ALMA & JVLA: Insight into Astrophysical Jets

1. ALMA & JVLA: Insight into Astrophysical Jets Debra Shepherd NRAO 9th International Conference on High Energy-Density Laboratory Astrophysics HEDLA 2012

2. Atacama Large Millimeter Array (84-950 GHz) Key to recovering extended emission: 12m array (50) + 7m array (12) + 4 total power dishes

3. Atacama Large Millimeter Array

4. Jansky Very Large Array (1-50 GHz) • 8 wideband receivers • Switching can be as fast as 20s

5. Jansky Very Large Array – upgraded VLA • All 28 antennas converted to JVLA standards (new optics, IF electronics, samplers, Digital Transmission System) • Ongoing receiver installation with expanding WIDAR (Wideband Interferometric Digital ARchitecture) correlator capabilities • Comparison with VLA: • Sensitivity increased by factor of 10 • Maximum bandwidth possible increased by a factor of 80 (0.1 GHz to 8 GHz) • Maximum number of channels increased by > 8000 (from 512 to 4,194,304) • Frequency coverage (1-50 GHz) from 22% (VLA) to 100% (JVLA)

6. New capabilities in context • Collecting Area: # antennas (# baselines) • Sensitivity goes as collecting area • Image fidelity goes as # of baselines JVLA 27x25m (351 BL) SMA 8 (28) ALMA Synthesis 50x12m + 12x7m (1291 BL) CARMA 23 (253) IRAM PdBI 6 (15)

7. Science • Astrophysical jets using ALMA & JVLA, focus on: • MHD acceleration & collimation • Ionized gas morphology & kinematics: • Sensitive, wide-band continuum studies and radio recombination lines. • Molecular disk conditions • Not addressed here: • Jet collimation far from the central source • Molecular entrainment in the large-scale flow • Shock interaction zones in, e.g., jet internal working surfaces, Mach stems and terminal jet bow shocks.

8. MHD Jet Acceleration & Collimation (low mass YSOs) MHD acceleration mechanisms: • Uchida-Shibata, Lovelace – toroidal B field • Pudritz et al. disk wind – poloidal B field • Shu et al. X-wind – linked star-disk B field (low-mass YSOs with low accretion rates) Collimation from: • Magnetic hoop stress • Confinement due to high density of surrounding material (wind-blown bubble) S106, Subaru HH212, H2 McCaughrean & Zinnecker, VLT

9. Spatial scales & dynamics of disks & jet “footprints” • JVLA highest resolution at 45 GHz/7 mm (~0.043”) • Ionized gas (RRLs, continuum: thermal & synchrotron) • Lower resolution: • Dense molecular gas (NH3) • Water masers • ALMA highest resolution at 350 GHz/0.9 mm (~0.015”) • Molecular lines (low density, shock-enhanced) • Ionized gas (RRLs) 100 AU = 0.3” at d=300pc ALMA resolution at 850 GHz/350 mm Difficulties to determine which model drives the flow include: 1) young stars are heavily embedded; 2) spatial scales are small; 3) complex infall & outflow kinematics close to the source (Ray et al. 2007).  ALMA & JVLA address issues 1) & 2).

10. Ionized Gas – tracing the jet to the disk • Support for magneto-centrifugal launching of the jet: forbidden emission lines trace the ionized outflow back to the disk; Assuming jet is co-rotating with the disk  determine radius over which the jet is launched. • Jet rotation studies with HST challenging, pushing the limits of current capabilities. Evidence for jet rotation detected by, e.g., Bacciotti et al. 2002, Woitas et al 2005; Coffey et al 2012 and others. • JVLA & ALMA will now be able to provide supporting evidence using continuum & radio-recombination lines, even in very embedded systems. Image: Chris Burrows (STScI), the WFPC2 Science Team & NASA; Rotation: Bacciotti et al. 2002

11. Ionized Gas – thermal/synchrotron continuum B2 star with disk & ionized outflow. 7 mm continuum (~100 AU resolution, sensitive to dust & ionized gas) & model. • Example of the best that could be done with the VLA: G192.16 (D=2kpc) • continuum emission with only 2 MHz bandwidth shows the jet pushing through the UC HII region is detected at the 4 s (no velocity information possible). • JVLA will improve continuum sensitivity by a factor of 9 with same integration time due to increased bandwidth (16 GHz) to get morphology of the jet & HII region. • Can magnetic collimation remain intact during propagation through an HII region? 1000 AU (D=2 kpc)

12. Ionized Gas - RRLs Radio Recombination Lines (RRLs) can track velocity structure in ionized jets (also HII regions & shock/interaction zones). – RRL stacking now possible with ~8 lines observed simultaneously: Frequency (GHz) 8 lines observed at once, then “stacked” 1 line, 2 s detection: Amanda Kepley, in prep.

13. Jets & Disks Coupled • We don’t understand how micro-instabilities on a disk surface might serve to lift partially ionized material off of the disk and onto the B-field lines and how this material is accelerated to 100’s of km/s. • ALMA will be able to image active disk regions where the jet is being launched but its not clear what molecular or ionized gas tracer to use. • Can laboratory experiments shed light on this issue?

14. ALMA – chemistry challenge • Challenge to observers: find molecular lines that trace the base of the jet/disk. • Challenge to laboratory physics: identify “interesting” lines that were previously unidentified to understand the physics and chemistry of the region being traced. Early ALMA band 6 spectrum towards Sgr B2(N). ~ 50% of the lines are unidentified. (Ziurys& the Arizona Radio Observatory staff) More recent ALMA test data (thanks to Remijan):

15. Consider the power of the JVLA for studying jets in a variety of astrophysical sources:

16. Jet in SS433 microquasar BH or NS accreting from companion star. D = 5 kpc VLBA & JVLA jet velocity = 0.26 c – no gradual speed up. VLBA 15 GHz: Mioduszewski et al. 3 AU resolution JVLA 26 GHz 520 AU resolution

17. Hercules A • Light color represents flat spectrum, optically thick synchrotron emission (energy is being pumped into the gas). • Darker red represents steep negative spectrum, optically thin synchrotron emission (regions that have ‘aged’ and are not being actively pumped). • 4-9 GHz spectral index overlaid on HST optical image (Cotton et al.)

18. Relics & Jets in Abell 2256 Galaxy cluster 1-2 GHz continuum image, 20’ on a side, color corresponds to spectral index (Owen, Rudnick, Eilek, Rau, Bhatnagar, Kogan)

19. Summary • ALMA & JVLA increased sensitivity, resolution & bandwidth will provide new views of astrophysical jets and disks. • Complex infall & outflow dynamics close to the source as well as complex chemistry will continue to challenge interpretation of even the best images. • Laboratory experiments which may help in the interpretation include: • How do micro-instabilities lift material off of disk surfaces which have a variety of physical conditions? • How can magnetic jet collimation remain intact during propagation through a compact HII region? • Identify molecular lines that highlight areas where the jet is being generated.

21. Disks in very young low-mass & massive YSOs • What happens when the disk is thick, self-gravitating and turbulent and the accretion is > 10-3 Msun/yr? • How can an outflow be launched from a turbulent, thick and self-gravitating disk like those surrounding massive stars? • Could laboratory experiments verify jet creation under these conditions? • Hosokawa & Omuka (2009, 2010) argue that when massive YSOs accrete at >10-3 Msun/year, they develop thick, convective surfaces giving rise to magnetic fields. The surface would be “coolish” so the star doesn’t ionize the disk even though may be on the Main Sequence already. • ALMA would be able to constrain the mass of the central object based on the dynamics of the disk (e.g., like around BH candidates). • The B-field and inner dynamics of a 15 Msun proto-stellar object would be very different than that of a LM protostar. Would the jet-production mechanism be different?