1 / 40

Galaxy Centers

Galaxy Centers. Tim de Zeeuw. Early- and late-type galaxies Nuclei of E/S0 galaxies Power of integral-field spectroscopy Black hole masses from stellar kinematics Emission-line gas and activity Nuclei of late-type galaxies Classical and exponential ‘bulges’ Central Compact Sources

filomena-veagh
Download Presentation

Galaxy Centers

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Galaxy Centers Tim de Zeeuw • Early- and late-type galaxies • Nuclei of E/S0 galaxies • Power of integral-field spectroscopy • Black hole masses from stellar kinematics • Emission-line gas and activity • Nuclei of late-type galaxies • Classical and exponential ‘bulges’ • Central Compact Sources • Opportunities for HST

  2. Two families of galaxies • `Early-type’ galaxies • R1/4 bulges, high surface brightness, red, old stars • Global and nuclear properties correlate • Emission-line studies: >75% have ‘activity’  BH • More powerful AGN: more evidence for young stars • `Late-type’ galaxies • Young stars, low SB • Strong line-strength gradients • Many: bulgeless disks (M33) • Often: nuclear star cluster • ~0% AGN  no BH (but cf NGC 4395) SDSS

  3. Integral-field Spectroscopy Velocity curve Longslit Velocity field Integralfield GalaxyImage

  4. Rich Physical Content Mgb Line Index Gas Velocity Field [OIII] Line intensity Stellar Velocity Field Reconstructed V image • Total flux • Morphology, photometry • Absorption lines • Stellar kinematics • LOSVD (V,s,h3,h4) • Line strength index • Hb, Mgb, Fe5015, Fe5270 • Emission lines • Gas distribution • Hb, [OIII], [NI] • Line ratios • Gas kinematics • V(Hb), V([OIII]), FWHM(Hb), FWHM([OIII])

  5. 48 representative E/S0 Galaxies

  6. Stellar Velocity Fields Emsellem, Cappellari et al. 2004, MNRAS, in press

  7. i=46° i=79° i=20° HST and

  8. Stellar Velocity Fields 2’’ McDermid, Shapiro, et al. 2004, AN, 325, 100

  9. Kinematic structure on all scales • SAURON: global kinematics and line-strengths • OASIS spatial resolution: zoom-in on nucleus • Allows study of orbital structure near central BH • Single slit STIS: incomplete view on smaller scales? NGC 4382 McDermid et al., 2004, AN, 325, 100

  10. The Black Hole in M32 M32 • Small companion of Andromeda Nebula • D ~ 0.8 Mpc • MBH~ 3 x 106 Mסּ • Influences kinematics inside ~ 0.1" • Use stellar absorption-line spectroscopy: • Integral-field data to measure intrinsic shape and M/L • HST/STIS to measure BH mass • Fit with numerical dynamical models

  11. M32: Best-fitting Parameters • Dynamical models for stellar motions have 3 parameters: M/L, MBH, and inclination • These are tightly constrained by STIS and SAURON data • Significant improvement over STIS + 4 slits from ground • MBH = (2.5 ± 0.4) x 106 Mסּ(cf. van der Marel et al. 1998, ApJ, 493, 613) 3 level Verolme et al. 2002, MNRAS, 335, 517

  12. Same data set STIS major axis SAURON large scale Independent codes Nukers/Leiden group Different orbit sampling Different smoothing Good agreement MBH error decreases when two-dimensional kinematics is included MBH error ~30% External check: NGC 821 (E6) Gebhardt 2004, Carnegie symposium

  13. Importance of 2D kinematics Symmetrized data for NGC 4473 • Model fits major-axis kinematics perfectly • Little can be recovered of the true orbital structure from incomplete kinematic coverage Axisymmetric model  V h3 h4

  14. MBH from Stellar Kinematics • BH masses for ~20 E/S0 galaxies and bulges • Based on one STIS slit, and ~2 ground-based slits • MBH accuracy can be improved by using integral-field data; this also provides accurate M/L’s and inclinations • Possible for all nearby E/S0s in HST/STIS archive • Limitations • Only for bright nearby nuclei • Modest spatial resolution at Virgo (0.2'' slit) • Not enough S/N for core galaxies in Virgo: these are targets for AO-assisted IFU’s on 8m groundbased telescopes (e.g. SINFONI on VLT)

  15. The S0 galaxy NGC 3245 MBH ~ 2.1 x 108 M Barth, Sarzi, et al 2001, ApJ, 555, 685

  16. Nuclear emission-line gas • Prominent in active nuclei and spiral bulges • ~20% have regular dust disks • H, [NII] kinematics from STIS resolves region where black hole dominates motion, but is often irregular • About 100 objects observed with HST • Up to ~100 Mpc distance; often multiple parallel slits • ~20% can be ~fitted with circular rotation • Modest number of published black hole masses • Few cases with MBH from gas and from stars • Mixed results: good agreement in one case • Important to test this in carefully selected galaxies • Improved kinematic (hydrodynamic) model needed

  17. Verdoes Kleijn et al., 1999, AJ, 118, 2592 WFPC2 V-band

  18. Nearby Radio Galaxies • All have emission-line gas; many dust disks/lanes • Dust distribution in radio- and in quiescent galaxies very similar • Jets nearly perpendicular to dust except when dust is aligned with major axis (e.g., Schmitt et al. 2002; Verdoes & de Zeeuw astro-ph/0405034) • Trigger of activity: likely related to stellar/gaseous kinematics on small scales • This can be probed with STIS multiple parallel slits

  19. Late-type galaxies F606W, F160W & F110W

  20. Sb and Sc galaxies • HST allows study of bulges with effective radii Re smaller than 1’’ • Surveys reveal large nuclear complexity in late-type spirals • Here: results from survey of ~100 nearby Sb & Sc galaxies with WFC2 & NICMOS 9” Carollo, Stiavelli, de Zeeuw, et al. 1997-2002

  21. Structure of smallest bulges • HST allows extension of earlier ground-based studies to smallest scales • Many ~exponential stellar density profiles • These ‘bulges’ may be disks (e.g. Kormendy 1993) • Formation mechanism is currently unclear

  22. Central Compact Sources ~400 pc • Late-type bulges often host central compact sources • Most are resolved on pc scales • Radii up to 20 pc • 70% of spirals hosts CCS

  23. Structural Parameters • Narrow R1/4 sequence down to ~ 300 pc • Exponential bulges bridge dwarf and R1/4 sequences • Central Compact Sources intermediate between MW GC’s & young star clusters

  24. Central Compact Sources • Many CCS: like star clusters of 106 - 108 M • Others: colors influenced by activity/dust • Very difficult to detect black holes inside a CCS Bruzual & Charlot tracks for a 3x106 M cluster 13 Gyrs 13 Gyrs 100 Myrs

  25. Stellar Populations of Bulges • Massive R1/4 bulges • Mean age 8-10 Gyr • Age spread ~2 Gyr • Small bulges • Mean age 2-5 Gyr • Age spread 10 Gyr • Small bulges younger than massive spheroids, similar age as host disk V-H~1.4 (V-H)~0.1 V-H~0.9 (V-H)~0.4

  26. Next steps NGC3259 • ACS follow-up • Cycle 11; 25 orbits; • B, I and U (HRC) • Improved age and metallicity estimates • STIS follow-up • Cycle 13; 35 orbits • V and  of 2 CCS • Provides mass, and rotational support • HST resolution cannot be matched from ground + F330W (HRC) Carollo, Stiavelli, et al.

  27. Opportunities for HST • Stellar absorption-line studies of E/S0 galaxies • No need for additional single STIS slits • Useful to study some nuclei at multiple position angles • Emission-line gas • Map small number of carefully chosen nearby nuclei • Will provide MBH, and may establish trigger of activity • Late-type galaxies • HST can make key contribution by imaging and spectroscopy of compact nuclei and exponential ‘bulges’ • Will help establish formation mechanism • Next step: fly an integral-field spectrograph on RM2

  28. Slow Rotators E E E S0 E E E E E E E E General agreement with RC3

  29. E S0 S0 S0 E S0 E S0 S0 S0 S0 E S0 S0 S0 S0 E S0 E S0 S0 S0 S0 E S0 E E S0 S0 S0 S0 S0 E E E E 40% classified as ellipticals in RC3 Fast Rotators

  30. M33 and NGC 205 Central star cluster No AGN Strong upper limit on black hole mass If they have a BH, then its mass is well below the (MBH,σ) relation Galaxies without black holes

  31. Black Hole Demographics • Ellipticals • Be careful with masses from gas kinematics • Need stellar kinematics for core galaxies (8m) • Spirals • Not many masses, especially < 4x107 M • Late type disks: no BH? • Scatter • Observational errors • Systematics (triaxiality, asymmetries) • Related to merger history?

  32. NGC 821 continued • Modifications • Nukers corrected STIS/PSF convolution in code, reran models with own long-slit kinematics • SAURON maps finalized (Emsellem et al. 2004) • Agreement remains good • MBH’s agree within 1 • Addition of SAURON data improves accuracy • Data is published, so anyone can test their code

  33. Importance of 2D Kinematics 3 level Four slits + STIS SAURON + STIS

  34. Nuclear Stellar Cusps • Classical bulges • Massive, R1/4 • Cusp slopes like E/S0 galaxies • Sb/Sc bulges • Shallower nuclear cusps • Follow their own global/nuclear relation • Different structures on 10pc scales R1/4 bulges Sb/Sc bulges

  35. Nearby Radio Galaxies • All have emission-line gas; many dust disks/lanes • Trigger of activity: seems related to gas/stellar kinematics on small scales WFPC2 V-band; 5''x 5'' frames Verdoes Kleijn et al., 1999, AJ, 118, 2592

  36. The E5 galaxy NGC 3377 SAURON OASIS Combination • SAURON: low spatial resolution: upper limit on MBH • OASIS: lower limit on MBH, insufficient field of view • Combination: FOV and resolution: good MBH • Accuracy can be improved further with STIS data Copin, Cretton, Emsellem, 2004, AA

More Related