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Start Over Subject infrared photometry Subject quasars Subject sloan photometry
1. Compilation of known QSOs for the Gaia mission
ID:
ivo://CDS.VizieR/J/other/RAA/19.29
Title:
Compilation of known QSOs for the Gaia mission
Short Name:
J/other/RAA/19.2
Date:
21 Oct 2021
Publisher:
CDS
Description:
Quasars are essential for astrometric in the sense that they are spatial stationary because of their large distance from the Sun. The European Space Agency (ESA) space astrometric satellite Gaia is scanning the whole sky with unprecedented accuracy up to a few uas level. However, Gaia's two fields of view observations strategy may introduce a parallax bias in the Gaia catalog. Since it presents no significant parallax, quasar is perfect nature object to detect such bias. More importantly, quasars can be used to construct a Celestial Reference Frame in the optical wavelengths in Gaia mission. In this paper, we compile the most reliable quasars existing in literatures.The final compilation (designated as Known Quasars Catalog for Gaia mission, KQCG) contains 1842076 objects, among of them, 797632 objects are found in Gaia DR1 after cross-identifications. This catalog will be very useful in Gaia mission.
2. Deep CFHT imaging of VVDS-F22 field. II. Quasars
ID:
ivo://CDS.VizieR/J/AJ/155/110
Title:
Deep CFHT imaging of VVDS-F22 field. II. Quasars
Short Name:
J/AJ/155/110
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the results of a faint quasar survey in a one-square-degree field. The aim is to test the Y-K/g-z and J-K/i-Y color selection criteria for quasars at faint magnitudes to obtain a complete sample of quasars based on deep optical and near-infrared color-color selection and to measure the faint end of the quasar luminosity function (QLF) over a wide redshift range. We carried out a quasar survey based on the Y-K/g-z and J-K/i-Y quasar selection criteria, using the deep Y-band data obtained from our CFHT/WIRCam Y-band images in a two-degree field within the F22 field of the VIMOS VLT deep survey, optical co-added data from Sloan Digital Sky Survey Stripe 82 and deep near-infrared data from the UKIDSS Deep Extragalactic Survey in the same field. We discovered 25 new quasars at 0.5<z<4.5 and i<22.5 mag within one-square-degree field. The survey significantly increases the number of faint quasars in this field, especially at z~2-3. It confirms that our color selections are highly complete in a wide redshift range (z<4.5), especially over the quasar number density peak at z~2-3, even for faint quasars. Combining all previous known quasars and new discoveries, we construct a sample with 109 quasars and measure the binned QLF and parametric QLF. Although the sample is small, our results agree with a pure luminosity evolution at lower redshift and luminosity evolution and density evolution model at redshift z>2.5.
3. ELQS in SDSS. III. The full ELQS quasar catalog
ID:
ivo://CDS.VizieR/J/ApJ/871/258
Title:
ELQS in SDSS. III. The full ELQS quasar catalog
Short Name:
J/ApJ/871/258
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have designed the Extremely Luminous Quasar Survey (ELQS) to provide a highly complete census of unobscured UV-bright quasars during the cosmic noon, z=2.8-5.0. Here we report the discovery of 70 new quasars in the ELQS South Galactic Cap (ELQS-S) quasar sample, doubling the number of known extremely luminous quasars in 4237.3deg^2^ of the Sloan Digital Sky Survey footprint. These observations conclude the ELQS and we present the properties of the full ELQS quasar catalog, containing 407 quasars over 11838.5deg^2^. Our novel ELQS quasar selection strategy resulted in unprecedented completeness at the bright end and allowed us to discover 109 new quasars in total. This marks an increase of ~36% (109/298) in the known population at these redshifts and magnitudes, while we further are able to retain a selection efficiency of ~80%. On the basis of 166 quasars from the full ELQS quasar catalog, which adhere to the uniform criteria of the Two Micron All Sky Survey point source catalog, we measure the bright-end quasar luminosity function (QLF) and extend it one magnitude brighter than previous studies. Assuming a single power law with exponential density evolution for the functional form of the QLF, we retrieve the best-fit parameters from a maximum likelihood analysis. We find a steep bright-end slope of {beta}~-4.1, and we can constrain the bright-end slope to {beta}<=-3.4 with 99% confidence. The density is well modeled by the exponential redshift evolution, resulting in a moderate decrease with redshift ({gamma}~-0.4).
4. FIR properties of SDSS type 1 quasars
ID:
ivo://CDS.VizieR/J/ApJ/768/13
Title:
FIR properties of SDSS type 1 quasars
Short Name:
J/ApJ/768/13
Date:
21 Oct 2021
Publisher:
CDS
Description:
We use the Spitzer Space Telescope Enhanced Imaging Products and the Spitzer Archival Far-InfraRed Extragalactic Survey to study the spectral energy distributions (SEDs) of spectroscopically confirmed type 1 quasars selected from the Sloan Digital Sky Survey (SDSS). By combining the Spitzer and SDSS data with the Two Micron All Sky Survey, we are able to construct a statistically robust rest-frame 0.1-100{mu}m type 1 quasar template. We find that the quasar population is well-described by a single power-law SED at wavelengths less than 20{mu}m, in good agreement with previous work. However, at longer wavelengths, we find a significant excess in infrared luminosity above an extrapolated power-law, along with significant object-to-object dispersion in the SED. The mean excess reaches a maximum of 0.8dex at rest-frame wavelengths near 100{mu}m.
5. FIR properties of SDSS 0.1<z<5 quasars
ID:
ivo://CDS.VizieR/J/ApJ/811/58
Title:
FIR properties of SDSS 0.1<z<5 quasars
Short Name:
J/ApJ/811/58
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using the public data from the Herschel wide-field surveys, we study the far-infrared properties of optical-selected quasars from the Sloan Digital Sky Survey. Within the common area of ~172deg^2^, we have identified the far-infrared counterparts for 354 quasars, among which 134 are highly secure detections in the Herschel 250um band (signal-to-noise ratios >=5). This sample is the largest far-infrared quasar sample of its kind, and spans a wide redshift range of 0.14<=z<=4.7. Their far-infrared spectral energy distributions, which are due to the cold-dust components within the host galaxies, are consistent with being heated by active star formation. In most cases (>~80%), their total infrared luminosities as inferred from only their far-infrared emissions (L_IR_^(cd)^) already exceed 10^12^L_{sun}_, and thus these objects qualify as ultra-luminous infrared galaxies. There is no correlation between L_IR_^(cd)^ and the absolute magnitudes, the black hole masses or the X-ray luminosities of the quasars, which further support that their far-infrared emissions are not due to their active galactic nuclei. A large fraction of these objects (>~50%-60%) have star-formation rates >~300M_{sun}_/yr. Such extreme starbursts among optical quasars, however, is only a few percent. This fraction varies with redshift, and peaks at around z~2. Among the entire sample, 136 objects have secure estimates of their cold-dust temperatures (T), and we find that there is a dramatic increasing trend of T with increasing L_IR_^(cd)^. We interpret this trend as the envelope of the general distribution of infrared galaxies on the (T, L_IR_^(cd)^) plane.
6. IR measurement of quasar obscuration
ID:
ivo://CDS.VizieR/J/ApJ/679/140
Title:
IR measurement of quasar obscuration
Short Name:
J/ApJ/679/140
Date:
21 Oct 2021
Publisher:
CDS
Description:
Recent work has suggested that the fraction of obscured AGNs declines with increasing luminosity, but it has been difficult to quantify this trend. Here we attempt to measure this fraction as a function of luminosity by studying the ratio of mid-infrared to intrinsic nuclear bolometric luminosity in unobscured AGNs. Because the mid-infrared is created by dust reprocessing of shorter wavelength nuclear light, this ratio is a diagnostic of f_obsc_, the fraction of solid angle around the nucleus covered by obscuring matter. In order to eliminate possible redshift dependences while also achieving a large dynamic range in luminosity, we have collected archival 24um MIPS photometry from objects with z~1 in the Sloan Digital Sky Survey DR5, the Great Observatories Origins Deep Survey, and the Cosmic Evolution Survey. To measure the bolometric luminosity for each object, we used archival optical data supplemented by GALEX data.
7. Large area KX quasar catalogue
ID:
ivo://CDS.VizieR/J/MNRAS/424/2876
Title:
Large area KX quasar catalogue
Short Name:
J/MNRAS/424/2876
Date:
21 Oct 2021
Publisher:
CDS
Description:
The results of a large area, ~600deg^2^, K-band flux-limited spectroscopic survey for luminous quasars are presented. The survey utilizes the UKIRT Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS) in regions of sky within the Sloan Digital Sky Survey (SDSS) footprint. The K-band excess (KX) of all quasars with respect to Galactic stars is exploited in combination with a photometric redshift/classification scheme to identify quasar candidates for spectroscopic follow-up observations. The data contained within this investigation will be able to provide new constraints on the fraction of luminous quasars reddened by dust with E(B-V)<=0.5mag. The spectroscopic sample is defined using the K-band, 14.0<=K<=16.6, and SDSS i-band limits of i=19.5, 19.7 and 22.0 over sky areas of 287, 150 and 196deg^2^, respectively. The survey includes >3200 known quasars from the SDSS and more than 250 additional confirmed quasars from the KX selection. A well-defined subsample of quasars in the redshift interval 1.0<=z<=3.5 includes 1152 objects from the SDSS and 172 additional KX-selected quasars. The quasar selection is >95 per cent complete with respect to known SDSS quasars and >95 per cent efficient, largely independent of redshift and i-band magnitude. The properties of the new KX-selected quasars confirm the known redshift-dependent effectiveness of the SDSS quasar selection and provide a sample of luminous quasars experiencing intermediate levels of extinction by dust. The catalogue represents an important step towards the assembly of a well-defined sample of luminous quasars that may be used to investigate the properties of quasars experiencing intermediate levels of dust extinction within their host galaxies or due intervening absorption line systems.
8. Luminous K-band selected QSOs from UKIDSS
ID:
ivo://CDS.VizieR/J/MNRAS/386/1605
Title:
Luminous K-band selected QSOs from UKIDSS
Short Name:
J/MNRAS/386/1605
Date:
21 Oct 2021
Publisher:
CDS
Description:
The largest K-band flux-limited sample of luminous quasars to date has been constructed from the UKIRT (UK Infrared Telescope) Infrared Deep Sky Survey (UKIDSS) Large Area Survey Early Data Release, covering an effective area of 12.8deg^2^. Exploiting the K-band excess (KX) of all quasars with respect to foreground stars, including quasars experiencing dust reddening and objects with non-standard spectral energy distributions (SEDs), a list of targets suitable for spectroscopic follow-up observations with the AAOmega multi-object spectrograph is constructed, resulting in more than 200 confirmed active galactic nuclei (AGN). KX selection successfully identifies as quasar candidates objects that are excluded from the Sloan Digital Sky Survey (SDSS) quasar selection algorithm due to their colours being consistent with the stellar locus in optical colour space (with the space density of the excluded objects agreeing well with results from existing completeness analyses). Nearly half of the KX-selected quasars with K<=17.0 at z<3 are too faint in the i band to have been targeted by the SDSS quasar selection algorithm, revealing a large population of quasars with red i-K colours.
9. Luminous of high-z QSOs with SDSS and WISE. II
ID:
ivo://CDS.VizieR/J/ApJ/829/33
Title:
Luminous of high-z QSOs with SDSS and WISE. II
Short Name:
J/ApJ/829/33
Date:
21 Oct 2021
Publisher:
CDS
Description:
This is the second paper in a series on a new luminous z~5 quasar survey using optical and near-infrared colors. Here we present a new determination of the bright end of the quasar luminosity function (QLF) at z~5. Combining our 45 new quasars with previously known quasars that satisfy our selections, we construct the largest uniform luminous z~5 quasar sample to date, with 99 quasars in the range of 4.7<=z<5.4 and -29<M_1450_<=-26.8, within the Sloan Digital Sky Survey (SDSS) footprint. We use a modified 1/V_a_ method including flux limit correction to derive a binned QLF, and we model the parametric QLF using maximum likelihood estimation. With the faint-end slope of the QLF fixed as {alpha}=-2.03 from previous deeper samples, the best fit of our QLF gives a flatter bright end slope {beta}=-3.58+/-0.24 and a fainter break magnitude M_1450_^*^=-26.98+/-0.23 than previous studies at similar redshift. Combined with previous work at lower and higher redshifts, our result is consistent with a luminosity evolution and density evolution model. Using the best-fit QLF, the contribution of quasars to the ionizing background at z~5 is found to be 18%-45% with a clumping factor C of 2-5. Our sample suggests an evolution of radio loud fraction with optical luminosity but no obvious evolution with redshift.
10. Luminous WISE-selected quasars in SDSS Stripe 82
ID:
ivo://CDS.VizieR/J/ApJ/861/37
Title:
Luminous WISE-selected quasars in SDSS Stripe 82
Short Name:
J/ApJ/861/37
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a spectroscopically complete sample of 147 infrared-color-selected active galactic nuclei (AGNs) down to a 22{mu}m flux limit of 20mJy over the ~270deg^2^ of the Sloan Digital Sky Survey Stripe 82 region. Most of these sources are in the QSO luminosity regime (Lbol>~10^12^L_{sun}_) and are found out to z~3. We classify the AGNs into three types, finding 57 blue, unobscured Type-1 (broad-lined) sources; 69 obscured, Type-2 (narrow-lined) sources; and 21 moderately reddened Type-1 sources (broad-lined and E(B-V)>0.25). We study a subset of this sample in X-rays and analyze their obscuration to find that our spectroscopic classifications are in broad agreement with low, moderate, and large amounts of absorption for Type-1, red Type-1, and Type-2 AGNs, respectively. We also investigate how their X-ray luminosities correlate with other known bolometric luminosity indicators such as [OIII] line luminosity (L[OIII]) and infrared luminosity (L6{mu}m). While the X-ray correlation with L[OIII] is consistent with previous findings, the most infrared-luminous sources appear to deviate from established relations such that they are either underluminous in X-rays or overluminous in the infrared. Finally, we examine the luminosity function evolution of our sample, and by AGN type, in combination with the complementary, infrared-selected, AGN sample of Lacy et al. (2013), spanning over two orders of magnitude in luminosity. We find that the two obscured populations evolve differently, with reddened Type-1 AGNs dominating the obscured AGN fraction (~30%) for L_5{mu}m_>10^45^erg/s, while the fraction of Type-2 AGNs with L_5{mu}m_<10^45^erg/s rises sharply from 40% to 80% of the overall AGN population.

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