Extending the Little Red Dot population at intermediate redshift with VIPERS

RESUMO

Little red dots (LRDs) are a recently identified population of compact, red sources characterised by a distinctive V-shaped UV-to-optical continuum and broad emission lines. Their physical structure and evolution remain uncertain, while their properties at intermediate redshifts are largely unexplored. We identify and characterise LRD-like sources at 0.5<z<1.75 using the VIMOS Public Extragalactic Redshift Survey (VIPERS), extending observational studies to a previously poorly explored cosmic epoch. We select candidates from their UV and optical slopes measured from broadband photometry and refine the sample using broad emission lines in VIPERS spectroscopy. We investigate their photometric, spectroscopic, and morphological properties, constrain their physical sizes with HSC imaging, measure their comoving number density and evolution, and characterise their local environments using the VIPERS galaxy density field. We also model the multi-wavelength emission of the unique X-ray-detected source with CIGALE, including X-ray and AGN emission. We identify 14 LRD-like sources, including one X-ray-detected object, whose HSC morphology remains unresolved. We measure their number density in two redshift bins, 0.5<z<1 and 1<z<1.75, and combine our results with literature measurements. We find a rapid decline in number density after cosmic noon. The two sources with sufficiently constrained environments are located in underdense regions. The SED of the X-ray-detected source is best reproduced by a radiatively efficient accretion disk viewed at low inclination. Our results demonstrate that LRD-like sources are present at z>0.5, bridging local and high-redshift studies. Their abundance, compact morphology, environmental properties, and multi-wavelength emission provide new constraints on the evolution and physical origin of this population.