# Extremely-bright submillimeter galaxies beyond the Lupus-I star-forming region

**Authors:** Y. Tamura, R. Kawabe, Y. Shimajiri, T. Tsukagoshi, Y. Nakajima, Y. Oasa, D. J. Wilner, C. J. Chandler, K. Saigo, K. Tomida, M. S. Yun, A. Taniguchi, K. Kohno, B. Hatsukade, I. Aretxaga, J. E. Austermann, R. Dickman, H. Ezawa, W. M. Goss, M. Hayashi  
**arXiv:** [1506.06768](https://arxiv.org/abs/1506.06768)  
**Date:** 2015-06-22  
**Summary page:** https://www.summarizepaper.com/en/paper/1506.06768v1/

## Key points

- Researchers detected two candidate distant submillimeter galaxies (SMGs) in the Lupus-I star-forming region: MM J154506.4$-$344318 and MM J154132.7$-$350320.
- These SMGs exhibit 1.1 mm flux densities of 43.9 and 27.1 mJy, with identified Herschel/SPIRE counterparts.
- Photometric redshift estimates suggest redshifts of approximately $z_{\rm photo} \simeq$ 4-5 and 3 for the two SMGs.
- Proximity to low-redshift elliptical galaxy counterparts hints at gravitational magnification effects on their high apparent luminosities.
- Cumulative number counts at $S_{\rm 1.1mm} \ge 25$ mJy align with model predictions for flux magnification due to strong gravitational lensing phenomena.
- Similarity observed between a high-redshift SMG and a Galactic dense starless core underscores the need for comprehensive multi-wavelength observations in determining redshifts accurately.
- Overall, these findings emphasize the importance of comprehensive multi-wavelength observations in understanding the properties and origins of submillimeter galaxies in various astrophysical environments.

## Summary

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In a recent study, researchers have reported the detection of two candidate distant submillimeter galaxies (SMGs), MM J154506.4$-$344318 and MM J154132.7$-$350320, within the AzTEC/ASTE 1.1 mm survey conducted towards the Lupus-I star-forming region. These two objects exhibit 1.1 mm flux densities of 43.9 and 27.1 mJy, respectively, and have been identified to have Herschel/SPIRE counterparts as well. Further analysis revealed that the Submillimeter Array counterpart to the former SMG was identified at both 890 $\mu$m and 1.3 mm wavelengths. Researchers report detection of two distant SMGs in Lupus-I star-forming region. Photometric redshift estimates utilizing data spanning from mid-infrared to radio frequencies suggest that the redshifts of these two SMGs are approximately $z_{\rm photo} \simeq$ 4-5 and 3, respectively. Interestingly, near-infrared objects were found in close proximity to the SMGs, displaying characteristics consistent with low-redshift elliptical galaxies. Photometric redshift estimates reveal possible low-redshift elliptical galaxy counterparts near SMGs. This observation hints at the possibility that their high apparent luminosities may be attributed to gravitational magnification effects. Moreover, when considering cumulative number counts at $S_{\rm 1.1mm} \ge 25$ mJy along with other two brightest sources at 1.1 mm, it was determined that they amount to $0.70 ^{+0.56}_{-0.34}$ deg$^{-2}$. This result aligns well with model predictions accounting for flux magnification due to strong gravitational lensing phenomena. High apparent luminosities of SMGs may be attributed to this effect. An unexpected finding from this study is the similarity observed between a high-redshift ($z > 3$) SMG and a Galactic dense starless core in terms of their mid-infrared to millimeter spectral energy distributions and spatial structures at scales greater than or equal to $\gtrsim 1"$. This underscores the importance of employing broad-band photometry spanning optical to centimeter wavelengths alongside spectroscopic analyses for accurately determining redshifts when encountering compact objects within Galactic star-forming regions. Similarity between high-redshift SMG and Galactic dense starless core highlights need for comprehensive multi-wavelength observations. Overall, these findings shed light on the diverse nature of submillimeter galaxies and emphasize the significance of comprehensive multi-wavelength observations in unraveling their properties and origins in different astrophysical environments. Importance stressed for understanding properties and origins of submillimeter galaxies in various astrophysical environments.