Outline. Continuum Phenomena Interstellar Dust Ionized Gas Synchrotron Radiation. Emission Line Phenomena HII Regions Photo-Dissociation Regions

Transcription

1 Characterizing the Interstellar Medium within Galaxies Daniel Dale University of Wyoming

2 Outline Continuum Phenomena Interstellar Dust Ionized Gas Synchrotron Radiation Emission Line Phenomena HII Regions Photo-Dissociation Regions

3 Where is Wyoming?

4 Where is Wyoming? Seattle Boston Chicago New York City Denver San Francisco Washington, D.C. Los Angeles Dallas Miami

5 Where is Wyoming? Seattle Boston Chicago New York City Denver San Francisco Washington, D.C. Los Angeles Dallas Miami

6 Wyoming Infrared Observatory Where is Wyoming? Seattle Boston Chicago New York City Denver San Francisco Washington, D.C. Los Angeles Dallas Miami

7

8 Grand Tetons National park

9 Grand Tetons National park Yellowstone National park

10 Grand Tetons National Park Photo by Tyler Nordgren

11 Yellowstone National Park North entrance Old Faithful geyser Thermal feature

12 The Cosmic Infrared Background The predominant contribution to the CIB is emission from dust grains. Other contributions from galaxies include: Dole+2006

13 The Cosmic Infrared Background The predominant contribution to the CIB is emission from dust grains. Other contributions from galaxies include: synchrotron radiation Dole+2006

14 The Cosmic Infrared Background The predominant contribution to the CIB is emission from dust grains. Other contributions from galaxies include: synchrotron radiation free-free (thermal/bremsstrahlung) Dole+2006

15 The Cosmic Infrared Background The predominant contribution to the CIB is emission from dust grains. Other contributions from galaxies include: synchrotron radiation free-free (thermal/bremsstrahlung) emission lines Dole+2006

16 The Cosmic Infrared Background The predominant contribution to the CIB is emission from dust grains. Other contributions from galaxies include: synchrotron radiation free-free (thermal/bremsstrahlung) emission lines AGN Dole+2006

17 Interstellar Dust The diffuse cirrus emission from the Milky Way arises from dust grains of size ~ 100nm = 1000Å = 0.1 m

18 Interstellar Dust The diffuse cirrus emission from the Milky Way arises from dust grains of size ~ 100nm = 1000Å = 0.1 m Interstellar space is 106 times dirtier than Earth's atmosphere 1 Earth volume = 1 pair of dice

19 Interstellar Dust The diffuse cirrus emission from the Milky Way arises from dust grains of size ~ 100nm = 1000Å = 0.1 m Interstellar space is 106 times dirtier than Earth's atmosphere 1 Earth volume = 1 pair of dice 10% of ISM by (baryonic) mass Solar System grain

20 Interstellar Dust Interstellar dust grains m ( Å) C, Si, O, Mg, Fe,... thermal emitters dn/da a-3.5 PAHs Draine 2003

21 Interstellar Dust Interstellar dust grains m ( Å) C, Si, O, Mg, Fe,... thermal emitters dn/da a-3.5 PAHs PAHs m (50Å) stochastic heating Draine 2003

22 Interstellar Dust In the Milky Way, about 1/3 of the stellar light is re-processed into the infrared via dust grains.

23 Interstellar Dust In the Milky Way, about 1/3 of the stellar light is re-processed into the infrared via dust grains. The cosmic average is 50%.

24 Interstellar Dust If we model the dust distribution in the Milky Way as a uniform slab, we'd expect the dust emission to be proportional to the cosecant of the Galactic latitude b: f (IR) csc(b). This is consistent with observations. b

25 Interstellar Dust Milky Way HI emission If we model the dust distribution in the Milky Way as a uniform slab, we'd expect the dust emission to be proportional to the cosecant of the Galactic latitude b: f (IR) csc(b). This is consistent with observations. b Milky Way FIR dust emission Dust comes from the ISM! Binney & Merrifield 1998 Boulanger+1996

26 Interstellar Dust Milky Way HI emission If we model the dust distribution in the Milky Way as a uniform slab, we'd expect the dust emission to be proportional to the cosecant of the Galactic latitude b: f (IR) csc(b). This is consistent with observations. b Milky Way FIR dust emission The diffuse cirrus emission from COBE can be fit by a single modified blackbody of temperature ~ 17.5 K and emissivity 2. Dust comes from the ISM! Binney & Merrifield 1998 Boulanger+1996

27 Interstellar Dust Milky Way HI emission If we model the dust distribution in the Milky Way as a uniform slab, we'd expect the dust emission to be proportional to the cosecant of the Galactic latitude b: f (IR) csc(b). This is consistent with observations. b Milky Way FIR dust emission The diffuse cirrus emission from COBE can be fit by a single modified blackbody of temperature ~ 17.5 K and emissivity 2. In general, the dust luminosity is L = Ngr 4 a2 Q (a) B (Tgr) Ngr 4 a2 (2 a /c) B (Tgr) Dust comes from the ISM! Binney & Merrifield 1998 Boulanger+1996

28 The Milky Way, as seen from COBE/DIRBE/FIRAS Tgr ~ 17.5 K [CII] 158 m emissivity 2 Draine 2003 Boulanger+1996

29 A Day in the Life of Carbonaceous Grains E = Cv T CV = 3Nk T h /3Nk Draine 2003 (local ISRF) PAHS < 15Å responsible for 1/2 of neutral ISM heating (Hollenbach & Tielens 1999) Diffuse cirrus caused by ~ 2000Å grains

30 Coronene C24H12 Naphthalene PAHs (simple ones) Phenanthrene Chrysene

31 The mid-infrared features are attributed to vibrational modes (bending, stretching) of PAHs (e.g. Leger & Puget 1984). When H atoms are attached to the edge of an aromatic ring skeleton, the system will vibrate if triggered by an optical or UV photon. The bending modes can be 'mono' (no adjacent H), 'duo' (2 contiguous H), 'trio' (3 contiguous), or 'quartet' (4 contiguous). Draine 2003

32 A detailed decomposition of the mid-infrared shows the full beauty of the PAH zoo. PAHs responsible for up to 30% of the bolometric infrared in normal galaxies. NGC2978 Smith+2007

33 The mid-infrared spectrum can be used to classify the galaxy type. AGN, Normals, U/LIRGs Type 1 AGN Hao+2005 Spoon+2007

34 PAH features are typically seen in: planetary nebulae, proto-planetary nebulae, reflection nebulae, H II regions, circumstellar envelopes, Galactic diffuse cirrus, external galaxies, Peugeots, Renaults, Citroëns,...

35

36

37 Galaxy infrared spectra are full of features and lines ( m) ,6.2, 7.7,8.6, 11.2,12.0, 12.7,16.4, 17.1 identification ice (absorption) silicate (emiss/abs) silicate (emiss/abs) SiC silicate PAH PAH PAH PAH PAH Draine 2003

38 Q: What is the physical significance of the different far-infrared shapes below? Q: Make a quantitative prediction for the characteristics of the far-infrared bump. Q: Why don't the mid-infrared features change in wavelength as well? Q: Does inclusion of the IR spectrum help or hinder photometric redshift efforts? Kennicutt+2003 Dale & Helou 2002

39 Q: What is the physical significance of the different far-infrared shapes below? Different average dust temperatures Q: Make a quantitative prediction for the characteristics of the far-infrared bump. T = 0.29 cm K Q: Why don't the mid-infrared features change in wavelength as well? Essentially fixed transitions Q: Does inclusion of the IR spectrum help or hinder photometric redshift efforts? Fixed PAH wavelengths help; redshift-t degeneracy Kennicutt+2003 Dale & Helou 2002

40 In truth, PAH features are not fixed in either wavelength or relative amplitude Peeters+2002

41 In truth, PAH features are not fixed in either wavelength or relative amplitude Li & Draine 2001

42 In truth, PAH features are not fixed in either wavelength or relative amplitude Diamond-Stanic & Rieke 2010

43 Profound differences can be observed on small scales Cesarsky+1996 NGC 7023 (reflection nebula) M 17 (star-forming/hii region)

44 Profound differences can be observed on small scales Cesarsky+1996 NGC 7023 (reflection nebula) M 17 (star-forming/hii region) PAHs NeII vs SIV and NeIII

45 Galaxy Infrared SED Models Templates - A collection of observed spectra or single-parameter models Grids multi-dimensional models Useful for interpreting number counts from surveys

46 Some Popular Infrared SED templates

47 Some Popular Infrared SED templates Parameterized by either shape (for multi- surveys) or by luminosity (e.g., cosmology surveys)

48 Some Popular Infrared SED templates Parameterized by either shape (for multi- surveys) or by luminosity (e.g., cosmology surveys) Local bivariate infrared color-luminosity relation: Chapman et al. 2003

49 Dale & Helou (2002) Désert+1990 framework: PAHs + VSGs + BGs, for each 0.3<U<103

50 Dale & Helou (2002) Désert+1990 framework: PAHs + VSGs + BGs, for each 0.3<U<103 PAHs via ISO VSGs given new temperature distribution profiles

51 Dale & Helou (2002) Désert+1990 framework: PAHs + VSGs + BGs, for each 0.3<U<103 PAHs via ISO VSGs given new temperature distribution profiles Far-IR via ISO/IRAS/SCUBA

52 Dale & Helou (2002) Désert+1990 framework: PAHs + VSGs + BGs, for each 0.3<U<103 PAHs via ISO VSGs given new temperature distribution profiles Far-IR via ISO/IRAS/SCUBA, e.g., ( >200 m) = logU

53 Dale & Helou (2002) Désert+1990 framework: PAHs + VSGs + BGs, for each 0.3<U<103 PAHs via ISO VSGs given new temperature distribution profiles Far-IR via ISO/IRAS/SCUBA, e.g., ( >200 m) = logU Variable power-law dist'n of radiation fields dmd(u) U- du

54 Dale & Helou (2002) Extends only to LIRGs Single-parameter family

55 Dale & Helou (2002) Extends only to LIRGs Single-parameter family

56 Chary & Elbaz (2001) Silva+1998: ULIRG,LIRG,SB,normal Arp220,N6090,M82,M L 1011 L 1010 L sequence defined by infrared luminosity

57 Chary & Elbaz (2001) Silva+1998: ULIRG,LIRG,SB,normal Arp220,N6090,M82,M m replaced with ISO spectrum 1012 L 1011 L 1010 L sequence defined by infrared luminosity

58 Chary & Elbaz (2001) Silva+1998: ULIRG,LIRG,SB,normal Arp220,N6090,M82,M m replaced with ISO spectrum Interpolated; added Dale+2001 templates to increase variety 1012 L 1011 L 1010 L sequence defined by infrared luminosity

59 Chary & Elbaz (2001) Silva+1998: ULIRG,LIRG,SB,normal Arp220,N6090,M82,M L 1011 L 1010 L sequence defined by infrared luminosity

60 Lagache et al. (2003) Starburst + Normals; tweaked Désert+1990 / Dale+2001, to better fit galaxy number counts L L 1011 L 1010 L sequence defined by infrared luminosity

61 Lagache et al. (2003) Starburst + Normals; tweaked Désert+1990 / Dale+2001, to better fit galaxy number counts L L 1011 L 1010 L sequence defined by infrared luminosity

62 Brandl et al. (2006) Collection of 22 Spitzer mid-infrared spectra (starbust or starburst+agn) Span wide range in silicate absorption

63 Rieke et al. (2009) Empirical data for ULIRGs and LIRGs, including IRS spectra Single T blackbody Extends to lower LIR using DH02 & Smith+2007 sequenced according to LIR

64 Rieke et al. (2009) Empirical data for ULIRGs and LIRGs, including IRS spectra Single T blackbody Extends to lower LIR using DH02 & Smith+2007 Stronger PAH at high L than CE01 sequenced according to LIR More peaked at high L than DH02 Less cold dust emission at low L and more Si absorption at high L than SK07

65 Some Popular Infrared SED grids

66 Some Popular Infrared SED grids The larger number of free parameters allow for more sophisticated interpretations

67 Siebenmorgen & Krügel (2007) Radiative transfer assuming spherical symmetry and no clumps Tested with 7 galaxies NSED=7000

68 Siebenmorgen & Krügel (2007) Radiative transfer assuming spherical symmetry and no clumps Tested with 7 galaxies NSED=7000 Varies with: Luminosity Visual obscuration Nuclear size OB-to-total luminosity Dust density in hot spots

69 da Cunha et al. (2008) Balances the inferred stellar attenuation with dust output

70 da Cunha et al. (2008) Balances the inferred stellar attenuation with dust output Fitted components: Age SFR Metallicity Attenuation of old stars Attenuation of young stars PAHs VSGs Warm BGs Cold Bgs See also CIGALE from the Marseille group

71 Draine & Li (2007) Physical dust models for PAHs, carbonaceous, amorphous silicate grains Power-law distribution over radiation field intensities U stellar diffuse fraction 1- for U = Umin ~ G0 PDR fraction

72 Draine & Li (2007) Physical dust models for PAHs, carbonaceous, amorphous silicate grains PAH mass fraction Umin (and Umax) Mdust PDR fraction See also Zubko+2004 Jonsson+2010 Compiègne+2010 Narayanan

73 KINGFISH Key Insights on Nearby Galaxies: A Far-Infrared Survey with Herschel Kennicutt SINGS galaxies + IC342,N2146,N3077,M101 Far-IR/submm imaging & spectral line maps U. Colorado CCAT Workshop 20 September 2012

74 Range of galaxy types, Z, ssfr, L,... Kennicutt+2011 U. Colorado CCAT Workshop 20 September 2012

75 Both Spitzer and Herschel Kennicutt U. Colorado CCAT Workshop 20 September 2012

76 NGC6946 Kennicutt+ 2011

77 Global photometry no obvious trends with T or Z Dale U. Colorado CCAT Workshop 20 September 2012

78 DL07-type fits Thank You Similar to expectations based on extrapolations from Spitzer U. Colorado CCAT Workshop 20 September 2012 Dale+ 2012

79 (Modified) blackbody- and DL07-based dust masses systematically different Dale+ 2012

80 (Modified) blackbody- and DL07-based dust masses systematically different Dale+ 2012

81 DL07 output parameters Draine+ 2007

82 DL07 output parameters e.g., dust outside Orion bar PDR heated by U ~ % of MW bolometric L from M > 20 Msun Dale+ 2012

83 SEDs at long wavelengths ( 1 mm) Variable submm emissivity vs very cold dust Spinning dust Synchrotron Free-Free (Bremsstrahlung)

84 SEDs at long wavelengths ( 1 mm) Variable submm emissivity vs very cold dust Spinning dust Synchrotron Free-Free (Bremsstrahlung) dust non-thermal -0.8 thermal -0.1 Murphy 2009

85 Spinning dust in the Milky Way Draine 2003

86 Spinning dust in NGC6946? Murphy+2010

87 Spinning dust in NGC6946? Murphy+2010

88 Magellanic Clouds: evidence for spinning dust, and/or emissivity variations Bot+2010