Modelling type 1 quasar colours in the era of Rubin and Euclid

Temple, Matthew J.; Hewett, Paul C.; Banerji, M.

doi:10.1093/mnras/stab2586

Cited by 22 publications

(12 citation statements)

References 104 publications

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“…This could imply that rQSOs have dust composed of smaller grains, described by a steeper curve, suggesting a higher level of nuclear activity or that the dust is formed within the vicinity of the central nucleus (Zafar et al 2015 ). This is consistent with previous work which have found the characteristic 2175 Å bump (expected from small carbonaceous grains present in our Galaxy) absent in rQSOs (Richards et al 2003 ;Czerny et al 2004 ;Zafar et al 2015 ;Temple et al 2021 ). This result is also in agreement with Willott ( 2005 ), who claim that flatter extinction curves are driven by redshift selection effects incorporated in composites that are constructed from large QSO samples.…”

Section: The Nature Of Dust In Red Qsossupporting

confidence: 90%

“…Typically, studies have used an SMC-like extinction curve ( R V = 2.74) to explain dust reddening in QSOs, although the ef fecti veness of this for describing the dust in all QSOs has been debated. For example, Czerny et al ( 2004 ) construct a QSO extinction curve based on the blue and red composite spectra from Richards et al ( 2003 ) and find a flatter 'grey' curve that deviates from an SMC-like curve at shorter wavelengths, which has also been found in other studies (Gaskell et al 2004 ;Gaskell & Benker 2007 ;Mehdipour & Costantini 2018 ;Temple, Hewett & Banerji 2021 ). They found their derived grey e xtinction curv e is best described by dust containing no graphite, with a fairly large grain size of > 0 .…”

Section: The Nature Of Dust In Red Qsossupporting

confidence: 65%

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Fundamental differences in the properties of red and blue quasars: measuring the reddening and accretion properties with X-shooter

Fawcett

Alexander

Rosario

et al. 2022

Monthly Notices of the Royal Astronomical Society

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We have recently found fundamental differences in the radio properties of red quasars when compared to typical blue quasars. In this paper we use data from the X-shooter spectrograph on the Very Large Telescope, providing spectral coverage from ∼3000–25000 Å, of a sample of 40 red and blue luminous quasars at 1.45 < z < 1.65 to explore the connections between the radio, emission-line, and accretion-disc properties. We fit various dust-extinction curves to the data and find that dust reddening can fully explain the observed colours for the majority of the red quasars in our sample, with moderate extinctions ranging from AV ∼ 0.06–0.7 mags. We confront our spectra with a simple thin accretion-disc model and find this can describe the continua of both the blue and red quasars, once corrected for dust extinction; we also find no significant differences in the accretion properties. We detect ionized outflows in a number of red and blue quasars, but do not find any significant evidence that they are more prevalent in the red quasar population. Overall our findings imply that the radio emission is more closely connected to circumnuclear/ISM opacity rather than accretion disc or outflow differences.

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Section: The Nature Of Dust In Red Qsossupporting

confidence: 90%

Section: The Nature Of Dust In Red Qsossupporting

confidence: 65%

Fundamental differences in the properties of red and blue quasars: measuring the reddening and accretion properties with X-shooter

Fawcett

Alexander

Rosario

et al. 2022

Monthly Notices of the Royal Astronomical Society

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“…One of the main assumptions for our determination of the selection function is the simqso quasar model itself. To test the robustness of this model, we compare it to the quasar model presented by Temple et al (2021;hereafter, qsogen). The Euclid Collaboration et al (2019) used qsogen to predict the quasar yields in the Euclid survey.…”

Section: Discussionmentioning

confidence: 99%

“…To test the robustness of our simqso quasar model, we compare its synthetic photometry to the recently published qsogen model by Temple et al (2021). The latter has been used in the prediction of quasar yields for the Euclid mission (Euclid Collaboration et al 2019).…”

Section: Appendix B Extended Discussion Of the Quasar Modelmentioning

confidence: 99%

The Pan-STARRS1 z > 5.6 Quasar Survey. III. The z ≈ 6 Quasar Luminosity Function

Schindler

Bañados

Connor

et al. 2023

ApJ

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We present the z ≈ 6 type-1 quasar luminosity function (QLF), based on the Pan-STARRS1 (PS1) quasar survey. The PS1 sample includes 125 quasars at z ≈ 5.7–6.2, with −28 ≲ M 1450 ≲ −25. With the addition of 48 fainter quasars from the SHELLQs survey, we evaluate the z ≈ 6 QLF over −28 ≲ M 1450 ≲ −22. Adopting a double power law with an exponential evolution of the quasar density (Φ(z) ∝ 10 k(z−6); k = −0.7), we use a maximum likelihood method to model our data. We find a break magnitude of M * = − 26.38 − 0.60 + 0.79 mag , a faint-end slope of α = − 1.70 − 0.19 + 0.29 , and a steep bright-end slope of β = − 3.84 − 1.21 + 0.63 . Based on our new QLF model, we determine the quasar comoving spatial density at z ≈ 6 to be n ( M 1450 < − 26 ) = 1.16 − 0.12 + 0.13 cGpc − 3 . In comparison with the literature, we find the quasar density to evolve with a constant value of k ≈ −0.7, from z ≈ 7 to z ≈ 4. Additionally, we derive an ionizing emissivity of ϵ 912 ( z = 6 ) = 7.23 − 1.02 + 1.65 × 10 22 erg s − 1 Hz − 1 cMpc − 3 , based on the QLF measurement. Given standard assumptions, and the recent measurement of the mean free path by Becker et al. at z ≈ 6, we calculate an H i photoionizing rate of ΓH I(z = 6) ≈ 6 × 10−16 s−1, strongly disfavoring a dominant role of quasars in hydrogen reionization.

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“…While beyond the scope of this paper, more reliable samples of quasars could be generated using parametric SED modelling, which can account for intrinsic changes in quasar spectra as a function of luminosity and redshift (e.g. Temple et al 2021).…”

Section: Source Classesmentioning

confidence: 99%

Revealing new high-redshift quasar populations through Gaussian mixture model selection

Wagenveld

Saxena

Duncan

et al. 2022

A&A

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We present a novel method for identifying candidate high-redshift quasars (HzQs; z ≳ 5.5) –which are unique probes of supermassive black hole growth in the early Universe– from large-area optical and infrared photometric surveys. Using Gaussian mixture models to construct likelihoods and incorporating informed priors based on population statistics, our method uses a Bayesian framework to assign posterior probabilities that differentiate between HzQs and contaminating sources. We additionally include deep radio data to obtain informed priors. Using existing HzQ data in the literature, we set a posterior threshold that accepts ∼90% of known HzQs while rejecting > 99% of contaminants such as dwarf stars or lower redshift galaxies. Running the probability selection on test samples of simulated HzQs and contaminants, we find that the efficacy of the probability method is higher than traditional colour cuts, decreasing the fraction of accepted contaminants by 86% while retaining a similar fraction of HzQs. As a test, we apply our method to the Pan-STARRS Data Release 1 (PS1) source catalogue within the HETDEX Spring field area on the sky, covering 400 sq. deg. and coinciding with deep radio data from the LOFAR Two-metre Sky Survey Data Release 1. From an initial sample of ∼5 × 105 sources in PS1, our selection shortlists 251 candidate HzQs, which are further reduced to 63 after visual inspection. Shallow spectroscopic follow-up of 13 high-probability HzQs resulted in the confirmation of a previously undiscovered quasar at z = 5.66 with photometric colours i − z = 1.4, lying outside the typically probed regions when selecting HzQs based on colours. This discovery demonstrates the efficacy of our probabilistic HzQ selection method in selecting more complete HzQ samples, which holds promise when employed on large existing and upcoming photometric data sets.

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Modelling type 1 quasar colours in the era of Rubin and Euclid

Cited by 22 publications

References 104 publications

Fundamental differences in the properties of red and blue quasars: measuring the reddening and accretion properties with X-shooter

Fundamental differences in the properties of red and blue quasars: measuring the reddening and accretion properties with X-shooter

The Pan-STARRS1 z > 5.6 Quasar Survey. III. The z ≈ 6 Quasar Luminosity Function

Revealing new high-redshift quasar populations through Gaussian mixture model selection

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