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Title: The Post-periapsis Evolution of Galactic Center Source G1: The Second Case of a Resolved Tidal Interaction with a Supermassive Black Hole

Abstract

We present new adaptive optics (AO) imaging and spectroscopic measurements of Galactic center source G1 from W. M. Keck Observatory. Our goal is to understand its nature and relationship to G2, which is the first example of a spatially resolved object interacting with a supermassive black hole (SMBH). Both objects have been monitored with AO for the past decade (2003–2014) and are comparatively close to the black hole ( a {sub min} ∼ 200–300 au) on very eccentric orbits ( e {sub G1} ∼ 0.99; e {sub G2} ∼ 0.96). While G2 has been tracked before and during periapsis passage ( T {sub 0} ∼ 2014.2), G1 has been followed since soon after emerging from periapsis ( T {sub 0} ∼ 2001.3). Our observations of G1 double the previously reported observational time baseline, which improves its orbital parameter determinations. G1's orbital trajectory appears to be in the same plane as that of G2 but with a significantly different argument of periapsis (Δ ω = 21° ± 4°). This suggests that G1 is an independent object and not part of a gas stream containing G2, as has been proposed. Furthermore, we show for the first time that (1) G1 is extendedmore » in the epochs closest to periapsis along the direction of orbital motion, and (2) it becomes significantly smaller over time (450 au in 2004 to less than 170 au in 2009). Based on these observations, G1 appears to be the second example of an object tidally interacting with an SMBH. G1's existence 14 yr after periapsis, along with its compactness in epochs further from the time of periapsis, suggest that this source is stellar in nature.« less

Authors:
; ; ; ; ; ; ; ; ; ; ; ;  [1];  [2];  [3];  [4]
  1. Department of Physics and Astronomy, University of California, Los Angeles, 430 Portola Plaza, Los Angeles, CA 90095-1547 (United States)
  2. Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)
  3. Instituto de Astrofisica de Andalucia (CSIC), Glorieta de la Astronomia S/N, E-18008 Granada (Spain)
  4. Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States)
Publication Date:
OSTI Identifier:
22679815
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 847; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BLACK HOLES; GALAXIES; INTERACTIONS; OPTICS; ORBITS; QUASARS; SPECTRA; STAR CLUSTERS; STAR EVOLUTION; STARS; STREAMS; TRAJECTORIES

Citation Formats

Witzel, G., Sitarski, B. N., Ghez, A. M., Morris, M. R., Hees, A., Do, T., Naoz, S., Boehle, A., Martinez, G., Chappell, S., Meyer, L., Yelda, S., Becklin, E. E., Lu, J. R., Schödel, R., and Matthews, K., E-mail: witzel@astro.ucla.edu. The Post-periapsis Evolution of Galactic Center Source G1: The Second Case of a Resolved Tidal Interaction with a Supermassive Black Hole. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA80EA.
Witzel, G., Sitarski, B. N., Ghez, A. M., Morris, M. R., Hees, A., Do, T., Naoz, S., Boehle, A., Martinez, G., Chappell, S., Meyer, L., Yelda, S., Becklin, E. E., Lu, J. R., Schödel, R., & Matthews, K., E-mail: witzel@astro.ucla.edu. The Post-periapsis Evolution of Galactic Center Source G1: The Second Case of a Resolved Tidal Interaction with a Supermassive Black Hole. United States. doi:10.3847/1538-4357/AA80EA.
Witzel, G., Sitarski, B. N., Ghez, A. M., Morris, M. R., Hees, A., Do, T., Naoz, S., Boehle, A., Martinez, G., Chappell, S., Meyer, L., Yelda, S., Becklin, E. E., Lu, J. R., Schödel, R., and Matthews, K., E-mail: witzel@astro.ucla.edu. Wed . "The Post-periapsis Evolution of Galactic Center Source G1: The Second Case of a Resolved Tidal Interaction with a Supermassive Black Hole". United States. doi:10.3847/1538-4357/AA80EA.
@article{osti_22679815,
title = {The Post-periapsis Evolution of Galactic Center Source G1: The Second Case of a Resolved Tidal Interaction with a Supermassive Black Hole},
author = {Witzel, G. and Sitarski, B. N. and Ghez, A. M. and Morris, M. R. and Hees, A. and Do, T. and Naoz, S. and Boehle, A. and Martinez, G. and Chappell, S. and Meyer, L. and Yelda, S. and Becklin, E. E. and Lu, J. R. and Schödel, R. and Matthews, K., E-mail: witzel@astro.ucla.edu},
abstractNote = {We present new adaptive optics (AO) imaging and spectroscopic measurements of Galactic center source G1 from W. M. Keck Observatory. Our goal is to understand its nature and relationship to G2, which is the first example of a spatially resolved object interacting with a supermassive black hole (SMBH). Both objects have been monitored with AO for the past decade (2003–2014) and are comparatively close to the black hole ( a {sub min} ∼ 200–300 au) on very eccentric orbits ( e {sub G1} ∼ 0.99; e {sub G2} ∼ 0.96). While G2 has been tracked before and during periapsis passage ( T {sub 0} ∼ 2014.2), G1 has been followed since soon after emerging from periapsis ( T {sub 0} ∼ 2001.3). Our observations of G1 double the previously reported observational time baseline, which improves its orbital parameter determinations. G1's orbital trajectory appears to be in the same plane as that of G2 but with a significantly different argument of periapsis (Δ ω = 21° ± 4°). This suggests that G1 is an independent object and not part of a gas stream containing G2, as has been proposed. Furthermore, we show for the first time that (1) G1 is extended in the epochs closest to periapsis along the direction of orbital motion, and (2) it becomes significantly smaller over time (450 au in 2004 to less than 170 au in 2009). Based on these observations, G1 appears to be the second example of an object tidally interacting with an SMBH. G1's existence 14 yr after periapsis, along with its compactness in epochs further from the time of periapsis, suggest that this source is stellar in nature.},
doi = {10.3847/1538-4357/AA80EA},
journal = {Astrophysical Journal},
number = 1,
volume = 847,
place = {United States},
year = {Wed Sep 20 00:00:00 EDT 2017},
month = {Wed Sep 20 00:00:00 EDT 2017}
}