar light ❖ zodiacal light ❖ Milky-Way cirrus ❖ unresolved background galaxies (CIB) ❖ Cosmic Microwave Background ❖ Free-free and synchrotron emission λ credit: Planck
16. CMB background ✤ regions like nearby galaxies are impainted in maps of CMB fluctuations ✤ need for custom-made CMB estimates ✤ Magellanic Clouds on CMB hot spots
 now M31 too??!! (Planck collaboration 2015) Planck CMB fluctuations map Bot et al. 2010 Planck collaboration 2011
17. MW cirrus in front and around galaxies ✤ well defined on large scale (Boulanger et al. 1996, Arendt et al. 1998, Schlegel et al. 1998,Compiègne et al. 2011…..) ✤ optically thin to stellar radiation ✤ relatively constant & single ISRF (U=1) ✤ simple modified black-body emission with constant emissivity per NHI ✤ Cirrus emission can be removed by using HI templates Boulanger et al. 1996 Compiègne et al. 2011 Gordon et al. 2009
18. MW cirrus in front and around galaxies ✤ Bot et al. 2009: but on smaller scales (~4’) we observe variations in the IR colors! ✤ heating variations? dust evolution? ✤ Planck collaboration XVII 2014: ✤ confirmed color variations ✤ Ysard et al. 2015: can be reproduced by dust variations in THEMIS dust model
 (mantle thickness, size distribution) ✤ How do we remove varying cirrus emission in front of galaxies? 
 Important for dwarf galaxies but also at sub-mm/ mm wavelengths ✤ Other potential thesis project: cirrus as foreground of galaxies SINGS NGC6946 Bot et al. 2009 Planck collaboration XVII
19. I like faint stuff and I cannot lie dust in the Magellanic Stream? dust in the Magellanic Bridge? (Gordon, Bot et al. 2009) dust in the Leo intergalactic ring? (Bot et al. 2009) Magellanic Stream
20. Science perspectives & current future interests ❖ New IRIS data set ❖ finish paper!!! ❖ also 12, 25 and 60um, collaboration with M.-A. Miville- Deschêmes ❖ Study high galactic cirrus clouds color variations ❖ Study mm-cm excess in nearby galaxies ❖ Look at dust in between galaxies (tails, intergalactic clouds)
21. but first…