From diffuse to dense regionsFrom diffuse to dense regions

Carlos del Burgo DCarlos del Burgo DíazíazSchool of Cosmic PhysicsSchool of Cosmic Physics

Dublin Institute for Advanced StudiesDublin Institute for Advanced Studies

Seminar 14 December 2007 La Laguna

The far-infrared signature The far-infrared signature of dust in high latitude regionsof dust in high latitude regions

ContentsContents

1.1. EvidencesEvidences

2.2. Why is important to study the properties of dust?Why is important to study the properties of dust?

3.3. General introductionGeneral introduction

4.4. Data presentationData presentation

5.5. Analysis, results & conclusions for 8 translucent regionsAnalysis, results & conclusions for 8 translucent regions

6.6. TMC-2: a dense cloudTMC-2: a dense cloud

7.7. Dust in shell galaxiesDust in shell galaxies

Dust evidences Dust evidences ……

Discovery of dust particles in the IS space Discovery of dust particles in the IS space (Trumpler 1930)(Trumpler 1930)

Dust properties have been inferred mainly by Dust properties have been inferred mainly by indirect observations till few years ago (see indirect observations till few years ago (see reviews Draine 2003, Whittet 2003)reviews Draine 2003, Whittet 2003)

Direct observations: Direct observations: emissionemission from ZL at ~25 from ZL at ~25 m, dust trails of comets, circumstellar disks m, dust trails of comets, circumstellar disks of evolved stars, of evolved stars, ISMISM, IR and ULIRGs, AGNs, , IR and ULIRGs, AGNs, CFIRB, active star formation at high-redshiftCFIRB, active star formation at high-redshift

Why is it important to study Why is it important to study the dust properties?the dust properties?

Dust and gas (1:100 mass relation) are the Dust and gas (1:100 mass relation) are the components of the ISM. Dust contains ~50% of the components of the ISM. Dust contains ~50% of the heavy metals synthesized by starsheavy metals synthesized by stars

It plays a key role in many astrophysical It plays a key role in many astrophysical environments: thermodynamics and chemistry of gas, environments: thermodynamics and chemistry of gas, dynamics of star formation, …dynamics of star formation, …

It shapes the SED of many cosmic sources (e.g., It shapes the SED of many cosmic sources (e.g., galaxies). galaxies). Absorption and scattering of stellar light Absorption and scattering of stellar light and re-emission in the IR and submmand re-emission in the IR and submm

It affects estimations of basic properties of distant It affects estimations of basic properties of distant galaxies (SFR, mass determination)galaxies (SFR, mass determination)

Cirrus: thermal Cirrus: thermal emission from emission from interstellar dust heated interstellar dust heated by stars in the Milky by stars in the Milky WayWay

MJy/srMJy/sr

COBE/DIRBE Surface brightness at 100 COBE/DIRBE Surface brightness at 100 mm

Galactic dust emissionGalactic dust emission

de Oliveira-Costa 1999de Oliveira-Costa 1999

IntroductionIntroduction

The mid- and far-IR emission The mid- and far-IR emission of IS dust is due to of IS dust is due to

likely PAHslikely PAHs, , VSGsVSGs andand BGsBGs

(Desert et al. 1990; (Desert et al. 1990; Siebenmorgen & KrSiebenmorgen & Krüügel 1992gel 1992

Weingartner & Draine 2001)Weingartner & Draine 2001)

IR coloursIR colours are used to are used to study:study:

- - variations ofvariations of LSRFLSRF (Laureijs (Laureijs et al.et al. 1986; 1986; Bernard Bernard et al.et al. 1992) 1992) - - relativerelative abundancesabundances (Boulanger (Boulanger et al.et al. 1990; Lagache 1990; Lagache et al.et al. 1998)1998)

Polycyclic Aromatic HydrocarbonPolycyclic Aromatic HydrocarbonSizes: 0.4-1.2 nmSizes: 0.4-1.2 nm

PAHPAH

Silicates + dark refractory mantleSilicates + dark refractory mantle15-110 nm15-110 nm

BGBG

Siebenmorgen & Krügel. 1992, A&A 259, 614Siebenmorgen & Krügel. 1992, A&A 259, 614

Carbon dominatedCarbon dominated1.2-15 nm1.2-15 nm

VSGVSG

Draine 2003Draine 2003

coldwarm

From all-sky map, 1From all-sky map, 1oo beam (DIRBE, Lagache et al. 1998) beam (DIRBE, Lagache et al. 1998)

Data presentation:Data presentation:high-latitude dust regionshigh-latitude dust regions

Data archives (Data archives (COBE, IRASCOBE, IRAS, , ISO, ISO, SPITZERSPITZER,, SCUBA SCUBA)) IR and submillimetric data to study the dust emissionIR and submillimetric data to study the dust emission AkariAkari has been launched in February 2006 has been launched in February 2006 HerschelHerschel and and PlanckPlanck will be launched soon will be launched soon Other future missions: Other future missions: SOFIA, ALMA, JWTSOFIA, ALMA, JWT

We present results for 1 dense and 9We present results for 1 dense and 9 translucent regionstranslucent regions.. 60-200 60-200 μμm data from the m data from the ISO archiveISO archive to study: to study: - - VSGVSG emission, which peaks at emission, which peaks at ~ 60 ~ 60 μμmm

- - BGsBGs: : warm and cold componentswarm and cold components

We used additional information:We used additional information: - USNO and 2MASS catalogues - USNO and 2MASS catalogues extinction from star counts extinction from star counts - COBE/DIRBE - COBE/DIRBE ZL in eight translucent clouds ZL in eight translucent clouds - IRAS and molecular observations - IRAS and molecular observations LDN 1780 and TMC-2 LDN 1780 and TMC-2

TranslucenTranslucenttregions regions

Seminar 14 December 2007 Carlos del Burgo

High latitude regions: sample High latitude regions: sample descriptiondescription

9 diffuse to moderately dense 9 diffuse to moderately dense regions (peaks Aregions (peaks AVV~1-6 mag)~1-6 mag)

and TMC-2 and its and TMC-2 and its surroundings surroundings

(peak A(peak AVV~8 mag)~8 mag)

No dominant heating sourcesNo dominant heating sources

Galactic latitude |b| > 15°Galactic latitude |b| > 15°

Data sets with 150 and 200 Data sets with 150 and 200 μμmm

filterbands (except for filterbands (except for

LDN 1563, and TMC-2)LDN 1563, and TMC-2)

EMISSION maps: LDN 1563

area~175 arminarea~175 armin22

area~274 arminarea~274 armin22

del Burgo et al. 2003del Burgo et al. 2003

Sky at Galactic Sky at Galactic coordinates: observed coordinates: observed dust regionsdust regions

33 22

Map courtesy by Richard PowellMap courtesy by Richard Powell

22

Analysis approachAnalysis approach

Convolve C100 images with the C200’s theoretical beam Convolve C100 images with the C200’s theoretical beam profile and resample according to the same pixel size and profile and resample according to the same pixel size and gridgrid

Optical extinction AOptical extinction AV V from USNO and 2MASS star countsfrom USNO and 2MASS star counts Colours obtained from pixel-to-pixel correlation diagramsColours obtained from pixel-to-pixel correlation diagrams

ColoursColoursFitting with 1 (unimodal) orFitting with 1 (unimodal) or2 (bimodal) straight lines to 2 (bimodal) straight lines to determine the ratios Idetermine the ratios I/I/I200200

spectral energy spectral energy distributiondistribution

Fitting 150 and Fitting 150 and 200µm with a 200µm with a modified blackbody modified blackbody FFBB(T)(T)

colour colour temperaturetemperature

del Burgo et al. 2003, MNRAS 346, 403del Burgo et al. 2003, MNRAS 346, 403

Results – VSG coloursResults – VSG colours Unimodal and bimodal Unimodal and bimodal

correlationscorrelations Large variation in ratios Large variation in ratios

II6060/I/I200200 and I and I9090/I/I200200

Above a given IAbove a given I200200, the ratios , the ratios are loware low

I60/I200

I90/I200 60µm60µm200µm200µm90µm90µm

del Burgo et al. 2003del Burgo et al. 2003 Siebenmorgen & Krügel. 1992, A&A 259, 614Siebenmorgen & Krügel. 1992, A&A 259, 614

VSGs disappear above VSGs disappear above a certain column densitya certain column density

Results – BG coloursResults – BG colours

We find a unique relationship between 150 We find a unique relationship between 150 μμmm and 200 and 200 μμmm surface surface brightness. This is confirmed by the COBE data of Taurus cloud.brightness. This is confirmed by the COBE data of Taurus cloud.

del Burgo et al. 2003del Burgo et al. 2003

LB (obtained from COBE/DIRBE)LB (obtained from COBE/DIRBE)

All regionsAll regions

ZL subtracted fromZL subtracted fromDIRBE dataDIRBE data

BG colour temperaturesBG colour temperatures

Assuming Assuming ββ=2, we have derived colour temperatures (T) from I=2, we have derived colour temperatures (T) from I150150/I/I200 200

both for the regions (from ISO) and local sky background (from COBE)both for the regions (from ISO) and local sky background (from COBE)Colour temperature versus mean II200200

WarmWarm

ColdCold

del Burgo et al. 2003del Burgo et al. 2003

T changes continuously T changes continuously as a function of column as a function of column density (as traced by Idensity (as traced by I200200))

There is no indication of There is no indication of a discrete 2 T distribution a discrete 2 T distribution (Lagache (Lagache et al.et al. 1998) 1998)

II200200/A/AVV when colour T when colour T

This increase comes out even This increase comes out even stronger in stronger in 200200/A/AVV

For each For each loslos there are two BG there are two BG components: components: warm and and cold grainsgrains

Assuming Assuming TTww=17.5 K=17.5 K andand

TTcc=13.5 K=13.5 K

The colour T depends on the The colour T depends on the relative contribution of the relative contribution of the warm and cold components warm and cold components XX

enhancement in the enhancement in the emissivity of the cold grains wrt emissivity of the cold grains wrt DISM/warm grainsDISM/warm grains

Far-infrared opacities: BGsFar-infrared opacities: BGs

del Burgo et al., 2003del Burgo et al., 2003

=8=8

=4=4

=1=1

TTww=17.5 K=17.5 KTTcc=13.5 K=13.5 K

XX

60% cold60% cold40% warm40% warm

100% cold100% cold

100% warm100% warm

DISMDISM

Colder regions emit relatively Colder regions emit relatively more FIR emission per Amore FIR emission per AVV

The enhancement in FIR The enhancement in FIR emissivity can be due to the emissivity can be due to the coagulation of dust grains (del coagulation of dust grains (del Burgo et al. 2003) – also observed Burgo et al. 2003) – also observed by Cambrésy by Cambrésy et al.et al. (2001), (2001), Stepnik Stepnik et al.et al. (2003), Kramer (2003), Kramer et et al.al. (2003) (2003)

The gradual change in emissivity The gradual change in emissivity as a function of T indicates that as a function of T indicates that there is a close relationship there is a close relationship between colour temperature and between colour temperature and FIR dust propertiesFIR dust properties

Far-infrared opacities: Far-infrared opacities: implicationsimplications

Polaris Flare, Cambrésy et al. 2001

= 8= 8 = = 44 = 1= 1

DISM

Dust evolutionDust evolution

Evolution of dust grains in dense regions via gas accretion onto grains Evolution of dust grains in dense regions via gas accretion onto grains and the coagulation of grainsand the coagulation of grains

Particle cluster aggregation Cluster cluster aggregationParticle cluster aggregation Cluster cluster aggregation

CORECORE

UV radiation field produces UV radiation field produces complex molecules (e.g. CHcomplex molecules (e.g. CH33OH)OH)in the envelope of the dust in the envelope of the dust grainsgrains

COCO

HH2200NHNH33

HH22COCOPAHPAHCHCH44

0.1µm0.1µm

Chemistry and dynamicsChemistry and dynamics

Stognienko et al. 1995Stognienko et al. 1995

Ratios IRatios I6060/I/I200200, I, I9090/I/I200200 show a large/decreasing variation with I show a large/decreasing variation with I200200.. VSGVSGs disappear above a given column density.s disappear above a given column density.

Far-IR colour IFar-IR colour I150150/I/I200200 shows a very tight trend with I shows a very tight trend with I200200.. BGs have a BGs have a colourcolour temperature that depends on the column temperature that depends on the column densitydensity

Gradual variation of emissivity and opacity relative to AGradual variation of emissivity and opacity relative to AVV..

At lower temperatures the grains present an enhanced FIR At lower temperatures the grains present an enhanced FIR emissivityemissivity

Two component model. Two component model.

Cold componentCold component:: T T13 K, 13 K, enhanced FIR emissivity enhanced FIR emissivity Coagulation Coagulation

WWarm componentarm component: BGs with standard T and emissivity: BGs with standard T and emissivity

ConclusionsConclusions

TMC-2: TMC-2: a dense a dense cloudcloud

Seminar 14 December 2007 Carlos del Burgo

IntroductionIntroduction

HCHC55N (J=9-8) and NHN (J=9-8) and NH33 observations (Myers et al. observations (Myers et al. 1979): TMC-21979): TMC-2 i is a small (s a small (~0.1 pc in size~0.1 pc in size) dense ) dense ((~4 10~4 1044 cm cm-3-3) low-mass (1 M) low-mass (1 M) nearly round ) nearly round fragmentfragment in stable equilibriumin stable equilibrium

TMC-2 is part of B18 dark cloud (Barnard 1928). TMC-2 is part of B18 dark cloud (Barnard 1928). Observations in HI self absorption (Batrla et al. Observations in HI self absorption (Batrla et al. 1981,1981, PPööppel et al. 1983), Hppel et al. 1983), H22CO (PCO (Pööppel et al. 1983). ppel et al. 1983). Surveys in HI (Hartmann & Burton 1997), CO Surveys in HI (Hartmann & Burton 1997), CO (J=1-0)(J=1-0) (Dame et al. 2001), (Dame et al. 2001), 1313CO (J=1-0) (Mizuno et al. CO (J=1-0) (Mizuno et al. 1995)1995) and Cand C1818O (J=1-0) (Onishi et al. 1996)O (J=1-0) (Onishi et al. 1996)

2MASS extinction (Padoan et al. 2002)2MASS extinction (Padoan et al. 2002)

Area = 1767 Area = 1767 arcminarcmin22

Separation Separation of the of the coldcold and and warmwarm componentcomponents: vicinity s: vicinity of TMC-2of TMC-2

60 µm 100 µm60 µm 100 µm

120 µm 200µm120 µm 200µm

100 µm 100 100 µm 100 µm µm warm warm coldcold

120 µm 120 120 µm 120 µm µm warm warm coldcold

del Burgo & Laureijs, 2005del Burgo & Laureijs, 2005

HI coldHI cold

100 µm100 µm

60 µm60 µmWarm Warm componentcomponent

N(HI)/N(HN(HI)/N(H22))5 105 10-3-3

Pöppel et al. 1983Pöppel et al. 1983

T T 20 K 20 K AAVV~0.2 mag~0.2 mag(using (using 200200/ A/ AV V of the DISM)of the DISM)200200=0.2 10=0.2 10-4-4

, cold, cold

Cold component: T and Cold component: T and 200200 mapsmaps

200200 × 10 × 10-4-4T [K]T [K]

del Burgo & Laureijs, 2005del Burgo & Laureijs, 2005

W(CW(C1818O)[K km sO)[K km s-1-1]]+contours of +contours of 200200×10×10-4-4

CC1818O from Onishi et al. 1996, ApJ 465, 815O from Onishi et al. 1996, ApJ 465, 815

W(W(1313CO)[K km sCO)[K km s-1-1]]+contours of 100µm,cold+contours of 100µm,cold

del Burgo & Laureijs, 2005del Burgo & Laureijs, 2005

II200200/A/AV V andand 200200/A/AVV

ConclusionsConclusions

TMC-2:TMC-2: The The warmwarm and and coldcold components are components are spatially separatedspatially separated

WarmWarm component likely consists of component likely consists of BGs at BGs at 20 K20 K and VSGs and VSGs

ColdCold component has component has T=12.5 KT=12.5 K and and enhanced emissivityenhanced emissivity grain grain coagulationcoagulation and and mantle growthmantle growth processes processes

Column densities derived from Column densities derived from 1313COCO(J=1-0)(J=1-0) and 2MASS are in and 2MASS are in agreementagreement

Good correlation between W(Good correlation between W(1313CO) and ICO) and Icoldcold(100)(100)

change in the dust properties wrt DISM at n(Hchange in the dust properties wrt DISM at n(H22) ) 10 1033 cm cm-3-3

W(CW(C1818O) and O) and 200200 correlate very well for TMC-2* and Northern correlate very well for TMC-2* and Northern regionregion

Dust distribution in Dust distribution in the shell elliptical the shell elliptical NGC 5982NGC 5982

Seminar 14 December 2007 Carlos del Burgo

ShellShell galaxies (Malin & Carter 1980, 1983) are elliptical galaxies (Malin & Carter 1980, 1983) are elliptical galaxies with faint, sharp edged features in their galaxies with faint, sharp edged features in their envelopes, generally interpreted as the remnants of envelopes, generally interpreted as the remnants of mergers of low mass, low velocity dispersion galaxies with mergers of low mass, low velocity dispersion galaxies with the elliptical (Quinn 1984, Hernquist & Quinn 1988)the elliptical (Quinn 1984, Hernquist & Quinn 1988)

ISM in shell ellipticals: mostly X-ray emitting gas, some ISM in shell ellipticals: mostly X-ray emitting gas, some warm and cold gas and dust; ~70 % with HI gas (Morganti warm and cold gas and dust; ~70 % with HI gas (Morganti et al. 2006); ~70 % with warm gas (Sarzi et al. 2006);et al. 2006); ~70 % with warm gas (Sarzi et al. 2006);~28 % with CO gas (Combes et al. 2007); bulk of dust ~28 % with CO gas (Combes et al. 2007); bulk of dust traced by FIR: 10traced by FIR: 1055-10-1077 M M (Temi et al. 2004, 2007) (Temi et al. 2004, 2007)

IntroductionIntroduction

NGC 5982 (type I shell galaxy)NGC 5982 (type I shell galaxy)

SpitzerSpitzer

IRAC (7’x7’ (galaxy) + 7’x7’ (sky); IRAC (7’x7’ (galaxy) + 7’x7’ (sky); 1.8” FWHM):1.8” FWHM):a)a) 3.6 µm3.6 µmb)b) 4.5 µm4.5 µmc)c) 5.8 µm5.8 µmd)d) 8.0 µm8.0 µme)e) 8.0 µm excess8.0 µm excess

MIPS (similar field)MIPS (similar field)f) 24 µm (6” FWHM)f) 24 µm (6” FWHM)g) 70 µm (18” FWHM)g) 70 µm (18” FWHM)h) 160 µm (40” FWHM)h) 160 µm (40” FWHM)

HST (3.37’x3.37’)HST (3.37’x3.37’)

V- and I-bands (Sikkema et al. 2007)V- and I-bands (Sikkema et al. 2007)Del Burgo et al. 2008Del Burgo et al. 2008

SB calibration similar to Pahre et al. SB calibration similar to Pahre et al. (2004), but using also aperture (2004), but using also aperture corrections of Reach et al. 2005corrections of Reach et al. 2005

ELLIPSE and ELLIPFIT to measure the ELLIPSE and ELLIPFIT to measure the flux and ellipse propertiesflux and ellipse properties

Sérsic profile (1968):Sérsic profile (1968):

µ (r)= µµ (r)= µee + c + cnn [(r/r [(r/rnn))1/n1/n-1]-1]

ccnn=f(n) (Caon et al. 1993)=f(n) (Caon et al. 1993)

Excess emissionExcess emission

A scaled stellar photosphere A scaled stellar photosphere emission template is subtracted from emission template is subtracted from the 4.5, 5.8 and 8 µm emission mapsthe 4.5, 5.8 and 8 µm emission maps

Surface photometry: global parametersSurface photometry: global parameters

del Burgo, Carter, Sikkema (2008)del Burgo, Carter, Sikkema (2008)..

ShellsShells

R-bandR-band 3.6 µm3.6 µm

Del Burgo et al. 2008Del Burgo et al. 2008

Shell profilesShell profiles

Shells are bluer than the underlying galaxy:Shells are bluer than the underlying galaxy:V-I=1.16±0.10 mag (shell), 1.25 mag (underlying galaxy)V-I=1.16±0.10 mag (shell), 1.25 mag (underlying galaxy)[3.6]-[4.5]=-0.13 ±0.01 mag, -0.08 mag (underlying galaxy)[3.6]-[4.5]=-0.13 ±0.01 mag, -0.08 mag (underlying galaxy)

Metal-poorMetal-poorYounger stellar populationYounger stellar populationDifferent dust propertiesDifferent dust properties

Del Burgo et al. 2008Del Burgo et al. 2008

Results and interpretationResults and interpretation

Shells are clearly detected from their stellar emission at 3.6 and 4.5 Shells are clearly detected from their stellar emission at 3.6 and 4.5 µm. V-I and [3.6]-[4.5] colours bluer than underlying galaxy. Two µm. V-I and [3.6]-[4.5] colours bluer than underlying galaxy. Two new external shells new external shells estimated dynamical age ~1.1 10 estimated dynamical age ~1.1 1099 years years

Excess emission possibly trace dust originated by stellar mass lossExcess emission possibly trace dust originated by stellar mass loss

24 µm and 3.6 µm are very similar: circumstellar origin24 µm and 3.6 µm are very similar: circumstellar origin

Warm and cold dust traced by 70 and 160 µm: mass of 105 M and Warm and cold dust traced by 70 and 160 µm: mass of 105 M and irregular distributions, not coincident with Eastern HI cloud but irregular distributions, not coincident with Eastern HI cloud but consistent in mass (Morganti et al. 2006), not coincident with warm consistent in mass (Morganti et al. 2006), not coincident with warm gas (Sarzi et al. 2006).gas (Sarzi et al. 2006).

+ Presence of KDC. All this supports a merger scenario in NGC 5982+ Presence of KDC. All this supports a merger scenario in NGC 5982