A VLA Study of the Disturbed Massive Cluster PLCK G165.7 + 67.0 and Its Two Narrow Angle Tail Galaxies
Year: 2026
Type: preprint
Abstract: Since spectroscopic measurements provide only the line-of-sight velocity, transverse motions are difficult to constrain. In the vast majority of cases, transverse velocities have been measured only for local galaxies. Radio galaxies whose jets are bent back by ram pressure into nearly parallel Narrow-Angle Tails (NATs) offer a way to extend such measurements to higher redshifts. Here, we present proprietary 15~GHz (Ku-band) and archival 6~GHz (C-band) continuum observations from the Very Large Array (VLA) of six radio galaxies in the galaxy cluster field PLCK G165.7+67.0 (G165). VLA imaging resolves two of the cluster galaxies into NATs whose tails both extend toward the Southwest, away from the cluster center of mass. Spectral index maps made at matched angular resolution resolve a steepening gradient consistent with radiative aging along the length of the tails. Physical properties of the NATs are measured and used to constrain two independent models: a Mach cone model and a nonrelativistic hydrodynamic flow model based on Euler's equation. The models returned transverse velocities of $\sim 2000 ~\rm km~ \rm s^{-1}$ for both galaxies. One NAT is the brightest cluster galaxy (BCG) and has a measured radial velocity of $-3300 ~\rm km ~\rm s^{-1}$, resulting in an even higher space velocity. The high inferred 3D velocity of the BCG may be explained if it is intercepted close to core passage.
Source: arXiv (Cornell University)
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: G1055883707, G6608474652, G6722835988, THE PROPOSAL SEEKS TO ACCOMPLISH SEVERAL INVESTIGATIONS TO SIMULATE THE PERFORMANCE OF JWST DEEP FIELD SURVEYS, VARYING AS-YET-POORLY CHARACTERIZED P, IN 2002 WE WERE GRANTED 110 HOURS GTO TIME FOR A JWST MEDIUM-DEEP SURVEY. WITH HST AND SPITZER EXPERIENCE 14 YEARS LATER WE REDEFINE THIS SURVEY TO IMAGE~18 NIRCAM FIELDS IN 7 FILTERS TO AB<~ 29 29.3 MAG YIELDING 140 000 GALAXIES AT 0<~ Z<~ 12 15 IN 0.05 DEG2 (>~ 30 HUDFS!). WE WILL STUDY GALAXY ASSEMBLY + SUPER-MASSIVE BLACK-HOLE GROWTH AT Z 0 7 INCLUDING OBJECT VARIABILITY ON MONTHS YEARS TIMESCALES. WE STUDY THE REIONIZING POPULATION AT Z 2 8 AND USE THE BEST LENSING TARGETS TO OPTIMIZE OUR STUDY OF FIRST LIGHT OBJECTS AT Z 10 15. OUR SCIENCE GOALS ARE: 1. GALAXY ASSEMBLY; 2. SUPER-MASSIVE BLACK-HOLE GROWTH; 3. REIONIZATION; 4. FIRST LIGHT; 5. STUDY THE BEST LENSING CLUSTERS TO FIND JWST OBJECTS. MAP&REMOVE STRAYLIGHT GRADIENTS AND QUANTIFY SAMPLE COMPLETENESS IN RANDOM FIELD&CLUSTER IMAGES: WE WILL: A) USE HUDF AND HFF DATA TO SIMULATE MAP AND REMOVE A RANGE OF STRAYLIGHT AMPLITUDES AND GRADIENTS THAT COULD AFFECT RANDOM DEEP FIELDS (DFS) AND CLUSTER FIELDS WITH JWST; B) DETERMINE ACCURATE COMPLETENESS CORRECTIONS VS. GALAXY FLUX SIZE WAVELENGTH AND LOCATION IN JWST DFS OF VARIOUS DEPTH AND IN CLUSTER FIELDS WITH THEIR KNOWN GALAXY CLUSTER+ICL FOREGROUND; C) DETERMINE THE CLUSTER SELECTION FUNCTIONS BY FOLDING LENSING MAPS WITH SIMULATED BACKGROUND IMAGES YIELDING SIMULATED LENSED IMAGES AND THEIR COMPLETENESS CORRECTIONS FOR LENSED SOURCES WHICH WE SHOW CAN BE FACTORS 2 3; AND D) MODEL COSMIC VARIANCE IN HIERARCHICAL MODELS AT Z 6 15. WE WILL CORRECT THE LFS FOR THESE COMPLETENESS FUNCTIONS. WE WILL THEN USE A BAYESIAN CODE TO DETERMINE THE OPTIMAL SET OF LF EVOLUTION PARAMETERS FROM THE AVAILABLE JWST DATA TO QUANTIFY HOW GALAXIES ASSEMBLED SINCE Z<~ 15.
OpenAlex ID: W7214648334