- ID:
- ivo://CDS.VizieR/J/A+A/636/A37
- Title:
- High-z AGN obscured by host galaxy ISM
- Short Name:
- J/A+A/636/A37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Submillimeter Galaxies (SMGs) at high redshift are among the best targets to investigate the early evolutionary phases in the lifetime of massive systems, during which large gas reservoirs sustain vigorous star formation and efficiently feed the central, buried Super Massive Black Hole (SMBH). We present the analysis of new ALMA band 4 (1.8-2.4mm) continuum and high-J CO observation of six obscured QSOs (logN_H_>23) hosted by SMGs at z>2.5 in the 7 Ms Chandra Deep Field South (CDF-S). Sizes and masses of the galaxies are measured to estimate to which extent the host ISM may contribute to the nuclear absorption. We found that at high redshift the galaxy ISM can substantially contribute to the AGN obscuration up to the Compton-thick (10^24^cm^-2^) regime. In addition, we found that all the detected sources show a velocity gradient possibly ascribed to a rotating system, even though two of them could be even associated with a chaotic, possibly merging, structure.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/862/156
- Title:
- High-z galaxy candidates in the HFF cluster fields
- Short Name:
- J/ApJ/862/156
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Acting as powerful gravitational lenses, the strong lensing galaxy clusters of the deep Hubble Frontier Fields (HFF) program permit access to lower-luminosity galaxies lying at higher redshifts than hitherto possible. We analyzed the HFF to measure the volume density of Lyman-break galaxies at z>4.75 by identifying a complete and reliable sample up to z~10. A marked deficit of such galaxies was uncovered in the highly magnified regions of the clusters relative to their outskirts, implying that the magnification of the sky area dominates over additional faint galaxies magnified above the flux limit. This negative magnification bias is consistent with a slow rollover at the faint end of the UV luminosity function and it indicates a preference for Bose-Einstein condensate dark matter with a light boson mass of m_B_~10^-22^eV over standard cold dark matter. We emphasize that measuring the magnification bias requires no correction for multiply-lensed images (with typically three or more images per source), whereas directly reconstructing the luminosity function will lead to an overestimate unless such images can be exhaustively matched up, especially at the faint end that is only accessible in the strongly lensed regions. In addition, we detected a distinctive downward transition in galaxy number density at z>~8, which may be linked to the relatively late reionization reported by Planck. Our results suggests that JWST will likely peer into an "abyss" with essentially no galaxies detected in deep NIR imaging at z>10.
- ID:
- ivo://CDS.VizieR/J/MNRAS/478/3740
- Title:
- High-z LAEs and LBGs in SHARDS survey
- Short Name:
- J/MNRAS/478/3740
- Date:
- 11 Mar 2022 14:56:32
- Publisher:
- CDS
- Description:
- We have undertaken a comprehensive search for both Lyman alpha emitters (LAEs) and Lyman break galaxies (LBGs) in the Survey for High-z Absorption Red and Dead Sources (SHARDS) Survey of the Great Observatories Origins Deep Survey North field. SHARDS is a deep imaging survey, made with the 10.4m Gran Telescopio Canarias, employing 25 medium band filters in the range from 500 to 941nm. This is the first time that both LAEs and LBGs are surveyed simultaneously in a systematic way in a large field. We draw a sample of 1558 sources; 528 of them are LAEs. Most of the sources (1434) show rest-frame UV continua. A minority of them (124) are pure LAEs with virtually no continuum detected in SHARDS. We study these sources from z~3.35 up to z~6.8, well into the epoch of reionization. Note that surveys done with just one or two narrow band filters lack the possibility to spot the rest-frame UV continuum present in most of our LAEs. We derive redshifts, star formation rates, Ly{alpha} equivalent widths, and luminosity functions (LFs). Grouping within our sample is also studied, finding 92 pairs or small groups of galaxies at the same redshift separated by less than 60 comoving kpc. In addition, we relate 87 and 55 UV-selected objects with two known overdensities at z=4.05 and z=5.198, respectively. Finally, we show that surveys made with broad-band filters are prone to introduce many unwanted sources (~20 per cent interlopers), which means that previous studies may be overestimating the calculated LFs, specially at the faint end.
- ID:
- ivo://CDS.VizieR/J/ApJ/764/9
- Title:
- High-z MgII absorption QSOs with FIRE. II.
- Short Name:
- J/ApJ/764/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed study of HI and metals for 110 MgII absorption systems discovered at 1.98<=z<=5.33 in the infrared spectra of high-redshift QSOs. Using new measurements of rest-frame UV lines from optical spectra of the same targets, we compare the high-redshift sample with carefully constructed low-redshift control samples from the literature to study evolutionary trends from z=0-->5.33 (>12Gyr). We observe a significant strengthening in the characteristic N(HI) for fixed MgII equivalent width as one moves toward higher redshift. Indeed, at our sample's mean <Z>=3.402, all MgII systems are either damped Ly{alpha} absorbers (DLAs) or sub-DLAs, with 40.7% of systems exceeding the DLA threshold (compared to 16.7% at <Z>=0.927). We set lower limits on the metallicity of the MgII systems where we can measure HI; these results are consistent with the full DLA population. The classical MgII systems (W({lambda}2796)_0_=0.3-1.0{AA}), which preferentially associate with sub-DLAs, are quite metal rich at ~0.1 solar. We applied quantitative classification metrics to our absorbers to compare with low-redshift populations, finding that weak systems are similar to classic MgII absorbers at low redshift. The strong systems either have very large MgII and FeII velocity spreads implying non-virialized dynamics or are more quiescent DLAs. There is tentative evidence that the kinetically complex systems evolve in similar fashion to the global star formation rate. We speculate that if weaker MgII systems represent accreting gas as suggested by recent studies of galaxy-absorber inclinations, then their high metal abundance suggests re-accretion of recently ejected material rather than first-time infall from the metal-poor intergalactic medium, even at early times.
- ID:
- ivo://CDS.VizieR/J/ApJ/594/1
- Title:
- High-z supernovae VRI mag and distances
- Short Name:
- J/ApJ/594/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The High-z Supernova Search Team has discovered and observed eight new supernovae in the redshift interval z=0.3-1.2. These independent observations, analyzed by similar but distinct methods, confirm the results of Riess (1998AJ....116.1009R) and Perlmutter (1999ApJ...517..565P) and coworkers that supernova luminosity distances imply an accelerating universe.
- ID:
- ivo://CDS.VizieR/J/AJ/141/23
- Title:
- HI holes in THINGS galaxies
- Short Name:
- J/AJ/141/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of the properties of HI holes detected in 20 galaxies that are part of "The HI Nearby Galaxy Survey." We detected more than 1000 holes in total in the sampled galaxies. Where they can be measured, their sizes range from about 100pc (our resolution limit) to about 2kpc, their expansion velocities range from 4 to 36km/s, and their ages are estimated to range between 3 and 150Myr. The holes are found throughout the disks of the galaxies, out to the edge of the HI disk; 23% of the holes fall outside R25. We find that shear limits the age of holes in spirals (shear is less important in dwarf galaxies) which explains why HI holes in dwarfs are rounder, on average than in spirals.
- ID:
- ivo://CDS.VizieR/J/AJ/132/242
- Title:
- H II absorption regions at 74MHz
- Short Name:
- J/AJ/132/242
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this work we present 74MHz observations in the region 26{deg}>l>-15{deg}, -5{deg}<b<5{deg} report the detection of 92 absorption features associated with known HII regions; and derive the brightness temperature of the Galactic cosmic-ray electron synchrotron emission emanating from the column behind these regions. For the 42 HII regions with known distances, the average emissivity of the column behind the HII region is derived. The 74MHz emissivity values range between 0.3 and 1.0K/pc for a model assuming uniform distribution of emissivity. Methods for using this type of data to model the three-dimensional distribution of cosmic-ray emissivity and the possibility of using this method to break the HII region kinematic distance degeneracy are discussed.
- ID:
- ivo://CDS.VizieR/J/A+A/652/A23
- Title:
- HII-chi-mistry-IR. Abundances
- Short Name:
- J/A+A/652/A23
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We provide a new method to derive heavy element abundances based on the unique suite of nebular lines in the mid- to far-infrared (IR) range. Using grids of photo-ionisation models that cover a wide range in O/H and N/O abundances, and ionisation parameter, our code HII-CHI-MISTRY-IR (HCm-IR) provides model-based abundances based on extinction free and temperature insensitive tracers, two significant advantages over optical diagnostics. The code is probed using a sample of 56 galaxies observed with Spitzer and Herschel covering a wide range in metallicity, 7.2~<12+log(O/H)~<8.9. The IR model-based metallicities obtained are robust within a scatter of 0.03dex when the hydrogen recombination lines, which are typically faint transitions in the IR range, are not available. When compared to the optical abundances obtained with the direct method,model- based methods, and strong-line calibrations, HCm-IR estimates show a typical dispersion of ~0.2dex, in line with previous studies comparing IR and optical abundances, a do not introduce a noticeable systematic above 12+log(O/H)>7.6. This accuracy can be achieved using the lines [SIV]10.5um, [SIII]18.7,33.5um, [NeIII]15.6um and [NeII]12.8um. Additionally, HCm-IR provides an independent N/O measurement when the [OIII]52,88um and [NIII]57um transitions are measured, and therefore the derived abundances in this case do not rely on particular assumptions in the N/O ratio. Large uncertainties (~0.4dex) may affect the abundance determinations of galaxies at sub- or over-solar metallicities when a solar-like N/O ratio is adopted. Finally, the code has been applied to 8 galaxies located at 1.8<z<7.5 with ground-based detections of far-IR lines redshifted in the submm range, revealing solar-like N/O and O/H abundances in agreement with recent studies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/444/757
- Title:
- HII complexes optical and IR emissions
- Short Name:
- J/MNRAS/444/757
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of optical spectroscopy and infrared aperture photometry of more than 100 HII complexes in nine galaxies. Spectra obtained with the 6-m telescope of Special Astrophysical Observatory of the Russian Academy of Sciences are used along with archival data from Spitzer and several ground-based telescopes to infer a strength of polycyclic aromatic hydrocarbon (PAH) emission, age, properties of the UV radiation field, and metallicity of studied HII complexes. Physical properties (age, radiation field parameters, metallicity) are related to the F_8_/F_24_ ratio used as a proxy for the PAH abundance in order to reveal factors that may influence the PAH evolution in HII complexes. The well-known correlation between the F_8_/F_24_ ratio and metallicity is confirmed in the studied complexes. The infrared flux ratio also correlates with the [Oiii]{lambda}5007/H{beta} ratio which is often considered as an indicator of the radiation field hardness, but this correlation seems to be a mere reflection of a correlation between [Oiii]{lambda}5007/H{beta} and metallicity. In separate metallicity bins, the F_8_/F_24_ ratio is found to correlate with an age of an Hii complex, which is estimated from the equivalent width of H{beta} line. The correlation is positive for low-metallicity complexes and negative for high-metallicity complexes. Analysing various mechanisms of PAH formation and destruction in the context of found correlations, we suggest that PAH abundance is likely altered by the UV radiation within HII complexes, but this is not necessarily due to their destruction. If PAHs can also form in Hii complexes due to some processes like aromatization, photodestruction, shattering and sputtering of very small grains, the net F_8_/F_24_ ratio is determined by a balance between all these processes that can be different at different metallicities.
- ID:
- ivo://CDS.VizieR/J/A+A/476/89
- Title:
- HII galaxies narrow-band Hbeta images
- Short Name:
- J/A+A/476/89
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Our aims is to create a catalog of images of HII galaxies and their individual star-formation regions in order to study the distribution of the gas emission and their underlying stellar continuum. We have used H{beta} narrow-band images of 43 selected HII galaxies obtained at ESO NTT 3.58m telescope using the SUSI2 camera. Surface photometric H{beta} fluxes and equivalent widths for all objects and star-formation regions are presented in this catalog.