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

2021 ◽  
Vol 508 (1) ◽  
pp. 737-754
Author(s):  
Matthew J Temple ◽  
Paul C Hewett ◽  
Manda Banerji
Keyword(s):  
Emission Line ◽  
Rest Frame ◽  
Optical Emission ◽  
Host Galaxy ◽  
Model Parameters ◽  
Population Variance ◽  
Photometric Redshifts ◽  
Model Code ◽  
Wide Range

ABSTRACT We construct a parametric SED model which is able to reproduce the average observed SDSS–UKIDSS–WISE quasar colours to within one-tenth of a magnitude across a wide range of redshift (0 < z < 5) and luminosity (−22 > Mi > −29). This model is shown to provide accurate predictions for the colours of known quasars which are less luminous than those used to calibrate the model parameters, and also those at higher redshifts z > 5. Using a single parameter, the model encapsulates an up-to-date understanding of the intra-population variance in the rest-frame ultraviolet and optical emission lines of luminous quasars. At fixed redshift, there are systematic changes in the average quasar colours with apparent i-band magnitude, which we find to be well explained by the contribution from the host galaxy and our parametrization of the emission-line properties. By including redshift as an additional free parameter, the model could be used to provide photometric redshifts for individual objects. For the population as a whole we find that the average emission line and host-galaxy contributions can be well described by simple functions of luminosity which account for the observed changes in the average quasar colours across 18.1 < iAB < 21.5. We use these trends to provide predictions for quasar colours at the luminosities and redshifts which will be probed by the Rubin Observatory LSST and ESA-Euclid wide survey. The model code is applicable to a wide range of upcoming photometric and spectroscopic surveys, and is made publicly available.

scholarly journals A Comparison of Rest-frame Ultraviolet and Optical Emission-line Diagnostics in the Lensed Galaxy SDSS J1723+3411 at Redshift z = 1.3293

2021 ◽  
Vol 908 (2) ◽  
pp. 154
Author(s):  
J. R. Rigby ◽  
Michael Florian ◽  
A. Acharyya ◽  
Matthew Bayliss ◽  
Michael D. Gladders ◽  
...  
Keyword(s):  
Emission Line ◽  
Rest Frame ◽  
Optical Emission

scholarly journals Peculiar emission line spectra of core extremely red BOSS quasars at z∼2–3: orientation and/or evolution?

2020 ◽  
Vol 634 ◽  
pp. A116 ◽  
Author(s):  
M. Villar Martín ◽  
M. Perna ◽  
A. Humphrey ◽  
N. Castro Rodríguez ◽  
L. Binette ◽  
...  
Keyword(s):  
Emission Line ◽  
Near Infrared ◽  
Outer Part ◽  
Line Emission ◽  
Optical Emission ◽  
Broad Line ◽  
Broad Line Region ◽  
Line Region ◽  
Evolutionary Phase

Context. Core extremely red quasars (core ERQ) have been proposed to represent an intermediate evolutionary phase in which a heavily obscured quasar blows out the circumnuclear interstellar medium with very energetic outflows before it becomes an optical quasar. Aims. We investigate whether the properties of core ERQ fit the AGN orientation-based unification scenario. Methods. We revised the general UV and optical emission line properties of core ERQ in the context of the orientation-based scenario. We used diagnostic diagrams based on UV emission line ratios and UV-to-optical line kinematic information to compare the physical and kinematic gas properties of core ERQ with those of other luminous narrow- and broad-line AGN. In particular, we provide a revised comparison of the [OIII] kinematics in 21 core ERQ (20 from Perrotta et al. 2019, MNRAS, 488, 4126 and SDSS J171420.38+414815.7, based on GTC EMIR near-infrared spectroscopy) with other samples of quasars with matching luminosity with the aim of evaluating whether core ERQ host the most extreme [OIII] outflows. Results. The UV line ratios suggest that the physical properties (e.g., density and metallicity) of the ionised gas in core ERQ are similar to those observed in the broad-line region of blue nitrogen-loud quasars. The [OIII] outflow velocities of core ERQ are on average consistent with those of very luminous blue type 1 quasars, although extreme outflows are much more frequent in core ERQ. These similarities can be explained in the context of the AGN unification model under the assumption that core ERQ are viewed with an intermediate orientation between type 2 (edge-on) and type 1 (face-on) quasars. Conclusions. We propose that core ERQ are very luminous but otherwise normal quasars viewed at an intermediate orientation. This orientation allows a direct view of the outer part of the large broad-line region from which core ERQ UV line emission originates; the extreme [OIII] outflow velocities are instead a consequence of the very high luminosity of core ERQ.

scholarly journals Galaxies of the z ∼ 2 Universe. I. Grism-selected Rest-frame Optical Emission-line Galaxies

2019 ◽  
Vol 875 (2) ◽  
pp. 152 ◽  
Author(s):  
William P. Bowman ◽  
Gregory R. Zeimann ◽  
Robin Ciardullo ◽  
Caryl Gronwall ◽  
Donald P. Schneider ◽  
...  
Keyword(s):  
Emission Line ◽  
Rest Frame ◽  
Optical Emission ◽  
Emission Line Galaxies

scholarly journals A large, deep 3 deg2 survey of H α, [O iii], and [O ii] emitters from LAGER: constraining luminosity functions

2020 ◽  
Vol 493 (3) ◽  
pp. 3966-3984 ◽  
Author(s):  
A A Khostovan ◽  
S Malhotra ◽  
J E Rhoads ◽  
C Jiang ◽  
J Wang ◽  
...  
Keyword(s):  
Star Formation ◽  
Emission Line ◽  
Rest Frame ◽  
Formation Rate ◽  
Photometric Redshifts ◽  
Lyman Alpha ◽  
Star Formation Activity ◽  
Luminosity Functions ◽  
Emission Line Galaxies ◽  
Dust Attenuation

ABSTRACT We present our measurements of the H α, [O iii], and [O ii] luminosity functions as part of the Lyman Alpha Galaxies at Epoch of Reionization (LAGER) survey using our samples of 1577 z = 0.47 H α-, 3933 z = 0.93 [O iii]-, and 5367 z = 1.59 [O ii]-selected emission line galaxies in a 3 deg2 single, CTIO/Blanco DECam pointing of the COSMOS field. Our observations reach 5σ depths of 8.2 × 10−18 erg s−1 cm−2 and comoving volumes of (1−7) × 105 Mpc3 making our survey one of the deepest narrow-band surveys. We select our emission line galaxies via spectroscopic confirmation, photometric redshifts, and colour–colour selections. We measure the observed luminosity functions for each sample and find best fits of $\phi ^\star = 10^{-3.16^{+0.09}_{-0.09}}$ Mpc−3 and $L^\star = 10^{41.72^{+0.09}_{-0.09}}$ erg s−1 for H α, $\phi ^\star = 10^{-2.16^{+0.10}_{-0.12}}$ Mpc−3 and $L^\star = 10^{41.38^{+0.07}_{-0.06}}$ erg s−1 for [O iii], and $\phi ^\star = 10^{-1.97^{+0.07}_{-0.07}}$ Mpc−3 and $L^\star = 10^{41.66^{+0.03}_{-0.03}}$ erg s−1 for [O ii], with α fixed to −1.75, −1.6, and −1.3, respectively. An excess of bright >1042 erg s−1 [O iii] emitters is observed and may be due to active galactic nucleus (AGN) contamination. Corrections for dust attenuation are applied assuming AHα = 1 mag. We also design our own empirical rest-frame g − r calibration using SDSS DR12 data, test it against our z = 0.47 H α emitters with zCOSMOS 1D spectra, and calibrate it for (g − r) between −0.8 and 1.3 mag. Dust and AGN-corrected star formation rate densities (SFRDs) are measured as log10ρSFR/(M⊙ yr−1 Mpc−3) = −1.63 ± 0.04, −1.07 ± 0.06, and −0.90 ± 0.10 for H α, [O iii], and [O ii], respectively. We find our [O iii] and [O ii] samples fully trace cosmic star formation activity at their respective redshifts in comparison to multiwavelength SFRDs, while the H α sample traces ∼70 per cent of the total z = 0.47 SFRD.

scholarly journals Quasars as standard candles II

2019 ◽  
Vol 631 ◽  
pp. A120 ◽  
Author(s):  
F. Salvestrini ◽  
G. Risaliti ◽  
S. Bisogni ◽  
E. Lusso ◽  
C. Vignali
Keyword(s):  
Active Galactic Nuclei ◽  
Rest Frame ◽  
Galactic Nuclei ◽  
Observational Cosmology ◽  
X Ray ◽  
Uv Emission ◽  
Wide Range ◽  
Photon Index ◽  
Lower Redshift

A tight non-linear relation between the X-ray and the optical-ultraviolet (UV) emission has been observed in active galactic nuclei (AGN) over a wide range of redshift and several orders of magnitude in luminosity, suggesting the existence of an ubiquitous physical mechanism regulating the energy transfer between the accretion disc and the X-ray emitting corona. Recently, our group developed a method to use this relation in observational cosmology, turning quasars into standardizable candles. This work mainly seeks to investigate the potential evolution of this correction at high redshifts. We thus studied the LX − LUV relation for a sample of quasars in the redshift range 4 <  z <  7, adopting the selection criteria proposed in our previous work regarding their spectral properties. The resulting sample consists of 53 type 1 (unobscured) quasars, observed either with Chandra or XMM-Newton, for which we performed a full spectral analysis, determining the rest-frame 2 keV flux density, as well as more general X-ray properties such as the estimate of photon index, and the soft (0.5–2 keV) and hard (2–10 keV) unabsorbed luminosities. We find that the relation shows no evidence for evolution with redshift. The intrinsic dispersion of the LX–LUV for a sample free of systematics/contaminants is of the order of 0.22 dex, which is consistent with previous estimates from our group on quasars at lower redshift.

scholarly journals X-ray detected AGN in SDSS dwarf galaxies

2020 ◽  
Vol 492 (2) ◽  
pp. 2268-2284 ◽  
Author(s):  
Keir L Birchall ◽  
M G Watson ◽  
J Aird
Keyword(s):  
Black Holes ◽  
Power Law ◽  
Growth Rates ◽  
Dwarf Galaxies ◽  
Optical Emission ◽  
Host Galaxy ◽  
X Ray ◽  
Wide Range ◽  
Accretion Rates ◽  
Parent Sample

ABSTRACT In this work we present a robust quantification of X-ray selected AGN in local (z ≤ 0.25) dwarf galaxies ($M_\mathrm{*} \le 3 \times 10^9 \, \mathrm{M_\odot }$). We define a parent sample of 4331 dwarf galaxies found within the footprint of both the MPA-JHU galaxy catalogue (based on SDSS DR8) and 3XMM DR7, performed a careful review of the data to remove misidentifications and produced a sample of 61 dwarf galaxies that exhibit nuclear X-ray activity indicative of an AGN. We examine the optical emission line ratios of our X-ray selected sample and find that optical AGN diagnostics fail to identify 85 per cent of the sources. We then calculated the growth rates of the black holes powering our AGN in terms of their specific accretion rates (∝ LX/M*, an approximate tracer of the Eddington ratio). Within our observed sample, we found a wide range of specific accretion rates. After correcting the observed sample for the varying sensitivity of 3XMM, we found further evidence for a wide range of X-ray luminosities and specific accretion rates, described by a power law. Using this corrected AGN sample we also define an AGN fraction describing their relative incidence within the parent sample. We found the AGN fraction increases with host galaxy mass (up to ≈6 per cent) for galaxies with X-ray luminosities between $10^{39} \, $ and $10^{42} \, \mathrm{erg\, s^{-1}}$, and by extrapolating the power law to higher luminosities, we found evidence to suggest the fraction of luminous AGN ($L_\mathrm{X} \ge 10^{42.4} \, \mathrm{erg\, s^{-1}}$) is constant out to z ≈ 0.7.

scholarly journals Resolved imaging and spectroscopy of QSOs

1986 ◽  
Vol 119 ◽  
pp. 117-119 ◽  
Author(s):  
Paul Hickson ◽  
J. B. Hutchings
Keyword(s):  
Emission Line ◽  
Host Galaxy ◽  
Host Galaxies ◽  
X Ray ◽  
Line Intensities ◽  
Wide Range ◽  
Luminous Galaxies ◽  
Nuclear Changes ◽  
Imaging And Spectroscopy ◽  
Absorption Features

We have obtained direct images and off-nuclear spectra for five QSOs having a wide range of radio, optical and X-ray luminosity. Four objects show absorption features identified with stars in a host galaxy, and off-nuclear changes in emission line wavelengths. All objects show off-nuclear changes in continuum coulour, and in emission line intensities and ratios. The radio loud objects have more luminous galaxies, strong and extended [OII] and [OIII], and UV-bright nuclei. They tend to have luminous nuclei, high nuclear to galaxy luminosity ratio, and blue host galaxies. This paper is a brief summary of results that will appear in more detail elsewhere.

scholarly journals The MOSDEF Survey: Significant Evolution in the Rest-frame Optical Emission Line Equivalent Widths of Star-forming Galaxies at z = 1.4–3.8

2018 ◽  
Vol 869 (2) ◽  
pp. 92 ◽  
Author(s):  
Naveen A. Reddy ◽  
Alice E. Shapley ◽  
Ryan L. Sanders ◽  
Mariska Kriek ◽  
Alison L. Coil ◽  
...  
Keyword(s):  
Emission Line ◽  
Rest Frame ◽  
Optical Emission ◽  
Star Forming

scholarly journals Investigating the physical properties of galaxies in the Epoch of Reionization with MIRI/JWST spectroscopy

2019 ◽  
Vol 629 ◽  
pp. A9
Author(s):  
J. Álvarez-Márquez ◽  
L. Colina ◽  
R. Marques-Chaves ◽  
D. Ceverino ◽  
A. Alonso-Herrero ◽  
...  
Keyword(s):  
Star Formation ◽  
Physical Properties ◽  
Rest Frame ◽  
Near Infrared ◽  
Signal To Noise Ratio ◽  
Full Range ◽  
Optical Emission ◽  
Emission Lines ◽  
Wide Range ◽  
Stellar Masses

The James Webb Space Telescope (JWST) will provide deep imaging and spectroscopy for sources at redshifts above 6, covering the entire Epoch of Reionization (EoR, 6 <  z <  10), and enabling the detailed exploration of the nature of the different sources during the first 1 Gyr of the history of the Universe. The Medium Resolution Spectrograph (MRS) of the mid-IR Instrument (MIRI) will be the only instrument on board JWST able to observe the brightest optical emission lines Hα and [OIII]0.5007 μm at redshifts above 7 and 9, respectively, providing key insights into the physical properties of sources during the early phases of the EoR. This paper presents a study of the Hα fluxes predicted by state-of-the-art FIRSTLIGHT cosmological simulations for galaxies at redshifts of 6.5–10.5, and its detectability with MIRI. Deep (40 ks) spectroscopic integrations with MRS will be able to detect (signal-to-noise ratio > 5) EoR sources at redshifts above 7 with intrinsic star formation rates (SFR) of more than 2 M⊙ yr−1, and stellar masses above 4–9 × 107 M⊙. These limits cover the upper end of the SFR and stellar mass distribution at those redshifts, representing ∼6% and ∼1% of the predicted FIRSTLIGHT population at the 6.5–7.5 and 7.5–8.5 redshift ranges, respectively. In addition, the paper presents realistic MRS simulated observations of the expected rest-frame optical and near-infrared spectra for some spectroscopically confirmed EoR sources recently detected by ALMA as [OIII]88 μm emitters. The MRS simulated spectra cover a wide range of low metallicities from about 0.2–0.02 Z⊙, and different [OIII]88 μm/[OIII]0.5007 μm line ratios. The simulated 10 ks MRS spectra show S/N in the range of 5–90 for Hβ, [OIII]0.4959,0.5007 μm, Hα and HeI1.083 μm emission lines of the currently highest spectroscopically confirmed EoR (lensed) source MACS1149-JD1 at a redshift of 9.11, independent of metallicity. In addition, deep 40 ksec simulated spectra of the luminous merger candidate B14-65666 at 7.15 shows the MRS capabilities of detecting, or putting strong upper limits on, the weak [NII]0.6584 μm, [SII]0.6717,0.6731 μm, and [SIII]0.9069,0.9532 μm emission lines. These observations will provide the opportunity of deriving accurate metallicities in bright EoR sources using the full range of rest-frame optical emission lines up to 1 μm. In summary, MRS will enable the detailed study of key physical properties such as internal extinction, instantaneous star formation, hardness of the ionizing continuum, and metallicity in bright (intrinsic or lensed) EoR sources.

scholarly journals Near infrared spectroscopy and star-formation histories of 3 ≤ z ≤ 4 quiescent galaxies

2018 ◽  
Vol 618 ◽  
pp. A85 ◽  
Author(s):  
C. Schreiber ◽  
K. Glazebrook ◽  
T. Nanayakkara ◽  
G. G. Kacprzak ◽  
I. Labbé ◽  
...  
Keyword(s):  
Star Formation ◽  
Rest Frame ◽  
Stellar Population ◽  
Main Sequence ◽  
Near Infrared ◽  
Photometric Redshifts ◽  
Wide Range ◽  
Order Of Magnitude ◽  
Star Formation Histories ◽  
Absorption Features

We present Keck–MOSFIRE H and K spectra for a sample of 24 candidate quiescent galaxies at 3 < z < 4, identified from their rest-frame UVJ colors and photometric redshifts in the ZFOURGE and 3DHST surveys. With median integration times of one hour in H and five in K, we obtain spectroscopic redshifts for half of the sample, using either Balmer absorption lines or nebular emission lines. We confirm the high accuracy of the photometric redshifts for this spectroscopically-confirmed sample, with a median |Zphot − Zspec|/(1 + Zspec) of 1.2%. Two galaxies turn out to be dusty Hα emitters at lower redshifts (z < 2.5), and these are the only two detected in the sub-mm with ALMA. High equivalent-width [O III] emission is observed in two galaxies, contributing up to 30% of the K-band flux and mimicking the UVJ colors of an old stellar population. This implies a failure rate of only 20% for the UVJ selection at these redshifts. Lastly, Balmer absorption features are identified in four galaxies, among the brightest of the sample, confirming the absence of OB stars. We then modeled the spectra and photometry of all quiescent galaxies with a wide range of star-formation histories. We find specific star-formation rates (sSFR) lower than 0.15 Gyr−1 (a factor of ten below the main sequence) for all but one galaxy, and lower than 0.01 Gyr−1 for half of the sample. These values are consistent with the observed Hβ and [O II] luminosities, and the ALMA non-detections. The implied formation histories reveal that these galaxies have quenched on average 300 Myr prior to being observed, between z  =  3.5 and 5, and that half of their stars were formed by z ∼ 5.5 with a mean SFR ~ 300 M⊙ yr−1. We finally compared the UVJ selection to a selection based instead on the sSFR, as measured from the photometry. We find that galaxies a factor of ten below the main sequence are 40% more numerous than UVJ-selected quiescent galaxies, implying that the UVJ selection is pure but incomplete. Current models fail at reproducing our observations, and underestimate either the number density of quiescent galaxies by more than an order of magnitude, or the duration of their quiescence by a factor two. Overall, these results confirm the existence of an unexpected population of quiescent galaxies at z > 3, and offer the first insights on their formation histories.

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