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Title: Extreme Variability Quasars from the Sloan Digital Sky Survey and the Dark Energy Survey

Abstract

We perform a systematic search for long-term extreme variability quasars (EVQs) in the overlapping Sloan Digital Sky Survey (SDSS) and 3-Year Dark Energy Survey (DES) imaging, which provide light curves spanning more than 15 years. We identified ~1000 EVQs with a maximum g band magnitude change of more than 1 mag over this period, about 10% of all quasars searched. The EVQs have L_bol~10^45-10^47 erg/s and L/L_Edd~0.01-1. Accounting for selection effects, we estimate an intrinsic EVQ fraction of ~30-50% among all g<~22 quasars over a baseline of ~15 years. These EVQs are good candidates for so-called "changing-look quasars", where a spectral transition between the two types of quasars (broad-line and narrow-line) is observed between the dim and bright states. We performed detailed multi-wavelength, spectral and variability analyses for the EVQs and compared to their parent quasar sample. We found that EVQs are distinct from a control sample of quasars matched in redshift and optical luminosity: (1) their UV broad emission lines have larger equivalent widths; (2) their Eddington ratios are systematically lower; and (3) they are more variable on all timescales. The intrinsic difference in quasar properties for EVQs suggest that internal processes associated with accretion are the main drivermore » for the observed extreme long-term variability. However, despite their different properties, EVQs seem to be in the tail of a continuous distribution of quasar properties, rather than standing out as a distinct population. We speculate that EVQs are normal quasars accreting at relatively low accretion rates, where the accretion flow is more likely to experience instabilities that drive the factor of few changes in flux on multi-year timescales.« less

Authors:
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Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States); Brookhaven National Lab. (BNL), Upton, NY (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP)
Contributing Org.:
DES Collaboration
OSTI Identifier:
1425676
Alternate Identifier(s):
OSTI ID: 1389253; OSTI ID: 1409080; OSTI ID: 1435204
Report Number(s):
BNL-114280-2017-JA; FERMILAB-PUB-17-211-AE; arXiv:1706.07875
Journal ID: ISSN 1538-4357; TRN: US1802147
Grant/Contract Number:  
AC02-76SF00515; AST-1138766; AYA2012-39559; ESP2013-48274; FPA2013-47986; 240672; 291329; 306478; SC0012704; AC02-07CH11359; AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 854; Journal Issue: 2; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; black hole physics; galaxies: active; line: profiles; quasars: general; surveys

Citation Formats

Rumbaugh, N., Shen, Yue, Morganson, Eric, Liu, Xin, Banerji, M., McMahon, R. G., Abdalla, F. B., Benoit-Lévy, A., Bertin, E., Brooks, D., Buckley-Geer, E., Capozzi, D., Carnero Rosell, A., Carrasco Kind, M., Carretero, J., Cunha, C. E., D’Andrea, C. B., da Costa, L. N., DePoy, D. L., Desai, S., Doel, P., Frieman, J., García-Bellido, J., Gruen, D., Gruendl, R. A., Gschwend, J., Gutierrez, G., Honscheid, K., James, D. J., Kuehn, K., Kuhlmann, S., Kuropatkin, N., Lima, M., Maia, M. A. G., Marshall, J. L., Martini, P., Menanteau, F., Plazas, A. A., Reil, K., Roodman, A., Sanchez, E., Scarpine, V., Schindler, R., Schubnell, M., Sheldon, E., Smith, M., Soares-Santos, M., Sobreira, F., Suchyta, E., Swanson, M. E. C., Walker, A. R., and Wester, W.. Extreme Variability Quasars from the Sloan Digital Sky Survey and the Dark Energy Survey. United States: N. p., 2018. Web. https://doi.org/10.3847/1538-4357/aaa9b6.
Rumbaugh, N., Shen, Yue, Morganson, Eric, Liu, Xin, Banerji, M., McMahon, R. G., Abdalla, F. B., Benoit-Lévy, A., Bertin, E., Brooks, D., Buckley-Geer, E., Capozzi, D., Carnero Rosell, A., Carrasco Kind, M., Carretero, J., Cunha, C. E., D’Andrea, C. B., da Costa, L. N., DePoy, D. L., Desai, S., Doel, P., Frieman, J., García-Bellido, J., Gruen, D., Gruendl, R. A., Gschwend, J., Gutierrez, G., Honscheid, K., James, D. J., Kuehn, K., Kuhlmann, S., Kuropatkin, N., Lima, M., Maia, M. A. G., Marshall, J. L., Martini, P., Menanteau, F., Plazas, A. A., Reil, K., Roodman, A., Sanchez, E., Scarpine, V., Schindler, R., Schubnell, M., Sheldon, E., Smith, M., Soares-Santos, M., Sobreira, F., Suchyta, E., Swanson, M. E. C., Walker, A. R., & Wester, W.. Extreme Variability Quasars from the Sloan Digital Sky Survey and the Dark Energy Survey. United States. https://doi.org/10.3847/1538-4357/aaa9b6
Rumbaugh, N., Shen, Yue, Morganson, Eric, Liu, Xin, Banerji, M., McMahon, R. G., Abdalla, F. B., Benoit-Lévy, A., Bertin, E., Brooks, D., Buckley-Geer, E., Capozzi, D., Carnero Rosell, A., Carrasco Kind, M., Carretero, J., Cunha, C. E., D’Andrea, C. B., da Costa, L. N., DePoy, D. L., Desai, S., Doel, P., Frieman, J., García-Bellido, J., Gruen, D., Gruendl, R. A., Gschwend, J., Gutierrez, G., Honscheid, K., James, D. J., Kuehn, K., Kuhlmann, S., Kuropatkin, N., Lima, M., Maia, M. A. G., Marshall, J. L., Martini, P., Menanteau, F., Plazas, A. A., Reil, K., Roodman, A., Sanchez, E., Scarpine, V., Schindler, R., Schubnell, M., Sheldon, E., Smith, M., Soares-Santos, M., Sobreira, F., Suchyta, E., Swanson, M. E. C., Walker, A. R., and Wester, W.. Wed . "Extreme Variability Quasars from the Sloan Digital Sky Survey and the Dark Energy Survey". United States. https://doi.org/10.3847/1538-4357/aaa9b6. https://www.osti.gov/servlets/purl/1425676.
@article{osti_1425676,
title = {Extreme Variability Quasars from the Sloan Digital Sky Survey and the Dark Energy Survey},
author = {Rumbaugh, N. and Shen, Yue and Morganson, Eric and Liu, Xin and Banerji, M. and McMahon, R. G. and Abdalla, F. B. and Benoit-Lévy, A. and Bertin, E. and Brooks, D. and Buckley-Geer, E. and Capozzi, D. and Carnero Rosell, A. and Carrasco Kind, M. and Carretero, J. and Cunha, C. E. and D’Andrea, C. B. and da Costa, L. N. and DePoy, D. L. and Desai, S. and Doel, P. and Frieman, J. and García-Bellido, J. and Gruen, D. and Gruendl, R. A. and Gschwend, J. and Gutierrez, G. and Honscheid, K. and James, D. J. and Kuehn, K. and Kuhlmann, S. and Kuropatkin, N. and Lima, M. and Maia, M. A. G. and Marshall, J. L. and Martini, P. and Menanteau, F. and Plazas, A. A. and Reil, K. and Roodman, A. and Sanchez, E. and Scarpine, V. and Schindler, R. and Schubnell, M. and Sheldon, E. and Smith, M. and Soares-Santos, M. and Sobreira, F. and Suchyta, E. and Swanson, M. E. C. and Walker, A. R. and Wester, W.},
abstractNote = {We perform a systematic search for long-term extreme variability quasars (EVQs) in the overlapping Sloan Digital Sky Survey (SDSS) and 3-Year Dark Energy Survey (DES) imaging, which provide light curves spanning more than 15 years. We identified ~1000 EVQs with a maximum g band magnitude change of more than 1 mag over this period, about 10% of all quasars searched. The EVQs have L_bol~10^45-10^47 erg/s and L/L_Edd~0.01-1. Accounting for selection effects, we estimate an intrinsic EVQ fraction of ~30-50% among all g<~22 quasars over a baseline of ~15 years. These EVQs are good candidates for so-called "changing-look quasars", where a spectral transition between the two types of quasars (broad-line and narrow-line) is observed between the dim and bright states. We performed detailed multi-wavelength, spectral and variability analyses for the EVQs and compared to their parent quasar sample. We found that EVQs are distinct from a control sample of quasars matched in redshift and optical luminosity: (1) their UV broad emission lines have larger equivalent widths; (2) their Eddington ratios are systematically lower; and (3) they are more variable on all timescales. The intrinsic difference in quasar properties for EVQs suggest that internal processes associated with accretion are the main driver for the observed extreme long-term variability. However, despite their different properties, EVQs seem to be in the tail of a continuous distribution of quasar properties, rather than standing out as a distinct population. We speculate that EVQs are normal quasars accreting at relatively low accretion rates, where the accretion flow is more likely to experience instabilities that drive the factor of few changes in flux on multi-year timescales.},
doi = {10.3847/1538-4357/aaa9b6},
journal = {The Astrophysical Journal (Online)},
number = 2,
volume = 854,
place = {United States},
year = {2018},
month = {2}
}

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Figures / Tables:

Figure 1 Figure 1: The g band magnitude change between the first and second extrema is plotted versus the corresponding change in g − i, so that a positive ∆g indicates a decrease in brightness. The red points are the selected EVQs. For quasars at all levels of variability, we see amore » correlation between changes in magnitude and color. This implies that the i-band flux varies in the same direction as the g-band flux, but with a reduced amplitude.« less

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journal, August 2016

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journal, December 2009

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journal, April 2016

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A Population of X-Ray weak Quasars: phl 1811 Analogs at high Redshift
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The Dark Energy Survey
conference, January 2006

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  • THE DARK SIDE OF THE UNIVERSE: 2nd International Conference on The Dark Side of the Universe DSU 2006, AIP Conference Proceedings
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Slow-blue nuclear hypervariables in PanSTARRS-1
text, January 2016

  • Lawrence, A.; Bruce, A. G.; MacLeod, C.
  • Apollo - University of Cambridge Repository
  • DOI: 10.17863/cam.4650

The Dark Energy Survey
conference, May 2012

  • Sevilla, Ignacio
  • Proceedings of XXIst International Europhysics Conference on High Energy Physics — PoS(EPS-HEP2011)
  • DOI: 10.22323/1.134.0080

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