15 research outputs found
Black Hole Growth Is Mainly Linked to Host-galaxy Stellar Mass Rather Than Star Formation Rate
We investigate the dependence of black-hole accretion rate (BHAR) on host-galaxy star formation rate (SFR) and stellar mass (M∗) in the CANDELS/GOODS-South field in the redshift range of 0.5≤z<2.0. Our sample consists of ≈18000 galaxies, allowing us to probe galaxies with 0.1≲SFR≲100 M⊙ yr−1 and/or 108≲M∗≲1011 M⊙. We use sample-mean BHAR to approximate long-term average BHAR. Our sample-mean BHARs are derived from the Chandra Deep Field-South 7 Ms observations, while the SFRs and M∗ have been estimated by the CANDELS team through SED fitting. The average BHAR is correlated positively with both SFR and M∗, and the BHAR-SFR and BHAR-M∗ relations can both be described acceptably by linear models with a slope of unity. However, BHAR appears to be correlated more strongly with M∗ than SFR. This result indicates that M∗ is the primary host-galaxy property related to black-hole growth, and the apparent BHAR-SFR relation is largely a secondary effect due to the star-forming main sequence. Among our sources, massive galaxies (M∗≳1010M⊙) have significantly higher BHAR/SFR ratios than less-massive galaxies, indicating the former have higher black-hole fueling efficiency and/or higher SMBH occupation fraction than the latter. Our results can naturally explain the observed proportionality between MBH and M∗ for local giant ellipticals, and suggest their MBH/M∗ is higher than that of local star-forming galaxies. Among local star-forming galaxies, massive systems might have higher MBH/M∗ compared to dwarfs
X-ray Survey Results on Active Galaxy Physics and Evolution
This "pedagogical" review describes the key Chandra and XMM-Newton
extragalactic surveys to date and details some of their implications for AGN
physics and evolution. We additionally highlight two topics of current
widespread interest: (1) X-ray constraints on the AGN content of luminous
submillimeter galaxies, and (2) the demography and physics of high-redshift (z
> 4) AGN as revealed by X-ray observations. Finally, we discuss prospects for
future X-ray surveys with Chandra, XMM-Newton, and upcoming missions.Comment: 26 pages, in Physics of Active Galactic Nuclei at All Scales, eds.
Alloin D., Johnson R., Lira P. (Springer-Verlag, Berlin), version with all
figures at http://www.astro.psu.edu/users/niel/papers/papers.htm
ALMA lensing cluster survey: ALMA-Herschel joint study of lensed dusty star-forming galaxies across z ≃ 0.5 - 6
Galaxie
The Properties and Redshift Evolution of Intermediate-Luminosity Off-Nuclear X-Ray Sources in the Chandra Deep Fields
We analyze a population of intermediate-redshift (z~0.05-0.3) off-nuclear X-ray sources located within optically bright galaxies in the Great Observatories Origins Deep Survey and Galaxy Evolution from Morphology and SEDs fields. A total of 24 off-nuclear source candidates are classified using deep Chandra X-Ray Observatory exposures from the Chandra Deep Field-North, Chandra Deep Field-South, and Extended Chandra Deep Field-South 15 of these are newly identified. These sources have average X-ray spectral shapes and optical environments similar to those observed for off-nuclear intermediate-luminosity (LX>=1039 ergs s-1 in the 0.5-2.0 keV band) X-ray objects (IXOs; sometimes referred to as ultraluminous X-ray sources) in the local universe. This sample improves the available source statistics for intermediate-redshift off-nuclear sources with LX>~1039.5 ergs s-1, and it places significant new constraints on the redshift evolution of the off-nuclear source frequency in field galaxies. The fraction of intermediate-redshift field galaxies containing an off-nuclear source with LX>~1039 ergs s-1 is suggestively elevated (~80% confidence level) with respect to that observed for IXOs in the local universe; we calculate this elevation to be a factor of ~1.9+1.4-1.3. A rise in this fraction is plausibly expected as a consequence of the observed increase in global star formation density with redshift, and our results are consistent with the expected magnitude of the rise in this fraction
X-Ray Properties of Lyman Break Galaxies in the Great Observatories Origins Deep Survey
We constrain the X-ray emission properties of Lyman break galaxies (LBGs) at z 3–6 using the 2 Ms Chandra Deep Field North and 1 Ms Chandra Deep Field South. Large samples of LBGs were discovered using the Hubble Space Telescope as part of the Great Observatories Origins Deep Survey (GOODS). Deep optical and X-ray imaging over the GOODS fields have allowed us to place the most significant constraints on the X-ray properties of LBGs to date. Mean X-ray properties of 449, 1734, 629, and 247 LBGs with z ~ 3, 4, 5, and 6, respectively, were determined using stacking techniques. When stacked, we detect X-ray emission from LBGs at z ~ 3 (~7 σ) and from an optically bright subset (brightest 25%) of LBGs at z ~ 4 (~3 σ); the latter is the highest redshift detection yet for "normal" galaxies in the X-ray band. The effective exposure times for these stacked observations are 0.7 and 0.5 Gs, respectively. The derived average rest-frame 2.0–8.0 keV luminosities are 1.5 × 1041 and 1.4 × 1041 ergs s-1, respectively. X-ray emission from these LBGs is likely due to high-mass X-ray binaries and Type II supernovae; the corresponding star formation rates are 10–30 M yr-1. The X-ray–to–B-band mean luminosity ratio (LX/LB) at z ~ 3 is somewhat elevated with respect to that measured for starburst galaxies in the local universe (significance ~3 σ). When stacking full samples of LBGs at z ~ 4, 5, and 6, we do not obtain significant detections (<3 σ) and derive rest-frame 2.0–8.0 keV luminosity upper limits (3 σ) of 0.9, 2.8, and 7.1 × 1041 ergs s-1, respectively. These upper limits constrain any widespread active galactic nucleus (AGN) activity in these objects to be modest at best. Furthermore, we find that ~0.5% of our LBGs from z 3 to z 6 are detected individually in the X-ray band. These LBGs have spectral shapes and luminosities characteristic of moderate-power AGNs (e.g., Seyfert galaxies and quasars)
Identifications and Photometric Redshifts of the 2 Ms Chandra Deep Field-South Sources
[Abridged] We present reliable multiwavelength identifications and
high-quality photometric redshifts for the 462 X-ray sources in the ~2 Ms
Chandra Deep Field-South. Source identifications are carried out using deep
optical-to-radio multiwavelength catalogs, and are then combined to create
lists of primary and secondary counterparts for the X-ray sources. We
identified reliable counterparts for 446 (96.5%) of the X-ray sources, with an
expected false-match probability of ~6.2%. A likelihood-ratio method is used
for source matching, which effectively reduces the false-match probability at
faint magnitudes compared to a simple error-circle matching method. We
construct a master photometric catalog for the identified X-ray sources
including up to 42 bands of UV-to-infrared data, and then calculate their
photometric redshifts (photo-z's). The reliability of the photo-z's is
evaluated using the subsample of 220 sources with secure spectroscopic
redshifts. We achieve an accuracy of ~1% [|Delta z|/(1+z)] and an outlier
fraction of ~1.4% for sources with spectroscopic redshifts. We performed blind
tests to derive a more realistic estimate of the photo-z quality for sources
without spectroscopic redshifts. We expect there are ~9% outliers for the
relatively brighter sources (R<26), and the outlier fraction will increase to
~15-25% for the fainter sources (R>26). The typical photo-z accuracy is ~6-7%.
The outlier fraction and photo-z accuracy do not appear to have a redshift
dependence (for z~0-4). These photo-z's appear to be the best obtained so far
for faint X-ray sources, and they have been significantly (>50%) improved
compared to previous estimates of the photo-z's for the X-ray sources in the ~2
Ms Chandra Deep Field-North and ~1 Ms Chandra Deep Field-South.Comment: ApJS accepted. Minor updates compared to the submitted version. 22
pages, 15 figures. Catalogs may be requested from [email protected]
The Extended Chandra Deep Field-South Survey: Chandra Point-Source Catalogs
We present Chandra point‐source catalogs for the Extended Chandra Deep Field–South (E‐CDF‐S) survey. The E‐CDF‐S consists of four contiguous 250 ks Chandra observations covering an approximately square region of total solid angle ≈0.3 deg2, which flank the existing ≈1 Ms Chandra Deep Field–South (CDF‐S). The survey reaches sensitivity limits of ≈ and ≈ ergs cm−2 s−1 for the 0.5–2.0 and 2–8 keV bands, respectively. We detect 762 distinct X‐ray point sources within the E‐CDF‐S exposure; 589 of these sources are new (i.e., not previously detected in the ≈1 Ms CDF‐S). This brings the total number of X‐ray point sources detected in the E‐CDF‐S region to 915 (via the E‐CDF‐S and ≈1 Ms CDF‐S observations). Source positions are determined using matched‐filter and centroiding techniques; the median positional uncertainty is ≈035. The basic X‐ray and optical properties of these sources indicate a variety of source types, although absorbed active galactic nuclei (AGNs) seem to dominate. In addition to our main Chandra catalog, we constructed a supplementary source catalog containing 33 lower significance X‐ray point sources that have bright optical counterparts (R < 23). These sources generally have X‐ray–to–optical flux ratios expected for normal and starburst galaxies, which lack a strong AGN component. We present basic number‐count results for our main Chandra catalog and find good agreement with the ≈1 Ms CDF‐S for sources with 0.5–2.0 and 2–8 keV fluxes greater than and ergs cm−2 s−1, respectively. Furthermore, three extended sources are detected in the 0.5–2.0 keV band, which are found to be likely associated with galaxy groups or poor clusters at ; these have typical rest‐frame 0.5–2.0 keV luminosities of ergs s−1
The Chandra Deep Field-South Survey: 2 Ms Source Catalogs
We present point-source catalogs for the ~2 Ms exposure of the Chandra Deep
Field-South (CDF-S); this is one of the two most-sensitive X-ray surveys ever
performed. The survey covers an area of ~436 arcmin^2 and reaches on-axis
sensitivity limits of ~1.9x10^{-17} and ~1.3x10^{-16} ergs/cm^2/s for the
0.5-2.0 and 2-8 keV bands, respectively. Four hundred and sixty-two X-ray point
sources are detected in at least one of three X-ray bands that were searched;
135 of these sources are new compared to the previous ~1 Ms CDF-S detections.
Source positions are determined using centroid and matched-filter techniques;
the median positional uncertainty is ~0.36". The X-ray-to-optical flux ratios
of the newly detected sources indicate a variety of source types; ~55% of them
appear to be active galactic nuclei while ~45% appear to be starburst and
normal galaxies. In addition to the main Chandra catalog, we provide a
supplementary catalog of 86 X-ray sources in the ~2 Ms CDF-S footprint that was
created by merging the ~250 ks Extended Chandra Deep Field-South with the
CDF-S; this approach provides additional sensitivity in the outer portions of
the CDF-S. A second supplementary catalog that contains 30 X-ray sources was
constructed by matching lower significance X-ray sources to bright optical
counterparts (R<23.8); the majority of these sources appear to be starburst and
normal galaxies. The total number of sources in the main and supplementary
catalogs is 578. R-band optical counterparts and basic optical and infrared
photometry are provided for the X-ray sources in the main and supplementary
catalogs. We also include existing spectroscopic redshifts for 224 of the X-ray
sources. (Abstract abridged)Comment: 18 pages, 15 figures, ApJS in press. Data and images available at
http://www.astro.psu.edu/users/niel/cdfs/cdfs-chandra.htm
The Chandra Deep Field-South Survey: 4 Ms Source Catalogs
[abridged] We present point-source catalogs for the 4Ms Chandra Deep
Field-South (CDF-S), which is the deepest Chandra survey to date and covers an
area of 464.5 arcmin^2. We provide a main source catalog, which contains 740
X-ray point sources that are detected with wavdetect at a false-positive
probability threshold of 1E-5 and also satisfy a binomial-probability
source-selection criterion of P<0.004; this approach is designed to maximize
the number of reliable sources detected. A total of 300 main-catalog sources
are new compared to the previous 2Ms CDF-S main-catalog sources. We also
provide a supplementary catalog, which consists of 36 sources that are detected
with wavdetect at 1E-5, satisfy 0.004< P<0.1, and have an optical counterpart
with R<24. Multiwavelength identifications, basic optical/infrared/radio
photometry, and spectroscopic/photometric redshifts are provided for the X-ray
sources. Basic analyses of the X-ray and multiwavelength properties of the
sources indicate that >75% of the main-catalog sources are AGNs; of the 300 new
main-catalog sources, about 35% are likely normal and starburst galaxies,
reflecting the rise of normal and starburst galaxies at the very faint flux
levels uniquely accessible to the 4Ms CDF-S. Near the center of the 4Ms CDF-S,
the observed AGN and galaxy source densities have reached ~9800 and 6900 per
square degree, respectively. The 4 Ms CDF-S reaches on-axis flux limits of
~9.1E-18 and 5.5E-17 erg/cm^2/s for the soft and hard bands, respectively. An
increase in the CDF-S exposure by a factor of ~2-2.5 would provide further
significant gains and probe key unexplored discovery space.Comment: 31 pages, 24 figures, 8 tables, ApJS in press. Data and images
available at http://www.astro.psu.edu/users/niel/cdfs/cdfs-chandra.htm