Warm Ionized Gas in Early-type Galaxies & SDSS-IV/MaNGA. Renbin Yan ( 严 人斌 ) (University of Kentucky)

Transcription

1 Warm Ionized Gas in Early-type Galaxies & SDSS-IV/MaNGA Renbin Yan ( 严 人斌 ) (University of Kentucky)

2 Galaxy Bi-modality Spiral disk galaxies: young, rich of cold gas, forming stars actively. (late-type galaxies)! Elliptical and lenticular galaxies: old, poor of cold gas, no new stars being formed (early-type galaxies)

3 Exponential cutoff of the luminosity function Yang et al. (2003)

4 Origin of the bi-modality Exponential cutoff of the galaxy luminosity function

5 Origin of the bi-modality Exponential cutoff of the galaxy luminosity function Why early-type galaxies stop forming stars? How do they maintain low or zero star formation rate?

6 Can it be explained by shortage of cold gas? Hot gas in the very center can cool fast. Stellar mass loss alone could provide plenty of cold gas and dust. Need heating to balance cooling and heat up the stellar mass loss.

7 Cold gas in early-type galaxies How much cold gas is there in early-type galaxies? Where do these cold gas come from? Do these gas cool down to form stars? If so, how efficient is the star formation here?

8 Warm Ionized Gas in Early-type Galaxies SAURON project Sarzi et al. (2006) 75% of early-type galaxies display line emission, often spatially extended. The line ratio pattern is LINER-like. (Phillips et al. 1986, Kim 1989, Buson et al. 1993, Goudfrooij et al. 1994, Macchetto et al. 1996, Zeilinger et al. 1996, Eisenstein et al. 2003, Yan et al. 2006)

9 LINER emission Palomar Survey SDSS Ho (2008) Yan & Blanton (2012) Nuclear Spectra (r< 200pc) Bulge/Center Spectra (r~2.5kpc at z~0.1)

10 LINERs are very common! LINER is the most common spectral type found in the nuclei of early-type galaxies, comprising ~50% of all early-types: elliptical (E) and lenticular (S0) galaxies. Ho et al. (1997)

11 Potential Ionization Mechanisms for LINERs Photoionization by an AGN (Ferland & Netzer 1983, Halpern & Steiner 1983) Photoionization by hot evolved stars, e.g. post-agbs (di Serego Alighieri et al. 1990, Binette et al. 1994) Photoionization by hot X-ray emitting gas (Voit & Donahue 1990, 1991; Kim 1989) Collisional ionization by fast shocks (Heckman et al. 1989, Dopita & Sutherland 1995)

12 Emission line as AGN indicator? Star-forming Galaxies Quiescent Galaxies (Early-type) Mostly Seyferts Mostly LINERs Lbol/LEdd Kauffmann & Heckman (2010)

13 How to distinguish? A central point source Distributed ionizing sources Gas Clouds vs. AGN e.g. Post-AGB stars

14 How to distinguish? A central point source Distributed ionizing sources Gas Clouds vs. AGN e.g. Post-AGB stars Different ionizing flux profile => Different ionization parameter profile U => Different line ratio gradient with radius Ionizing Flux Gas Density

15 Are there data to do this? Need long-slit or integral field spectroscopy SAURON and ATLAS3D surveys had too short a wavelength coverage. What can I do? SDSS + Palomar

16 Sloan Digital Sky Survey Five-band imaging of 1/3 of the sky Image Source:

17 Sloan Digital Sky Survey Spectroscopy for ~1 million galaxies, ~120K quasars, covering A with R~ Image Source:

18 Idea: the Aperture Effect 3

19 Idea: the Aperture Effect 3 Color Red Blue Need to identify the same population of galaxies at different redshifts.! Select only red galaxies and remove star-forming contaminants based on D n (4000). Bright Faint Luminosity

20 Luminosity Profile Palomar Σ(r) r Palomar LINER emission in early-type galaxies is spatially extended. Nuclear LINERs are just the central part.

21 Luminosity Profile Palomar Σ(r) r Palomar LINER emission in early-type galaxies is spatially extended. Nuclear LINERs are just the central part. Low Ionization Nuclear Emission-line Region

22 Luminosity Profile Palomar Σ(r) r Palomar LINER emission in early-type galaxies is spatially extended. Nuclear LINERs are just the central part. Low Ionization Nuclear Emission-line Region

23 Luminosity Profile Palomar Σ(r) r Palomar LINER emission in early-type galaxies is spatially extended. Nuclear LINERs are just the central part. Low Ionization Nuclear Emission-line Region

24 Luminosity Profile Palomar Σ(r) r Palomar LINER emission in early-type galaxies is spatially extended. Nuclear LINERs are just the central part. Low Ionization Emission-line Region

25 AGN is ruled out Distributed ionizing sources n warm 1/2 star n warm r where 1 < < 0.5 AGN will produce an outward decreasing ionization parameter, opposite to what we see! AGN AGN The line ratio trend favors distributed ionizing sources that follow the stellar density profile. Yan & Blanton (2012)

26 Cumulative flux line ratio Luminosity Dependence γ=1.7 The observed γ=1.5 γ=1.3 luminosity dependence in line ratio gradient matches the general ngas nstar 1/2 trends predicted by distributed ionizing sources following the stellar density profile. Yan & Blanton (2012)

27 What about those supporting evidence for AGN? What about LINER s higher X-ray detection rate? What about the broad line components? What about UV variability?

28 What about radio galaxies? Are the LINER emission seen in radio galaxies mostly powered by the AGN?

29 What about radio galaxies? Are the LINER emission seen in radio galaxies mostly powered by the AGN? Not necessarily the case.

30 Line emission in Radio AGN Cumulative Fraction (<Hα EW) Log L (W/Hz) > < Log L (W/Hz) < 23.7 Log L (W/Hz) > A Hα EW (Å) Courtesy of Jessica Short Even in a radio galaxy with L~10 24 W/Hz, on average the AGN only contributes 30% to the total Hα emission.

31 Can the line emission be produced by shocks? Shock produces higher temperatures (10 5 K) than photoionization.

32 Temperature Measurement Low [NII]/[OII] stack High [NII]/[OII] stack

33 Temperature Measurement Low [NII]/[OII] stack [NII] 5755 High [NII]/[OII] stack

34 Temperature Measurement Low [NII]/[OII] stack [NII] 5755 High [NII]/[OII] stack

35 Consistency with photo-ionization CLOUDY simulations Input spectra: BC03 13Gyr-old SSP, solar metallicity, Charbrier IMF. Ionizing spectra shape vary little with stellar age and metallicity. Density ~200/cm 3 (based on [SII] ratio). Solar abundance pattern, except N/O scale with O/H according to Vila Costa & Edmund (1993).

36 Post-AGB stars Post-AGB AGB horizontal branch Main Sequence White Dwarf red giant A short-lived phase between Asymptotic Giant Branch (AGB) stage and white dwarf stage. Hot (~10 5 K) and luminous. The lower mass post-agbs outlive planetary nebulae and form a diffuse ionizing field.

37 Time Evolution of Ionizing Flux 1 Gyr after a starburst, the total ionizing flux is nearly constant with time. Binette et al. (1994)

38 Some new puzzles! Where does the gas come from? What controls the line strength, the ionizing flux or the amount of cold gas? Can we gain some insight from the metallicity of the gas?

39 Hint of mass-metallicity relation Bright galaxies Faint Galaxies

40 Metallicity Measurements in Galaxies Stellar metallicity from stellar spectrum Hot gas metallicity from X-ray spectra Ionized gas metallicity from absorption systems along quasar sight lines Warm gas metallicity from star-forming regions (not applicable in these old galaxies!)

41 Metallicity Measurements in Galaxies Stellar metallicity from stellar spectrum Hot gas metallicity from X-ray spectra Ionized gas metallicity from absorption systems along quasar sight lines Warm gas metallicity from star-forming regions (not applicable in these old galaxies!) Warm gas metallicity from emission line ratios in elliptical galaxies!

42 Metallicity Indicators AV=1 [NII]/[OII] is a better metallicity indicator. But it needs to be corrected for extinction.

43 Metallicity Indicators AV=1 [NII]/[OII] is a better metallicity indicator. But it needs to be corrected for extinction.

44 Extinction depends on line strength

45 Extinction depends on line strength

46 Extinction depends on line strength

47 Extinction depends on line strength

48 Extinction depends on line strength

49 Extinction depends on line strength

50 Extinction depends on line strength

51 Extinction depends on line strength

52 Extinction depends on line strength

53 Extinction increase with line strength We can explain this correlation in the picture of photons ionizing the surface of a neutral gas cloud.!! This suggests that the emission strength is set by the amount of ionizing photons, not by the total amount of available gas.

54 Extinction increase with line strength We can explain this correlation in the picture of photons ionizing the surface of a neutral gas cloud.!! This suggests that the emission strength is set by the amount of ionizing photons, not by the total amount of available gas.

55 Elemental abundance reveals the origin of the gas Dust-free galaxies only [OIII]/[OII] --- Ionization parameter [NII]/[OII] --- Oxygen abundance

56 Metallicity of the Gas Dust-free galaxies only + Star-forming Galaxies + Passive Red Galaxies The red galaxies have lower gas phase metallicities than starforming galaxies with similar masses.

57 Summary (Part I) AGN is not the dominant ionizing source for the LINERlike line emission commonly found in early-type galaxies, neither are shocks. The dominant ionizing sources are probably distributed like the stars. Line strength in LINERs found with large aperture (>100pc) spectra cannot be used to trace AGN luminosity, but can be used to trace the warm/cold gas. Gas elemental abundance measurement in early-type galaxies opens a new window to study their interstellar medium and its co-evolution with the stars.

58 Part II: SDSS-IV/MaNGA

59 Wonders of Spectroscopic Surveys (e.g. SDSS) Star Formation Rate Environment Wind/outflow Velocity Dispersion Star formation history Stellar Mass AGN Elemental Abundances

60 Wonders of Spectroscopic Surveys (e.g. SDSS)

61 Wonders of Spectroscopic Surveys (e.g. SDSS)

62 Wonders of Spectroscopic Surveys (e.g. SDSS)

63 Wonders of Spectroscopic Surveys (e.g. SDSS)

64 Wonders of Spectroscopic Surveys (e.g. SDSS)

65 Wonders of Spectroscopic Surveys (e.g. SDSS)

66 Wonders of Spectroscopic Surveys (e.g. SDSS)

67 Wonders of Spectroscopic Surveys (e.g. SDSS) Integral Field Spectroscopy (3D Spectroscopy)

68 And Mgb SAURON Survey: Emsellem et al. 2004

69 NGC 2974 And Total Flux Mgb SAURON Survey: Emsellem et al. 2004

70 And V NGC 2974 Total Flux σ h 3 h 4 Mgb SAURON Survey: Emsellem et al. 2004

71 And V NGC 2974 Total Flux σ Hβ h 3 Fe5015 h 4 Mgb SAURON Survey: Emsellem et al. 2004

72 NGC 2974 And V Total Flux [OIII] σ Hβ Hβ h 3 Fe5015 V gas h 4 Mgb σ gas SAURON Survey: Emsellem et al. 2004

73 NGC 2974 And V Total Flux [OIII] EW [OIII] σ Hβ Hβ EW Hβ h 3 Fe5015 V gas [OIII]/Hβ h 4 Mgb σ gas SAURON Survey: Emsellem et al. 2004

74 NGC 2974 And V Total Flux [OIII] EW [OIII] age σ Hβ Hβ EW Hβ Z/H h 3 Fe5015 V gas [OIII]/Hβ α/fe h 4 Mgb σ gas SAURON Survey: Emsellem et al. 2004

75 SDSS-IV/MaNGA Mapping Nearby Galaxies at APO Part of SDSS-IV. 10,000 galaxies in 6 years. Spatial resolution: 2.5 (1-2kpc); spectral resolution: km/s (sigma); spectral coverage: ,500A. Multi-object IFS: 17 galaxies per 7 sq. deg. pointing Median S/N per A of 5.5 per fiber in r-band at 1.5Re. The fiber bundles and slit assembly are commissioned successfully in March. Survey observation begins on July 1st!

76 MaNGA Organizational Team:! Principal Investigator: Chief Engineer: Survey Scientist: Instrument Scientist: SDSS-IV Project Scientist: Lead Data Scientist: Sample Design Lead: Lead Observer: Science Team Chairs: Kevin Bundy (Kavli IPMU) Nick MacDonald (Univ. of Washington) Renbin Yan (Univ. of Kentucky) Niv Drory (Univ. of Texas, Austin) Matt Bershady (Univ. of Wisconsin) David Law (Univ. of Toronto) David Wake (Open University) Anne-Marie Weijmans (Univ. of St. Andrews) Daniel Thomas (Portsmouth) Sebastian Sanchez (UNAM) Composition Strategic Committee: Christy Tremonti, Alfonso Aragon-Salamanca, Roberto Maiolino, Cheng Li Kinematic Strategic Committee: Karen Masters, Remco van den Bosch, Mike Merrifield, Eric Emsellem

77 IFS Surveys of Nearby Galaxies SAURON 48 ellipticals ATLAS3D 260 ellipticals VENGA 32 spirals DiskMass 146 spirals CALIFA 600 all types (on-going)

78 IFS Surveys of Nearby Galaxies SAURON 48 ellipticals ATLAS3D 260 ellipticals VENGA 32 spirals DiskMass 146 spirals CALIFA 600 all types (on-going) Why do we need IFU surveys with a much bigger sample?

79 Power of a much larger IFS Sample Statistical power: allow binning by different galaxy properties: mass, color, morphology, environment, SFR, AGN/non-AGN, kinematics etc. Rare objects, such as mergers, post-starburst galaxies, passive spirals, blue spheroids, etc. Power of stacking: low SB features, weak lensing Enable many more unforseen studies

80 Comparison to other IFU surveys 4 étendue (light collecting area, A) (field of view, Ω) (efficiency, ε)

81 Science Goals of MaNGA Growth of disks Assembly of bulges and spheroids Quenching of star formation Distribution and transfer of angular momentum Weighing galaxy subcomponents

82 Target Selection Flat stellar mass distribution Uniform spatial coverage in units of Re - 2/3 of the sample covered to 1.5Re - 1/3 of the sample covered to 2.5Re Simple selection based on M i and redshift. Secondary sample (2.5Re) Primary sample (1.5Re) No size or inclination cuts 2x 4x 4x 2x 5x 12 32

83 Current Field Choice

84 Example science outcome Plots made by K. Bundy, C. Conroy, & R. van den Bosch

85

86 Courtesy of David Law

87 Stay tuned.