Reevaluation in Space Research: The Webb Telescope’s ERO and Subaru’s BluDOG Similarities

by Hiroshi Tanaka
JWST EROs BluDOGs Comparison

In a recent study of the James Webb Space Telescope (JWST) data, scientists discovered that the extremely red objects (EROs) closely resemble the blue-excess dust obscured galaxies (BluDOGs) previously identified in the Subaru Telescope data. This finding highlights the complexities in understanding quasar evolution and suggests the necessity for further research using advanced telescopes such as GREX-PLUS. Source:

Researchers examining the JWST data found a striking resemblance between the EROs and the BluDOGs, previously observed by the Subaru Telescope. This discovery challenges earlier beliefs and emphasizes the intricate nature of quasar evolutionary studies.

In the realm of astronomical findings, not every discovery is novel. This was evident in the case of the EROs detected in the JWST data. These objects bear a strong resemblance to the BluDOGs, already noted in the data from the Subaru Telescope.

Quasars, among the brightest entities in the cosmos, are powered by supermassive black holes with masses exceeding a billion solar masses. Their formation is a key area of astronomical research, yet the process remains elusive. The dominant hypothesis suggests that they originate in dust and gas-rich galaxies, where they remain obscured until they gain enough power to clear these obscuring materials. Capturing this brief transitional phase is crucial to understanding quasar formation.

An image of a BluDOG was captured by the Subaru Telescope, as noted by the NAOJ/HSC Collaboration.

The brief nature of this transition necessitates the observation of numerous pre-quasar candidates, hoping to observe a quasar emerging from its dust cloud. In this context, researchers identified EROs in the JWST data as potential transitional quasars. However, the Subaru Telescope team in Hawai`i observed that despite being termed “red,” EROs also exhibit significant blue components, akin to BluDOGs previously identified in the Subaru Telescope’s Big Data and reported last year.

Further analysis revealed that EROs and BluDOGs might represent the same class of objects, albeit with notable differences. One theory is that EROs are at an earlier evolutionary stage compared to BluDOGs. To clarify the relationship between EROs, BluDOGs, and quasars, a larger sample is required. This expanded dataset will be examined by next-generation astronomical instruments, including the GREX-PLUS infrared space telescope project in Japan.


  • Noboriguchi, A. K. Inoue, T. Nagao, Y. Toba, T. Misawa. “Similarity between Compact Extremely Red Objects Discovered with JWST in Cosmic Dawn and Blue-excess Dust-obscured Galaxies Known in Cosmic Noon.” The Astrophysical Journal Letters, 14 December 2023. DOI: 10.3847/2041-8213/ad0e00

  • Noboriguchi, T. Nagao, Y. Toba, K. Ichikawa, et al. “Extreme Nature of Four Blue-excess Dust-obscured Galaxies Revealed by Optical Spectroscopy.” The Astrophysical Journal, 23 December 2022. DOI: 10.3847/1538-4357/aca403

  • Noboriguchi, T. Nagao, Y. Toba, M. Niida, et al. “Optical Properties of Infrared-bright Dust-obscured Galaxies Viewed with Subaru Hyper Suprime-Cam.” The Astrophysical Journal, 13 May 2019. DOI: 10.3847/1538-4357/ab1754

Frequently Asked Questions (FAQs) about JWST EROs BluDOGs Comparison

What are Extremely Red Objects (EROs) in JWST data?

Extremely Red Objects (EROs) are a type of astronomical object identified in the James Webb Space Telescope (JWST) data, characterized by their distinct red color. These objects are of interest to astronomers as they study the evolution of quasars and other cosmic phenomena.

How do EROs relate to BluDOGs from Subaru Telescope data?

Researchers have found that EROs identified in JWST data share similarities with blue-excess dust obscured galaxies (BluDOGs) previously observed in Subaru Telescope data. This similarity challenges existing theories and offers new insights into the study of quasar evolution.

What is the significance of the similarity between EROs and BluDOGs?

The similarity between EROs and BluDOGs suggests that our understanding of quasar evolution might need to be revised. It underscores the complexity of cosmic evolution and the need for further study using advanced telescopes like GREX-PLUS.

What is the role of GREX-PLUS in the study of EROs and BluDOGs?

GREX-PLUS is a planned advanced telescope project in Japan. It is expected to play a crucial role in further studying the relationship between EROs, BluDOGs, and quasars, by providing a larger sample of candidates and more detailed observations.

How do these findings impact our understanding of the universe?

These findings highlight the dynamic and complex nature of the universe, particularly in the context of quasar evolution. Understanding the relationship between EROs and BluDOGs can provide valuable insights into how some of the brightest objects in the universe, quasars, evolve over time.

More about JWST EROs BluDOGs Comparison

  • Article on JWST and Subaru Telescope Findings
  • The Astrophysical Journal Letters: EROs and BluDOGs Comparison Study
  • The Astrophysical Journal: Nature of Blue-excess Dust-obscured Galaxies
  • Subaru Telescope’s Official Website: BluDOG Research
  • James Webb Space Telescope: EROs Discovery
  • GREX-PLUS Telescope Project Overview
  • Quasar Evolution Research Updates

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TaraS December 22, 2023 - 9:58 am

interesting read, but sometimes i wonder how much of this is just guesswork, I mean how do they really know all this stuff about EROs and BluDOGs?

ScienceLuvr91 December 22, 2023 - 3:09 pm

The article is good but feels a bit complex? maybe could use simpler terms for us non-astronomers haha.

AstroNerd December 22, 2023 - 5:49 pm

This is groundbreaking! shows how much we still have to learn about quasars and the universe, Can’t wait to see what GREX-PLUS uncovers next.

MarkT December 22, 2023 - 9:53 pm

i’m not sure I get all the technical stuff but its cool that telescopes can find things like this. space is wild!

Jessie K December 22, 2023 - 10:15 pm

wow, its crazy how EROs from JWST are similar to BluDOGS, space stuff is always full of surprises, isn’t it??


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