Joint Survey Processing. III. Compact Oddballs in the COSMOS Field—Little Red Dots and Transients
We present the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) G800L grism spectroscopy observation of the faint active galactic nuclei (AGN) candidates in the Cosmic Evolution Survey field at redshift of 6 selected by the point-source morphology and the photometry drop-off at 8000 Å....
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2025-01-01
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| Online Access: | https://doi.org/10.3847/1538-4357/add7d9 |
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| author | Yu-Heng Lin Andreas L. Faisst Ranga-Ram Chary Anton M. Koekemoer Joseph Masiero Daniel Masters Vihang Mehta Harry I. Teplitz Gregory L. Walth John R. Weaver |
| author_facet | Yu-Heng Lin Andreas L. Faisst Ranga-Ram Chary Anton M. Koekemoer Joseph Masiero Daniel Masters Vihang Mehta Harry I. Teplitz Gregory L. Walth John R. Weaver |
| author_sort | Yu-Heng Lin |
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| description | We present the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) G800L grism spectroscopy observation of the faint active galactic nuclei (AGN) candidates in the Cosmic Evolution Survey field at redshift of 6 selected by the point-source morphology and the photometry drop-off at 8000 Å. Among the sample of seven objects, only one is detected by multiple bands and has a similar shape of spectral energy distribution as the so-called “little red dots” of James Webb Space Telescope (JWST)–selected AGN candidates, but our object is 3 mag brighter than the JWST sample. We draw the upper limit of the AGN luminosity function Φ = 1.1 × 10 ^−7 Mpc ^3 mag ^−1 for M _UV = −21 at redshift of 6. The rest of the sample shows inconsistent flux density when comparing magnitudes of HST ACS F814W to the Subaru i -band and z -band magnitudes combined. The HST ACS G800L grism observation shows that this inconsistency cannot be created from an emission line. Therefore, we speculate that these objects are transients with the light-curve decay timescale of at most 6 yr in the observed frame. |
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| institution | Kabale University |
| issn | 1538-4357 |
| language | English |
| publishDate | 2025-01-01 |
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| spelling | doaj-art-cd2e006e402148fe823de3a2f3b17e7a2025-08-20T03:27:52ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-0198714910.3847/1538-4357/add7d9Joint Survey Processing. III. Compact Oddballs in the COSMOS Field—Little Red Dots and TransientsYu-Heng Lin0https://orcid.org/0000-0001-8792-3091Andreas L. Faisst1https://orcid.org/0000-0002-9382-9832Ranga-Ram Chary2https://orcid.org/0000-0001-7583-0621Anton M. Koekemoer3https://orcid.org/0000-0002-6610-2048Joseph Masiero4https://orcid.org/0000-0003-2638-720XDaniel Masters5https://orcid.org/0000-0001-5382-6138Vihang Mehta6https://orcid.org/0000-0001-7166-6035Harry I. Teplitz7https://orcid.org/0000-0002-7064-5424Gregory L. Walth8https://orcid.org/0000-0002-6313-6808John R. Weaver9https://orcid.org/0000-0003-1614-196XCaltech/IPAC , 1200 E. California Blvd. Pasadena, CA 91125, USA ; ianlin@ipac.caltech.eduCaltech/IPAC , 1200 E. California Blvd. Pasadena, CA 91125, USA ; ianlin@ipac.caltech.eduSPACE Institute, University of California , 603 Charles E. Young Drive East, Los Angeles, CA 90095-1567, USASpace Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USACaltech/IPAC , 1200 E. California Blvd. Pasadena, CA 91125, USA ; ianlin@ipac.caltech.eduCaltech/IPAC , 1200 E. California Blvd. Pasadena, CA 91125, USA ; ianlin@ipac.caltech.eduCaltech/IPAC , 1200 E. California Blvd. Pasadena, CA 91125, USA ; ianlin@ipac.caltech.eduCaltech/IPAC , 1200 E. California Blvd. Pasadena, CA 91125, USA ; ianlin@ipac.caltech.eduCaltech/IPAC , 1200 E. California Blvd. Pasadena, CA 91125, USA ; ianlin@ipac.caltech.eduDepartment of Astronomy, University of Massachusetts , Amherst, MA 01003, USAWe present the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) G800L grism spectroscopy observation of the faint active galactic nuclei (AGN) candidates in the Cosmic Evolution Survey field at redshift of 6 selected by the point-source morphology and the photometry drop-off at 8000 Å. Among the sample of seven objects, only one is detected by multiple bands and has a similar shape of spectral energy distribution as the so-called “little red dots” of James Webb Space Telescope (JWST)–selected AGN candidates, but our object is 3 mag brighter than the JWST sample. We draw the upper limit of the AGN luminosity function Φ = 1.1 × 10 ^−7 Mpc ^3 mag ^−1 for M _UV = −21 at redshift of 6. The rest of the sample shows inconsistent flux density when comparing magnitudes of HST ACS F814W to the Subaru i -band and z -band magnitudes combined. The HST ACS G800L grism observation shows that this inconsistency cannot be created from an emission line. Therefore, we speculate that these objects are transients with the light-curve decay timescale of at most 6 yr in the observed frame.https://doi.org/10.3847/1538-4357/add7d9Galaxy photometryHigh-redshift galaxies |
| spellingShingle | Yu-Heng Lin Andreas L. Faisst Ranga-Ram Chary Anton M. Koekemoer Joseph Masiero Daniel Masters Vihang Mehta Harry I. Teplitz Gregory L. Walth John R. Weaver Joint Survey Processing. III. Compact Oddballs in the COSMOS Field—Little Red Dots and Transients The Astrophysical Journal Galaxy photometry High-redshift galaxies |
| title | Joint Survey Processing. III. Compact Oddballs in the COSMOS Field—Little Red Dots and Transients |
| title_full | Joint Survey Processing. III. Compact Oddballs in the COSMOS Field—Little Red Dots and Transients |
| title_fullStr | Joint Survey Processing. III. Compact Oddballs in the COSMOS Field—Little Red Dots and Transients |
| title_full_unstemmed | Joint Survey Processing. III. Compact Oddballs in the COSMOS Field—Little Red Dots and Transients |
| title_short | Joint Survey Processing. III. Compact Oddballs in the COSMOS Field—Little Red Dots and Transients |
| title_sort | joint survey processing iii compact oddballs in the cosmos field little red dots and transients |
| topic | Galaxy photometry High-redshift galaxies |
| url | https://doi.org/10.3847/1538-4357/add7d9 |
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