ABSTRACT
We study the genesis and evolution of supermassive black hole (SMBH) seeds through different formation channels, from PopIII remnants to massive seeds, modelled within the L-Galaxies ...semi-analytic code. We run the model on the Millennium-II simulation (MR-II) merger trees, as their halo-mass resolution ($M_{\rm vir,res} \sim 10^7\, \mathrm{M}_\odot \, h^{-1}$) allows to study in a cosmological volume ($L_{\rm box}=100\, \mathrm{Mpc}\, h^{-1}$) the evolution of atomic-cooling haloes ($T_{\rm vir} \gtrsim 10^4\, \mathrm{K}$) where intermediate-mass and heavy seeds are expected to form. We track the formation of these seeds according to spatial variations of the chemical and radiative feedback of star formation. Not being able to resolve the first mini-haloes ($T_{\rm vir} \sim 10^3\, \mathrm{K}$), we inherit evolved PopIII remnants in a sub-grid fashion, using the results of the GQd model. We also include the formation of heavy seeds in gas-rich massive mergers, which are very rare in the MR-II volume. The descendants of light seeds numerically prevail among our SMBHs population at all masses and z. Heavier seeds form in dense environments where close neighbours provide the required UV illumination. Overall, our model produces a z = 0 SMBHs population whose statistical properties meet current constraints. We find that the BH occupation fraction highly depends on the seeding efficiency and that the scaling relation between BH and stellar mass, in the dwarf-mass regime, is flatter than in the high-mass range. Finally, a fraction of BHs hosted in local dwarf galaxies never grow since they form at z > 6.
We present the results of prompt optical follow-up of the electromagnetic counterpart of the gravitational-wave event GW170817 by the Transient Optical Robotic Observatory of the South Collaboration. ...We detected highly significant dimming in the light curves of the counterpart ( mag, mag, mag) over the course of only 80 minutes of observations obtained ∼35 hr after the trigger with the T80-South telescope. A second epoch of observations, obtained ∼59 hr after the event with the EABA 1.5 m telescope, confirms the fast fading nature of the transient. The observed colors of the counterpart suggest that this event was a "blue kilonova" relatively free of lanthanides.
Abstract The James Webb Space Telescope (JWST) North Ecliptic Pole (NEP) Time-domain Field (TDF) is a >14′ diameter field optimized for multiwavelength time-domain science with JWST. It has been ...observed across the electromagnetic spectrum both from the ground and from space, including with the Hubble Space Telescope (HST). As part of HST observations over three cycles (the “TREASUREHUNT” program), deep images were obtained with the Wide Field Camera on the Advanced Camera for Surveys in F435W and F606W that cover almost the entire JWST NEP TDF. Many of the individual pointings of these programs partially overlap, allowing an initial assessment of the potential of this field for time-domain science with HST and JWST. The cumulative area of overlapping pointings is ∼88 arcmin 2 , with time intervals between individual epochs that range between 1 day and 4+ yr. To a depth of m AB ≃ 29.5 mag (F606W), we present the discovery of 12 transients and 190 variable candidates. For the variable candidates, we demonstrate that Gaussian statistics are applicable and estimate that ∼80 are false positives. The majority of the transients will be supernovae, although at least two are likely quasars. Most variable candidates are active galactic nuclei (AGNs), where we find 0.42% of the general z ≲ 6 field galaxy population to vary at the ∼3 σ level. Based on a 5 yr time frame, this translates into a random supernova areal density of up to ∼0.07 transients arcmin −2 (∼245 deg −2 ) per epoch and a variable AGN areal density of ∼1.25 variables arcmin −2 (∼4500 deg −2 ) to these depths.
ABSTRACT We use the low-redshift Zurich Environmental Study (ZENS) catalog to study the dependence of the quenched satellite fraction at , and of the morphological mix of these quenched satellites, ...on three different environmental parameters: group halo mass, halo-centric distance, and large-scale structure (LSS) overdensity. Within the two mass bins into which we divide our galaxy sample, the fraction of quenched satellites is more or less independent of halo mass and the surrounding LSS overdensity, but it increases toward the centers of the halos, as found in previous studies. The morphological mix of these quenched satellites is, however, constant with radial position in the halo, indicating that the well-known morphology-density relation results from the increasing fraction of quenched galaxies toward the centers of halos. If the radial variation in the quenched fraction reflects the action of two quenching processes, one related to mass and the other to environment, then the constancy with radius of the morphological outcome suggests that both have the same effect on the morphologies of the galaxies. Alternatively, mass and environment quenching may be two reflections of a single physical mechanism. The quenched satellites have larger bulge-to-total ratios (B/T) and smaller half-light radii than the star-forming satellites. The bulges in quenched satellites have very similar luminosities and surface brightness profiles, and any mass growth of the bulges associated with quenching cannot greatly change these quantities. The differences in the light-defined B/T and in the galaxy half-light radii are mostly due to differences in the disks, which have lower luminosities in the quenched galaxies. The difference in galaxy half-light radii between quenched and star-forming satellites is however larger than can be explained by uniformly fading the disks following quenching, and the quenched disks have smaller scale lengths than in star-forming satellites. This can be explained either by a differential fading of the disks with galaxy radius or the disks being generally smaller in the past, both of which would be expected in an inside-out disk growth scenario. The overall conclusion is that, at least at low redshifts, the structure of massive quenched satellites at these masses is produced by processes that operate before the quenching takes place. A comparison of our results with semianalytic models argues for a reduction in the efficiency of group halos in quenching their disk satellites and for mechanisms to increase the B/T of low-mass quenched satellites.
Context.
Future astrophysical surveys such as J-PAS will produce very large datasets, the so-called “big data”, which will require the deployment of accurate and efficient machine-learning (ML) ...methods. In this work, we analyze the miniJPAS survey, which observed about ∼1 deg
2
of the AEGIS field with 56 narrow-band filters and 4
u
g
r
i
broad-band filters. The miniJPAS primary catalog contains approximately 64 000 objects in the
r
detection band (mag
A
B
≲ 24), with forced-photometry in all other filters.
Aims.
We discuss the classification of miniJPAS sources into extended (galaxies) and point-like (e.g., stars) objects, which is a step required for the subsequent scientific analyses. We aim at developing an ML classifier that is complementary to traditional tools that are based on explicit modeling. In particular, our goal is to release a value-added catalog with our best classification.
Methods.
In order to train and test our classifiers, we cross-matched the miniJPAS dataset with SDSS and HSC-SSP data, whose classification is trustworthy within the intervals 15 ≤
r
≤ 20 and 18.5 ≤
r
≤ 23.5, respectively. We trained and tested six different ML algorithms on the two cross-matched catalogs: K-nearest neighbors, decision trees, random forest (RF), artificial neural networks, extremely randomized trees (ERT), and an ensemble classifier. This last is a hybrid algorithm that combines artificial neural networks and RF with the J-PAS stellar and galactic loci classifier. As input for the ML algorithms we used the magnitudes from the 60 filters together with their errors, with and without the morphological parameters. We also used the mean point spread function in the
r
detection band for each pointing.
Results.
We find that the RF and ERT algorithms perform best in all scenarios. When the full magnitude range of 15 ≤
r
≤ 23.5 is analyzed, we find an area under the curve AUC = 0.957 with RF when photometric information alone is used, and AUC = 0.986 with ERT when photometric and morphological information is used together. When morphological parameters are used, the full width at half maximum is the most important feature. When photometric information is used alone, we observe that broad bands are not necessarily more important than narrow bands, and errors (the width of the distribution) are as important as the measurements (central value of the distribution). In other words, it is apparently important to fully characterize the measurement.
Conclusions.
ML algorithms can compete with traditional star and galaxy classifiers; they outperform the latter at fainter magnitudes (
r
≳ 21). We use our best classifiers, with and without morphology, in order to produce a value-added catalog.
MiniJPAS is a ∼1 deg
2
imaging survey of the AEGIS field in 60 bands, performed to demonstrate the scientific potential of the upcoming Javalambre-Physics of the Accelerating Universe Astrophysical ...Survey (J-PAS). Full coverage of the 3800–9100 Å range with 54 narrow-band filters, in combination with 6 optical broad-band filters, allows for extremely accurate photometric redshifts (photo-
z
), which, applied over areas of thousands of square degrees, will enable new applications of the photo-
z
technique, such as measurement of baryonic acoustic oscillations. In this paper we describe the method we used to obtain the photo-
z
that is included in the publicly available miniJPAS catalogue, and characterise the photo-
z
performance. We built photo-spectra with 100 Å resolution based on forced-aperture photometry corrected for point spread function. Systematic offsets in the photometry were corrected by applying magnitude shifts obtained through iterative fitting with stellar population synthesis models. We computed photo-
z
with a customised version of L
E
P
HARE
, using a set of templates that is optimised for the J-PAS filter-set. We analysed the accuracy of miniJPAS photo-
z
and their dependence on multiple quantities using a subsample of 5266 galaxies with spectroscopic redshifts from SDSS and DEEP, which we find to be representative of the whole
r
< 23 miniJPAS sample. Formal 1
σ
uncertainties for the photo-
z
that are calculated with the Δ
χ
2
method underestimate the actual redshift errors. The
o
d
d
s
parameter has a stronger correlation with |Δ
z
| and accurately reproduces the probability of a redshift outlier (|Δ
z
| > 0.03), regardless of the magnitude, redshift, or spectral type of the sources. We show that the two main summary statistics characterising the photo-
z
accuracy for a population of galaxies (
σ
NMAD
and
η
) can be predicted by the distribution of
o
d
d
s
in this population, and we use this to estimate the statistics for the whole miniJPAS sample. At
r
< 23, there are ∼17 500 galaxies per deg
2
with valid photo-
z
estimates, ∼4200 of which are expected to have |Δ
z
| < 0.003. The typical error is
σ
NMAD
= 0.013 with an outlier rate
η
= 0.39. The target photo-
z
accuracy
σ
NMAD
= 0.003 is achieved for
o
d
d
s
> 0.82 with
η
= 0.05, at the cost of decreasing the density of selected galaxies to
n
∼ 5200 deg
−2
(∼2600 of which have |Δ
z
| < 0.003).
We present photometric measurements for the galaxies-and when possible their bulges and disks-in the 0.05 < z < 0.0585 groups of the Zurich Environmental Study (ZENS); these measurements include (B - ...I) colors, color gradients and maps, color dispersions, as well as stellar masses and star formation rates. The ZENS galaxies are classified into quenched, moderately star-forming, and strongly star-forming using a combination of spectral features and far-UV-to-optical colors; this approach optimally distinguishes quenched systems from dust-reddened star-forming galaxies. The latter contribute up to 50% to the (B - I) "red sequence" at ~10 super(10) M sub(middot in circle). At fixed morphological or spectral type, we find that galaxy stellar masses are largely independent of environment, and especially of halo mass. As a first utilization of our photometric database, we study, at fixed stellar mass and Hubble type, how (B - I) colors, color gradients, and color dispersion of disk satellites depend on group mass M sub(GROUP), group-centric distance R/R sub(200), and large-scale structure overdensity delta sub(LSS). The strongest environmental trend is found for disk-dominated satellites with M sub(GROUP) and R/R sub(200). At M lap 10 super(10) M sub(middot in circle), disk-dominated satellites are redder in the inner regions of the groups than in the outer parts. At M gap 10 super(10) M sub(middot in circle), these satellites have shallower color gradients in higher mass groups and in the cores of groups compared with lower mass groups and the outskirts of groups. Stellar population analyses and semi-analytic models suggest that disk-dominated satellites undergo quenching of star formation in their outer disks, on timescales tau sub(quench) ~ 2 Gyr, as they progressively move inside the group potential.
The miniJPAS survey Doubrawa, L; Cypriano, E S; Finoguenov, A ...
Astronomy and astrophysics (Berlin),
05/2024, Letnik:
685
Journal Article
Recenzirano
Odprti dostop
Context. Galaxy clusters are an essential tool to understand and constrain the cosmological parameters of our universe. Thanks to its multi-band design, J-PAS offers a unique group and cluster ...detection window using precise photometric redshifts and sufficient depths. Aims. We produced galaxy cluster catalogues from miniJPAS, which is a pathfinder survey for the wider J-PAS survey, using the PZWav algorithm. Methods. Relying only on photometric information, we provide optical mass tracers for the identified clusters, including richness, optical luminosity, and stellar mass. By reanalysing the Chandra mosaic of the AEGIS field, alongside the overlapping XMM-Newton observations, we produced an X-ray catalogue. Results. The analysis revealed the possible presence of structures with masses of 4 × 1013 M⊙ at redshift 0.75, highlighting the depth of the survey. Comparing results with those from two other cluster catalogues provided by AMICO and VT, we found 43 common clusters with cluster centre offsets of 100 ± 60 kpc and redshift differences below 0.001. We provide a comparison of the cluster catalogues with a catalogue of massive galaxies and report on the significance of cluster selection. In general, we were able to recover approximately 75% of the galaxies with M⋆ > 2 × 1011 M⊙. Conclusions. This study emphasises the potential of the J-PAS survey and the employed techniques, including down to group scales.
Aims. Our goal is to morphologically classify the sources identified in the images of the J-PLUS early data release (EDR) as compact (stars) or extended (galaxies) using a dedicated Bayesian ...classifier. Methods. J-PLUS sources exhibit two distinct populations in the r-band magnitude versus concentration plane, corresponding to compact and extended sources. We modelled the two-population distribution with a skewed Gaussian for compact objects and a log-normal function for the extended objects. The derived model and the number density prior based on J-PLUS EDR data were used to estimate the Bayesian probability that a source is a star or a galaxy. This procedure was applied pointing-by-pointing to account for varying observing conditions and sky positions. Finally, we combined the morphological information from the g, r, and i broad bands in order to improve the classification of low signal-to-noise sources. Results. The derived probabilities are used to compute the pointing-by-pointing number counts of stars and galaxies. The former increases as we approach the Milky Way disk, and the latter are similar across the probed area. The comparison with SDSS in the common regions is satisfactory up to r ~ 21, with consistent numbers of stars and galaxies, and consistent distributions in concentration and (g−i) colour spaces. Conclusions. We implement a morphological star/galaxy classifier based on probability distribution function analysis, providing meaningful probabilities for J-PLUS sources to one magnitude deeper (r ~ 21) than a classical Boolean classification. These probabilities are suited for the statistical study of 150 thousand stars and 101 thousand galaxies with 15 < r ≤ 21 present in the 31.7 deg2 of the J-PLUS EDR. In a future version of the classifier, we will include J-PLUS colour information from 12 photometric bands.
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