1 / 17

Introduction to M4 Science

Introduction to M4 Science. Observe 95 m m Polarized Radiation Map the “Magnetic Field of the Milky Way” (Central 100 degrees in l and 10 degrees in b) Technique for Constructing 3-D Field Relies on FIR/CO Associations

javier
Download Presentation

Introduction to M4 Science

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. Introduction to M4 Science • Observe 95 mm Polarized Radiation • Map the “Magnetic Field of the Milky Way”(Central 100 degrees in l and 10 degrees in b) • Technique for Constructing 3-D Field Relies on FIR/CO Associations • Detailed Studies of B in selected Supershells (Cirrus), Star-forming Regions, and External Galaxies

  2. The 20th Century Magnetic Field of the Milky Way Serkowski, Mathewson & Ford, et al. See Heiles for more, later.

  3. Summary of Method

  4. Milky Way Polarimetric Discoveries 1997-99 summarized by Alyssa Goodman Harvard University

  5. Grain Alignment • Role of Radiative Torques(Draine, Weingartner, Lazarian) • Spectral Dependence of Thermal Emission Polarization (Hildebrand et al. 1999; see Dowell) • Global Polarization-Extinction Relation (Arce et al. 1998; Goodman 1999)

  6. Radiative Torques on “Helical” Grains • Non-Davis-Greenstein processes likely dominate (see Draine, Weingartner,Lazarian) • Rapid alignment of grains in less than dim regions Draine & Weingartner, 1997

  7. Dark Cloud Complexes: 1-10 pc scales

  8. 0 1 2 3 4 3.0 2.5 2.0 [%] R P 1.5 1.0 0.5 0.0 0 1 2 3 4 A [mag] V Background to Cold Dark Cloud Background to General ISM “Go no further than AV~1.3 mag.” Arce et al. 1998

  9. Developments in Star-forming Regions • Interferometric Polarimetry of Outflow/Disk Sources (OVRO: Akeson et al. 1996; BIMA: Rao et al. 1998; see Myers) • Polarized Spectral-line Emission (BIMA: Girart et al. 1999) • Sub-mm (SCUBA) Polarimetry of Massive, and now Low-Mass, SFRs (e.g. Matthews & Wilson 1999; see Greaves)

  10. BIMA Interferometer M4 Beam Zooming on Orion BN/KL Rao et al. 1998 Schleuning 1998 STOKES on KAO

  11. On a Galactic Scale • Rand & Lyne (94) Pulsar RM/DM Mapping of B • Reid & Menten update of Galactic B from H2O Masers (in prep.) • Heiles’ Re-analysis of Galactic Plane Background Starlight Polarimetry Surveys (see Heiles) • SCUBA Polarimetry of the Galactic Center (see Greaves)

  12. On a Galactic Scale Rand & Lyne 1994

  13. On a Galactic Scale Rand & Lyne 1994

  14. On a Universal Scale • Connection to CMB Polarimetry(see Lazarian) • Our signal is their “foreground,” and we have MUCH better polarimetric sensitivity and resolution. • MAP launch November 2000 • Any light on galactic dynamo issues/origin of galacticfields (ask Zweibel)?

  15. 0.01 0.1 1 10 100 t K 0.1 1 10 100 1000 E [mag] 2 B-V 100 8 6 4 2 10 [%] 8 max 6 p 4 2 1 8 6 4 2 A [mag] 0.1 1 10 100 1000 V What can we expect? PV Theoretical Maximum BIMA Millimeter Orion Observations P100 mm Semi-Empirical Maximum 100 mm in Massive SFR pV Cold Dark Clouds pV Low-Density ISM Figure from Goodman 1999.

  16. Declination (1950) Right Ascension (1950) What can we expect? Polarization of Background Starlight in M17 Polarization of 100 mm Dust Emission in M17 (Schulz et al. 1981) (Dotson 1994) B? B? Declination (1950) B? 4% Right Ascension (1950) See Kristen, Goodman, Jones & Myers1999.

More Related