| 1. |
- Bendo, G. J., et al.
(författare)
-
The bright extragalactic ALMA redshift survey (BEARS) – II. Millimetre photometry of gravitational lens candidates
- 2023
-
Ingår i: Monthly Notices of the Royal Astronomical Society. - 0035-8711 .- 1365-2966. ; 522:2, s. 2995-3017
-
Tidskriftsartikel (refereegranskat)abstract
- We present 101- and 151-GHz ALMA continuum images for 85 fields selected from Herschel observations that have 500-μm flux densities >80 mJy and 250–500-μm colours consistent with z > 2, most of which are expected to be gravitationally lensed or hyperluminous infrared galaxies. Approximately half of the Herschel 500-μm sources were resolved into multiple ALMA sources, but 11 of the 15 brightest 500-μm Herschel sources correspond to individual ALMA sources. For the 37 fields containing either a single source with a spectroscopic redshift or two sources with the same spectroscopic redshift, we examined the colour temperatures and dust emissivity indices. The colour temperatures only vary weakly with redshift and are statistically consistent with no redshift-dependent temperature variations, which generally corresponds to results from other samples selected in far-infrared, submillimetre, or millimetre bands but not to results from samples selected in optical or near-infrared bands. The dust emissivity indices, with very few exceptions, are largely consistent with a value of 2. We also compared spectroscopic redshifts to photometric redshifts based on spectral energy distribution templates designed for infrared-bright high-redshift galaxies. While the templates systematically underestimate the redshifts by ∼15 per cent, the inclusion of ALMA data decreases the scatter in the predicted redshifts by a factor of ∼2, illustrating the potential usefulness of these millimetre data for estimating photometric redshifts.
|
|
| 2. |
- Fan, Lulu, 1982, et al.
(författare)
-
ALMA Detections of CO Emission in the Most Luminous, Heavily Dust-obscured Quasars at z > 3
- 2018
-
Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 856:1
-
Tidskriftsartikel (refereegranskat)abstract
- We report the results of a pilot study of CO(4 - 3) emission line of three Wide-field Infrared Survey Explorer (WISE)-selected hyper-luminous, dust-obscured quasars (QSOs) with sensitive ALMA Band 3 observations. These obscured QSOs with L bol > 10 14 L o; are among the most luminous objects in the universe. All three QSO hosts are clearly detected both in continuum and in CO(4 - 3) emission line. Based on CO(4 - 3) emission line detection, we derive the molecular gas masses (∼10 10-11 M o; ), suggesting that these QSOs are gas-rich systems. We find that the obscured QSOs in our sample follow the similar relation as unobscured QSOs at high redshifts. We also find the complex velocity structures of CO(4 - 3) emission line, which provide the possible evidence for a gas-rich merger in W0149+2350 and possible molecular outflow in W0220+0137 and W0410-0913. Massive molecular outflow can blow away the obscured interstellar medium and make obscured QSOs evolve toward the UV/optical bright, unobscured phase. Our result is consistent with the popular active galactic nucleus (AGN) feedback scenario involving the co-evolution between the supermassive black holes and host galaxy.
|
|
| 3. |
- Fan, Lulu, et al.
(författare)
-
ALMA Reveals a Gas-rich, Maximum Starburst in the Hyperluminous, Dust-obscured Quasar W0533-3401 at z similar to 2.9
- 2019
-
Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 887:1
-
Tidskriftsartikel (refereegranskat)abstract
- We present ALMA observations and multiwavelength spectral energy distribution analysis in a Wide-field Infrared Survey Explorer-selected, hyperluminous dust-obscured quasar W0533-3401 at z = 2.9. We derive the physical properties of each of its components, such as molecular gas, stars, dust, and the central supermassive black hole (SMBH). Both the dust continuum at 3 mm and the CO (3-2) line are detected. The derived molecular gas mass M-gas = 8.4 x 10(10) M-circle dot and its fraction f(gas) = 0.7 suggest that W0533-3401 is gas-rich. The star formation rate (SFR) has been estimated to be similar to 3000-7000M(circle dot) yr(-1) by using different methods. The high values of SFR and specific SFR suggest that W0533-3401 is a maximum starburst. The corresponding gas depletion timescales are very short (t(depl) similar to 12-28 Myr). The CO (3-2) emission line is marginally resolved and has a velocity gradient, which is possibly due to a rotating gas disk, gas outflow, or merger. Finally, we infer the black hole mass growth rate of W0533-3401 ((M)over dot(BH) = 49 M-circle dot yr(-1)), which suggests a rapid growth of the central SMBH. The observed black hole to stellar mass ratio M-BH/M-* of W0533-3401, which is dependent on the adopted Eddington ratio, is over one order of magnitude higher than the local value, and is evolving toward the evolutionary trend of unobscured quasars. Our results are consistent with the scenario that W0533-3401, with both a gas-rich maximum starburst and a rapid black hole growth, is experiencing a short transition phase toward an unobscured quasar.
|
|
| 4. |
- Fan, Lulu, 1982, et al.
(författare)
-
Infrared Spectral Energy Distribution Decomposition of Wise-Selected, Hyperluminous Hot Dust-Obscured Galaxies
- 2016
-
Ingår i: Astrophysical Journal. - 1538-4357 .- 0004-637X. ; 823:2, s. Art. no. 107-
-
Tidskriftsartikel (refereegranskat)abstract
- We utilize a Bayesian approach to fit the observed mid-IR-To-submillimeter/millimeter spectral energy distributions (SEDs) of 22 WISE-selected and submillimeter-detected, hyperluminous hot dust-obscured galaxies (Hot DOGs), with spectroscopic redshift ranging from 1.7 to 4.6. We compare the Bayesian evidence of a torus plusgraybody (Torus+GB) model with that of a torus-only (Torus) model and find that the Torus+GB model has higher Bayesian evidence for all 22 Hot DOGs than the torus-only model, which presents strong evidence in favor of the Torus+GB model. By adopting the Torus+GB model, we decompose the observed IR SEDs of Hot DOGs into torus and cold dust components. The main results are as follows. (1) Hot DOGs in our submillimeter-detected sample are hyperluminous , with torus emission dominating the IR energy output. However, cold dust emission is non-negligible, contributing on average of total IR luminosity. (2) Compared to QSO and starburst SED templates, the median SED of Hot DOGs shows the highest luminosity ratio between mid-IR and submillimeter at rest frame, while it is very similar to that of QSOs at , suggesting that the heating sources of Hot DOGs should be buried AGNs. (3) Hot DOGs have high dust temperatures ( K) and high IR luminosity of cold dust. The relation of Hot DOGs suggests that the increase in IR luminosity for Hot DOGs is mostly due to the increase of the dust temperature, rather than dust mass. Hot DOGs have lower dust masses than submillimeter galaxies (SMGs) and QSOs within a similar redshift range. Both high IR luminosity of cold dust and relatively low dust mass in Hot DOGs can be expected by their relatively high dust temperatures. (4) Hot DOGs have high dust-covering factors (CFs), which deviate from the previously proposed trend of the dust CF decreasing with increasing bolometric luminosity. Finally, we can reproduce the observed properties in Hot DOGs by employing a physical model of galaxy evolution. This result suggests that Hot DOGs may lie at or close to peaks of both star formation and black hole growth histories, and represent a transit phase during the evolutions of massive galaxies, transforming them from the dusty starburst-dominated phase to the optically bright QSO phase.
|
|
| 5. |
- Fan, Lulu, 1982, et al.
(författare)
-
Panchromatic modeling of the extremely luminous dust-obscured quasars at the cosmic noon
- 2019
-
Ingår i: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 15:S341, s. 268-270
-
Konferensbidrag (refereegranskat)abstract
- The massive galaxies and their central supermassive black holes (SMBHs) co-evolution scenario proposes that a gas-rich major merger can trigger the central starburst and feeding the SMBH accretion, and then star formation is eventually quenched by quasar feedback. In this evolutionary sequence, dust-obscured quasars may represent the critical transition phase between starburst and unobscured quasars. Modeling the panchromatic emission of these hidden monsters provides a unique way to explore their physical properties and therefore the co-evolution between SMBHs and their hosts. However, most of modelling methods are not suitable for the extremely luminous systems with obscured Active Galactic Nucleus (AGN) emission. Here we present two case studies of panchromatic modeling of the extremely luminous dust-obscured quasars at the cosmic noon.
|
|
| 6. |
- Fan, Lulu, 1982, et al.
(författare)
-
STRUCTURE AND MORPHOLOGY OF X-RAY-SELECTED ACTIVE GALACTIC NUCLEUS HOSTS AT 1
- 2014
-
Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 784:1, s. 5-
-
Tidskriftsartikel (refereegranskat)abstract
- We analyze morphologies of the host galaxies of 35 X-ray-selected active galactic nuclei (AGNs) at z similar to 2 in the Cosmic Evolution Survey field using Hubble Space Telescope/WFC3 imaging taken from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey. We build a control sample of 350 galaxies in total by selecting 10 non-active galaxies drawn from the same field with a similar stellar mass and redshift for each AGN host. By performing two-dimensional fitting with GALFIT on the surface brightness profile, we find that the distribution of the Sersic index (n) of AGN hosts does not show a statistical difference from that of the control sample. We measure the nonparametric morphological parameters (the asymmetry index A, the Gini coefficient G, the concentration index C, and the M-20 index) based on point-source-subtracted images. All the distributions of these morphological parameters of AGN hosts are consistent with those of the control sample. We finally investigate the fraction of distorted morphologies in both samples by visual classification. Only similar to 15% of the AGN hosts have highly distorted morphologies, possibly due to a major merger or interaction. We find there is no significant difference in the distortion fractions between the AGN host sample and control sample. We conclude that the morphologies of X-ray-selected AGN hosts are similar to those of non-active galaxies and most AGN activity is not triggered by a major merger.
|
|
| 7. |
- Fan, Lulu, et al.
(författare)
-
The Hyperluminous, Dust-obscured Quasar W2246-0526 at z=4.6: Detection of Parsec-scale Radio Activity
- 2020
-
Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 905:2
-
Tidskriftsartikel (refereegranskat)abstract
- WISE J224607.56-052634.9 (W2246-0526) is a hyperluminous (L-bol 1.7 x 10(14) L), dust-obscured, and radio-quiet quasar at redshift z = 4.6. It plays a key role in probing the transition stage between dusty starbursts and unobscured quasars in the coevolution of galaxies and supermassive black holes (SMBHs). To search for the evidence of the jet activity launched by the SMBH in W2246-0526, we performed very long baseline interferometry observations of its radio counterpart with the European VLBI Network (EVN) plus the enhanced Multi Element Remotely Linked Interferometer Network (e-MERLIN) at 1.66 GHz and the Very Long Baseline Array (VLBA) at 1.44 and 1.66 GHz. The deep EVN plus e-MERLIN observations detect a compact (size <= 32 pc) sub-mJy component contributing about 10% of its total flux density, which spatially coincides with the peak of dust continuum and [C II] emissions. Together with its relatively high brightness temperature ( >= 8 x 10(6) K), we interpret the component as a consequence of nonthermal radio activity powered by the central SMBH, which likely originates from a stationary jet base. The resolved-out radio emission possibly come from a diffuse jet, quasar-driven winds, or both, while the contribution by star formation activity is negligible. Moreover, we propose an updated geometry structure of its multiwavelength active nucleus and shed light on the radio quasar selection bias toward the blazars at z > 4.
|
|
| 8. |
- Fan, Lulu, 1982, et al.
(författare)
-
The SCUBA-2 850 mu m Follow-up of WISE-selected, Luminous Dust-obscured Quasars
- 2017
-
Ingår i: Publications of the Astronomical Society of the Pacific. - : IOP Publishing. - 0004-6280 .- 1538-3873. ; 129:982
-
Tidskriftsartikel (refereegranskat)abstract
- Hot dust-obscured galaxies (Hot DOGs) are a new population recently discovered in the Wide-field Infrared Survey Explorer All-Sky survey. Multiwavelength follow-up observations suggest that they are luminous, dust-obscured quasars at high redshift. Here we present the JCMT SCUBA-2 850 mu m follow-up observations of 10 Hot DOGs. Four out of ten Hot DOGs have been detected at >3 sigma level. Based on the IR SED decomposition approach, we derive the IR luminosities of AGN torus and cold dust components. Hot DOGs in our sample are extremely luminous with most of them having L-IR(tot) > 10(14) L-circle dot. The torus emissions dominate the total IR energy output. However, the cold dust contribution is still non-negligible, with the fraction of the cold dust contribution to the total IR luminosity (similar to 8%-24%) being dependent on the choice of torus model. The derived cold dust temperatures in Hot DOGs are comparable to those in UV bright quasars with similar IR luminosity, but much higher than those in SMGs. Higher dust temperatures in Hot DOGs may be due to the more intense radiation field caused by intense starburst and obscured AGN activities. Fourteen and five submillimeter serendipitous sources in the 10 SCUBA-2 fields around Hot DOGs have been detected at >3 sigma and >3.5 sigma levels, respectively. By estimating their cumulative number counts, we confirm the previous argument that Hot DOGs lie in dense environments. Our results support the scenario in which Hot DOGs are luminous, dust-obscured quasars lying in dense environments, and being in the transition phase between extreme starburst and UV-bright quasars.
|
|
| 9. |
- Fan, Lulu, 1982, et al.
(författare)
-
The Spectral Energy Distribution of the Hyperluminous, Hot Dust-obscured Galaxy W2246-0526
- 2018
-
Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 854:2
-
Tidskriftsartikel (refereegranskat)abstract
- Hot dust-obscured galaxies (Hot DOGs) are a luminous, dust-obscured population recently discovered in the WISE All-Sky survey. Multiwavelength follow-up observations suggest that they are mainly powered by accreting supermassive black holes (SMBHs), lying in dense environments, and being in the transition phase between extreme starburst and UV-bright quasars. Therefore, they are good candidates for studying the interplay between SMBHs, star formation, and environment. W2246-0526 (hereafter, W2246), a Hot DOG at z ∼ 4.6, has been taken as the most luminous galaxy known in the universe. Revealed by the multiwavelength images, the previous Herschel SPIRE photometry of W2246 is contaminated by a foreground galaxy (W2246f), resulting in an overestimation of its total IR luminosity by a factor of about two. We perfor m the rest-frame UV/optical-to-far-IR spectral energy distribution (SED) analysis with SED3FIT and re-estimate its physical properties. The derived stellar mass M ∗ = 4.3 × 10 11 M ⊙ makes it among the most massive galaxies with spectroscopic redshift z > 4.5. Its structure is extremely compact and requires an effective mechanism to puff-up. Most of ( > 95%) its IR luminosity is from AGN torus emission, revealing the rapid growth of the central SMBH. We also predict that W2246 may have a significant molecular gas reservoir based on the dust mass estimation.
|
|
| 10. |
- Fogasy, Judit, 1988, et al.
(författare)
-
SMM J04135+10277: a distant QSO-starburst system caught by ALMA
- 2020
-
Ingår i: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 493:3, s. 3744-3756
-
Tidskriftsartikel (refereegranskat)abstract
- The gas content of galaxies is a key factor for their growth, starting from star formation and black hole accretion to galaxy mergers. Thus, characterizing its properties through observations of tracers like the CO emission line is of big importance in order to understand the bigger picture of galaxy evolution. We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of dust continuum, CO(5-4) and CO(8-7) line emission in the quasar-star-forming companion system SMM J04135+10277 (z = 2.84). Earlier low-J CO studies of this system found a huge molecular gas reservoir associated with the companion galaxy, while the quasar appeared gas-poor. Our CO observations revealed that the host galaxy of the quasar is also gas-rich, with an estimated molecular gas mass of ∼ (0.7-2.3)× 10^{10} M_{☉}. The CO line profiles of the companion galaxy are very broad (∼ 1000 km s^{-1}), and show signs of rotation of a compact, massive system. In contrast to previous far-infrared observations, we resolve the continuum emission and detect both sources, with the companion galaxy dominating the dust continuum and the quasar having a ∼ 25{{ per cent}} contribution to the total dust emission. By fitting the infrared spectral energy distribution of the sources with MR-MOOSE and empirical templates, the infrared luminosities of the quasar and the companion are in the range of L_{IR, QSO}∼ (2.1-9.6)× 10^{12} L_{☉} and L_{IR, Comp.}∼ (2.4-24)× 10^{12} L_{☉}, while the estimated star formation rates are ∼ 210-960 and ∼ 240-2400 M_{☉} yr^{-1}, respectively. Our results demonstrate that non-detection of low-J CO transition lines in similar sources does not necessarily imply the absence of massive molecular gas reservoir but that the excitation conditions favour the excitation of high-J transitions.
|
|
