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Identification and Characterization of a Large Sample of Distant Active Dwarf Galaxies in XMM-SERVS

Zou, Fan; Brandt, W. N.; Ni, Qingling; Zhu, Shifu; Alexander, David M.; Bauer, Franz E.; Chen, Chien-Ting J.; Luo, Bin; Sun, Mouyuan; Vignali, Cristian; Vito, Fabio; Xue, Yongquan; Yan, Wei

Identification and Characterization of a Large Sample of Distant Active Dwarf Galaxies in XMM-SERVS Thumbnail


Fan Zou

W. N. Brandt

Qingling Ni

Shifu Zhu

Franz E. Bauer

Chien-Ting J. Chen

Bin Luo

Mouyuan Sun

Cristian Vignali

Fabio Vito

Yongquan Xue

Wei Yan


Active dwarf galaxies are important because they contribute to the evolution of dwarf galaxies and can reveal their hosted massive black holes. However, the sample size of such sources beyond the local universe is still highly limited. In this work, we search for active dwarf galaxies in the recently completed XMM-Spitzer Extragalactic Representative Volume Survey (XMM-SERVS). XMM-SERVS is currently the largest medium-depth X-ray survey covering 13 deg2 in three extragalactic fields, which all have well-characterized multiwavelength information. After considering several factors that may lead to misidentifications, we identify 73 active dwarf galaxies at z < 1, which constitutes the currently largest X-ray-selected sample beyond the local universe. Our sources are generally less obscured than predictions based on the massive-AGN (active galactic nucleus) X-ray luminosity function and have a low radio-excess fraction. We find that our sources reside in environments similar to those of inactive dwarf galaxies. We further quantify the accretion distribution of the dwarf-galaxy population after considering various selection effects and find that it decreases with X-ray luminosity, but redshift evolution cannot be statistically confirmed. Depending on how we define an AGN, the active fraction may or may not show a strong dependence on stellar mass. Their Eddington ratios and X-ray bolometric corrections significantly deviate from the expected relation, which is likely caused by several large underlying systematic biases when estimating the relevant parameters for dwarf galaxies. Throughout this work, we also highlight problems in reliably measuring photometric redshifts and overcoming strong selection effects for distant active dwarf galaxies.

Journal Article Type Article
Acceptance Date Apr 17, 2023
Online Publication Date Jun 16, 2023
Publication Date Jun 20, 2023
Deposit Date Oct 31, 2023
Publicly Available Date Oct 31, 2023
Journal The Astrophysical Journal
Print ISSN 0004-637X
Electronic ISSN 1538-4357
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 950
Issue 2
Article Number 136
Keywords Space and Planetary Science; Astronomy and Astrophysics
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Copyright Statement
© 2023. The Author(s). Published by the American Astronomical Society.
Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI

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