Chris Pearson: RAL Space. Chris Pearson: April

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1 Chris Pearson: RAL Space 1

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3 Young Star Dust Clouds Infra Red Light 3

4 Starlight reprocessed to infrared wavelengths 4

5 1983: The Dawn of Infrared Astronomy Infra-Red Astronomical Satellite (IRAS) All sky survey 12, 25, 60, 100 micrometres 5

6 The importance of DUST 50%-60% Star Formation in Universe in IR. Optical and IR backgrounds equal Normal galaxies infrared optical light ratio: LIR/Lopt - 30%. Luminous infrared galaxies: Starbursts LIR/Lopt %. Ultra-Luminous Infrared Galaxies extreme case LIR/Lopt % 6

7 ULIRGs : LIR>10 12 Lo (Local Archetype Arp220) Interacting, disturbed systems forming stars > 100Msun/yr Nearly always mergers Local density RARE ~0.001/sq. deg. IRAS ~ 5-7 times more numerous at redshft ~0.3 Requires strong evolution of the population to z~1 Possible progenitors of todays giant elliptical galaxies 7

8 BLOB COUNTING Large amounts of dust, present in the central regions of ULIRGs provide an ideal environment for circumnuclear starburst and/or Active Galactic Nucleus (AGN) 8

9 Evolution of ULIRGs: Interplay between different phases of interstellar medium (ISM) Star-formation AGN Gas Cooling (emission lines) 9

10 Gas cooling via emission lines [CII] is one of the strongest ISM cooling lines in galaxies Can account for between 0.1-1% of total emission from a galaxy! Powerful tracer of neutral/ionized ISM Star Formation indicator? 10

11 [CII] deficit in local ULIRGs 11

12 Largest Herschel Open Time OT1 programme ( 250hrs) Observations taken between 18 March October 2012 Comprehensive survey of ~43 nearby (z<0.2) ULIRGs D. Farrah, D. Rigopoulou, H. Spoon, C. Pearson, V. Lebouteiller et al. Observations and Target Lines SPIRE photometry 250, 350, 500 µm SPIRE spectroscopy CO Ladder, Water Lines, CI (607µm) PACS Spectroscopy [O III]52, [N III]57.3, [O I]63.2, [O III]88, [N II]121.9, [O I]145.5, [C II]157.7µm Products A comprehensive database for community exploitation An anchor for studies of ULIRGs in the high redshift Universe Important input catalogues for ALMA 12

13 Objectives Measure physical & chemical properties of the starbursts and AGN Construct new mid/far IR diagnostic diagrams (PDR/XDR models) Link local studies to high redshift Universe Lines Diagnostics: FIR FS lines properties of HII regions and PDRs FIR FS lines physical properties: U, density, temperature CO ladder properties of the warm CO gas/ism Expected Science CII deficit? NII (205µm ) : valid SFR tracer? CLOUDY+ full radiative transfer SED modelling 13

14 Target Redshift IRAS IRAS IRAS IRAS IRAS IRAS IRAS IRAS IRAS IRAS IRAS IRAS IRAS IRAS IRAS IRAS IRAS IRAS IRAS IRAS IRAS IRAS Target Redshift IRAS IRAS IRAS IRAS IRAS IRAS IRAS IRAS IRAS IRAS IRAS IRAS IRAS Mrk UGC C Mrk Mrk Mrk Arp NGC

15 Imaging 15

16 All data was reduced using HIPE Included encouraging Bruce to use HIPE rather than his pipeline cobbled together from IDL Results for processed data often show offset between spectrometer bands due to differences in background (including telescope) 16

17 SPIRE FTS Pipeline improvements Cooler Burp Correction 17

18 Using the Off axis detectors to remove the background SSW SLW Yellow : Detectors selected for Dark Red : Vignetted detectors SSW SLW 18

19 SLWB2 and SLWC2 marginal outliers SSWE2 clear outlier 19

20 z : OD: 886 Pearson, Rigopoulou, Hurley et al

21 z : OD: 1130 Pearson, Rigopoulou, Hurley et al

22 z : OD: 879 Pearson, Rigopoulou, Hurley et al

23 z : OD:

24 z : OD:

25 SPIRE FTS Pipeline improvements Higher S/N Calibration Products (instrument and telescope RSRF) HIPE 11 approximately 20% reduction in noise. HIPE7 HIPE8 HIPE9 HIPE10 HIPE11 25

26 Line Fitting performed with dedicated fitting algorithm with HIPE Fits to both continuum and lines Unresolved Lines: Sinc Function (more appropriate than Gaussian) Partially resolved lines: Sinc-Gauss function 26

27 Jackknife Tests confirm reality of lines z : OD: 1111? [CII] 158µm F(CII )= 2.80 ± 0.08 x Wm-2 27

28 Water everywhere 28

29 Strong CO ladders 29

30 CO Ladder probes different parts of the ISM PDR: low excitation region Low J CO lines PDR: medium excitation region Medium J CO lines XDR: high excitation region High J CO lines Van der Werf et al

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32 Compare CO line / FIR luminosity ratio with infrared colour (dust temperature) Low-J transitions: not correlated with far-ir luminosity Mid-J transitions: slope flattens (independent of temperature) High-J transitions: : not correlated (gas heating from other sources?) 32

33 Create CO Spectral Line Energy Distributions (CO SLEDs) Compare with models (e.g. RADEX, etc) Obtain characteristics of the ISM (intensity, temperature, density) 33

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35 CO SLEDs modelled using MLM (Hurley et al.) IRAS " 35

36 CO SLEDs modelled using MLM (Hurley et al.) Arp220" 36

37 CO SLEDs modelled using MLM (Hurley et al. ) IRAS " 37

38 Herschel SPIRE FTS exceeded expectations bringing space borne submm spectroscopy to cosmic distances HERUS ULIRGs show rich and diverse spectra Strong CO ladder seen in many cases Water lines seen in abundance HERUS SPIRE observations will form a valuable dataset for the worldwide astronomical community Serve as a stepping stone to what can be achieved with the next generation of space-borne infrared spectroscopic missions. 38

39 Epoch of Blobs Epoch of Science 39

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