Science with a next-generation Very Large Array

The ngVLA will have broad impact on many of the high priority goals of modern astronomy & astrophysics, including the science priorities described in the New Worlds, New Horizons Astro2010 Decadal Survey.  The ngVLA Science Working Groups (SWGs) have identified a number of key science programs that push the requirements of the telescope through a community driven Science Use Case capture exercise that is led by the ngVLA Science Advisory Council (SAC).  Community members are still encouraged to submit additional Science Use Cases and to coordinate a contributed to the ngVLA Science Book with the appropriate SWG chair. 

If you are interested in joining one of the SWGs, please contact the corresponding Science Working Group Chair directly. An initial set of science goals suggested by the four SWGs are described in white papers published in the ngVLA Memo Series.

 

 

ngVLA Key Science Goals (KSGs)


KSG1: Unveiling the Formation of Solar System Analogs

ngVLA Simulations of Protoplanetary Disks

Ricci et al. (2018, submitted) – ngVLA- (top row) and ALMA- (bottom row) simulated observations of the continuum emission of a protoplanetary disk perturbed by a Jupiter mass planet orbiting at 5 AU (left column), a 10 Earth mass planet orbiting at 5 AU (center column), and a 30 Earth mass planet orbiting at 2.5 AU (right column). The ngVLA observations at 100 GHz were simulated assuming an angular resolution of 5 mas and an rms noise level of 0.5 μJy/bm. ALMA observations at 345 GHz where simulated assuming the most extended array configuration comprising baselines up to 16 km and a rms noise level of 8 μJy/bm.

The ngVLA will measure the planet initial mass function down to a mass of 5–10 Earth masses and unveil the formation of planetary systems similar to our own Solar System by probing the presence of planets on orbital radii as small as 0.5 AU at the distance of 140 pc. The ngVLA will also reveal circumplanetary disks and sub-structures in the distribution of mm-size dust particles created by close-in planets and will measure the orbital motion of these features on monthly timescales. 


KSG2: Probing the Initial Conditions for Planetary Systems and Life with Astrochemistry

The ngVLA will be able to detect predicted, as yet unobserved, complex prebiotic species that are the basis of our understanding of chemical evolution toward amino acids and other biogenic molecules. It will also allow us to detect and study chiral molecules, to include testing ideas on the origins of homochirality in biological systems. The detection of such complex organic molecules will provide initial chemical conditions data of forming solar systems and individual planets. 

ngVLA Observations of Pre-biotics

A conservative simulation of a representative set of 30 currently undetected complex interstellar molecules (in black) which are likely to be detectable by the ngVLA above the confusion limit of an ngVLA survey in and around ‘hot' cores with source sizes typically of ~1” – 4”.  These lines are not observable with current facilities. A few key molecules are highlighted in color.


KSG3: Charting the Assembly, Structure, and Evolution of Galaxies from the First Billion Years to the Present

ngVLA Observations of Gas Cycling in Nearby Galaxies

(Top Panels) Simulations based on M51 with molecular mass scaled by factors of 1.4 (z = 0.5) and 3.5 (z = 2) to match it to the lowest molecular mass galaxies currently observable by ALMA and NOEMA (ngVLA Memo #13). The corresponding SFR for the z = 2 model would be 25 M⊙/yr. The synthesized beam shown in the bottom left corner is (left to right) θ = 0.19′′, 0.20′′, and 0.43′′ corresponding to spatial scales L = 1.2, 1.7, and 3.7 kpc respectively. Integration times are 30 hr in all cases. The spatial and kinematic information recovered by the ngVLA would require highly impractical time investments from ALMA. (Bottom Panels) A composite of the grand-design spiral galaxy M74 illustrating the molecular disk imaged in CO by ALMA (red; Schinnerer in prep.), the stellar disk imaged at 4.5 m by Spitzer (green; Kennicutt et al. 2003), and the atomic disk imaged in HI by the VLA (blue; Walter et al. 2008), showing the atomic and molecular gas phases to which the ngVLA will be sensitive. The right panel shows a close-up of the area mapped in CO J = 2 1 at 1” resolution: the ngVLA would be capable of quickly producing a significantly deeper map at similar resolution that would include not only CO J = 1 0 but also dense gas tracers, molecular isotopologues, and many other molecules throughout the = 3 – 4 mm band.

The ngVLA will provide an order-of-magnitude improvement in depth and area for surveys of cold gas in galaxies back to early cosmic epochs, and it will enable routine sub-kiloparsec scale resolution imaging of the gas reservoirs. The ngVLA will afford a unique view into how galaxies accrete and expel gas and how this gas is transformed inside galaxies. It does so by imaging their extended atomic reservoirs and circum-galactic regions, and by surveying the physical and chemical properties of molecular gas over the entire local galaxy population. These studies will reveal the detailed physical conditions for galaxy assembly and evolution throughout the history of the universe. 

 


KSG4: Using Pulsars in the Galactic Center to Make a Fundamental Test of Gravity

ngVLA Galactic Center Pulsars

(Credit: R. Wharton) The distribution of known pulsars near the Galactic center. Despite being the region of highest density in the Galaxy and despite having been searched multiple times at a range of frequencies with sensitivities comparable to that of the VLA, only a small number of pulsars are known. Even more puzzling, the closest pulsar to Sgr A* is the magnetar PSR J1745-2900, yet radio-emitting magnetars are an extremely rare sub-class of the field pulsar population (i.e., < 1%).

Pulsars in the Galactic Center represent clocks moving in the space-time potential of a super-massive black hole and would enable qualitatively new tests of theories of gravity. More generally, they offer the opportunity to constrain the history of star formation, stellar dynamics, stellar evolution, and the magneto-ionic medium in the Galactic Center. The ngVLA combination of sensitivity and frequency range will enable it to probe much deeper into the likely Galactic Center pulsar population to address fundamental questions in relativity and stellar evolution. 


KSG5: Understanding the Formation and Evolution of Stellar and Supermassive Black Holes in the Era of Multi-Messenger Astronomy

ngVLA Black Holes

Taylor (2014) – A binary system of SMBHs at z = 0.06. The black holes are separated by 7 pc (the white scale bar denotes 10 pc) with an orbital period of 30,000 yr, and jet emission is observed extending from the black hole C2. The ngVLA, with its deep high resolution imaging capabilities, will enable discovery of many more such systems, with intimate synergies to LISA and Pulsar Timing Arrays.

The ngVLA will be the ultimate black hole hunting machine, surveying everything from the remnants of massive stars to the supermassive black holes that lurk in the centers of galaxies. High-resolution imaging abilities will separate low-luminosity black holes in our local Universe from background sources, thereby providing critical constraints on their formation and growth for all sizes and mergers of black hole-black hole binaries. The ngVLA will also identify the radio counterparts to transient sources discovered by gravitational wave, neutrino, and optical observatories. Its high-resolution, fast-mapping capabilities will make it the preferred instrument to pinpoint transients associated with violent phenomena such as supermassive black hole mergers and blast waves.