scholarly journals Proximate molecular quasar absorbers

2019 ◽  
Vol 627 ◽  
pp. A32 ◽  
Author(s):  
P. Noterdaeme ◽  
S. Balashev ◽  
J.-K. Krogager ◽  
R. Srianand ◽  
H. Fathivavsari ◽  
...  
Keyword(s):  
Control Sample ◽  
Neutral Hydrogen ◽  
Sloan Digital Sky Survey ◽  
Metal Species ◽  
Physical Conditions ◽  
The Core ◽  
Sky Survey ◽  
Large Spread ◽  
Order Of Magnitude

We present results from a search for strong H2 absorption systems proximate to quasars (zabs ≈ zem) in the Sloan Digital Sky Survey (SDSS) Data Release 14. The search is based on the Lyman-Werner band signature of damped H2 absorption lines without any prior on the associated metal or neutral hydrogen content. This has resulted in the detection of 81 systems with N(H2) ∼ 1019 − 1020 cm−2 located within a few thousand km s−1 from the quasar. Compared to a control sample of intervening systems, this implies an excess of proximate H2 systems by about a factor of 4 to 5. The incidence of H2 systems increases steeply with decreasing relative velocity, reaching an order of magnitude higher than expected from intervening statistics at Δv <  1000 km s−1. The most striking feature of the proximate systems compared to the intervening ones is the presence of Ly − α emission in the core of the associated damped H I absorption line in about half of the sample. This puts constraints on the relative projected sizes of the absorbing clouds to those of the quasar line emitting regions. Using the SDSS spectra, we estimate the H I, metal and dust content of the systems, which are found to have typical metallicities of one tenth Solar, albeit with a large spread among individual systems. We observe trends between the fraction of leaking Ly − α emission and the relative absorber-quasar velocity as well as with the excitation of several metal species, similar to what has been seen in metal-selected proximate DLAs. With the help of theoretical H I-H2 transition relations, we show that the presence of H2 helps to break the degeneracy between density and strength of the UV field as main sources of excitation and hence provides unique constraints on the possible origin and location of the absorbing clouds. We suggest that most of these systems originate from galaxies in the quasar group, although a small fraction of them could be located in the quasar host as well. We conclude that follow-up observations are still required to investigate the chemical and physical conditions in individual clouds and to assess the importance of AGN feedback for the formation and survival of H2 clouds.

The Quest for Relics: Massive compact galaxies in the local Universe

2019 ◽  
Vol 15 (S359) ◽  
pp. 441-443
Author(s):  
F. S. Lohmann ◽  
A. Schnorr-Müller ◽  
M. Trevisan ◽  
R. Riffel ◽  
N. Mallmann ◽  
...  
Keyword(s):  
High Redshift ◽  
Control Sample ◽  
Sloan Digital Sky Survey ◽  
Integral Field Spectroscopy ◽  
Sky Survey ◽  
Size Evolution ◽  
Compact Galaxies ◽  
Minor Mergers ◽  
Significant Size ◽  
Integral Field

AbstractObservations at high redshift reveal that a population of massive, quiescent galaxies (called red nuggets) already existed 10 Gyr ago. These objects undergo a significant size evolution over time, likely due to minor mergers. In this work we present an analysis of local massive compact galaxies to assess if their properties are consistent with what is expected for unevolved red nuggets (relic galaxies). Using integral field spectroscopy (IFS) data from the MaNGA survey from the Sloan Digital Sky Survey (SDSS), we characterized the kinematics and properties of stellar populations of massive compact galaxies, and find that these objects exhibit, on average, a higher rotational support than a control sample of average sized early-type galaxies. This is in agreement with a scenario in which these objects have a quiet accretion history, rendering them candidates for relic galaxies.

scholarly journals Spitzer IRS Observations of Low-Mass Seyfert Galaxies

2009 ◽  
Vol 5 (S267) ◽  
pp. 268-268
Author(s):  
Carol E. Thornton ◽  
Aaron J. Barth ◽  
Luis C. Ho ◽  
Jenny E. Greene
Keyword(s):  
Dust Emission ◽  
Seyfert Galaxies ◽  
Sloan Digital Sky Survey ◽  
Physical Conditions ◽  
Sky Survey ◽  
Low Mass ◽  
Ngc 4395 ◽  
Black Hole Masses

The Sloan Digital Sky Survey has made it possible to identify the first samples of active galaxies with estimated black hole masses below ~ 106M⊙. We have obtained Spitzer IRS low-resolution spectra, covering 5–38 μm, of a sample of 41 Seyfert galaxies with low-mass black holes. Our sample includes SDSS-selected objects from the low-mass Seyfert 1 sample of Greene & Ho (2004) and the low-mass Seyfert 2 sample of Barth et al. (2008), as well as NGC 4395 and POX 52. The goals of this work are to examine the dust emission properties of these objects and investigate the relationship between type 1 and type 2 AGNs at low luminosities and low masses, to search for evidence of star formation, and to use emission-line diagnostics to constrain physical conditions within the narrow-line regions. Here we present preliminary results from this project.

scholarly journals Fundamental differences in the radio properties of red and blue quasars: insight from the LOFAR Two-metre Sky Survey (LoTSS)

2020 ◽  
Vol 494 (3) ◽  
pp. 3061-3079 ◽  
Author(s):  
D J Rosario ◽  
V A Fawcett ◽  
L Klindt ◽  
D M Alexander ◽  
L K Morabito ◽  
...  
Keyword(s):  
Star Formation ◽  
Control Sample ◽  
Low Frequency ◽  
Galactic Nuclei ◽  
Sloan Digital Sky Survey ◽  
Stellar Objects ◽  
Radio Detection ◽  
Sky Survey ◽  
Quasi Stellar Objects ◽  
First Time

ABSTRACT Red quasi-stellar objects (QSOs) are a subset of the luminous end of the cosmic population of active galactic nuclei (AGNs), most of which are reddened by intervening dust along the line of sight towards their central engines. In recent work from our team, we developed a systematic technique to select red QSOs from the Sloan Digital Sky Survey, and demonstrated that they have distinctive radio properties using the Faint Images of the Radio Sky at Twenty centimetres radio survey. Here we expand our study using low-frequency radio data from the LOFAR Two-metre Sky Survey (LoTSS). With the improvement in depth that LoTSS offers, we confirm key results: Compared to a control sample of normal ‘blue’ QSOs matched in redshift and accretion power, red QSOs have a higher radio detection rate and a higher incidence of compact radio morphologies. For the first time, we also demonstrate that these differences arise primarily in sources of intermediate radio loudness: Radio-intermediate red QSOs are × 3 more common than typical QSOs, but the excess diminishes among the most radio-loud systems and the most radio-quiet systems in our study. We develop Monte Carlo simulations to explore whether differences in star formation could explain these results, and conclude that, while star formation is an important source of low-frequency emission among radio-quiet QSOs, a population of AGN-driven compact radio sources is the most likely cause for the distinct low-frequency radio properties of red QSOs. Our study substantiates the conclusion that fundamental differences must exist between the red and normal blue QSO populations.

scholarly journals Megaparsec-scale structure around the protocluster core SPT2349–56 at z = 4.3

2020 ◽  
Vol 495 (3) ◽  
pp. 3124-3159 ◽  
Author(s):  
Ryley Hill ◽  
Scott Chapman ◽  
Douglas Scott ◽  
Yordanka Apostolovski ◽  
Manuel Aravena ◽  
...  
Keyword(s):  
Luminosity Function ◽  
Far Infrared ◽  
Main Structure ◽  
Star Forming ◽  
Galaxy Groups ◽  
The Core ◽  
Order Of Magnitude ◽  
Number Counts ◽  
Limited Coverage

ABSTRACT We present an extensive ALMA spectroscopic follow-up programme of the $z\, {=}\, 4.3$ structure SPT2349–56, one of the most actively star-forming protocluster cores known, to identify additional members using their [C ii] 158 μm and CO(4–3) lines. In addition to robustly detecting the 14 previously published galaxies in this structure, we identify a further 15 associated galaxies at $z\, {=}\, 4.3$, resolving 55$\, {\pm }\,$5 per cent of the 870 μm flux density at 0.5 arcsec resolution compared to 21 arcsec single-dish data. These galaxies are distributed into a central core containing 23 galaxies extending out to 300 kpc in diameter, and a northern extension, offset from the core by 400 kpc, containing three galaxies. We discovered three additional galaxies in a red Herschel-SPIRE source 1.5 Mpc from the main structure, suggesting the existence of many other sources at the same redshift as SPT2349–56 that are not yet detected in the limited coverage of our data. An analysis of the velocity distribution of the central galaxies indicates that this region may be virialized with a mass of (9$\pm 5)\, {\times }\, 10^{12}$  M⊙, while the two offset galaxy groups are about 30 and 60 per cent less massive and show significant velocity offsets from the central group. We calculate the [C ii] and far-infrared number counts, and find evidence for a break in the [C ii] luminosity function. We estimate the average SFR density within the region of SPT2349–56 containing single-dish emission (a proper diameter of 720 kpc), assuming spherical symmetry, to be roughly 4$\, {\times }\, 10^4$ M⊙ yr−1 Mpc−3; this may be an order of magnitude greater than the most extreme examples seen in simulations.

Further Investigation of the Effect of Galaxy Interactions on Star Formation

2013 ◽  
Vol 22 (2) ◽  
Author(s):  
Xin-Fa Deng ◽  
Fuyang Zhang
Keyword(s):  
Star Formation ◽  
Survey Data ◽  
Control Sample ◽  
Sloan Digital Sky Survey ◽  
Apparent Magnitude ◽  
Galaxy Interactions ◽  
Main Galaxy ◽  
Sky Survey ◽  
Data Release ◽  
Galaxy Sample

AbstractFrom the apparent magnitude-limited the Main galaxy sample of the Sloan Digital Sky Survey Data Release 7, we construct a paired galaxy sample and a control sample without close companions with the projected separations

scholarly journals Extreme ionised outflows are more common when the radio emission is compact in AGN host galaxies

2019 ◽  
Vol 631 ◽  
pp. A132 ◽  
Author(s):  
S. J. Molyneux ◽  
C. M. Harrison ◽  
M. E. Jarvis
Keyword(s):  
Radio Emission ◽  
Emission Line ◽  
Sloan Digital Sky Survey ◽  
Line Profiles ◽  
Host Galaxies ◽  
Gas Kinematics ◽  
Radio Jets ◽  
Sky Survey ◽  
Compact Sources

Using a sample of 2922 z <  0.2, spectroscopically identified active galactic nuclei (AGN), we explore the relationship between radio size and the prevalence of extreme ionised outflows, as traced using broad [O III] emission-line profiles in spectra obtained by the Sloan Digital Sky Survey (SDSS). To classify radio sources as compact or extended, we combined a machine-learning technique for morphological classification with size measurements from two-dimensional Gaussian models to data from all-sky radio surveys. We find that the two populations have statistically different [O III] emission-line profiles; the compact sources tend to have the most extreme gas kinematics. When the radio emission is confined within 3″ (i.e. within the spectroscopic fibre or ≲5 kpc at the median redshift), the chance of observing broad [O III] emission-line components, which are indicative of very high velocity outflows and have a full width at half-maximum > 1000 km s−1, is twice as high. This difference is greatest for the highest radio luminosity bin of log[L1.4 GHz/W Hz−1] = 23.5−24.5 where the AGN dominate the radio emission; specifically, > 1000 km s−1 components are almost four times as likely to occur when the radio emission is compact in this subsample. Our follow-up ≈0.3″–1″ resolution radio observations for a subset of targets in this luminosity range reveal that radio jets and lobes are prevalent, and suggest that compact jets might be responsible for the stronger outflows in the wider sample. Our results are limited by the available relatively shallow all-sky radio surveys, but forthcoming surveys will provide a more complete picture of the connection between radio emission and outflows. Overall, our results add to the growing body of evidence that ionised outflows and compact radio emission in highly accreting “radiative” AGN are closely connected, possibly as a result of young or weak radio jets.

scholarly journals THE SLOAN DIGITAL SKY SURVEY-II SUPERNOVA SURVEY: SEARCH ALGORITHM AND FOLLOW-UP OBSERVATIONS

2007 ◽  
Vol 135 (1) ◽  
pp. 348-373 ◽  
Author(s):  
Masao Sako ◽  
Bruce Bassett ◽  
Andrew Becker ◽  
David Cinabro ◽  
Fritz DeJongh ◽  
...  
Keyword(s):  
Search Algorithm ◽  
Sloan Digital Sky Survey ◽  
Sky Survey

XMM‐Newtonand Optical Follow‐up Observations of Three New Polars from the Sloan Digital Sky Survey

2005 ◽  
Vol 620 (2) ◽  
pp. 929-937 ◽  
Author(s):  
Lee Homer ◽  
Paula Szkody ◽  
Bing Chen ◽  
Arne Henden ◽  
Gary D. Schmidt ◽  
...  
Keyword(s):  
Sloan Digital Sky Survey ◽  
Sky Survey

scholarly journals Identifying Circumgalactic Medium Absorption in QSO Spectra: A Bayesian Approach

2021 ◽  
Vol 923 (1) ◽  
pp. 44
Author(s):  
Jennifer E. Scott ◽  
Emileigh S. Shoemaker ◽  
Colin D. Hamill
Keyword(s):  
Bayesian Methods ◽  
Statistical Approach ◽  
Hubble Space Telescope ◽  
Spectroscopic Studies ◽  
Photometric Data ◽  
Sloan Digital Sky Survey ◽  
Sky Survey ◽  
The Galaxy ◽  
Circumgalactic Medium

Abstract We present a study of candidate galaxy–absorber pairs for 43 low-redshift QSO sightlines (0.06 < z < 0.85) observed with the Hubble Space Telescope/Cosmic Origins Spectrograph that lie within the footprint of the Sloan Digital Sky Survey with a statistical approach to match absorbers with galaxies near the QSO lines of sight using only the SDSS Data Release 12 photometric data for the galaxies, including estimates of their redshifts. Our Bayesian methods combine the SDSS photometric information with measured properties of the circumgalactic medium to find the most probable galaxy match, if any, for each absorber in the line-of-sight QSO spectrum. We find ∼630 candidate galaxy–absorber pairs using two different statistics. The methods are able to reproduce pairs reported in the targeted spectroscopic studies upon which we base the statistics at a rate of 72%. The properties of the galaxies comprising the candidate pairs have median redshift, luminosity, and stellar mass, all estimated from the photometric data, z = 0.13, L = 0.1L *, and log ( M * / M ⊙ ) = 9.7 . The median impact parameter of the candidate pairs is ∼430 kpc, or ∼3.5 times the galaxy virial radius. The results are broadly consistent with the high Lyα covering fraction out to this radius found in previous studies. This method of matching absorbers and galaxies can be used to prioritize targets for spectroscopic studies, and we present specific examples of promising systems for such follow-up.

scholarly journals Detecting neutral hydrogen at z ≳ 3 in large spectroscopic surveys of quasars

2020 ◽  
Vol 498 (2) ◽  
pp. 1951-1962
Author(s):  
Michele Fumagalli ◽  
Sotiria Fotopoulou ◽  
Laura Thomson
Keyword(s):  
Random Forest ◽  
Neutral Hydrogen ◽  
Sloan Digital Sky Survey ◽  
Broad Absorption Line ◽  
Quasar Spectra ◽  
Sky Survey ◽  
William Herschel ◽  
High Column

ABSTRACT We present a pipeline based on a random forest classifier for the identification of high column density clouds of neutral hydrogen (i.e. the Lyman limit systems, LLSs) in absorption within large spectroscopic surveys of z ≳ 3 quasars. We test the performance of this method on mock quasar spectra that reproduce the expected data quality of the Dark Energy Spectroscopic Instrument and the WHT (William Herschel Telescope) Enhanced Area Velocity Explorer surveys, finding ${\gtrsim}90{{\ \rm per\ cent}}$ completeness and purity for $N_{\rm H\,\rm{\small I}} \gtrsim 10^{17.2}~\rm cm^{-2}$ LLSs against quasars of g &lt; 23 mag at z ≈ 3.5–3.7. After training and applying our method on 10 000 quasar spectra at z ≈ 3.5–4.0 from the Sloan Digital Sky Survey (Data Release 16), we identify ≈6600 LLSs with $N_{\rm H\,\rm{\small I}} \gtrsim 10^{17.5}~\rm cm^{-2}$ between z ≈ 3.1 and 4.0 with a completeness and purity of ${\gtrsim}90{{\ \rm per\ cent}}$ for the classification of LLSs. Using this sample, we measure a number of LLSs per unit redshift of ℓ(z) = 2.32 ± 0.08 at z = [3.3, 3.6]. We also present results on the performance of random forest for the measurement of the LLS redshifts and H i column densities, and for the identification of broad absorption line quasars.

Sign in / Sign up

Export Citation Format

Share Document