RAMPS: The Radio Ammonia Mid-Plane

Survey

James Jackson Institute for Astrophysical Research

Boston University

High Frequency Workshop, Green Bank, 21 September 2015

Collaborators (partial list) Taylor Hogge Boston University Ian Stephens Boston University Scott Whitaker Boston University Jonathan Foster Yale Anish Roshi NRAO

All (high-mass) stars form in clusters or groups from a single molecular “clump”

Orion Trapezium cluster – 4 high mass stars; – ~3500 total stars – 2 pc molecular clump – 4500 M gas mass

– The clump is the – fundamental unit of – cluster formation.

Lada et al. 1997, Lada & Lada 2003

Hubble Space Telescope; near-IR

How do high-mass star-forming clumps evolve? Determine their evolutionary stage Characterize their physical properties: Temperature Density Column Density Kinematics Chemistry Fragmentation

Image credit: NASA/JPL-Caltech/Univ. of Wisconsin Blue - 3.6µm, Green - 8µm, Red - 24µm

1.2 degrees

0.2

degr

ees

The evolutionary phases of high-mass star forming clumps

The “Nessie” Nebula Jackson et al. 2010 ApJ Letters

Image credit: NASA/JPL-Caltech/Univ. of Wisconsin Blue - 3.6µm, Green - 8µm, Red - 24µm

Pre-stellar

Early stage

Cold pre-stellar clump

Image credit: NASA/JPL-Caltech/Univ. of Wisconsin Blue - 3.6µm, Green - 8µm, Red - 24µm

Protostellar

Intermediate stage

Protostellar clump

Image credit: NASA/JPL-Caltech/Univ. of Wisconsin Blue - 3.6µm, Green - 8µm, Red - 24µm

H II region

Later stage

Stellar “H II region” clump

Image credit: NASA/JPL-Caltech/Univ. of Wisconsin Blue - 3.6µm, Green - 8µm, Red - 24µm

Photodissociation Region (PDR)

Latest stage

Photodissociation region (PDR)

Temperature and Column Density Evolution (MALT90 targets)

The Herschel data indicate evolution. The clumps’ dust temperature increases from 15 to 25 K. Column densities increase, then decrease

Guzman et al. 2015

1

4 3

2

Dust continuum surveys of high-mass star-forming regions: HiGAL, ATLASGAL, BGPS, …

Color: HiGAL Herschel images; Contours: GBT NH3 (1,1) integrated intensity

Limitations: 1. Blend of many dust

clouds along line of sight 2. Cannot establish

distances or internal motions.

3. Opaque at mid-IR (and sometimes FIR)

4. Luminosity dominated by hottest dust. (L~T4+β)

5. Relatively poor angular resolution at optically thin submm/mm wavelengths

Ammonia Inversion Lines

NH3 (1,1) NH3(2,2)

• Probe only dense star-forming gas • Velocities yield kinematic distances and internal

motions. • Multiple NH3 inversion lines at ~same frequency

yields gas temperature. • Relative intensity of hyperfine lines yields column

densities.

The Radio Ammonia Mid-Plane Survey: RAMPS K-band Focal Plane Array on the GBT Lines: NH3 (1,1); (2,2); (3,3); (4,4); (5,5) [7 beams] H2O maser (1 beam) CH3OH masers (1 beam)

Blind survey Goal: l = 10 to 40 d, b = -0.5 to 0.5 d

Status

Completed observations of 6.4 square degrees.

Completed processing of NH3 (1,1), NH3 (2,2), and H2O maser data

Upon verification, data cubes and moment maps will be available at www.bu.edu/ramps

NH3 (3,3), (4,4), and (5,5) data will be available ~ December 2015

RAMPS NH3 (1,1) integrated intensity

Blue represents 1 K km/s and red 20 K km/s

1 degree

RAMPS NH3 (1,1) integrated intensity

RAMPS (GBT KFPA) vs. HOPS (Mopra, Single pixel “13 mm”)

RAMPS HOPS

Walsh et al. 2008, 2010

Int. Intensity Velocity

Trot Column Density

Int. Intensity Velocity

Trot Column Density

Water Masers

Water masers

619 H2O Maser Sites Associations 60% star formation sites 26% evolved stars 14% unknown

One source has 28 velocity components spread over ~120 km/s

The unusual source G23.3+0.3

Enormous linewidths ∆V ~ 25 km/s ~10 x wider than

typical sources Odd line shapes,

especially in NH3 (3,3)

2nd moment (line width) image

NH3 (2,2)

The unusual source G23.3-0.3

Enormous linewidths ∆V ~ 25 km/s ~10 x wider than

typical sources Odd line shapes,

especially in NH3 (3,3)

2nd moment (line width) image

NH3 (2,2)

Associated with filamentary Infrared Dark Cloud

Blue - 3.6µm, Green - 8µm, Red - 24µm Contours RAMPS NH3 2,2

RAMPS NH3 spectra

Unrelated

G23.3+0.3

Compact Array NH3 1,1 and 2,2

6

6 6

6 6

Compact Array NH3 3,3

6

6 6

6 6

G23.3+0.3

Minimum surface brightness of NH3 (3,3) spike is ~8,000 K. It is a MASER. Very rare Likely shock-excited Powerful outflow

Enormous linewidths indicate extremely turbulent, active, high-mass star-forming region in very early stage

Important target for ALMA, JVLA, ….

Summary RAMPS has completed mapping 6.4 square

degrees along the galactic plane RAMPS has detected ~500 clumps in NH3

and measured their temperature, column density, and velocity.

RAMPS has detected 619 H2O maser sites. The unusual source G23.3+0.3 is an

extreme example of a very young high-mass star-forming region.

Data will soon be posted at www.bu.edu/ramps