Finding Quasars behind the Galactic Plane. I. Candidate Selections with Transfer Learning

Fu, Yuming; Wu, Xue-Bing; Yang, Qian; Feng, Xiaotong; Ma, Qinchun; Li, Shuyan

doi:10.3847/1538-4365/abe85e

Cited by 20 publications

(19 citation statements)

References 120 publications

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“…This estimate is also suggested by recent studies (e.g. Shu et al 2019;Bailer-Jones et al 2019;Fu et al 2021) of the QSOs as well as by the extragalactic results of Gaia DR3. Notes.…”

Section: Statistical Properties Of the Gaia-crf3 Sourcessupporting

confidence: 86%

“…The search for the QSOs in the Galactic plane is an important scientific problem that requires further investigation. We note that more advanced methods to combine different datasets in the search for QSOs in the Galactic plane are under development (e.g., Fu et al 2021). Combined with the expected use of Gaia's own object classification, one can hope that these methods will result in a much improved completeness of the Gaia-CRF in the Galactic plane in the future.…”

Section: Discussion Of the Selectionmentioning

confidence: 99%

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Gaia Early Data Release 3

Klioner

Lindegren

Mignard

et al. 2022

A&A

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Context. Gaia-CRF3 is the celestial reference frame for positions and proper motions in the third release of data from the Gaia mission, Gaia DR3 (and for the early third release, Gaia EDR3, which contains identical astrometric results). The reference frame is defined by the positions and proper motions at epoch 2016.0 for a specific set of extragalactic sources in the (E)DR3 catalogue. Aims. We describe the construction of Gaia-CRF3 and its properties in terms of the distributions in magnitude, colour, and astrometric quality. Methods. Compact extragalactic sources in Gaia DR3 were identified by positional cross-matching with 17 external catalogues of quasi-stellar objects (QSO) and active galactic nuclei (AGN), followed by astrometric filtering designed to remove stellar contaminants. Selecting a clean sample was favoured over including a higher number of extragalactic sources. For the final sample, the random and systematic errors in the proper motions are analysed, as well as the radio-optical offsets in position for sources in the third realisation of the International Celestial Reference Frame (ICRF3). Results. Gaia-CRF3 comprises about 1.6 million QSO-like sources, of which 1.2 million have five-parameter astrometric solutions in Gaia DR3 and 0.4 million have six-parameter solutions. The sources span the magnitude range G = 13 to 21 with a peak density at 20.6 mag, at which the typical positional uncertainty is about 1 mas. The proper motions show systematic errors on the level of 12 µas yr −1 on angular scales greater than 15 deg. For the 3142 optical counterparts of ICRF3 sources in the S/X frequency bands, the median offset from the radio positions is about 0.5 mas, but it exceeds 4 mas in either coordinate for 127 sources. We outline the future of Gaia-CRF in the next Gaia data releases. Appendices give further details on the external catalogues used, how to extract information about the Gaia-CRF3 sources, potential (Galactic) confusion sources, and the estimation of the spin and orientation of an astrometric solution.

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“…This estimate is also suggested by recent studies (e.g. Shu et al 2019;Bailer-Jones et al 2019;Fu et al 2021) of the QSOs as well as by the extragalactic results of Gaia DR3. Notes.…”

Section: Statistical Properties Of the Gaia-crf3 Sourcessupporting

confidence: 86%

Section: Discussion Of the Selectionmentioning

confidence: 99%

Gaia Early Data Release 3

Klioner

Lindegren

Mignard

et al. 2022

A&A

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“…For example, the Edinburgh-Cape Blue Object Survey (Stobie et al 1997;Kilkenny et al 2016) was restricted to |b| > 30 • ; the Hamburg/ESO quasar survey (Wisotzki et al 1996;Wisotzki et al 2000) searched at |b| > 25 • ; and the Calán-Tololo Survey (Maza et al 1988;Maza, Wischnjewsky, & Antezana 1996) observed to |b| > 20 • . Dedicated quasar searches closer to the Galactic Plane (e.g., Im et al 2007;Fu et al 2021) may produce samples of objects useful both in their own right and for studies of the gas and dust near the Galactic disk.…”

Section: Discussionmentioning

confidence: 99%

Discovery of the most luminous quasar of the last 9 Gyr

Onken

Lai

Wolf

et al. 2022

Publ. Astron. Soc. Aust.

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We report the discovery of a bright ( $g = 14.5$ mag (AB), $K = 11.9$ mag (Vega)) quasar at redshift $z=0.83$ — the optically brightest (unbeamed) quasar at $z>0.4$ . SMSS J114447.77-430859.3, at a Galactic latitude of $b=+18.1^{\circ}$ , was identified by its optical colours from the SkyMapper Southern Survey (SMSS) during a search for symbiotic binary stars. Optical and near-infrared spectroscopy reveals broad Mg ii, H $\unicode{x03B2}$ , H $\unicode{x03B1}$ , and Pa $\unicode{x03B2}$ emission lines, from which we measure a black hole mass of $\log_{10}\! (M_{\mathrm{BH}}/\mathrm{M}_{\odot}) = 9.4 \pm 0.5$ . With its high luminosity, $L_{\mathrm{bol}} = (4.7\pm1.0)\times10^{47}\,\mathrm{erg\,s}^{-1}$ or $M_{i}(z=2) = -29.74$ mag (AB), we estimate an Eddington ratio of $\approx1.4$ . As the most luminous quasar known over the last ${\sim}$ 9 Gyr of cosmic history, having a luminosity $8\times$ greater than 3C 273, the source offers a range of potential follow-up opportunities.

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“…In the first paper of this series (Fu et al 2021, hereafter Paper I), we reported the selection methods for GPQ candidates based on transfer learning, and a catalog of 160,946 GPQ candidates selected from Pan-STARRS1 (PS1; Chambers et al 2016) DR1 and the Wide-field Infrared Survey Explorer final catalog release (AllWISE; Wright et al 2010;Mainzer et al 2011). As has been evaluated by Paper I, the purity of quasars on the GPQ candidates that are matched to the SIMBAD 18 (Wenger et al 2000) database is ∼90%.…”

Section: Introductionmentioning

confidence: 99%

Finding Quasars behind the Galactic Plane. II. Spectroscopic Identifications of 204 Quasars at ∣b∣ < 20°

Fu¹,

Wu²,

Jiang³

et al. 2022

ApJS

Self Cite

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Quasars behind the Galactic plane (GPQs) are important astrometric references and valuable probes of Galactic gas, yet the search for GPQs is difficult due to severe extinction and source crowding in the Galactic plane. In this paper, we present a sample of 204 spectroscopically confirmed GPQs at ∣b∣ < 20°, 191 of which are new discoveries. This GPQ sample covers a wide redshift range from 0.069 to 4.487. For the subset of 230 observed GPQ candidates, the lower limit of the purity of quasars is 85.2%, and the lower limit of the fraction of stellar contaminants is 6.1%. Using a multicomponent spectral fitting, we measure the emission line and continuum flux of the GPQs, and estimate their single-epoch virial black hole masses. Due to selection effects raised from Galactic extinction and target magnitude, these GPQs have higher black hole masses and continuum luminosities in comparison to the SDSS DR7 quasar sample. The spectral-fitting results and black hole mass estimates are compiled into a main spectral catalog, and an extended spectral catalog of GPQs. The successful identifications prove the reliability of both our GPQ selection methods and the GPQ candidate catalog, shedding light on the astrometric and astrophysical programs that make use of a large sample of GPQs in the future.

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Finding Quasars behind the Galactic Plane. I. Candidate Selections with Transfer Learning

Cited by 20 publications

References 120 publications

Gaia Early Data Release 3

Gaia Early Data Release 3

Discovery of the most luminous quasar of the last 9 Gyr

Finding Quasars behind the Galactic Plane. II. Spectroscopic Identifications of 204 Quasars at ∣b∣ < 20°

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