Near-infrared Flux Distribution of Sgr A* from 2005–2022: Evidence for an Enhanced Accretion Episode in 2019
Sgr A* is the variable electromagnetic source associated with accretion onto the Galactic center supermassive black hole. While the near-infrared (NIR) variability of Sgr A* was shown to be consistent over two decades, unprecedented activity in 2019 challenges existing statistical models. We investi...
| Main Authors: | , , , , , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2023-01-01
|
| Series: | The Astrophysical Journal Letters |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/2041-8213/acf2f2 |
| _version_ | 1797692525475004416 |
|---|---|
| author | Grant C. Weldon Tuan Do Gunther Witzel Andrea M. Ghez Abhimat K. Gautam Eric E. Becklin Mark R. Morris Gregory D. Martinez Shoko Sakai Jessica R. Lu Keith Matthews Matthew W. Hosek Jr. Zoë Haggard |
| author_facet | Grant C. Weldon Tuan Do Gunther Witzel Andrea M. Ghez Abhimat K. Gautam Eric E. Becklin Mark R. Morris Gregory D. Martinez Shoko Sakai Jessica R. Lu Keith Matthews Matthew W. Hosek Jr. Zoë Haggard |
| author_sort | Grant C. Weldon |
| collection | DOAJ |
| description | Sgr A* is the variable electromagnetic source associated with accretion onto the Galactic center supermassive black hole. While the near-infrared (NIR) variability of Sgr A* was shown to be consistent over two decades, unprecedented activity in 2019 challenges existing statistical models. We investigate the origin of this activity by recalibrating and reanalyzing all of our Keck Observatory Sgr A* imaging observations from 2005–2022. We present light curves from 69 observation epochs using the NIRC2 imager at 2.12 μ m with laser-guide star adaptive optics. These observations reveal that the mean luminosity of Sgr A* increased by a factor of ∼3 in 2019, and the 2019 light curves had higher variance than in all time periods we examined. We find that the 2020–2022 flux distribution is statistically consistent with the historical sample and model predictions, but with fewer bright measurements above 0.6 mJy at the ∼2 σ level. Since 2019, we have observed a maximum K _s (2.2 μ m) flux of 0.9 mJy, compared to the highest pre-2019 flux of 2.0 mJy and highest 2019 flux of 5.6 mJy. Our results suggest that the 2019 activity was caused by a temporary accretion increase onto Sgr A*, possibly due to delayed accretion of tidally stripped gas from the gaseous object G2 in 2014. We also examine faint Sgr A* fluxes over a long time baseline to search for a quasi-steady quiescent state. We find that Sgr A* displays flux variations over a factor of ∼500, with no evidence for a quiescent state in the NIR. |
| first_indexed | 2024-03-12T02:29:52Z |
| format | Article |
| id | doaj.art-5008823664f14417aa9362fcf5917073 |
| institution | Directory Open Access Journal |
| issn | 2041-8205 |
| language | English |
| last_indexed | 2024-03-12T02:29:52Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal Letters |
| spelling | doaj.art-5008823664f14417aa9362fcf59170732023-09-05T08:15:34ZengIOP PublishingThe Astrophysical Journal Letters2041-82052023-01-019541L3310.3847/2041-8213/acf2f2Near-infrared Flux Distribution of Sgr A* from 2005–2022: Evidence for an Enhanced Accretion Episode in 2019Grant C. Weldon0https://orcid.org/0000-0003-4081-1839Tuan Do1https://orcid.org/0000-0001-9554-6062Gunther Witzel2https://orcid.org/0000-0003-2618-797XAndrea M. Ghez3https://orcid.org/0000-0003-3230-5055Abhimat K. Gautam4https://orcid.org/0000-0002-2836-117XEric E. Becklin5Mark R. Morris6https://orcid.org/0000-0002-6753-2066Gregory D. Martinez7Shoko Sakai8https://orcid.org/0000-0001-5972-663XJessica R. Lu9https://orcid.org/0000-0001-9611-0009Keith Matthews10Matthew W. Hosek Jr.11https://orcid.org/0000-0003-2874-1196Zoë Haggard12UCLA Galactic Center Group, Physics and Astronomy Department, University of California , Los Angeles, CA 90095, USA ; gweldon@astro.ucla.eduUCLA Galactic Center Group, Physics and Astronomy Department, University of California , Los Angeles, CA 90095, USA ; gweldon@astro.ucla.eduMax Planck Institute for Radio Astronomy , Auf dem Hügel 69, D-53121 Bonn (Endenich), GermanyUCLA Galactic Center Group, Physics and Astronomy Department, University of California , Los Angeles, CA 90095, USA ; gweldon@astro.ucla.eduUCLA Galactic Center Group, Physics and Astronomy Department, University of California , Los Angeles, CA 90095, USA ; gweldon@astro.ucla.eduUCLA Galactic Center Group, Physics and Astronomy Department, University of California , Los Angeles, CA 90095, USA ; gweldon@astro.ucla.eduUCLA Galactic Center Group, Physics and Astronomy Department, University of California , Los Angeles, CA 90095, USA ; gweldon@astro.ucla.eduUCLA Galactic Center Group, Physics and Astronomy Department, University of California , Los Angeles, CA 90095, USA ; gweldon@astro.ucla.eduUCLA Galactic Center Group, Physics and Astronomy Department, University of California , Los Angeles, CA 90095, USA ; gweldon@astro.ucla.eduUniversity of California , Berkeley, Department of Astronomy, Berkeley, CA 94720, USADivision of Physics, Mathematics, and Astronomy, California Institute of Technology , MC 301-17, Pasadena, California 91125, USAUCLA Galactic Center Group, Physics and Astronomy Department, University of California , Los Angeles, CA 90095, USA ; gweldon@astro.ucla.eduUCLA Galactic Center Group, Physics and Astronomy Department, University of California , Los Angeles, CA 90095, USA ; gweldon@astro.ucla.eduSgr A* is the variable electromagnetic source associated with accretion onto the Galactic center supermassive black hole. While the near-infrared (NIR) variability of Sgr A* was shown to be consistent over two decades, unprecedented activity in 2019 challenges existing statistical models. We investigate the origin of this activity by recalibrating and reanalyzing all of our Keck Observatory Sgr A* imaging observations from 2005–2022. We present light curves from 69 observation epochs using the NIRC2 imager at 2.12 μ m with laser-guide star adaptive optics. These observations reveal that the mean luminosity of Sgr A* increased by a factor of ∼3 in 2019, and the 2019 light curves had higher variance than in all time periods we examined. We find that the 2020–2022 flux distribution is statistically consistent with the historical sample and model predictions, but with fewer bright measurements above 0.6 mJy at the ∼2 σ level. Since 2019, we have observed a maximum K _s (2.2 μ m) flux of 0.9 mJy, compared to the highest pre-2019 flux of 2.0 mJy and highest 2019 flux of 5.6 mJy. Our results suggest that the 2019 activity was caused by a temporary accretion increase onto Sgr A*, possibly due to delayed accretion of tidally stripped gas from the gaseous object G2 in 2014. We also examine faint Sgr A* fluxes over a long time baseline to search for a quasi-steady quiescent state. We find that Sgr A* displays flux variations over a factor of ∼500, with no evidence for a quiescent state in the NIR.https://doi.org/10.3847/2041-8213/acf2f2Black hole physicsAccretionGalactic centerHigh angular resolution |
| spellingShingle | Grant C. Weldon Tuan Do Gunther Witzel Andrea M. Ghez Abhimat K. Gautam Eric E. Becklin Mark R. Morris Gregory D. Martinez Shoko Sakai Jessica R. Lu Keith Matthews Matthew W. Hosek Jr. Zoë Haggard Near-infrared Flux Distribution of Sgr A* from 2005–2022: Evidence for an Enhanced Accretion Episode in 2019 The Astrophysical Journal Letters Black hole physics Accretion Galactic center High angular resolution |
| title | Near-infrared Flux Distribution of Sgr A* from 2005–2022: Evidence for an Enhanced Accretion Episode in 2019 |
| title_full | Near-infrared Flux Distribution of Sgr A* from 2005–2022: Evidence for an Enhanced Accretion Episode in 2019 |
| title_fullStr | Near-infrared Flux Distribution of Sgr A* from 2005–2022: Evidence for an Enhanced Accretion Episode in 2019 |
| title_full_unstemmed | Near-infrared Flux Distribution of Sgr A* from 2005–2022: Evidence for an Enhanced Accretion Episode in 2019 |
| title_short | Near-infrared Flux Distribution of Sgr A* from 2005–2022: Evidence for an Enhanced Accretion Episode in 2019 |
| title_sort | near infrared flux distribution of sgr a from 2005 2022 evidence for an enhanced accretion episode in 2019 |
| topic | Black hole physics Accretion Galactic center High angular resolution |
| url | https://doi.org/10.3847/2041-8213/acf2f2 |
| work_keys_str_mv | AT grantcweldon nearinfraredfluxdistributionofsgrafrom20052022evidenceforanenhancedaccretionepisodein2019 AT tuando nearinfraredfluxdistributionofsgrafrom20052022evidenceforanenhancedaccretionepisodein2019 AT guntherwitzel nearinfraredfluxdistributionofsgrafrom20052022evidenceforanenhancedaccretionepisodein2019 AT andreamghez nearinfraredfluxdistributionofsgrafrom20052022evidenceforanenhancedaccretionepisodein2019 AT abhimatkgautam nearinfraredfluxdistributionofsgrafrom20052022evidenceforanenhancedaccretionepisodein2019 AT ericebecklin nearinfraredfluxdistributionofsgrafrom20052022evidenceforanenhancedaccretionepisodein2019 AT markrmorris nearinfraredfluxdistributionofsgrafrom20052022evidenceforanenhancedaccretionepisodein2019 AT gregorydmartinez nearinfraredfluxdistributionofsgrafrom20052022evidenceforanenhancedaccretionepisodein2019 AT shokosakai nearinfraredfluxdistributionofsgrafrom20052022evidenceforanenhancedaccretionepisodein2019 AT jessicarlu nearinfraredfluxdistributionofsgrafrom20052022evidenceforanenhancedaccretionepisodein2019 AT keithmatthews nearinfraredfluxdistributionofsgrafrom20052022evidenceforanenhancedaccretionepisodein2019 AT matthewwhosekjr nearinfraredfluxdistributionofsgrafrom20052022evidenceforanenhancedaccretionepisodein2019 AT zoehaggard nearinfraredfluxdistributionofsgrafrom20052022evidenceforanenhancedaccretionepisodein2019 |