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  • 1
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    VALES : VII. Molecular and ionized gas properties in the pressure balanced interstellar medium of starburst galaxies at z ∼ 0.15
    EDP Sciences ; 2020
    In:  Astronomy & Astrophysics Vol. 643 ( 2020-11), p. A78-
    Details
    In: Astronomy & Astrophysics, EDP Sciences, Vol. 643 ( 2020-11), p. A78-
    Abstract: Context. Spatially resolved observations of the ionized and molecular gas are critical for understanding the physical processes that govern the interstellar medium (ISM) in galaxies. The observation of starburst systems is also important as they present extreme gas conditions that may help to test different ISM models. However, matched resolution imaging at ∼kpc scales for both ISM gas phases are usually scarce, and the ISM properties of starbursts still remain poorly understood. Aims. We aim to study the morpho-kinematic properties of the ionized and molecular gas in three dusty starburst galaxies at z  = 0.12−0.17 to explore the relation between molecular ISM gas phase dynamics and the star-formation activity. Methods. We employ two-dimensional dynamical modelling to analyse Atacama Large Millimeter/submillimiter Array CO(1–0) and seeing-limited Spectrograph for INtegral Field Observations in the Near Infrared Paschen- α (Pa α ) observations, tracing the molecular and ionized gas morpho-kinematics at ∼kpc-scales. We use a dynamical mass model, which accounts for beam-smearing effects, to constrain the CO-to-H 2 conversion factor and estimate the molecular gas mass content. Results. One starburst galaxy shows irregular morphology, which may indicate a major merger, while the other two systems show disc-like morpho-kinematics. The two disc-like starbursts show molecular gas velocity dispersion values comparable with those seen in local luminous and ultra luminous infrared galaxies but in an ISM with molecular gas fraction and surface density values in the range of the estimates reported for local star-forming galaxies. We find that these molecular gas velocity dispersion values can be explained by assuming vertical pressure equilibrium. We also find that the star-formation activity, traced by the Pa α emission line, is well correlated with the molecular gas content, suggesting an enhanced star-formation efficiency and depletion times of the order of ∼0.1−1 Gyr. We find that the star-formation rate surface density (Σ SFR ) correlates with the ISM pressure set by self-gravity ( P grav ) following a power law with an exponent close to 0.8. Conclusions. In dusty disc-like starburst galaxies, our data support the scenario in which the molecular gas velocity dispersion values are driven by the ISM pressure set by self-gravity and are responsible for maintaining the vertical pressure balance. The correlation between Σ SFR and P grav suggests that, in these dusty starbursts galaxies, the star-formation activity arises as a consequence of the ISM pressure balance.
    Type of Medium: Online Resource
    ISSN: 0004-6361 , 1432-0746
    URL: Article
    DOI: 10.1051/0004-6361/202039008
    RVK:
    UA 1000
    RVK:
    US 1090
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2020
    detail.hit.zdb_id: 1458466-9
    SSG: 16,12
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  • 2
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    Estimating Lifetimes of UV-selected Massive Galaxies at 0.5 ≤ z ≤ 2.5 in the COSMOS/UltraVISTA Field through Clustering Analyses
    American Astronomical Society ; 2021
    In:  The Astrophysical Journal Vol. 911, No. 1 ( 2021-04-01), p. 59-
    Details
    In: The Astrophysical Journal, American Astronomical Society, Vol. 911, No. 1 ( 2021-04-01), p. 59-
    Abstract: To investigate the lifetimes of red sequence (RS), blue cloud (BC), and green valley (GV) galaxies, we derive their lifetimes using clustering analyses at 0.5 ≤ z ≤ 2.5 in the COSMOS/UltraVISTA field. Several essentials that may influence the lifetime estimation have been explored, including the dark matter (DM) halo mass function (HMF), the width of the redshift bin, the growth of DM halos within each redshift bin, and the stellar mass. We find that the HMF difference results in scatters of ∼0.2 dex on the lifetime estimation, adopting a redshift bin width of Δ z = 0.5 is good enough to estimate the lifetime, and no significant effect on lifetime estimation is found due to the growth of DM halos within each redshift bin. The galaxy subsamples with higher stellar masses generally have shorter lifetimes, but the lifetimes in different subsamples at z 〉 1.5 tend to be independent of stellar mass. Consistently, the clustering-based lifetime for each galaxy subsample agrees well with that inferred using the spectral energy distribution modeling. Moreover, the lifetimes of the RS and BC galaxies also coincide well with their typical gas-depletion timescales attributed to the consumption of star formation. Interestingly, the distinct lifetime behaviors of the GV galaxies at z ≤ 1.5 and z 〉 1.5 cannot be fully accounted for by their gas-depletion timescales. Instead, this discrepancy between the lifetimes and gas-depletion timescales of the GV galaxies suggests that there are additional physical processes, such as feedback of active galactic nuclei, which accelerates the quenching of GV galaxies at high redshifts.
    Type of Medium: Online Resource
    ISSN: 0004-637X , 1538-4357
    URL: Article
    DOI: 10.3847/1538-4357/abe7f4
    RVK:
    UA 1000
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2021
    detail.hit.zdb_id: 2207648-7
    detail.hit.zdb_id: 1473835-1
    SSG: 16,12
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  • 3
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    Calibrating Mg ii-based Black Hole Mass Estimators Using Low-to-high-luminosity Active Galactic Nuclei
    American Astronomical Society ; 2020
    In:  The Astrophysical Journal Vol. 901, No. 1 ( 2020-09-18), p. 35-
    Details
    In: The Astrophysical Journal, American Astronomical Society, Vol. 901, No. 1 ( 2020-09-18), p. 35-
    Type of Medium: Online Resource
    ISSN: 1538-4357
    URL: Article
    DOI: 10.3847/1538-4357/abada0
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2020
    detail.hit.zdb_id: 2207648-7
    detail.hit.zdb_id: 1473835-1
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  • 4
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    Investigation of Stellar Kinematics and Ionized Gas Outflows in Local (U)LIRGs
    American Astronomical Society ; 2023
    In:  The Astrophysical Journal Vol. 951, No. 1 ( 2023-07-01), p. 7-
    Details
    In: The Astrophysical Journal, American Astronomical Society, Vol. 951, No. 1 ( 2023-07-01), p. 7-
    Abstract: We explore the properties of stellar kinematics and ionized gas in a sample of 1106 local (U)LIRGs from the AKARI telescope. We combine data from Wide-field Infrared Survey Explorer and Sloan Digital Sky Survey Data Release 13 to fit the spectral energy distribution (SED) of each source to constrain the contribution of active galactic nuclei (AGNs) to the total IR luminosity and estimate physical parameters such as stellar mass and star formation rate (SFR). We split our sample into AGNs and weak/non-AGNs. We find that our sample is considerably above the main sequence. The highest SFRs and stellar masses are associated with ULIRGs. We also fit the H β and H α regions to characterize the outflows. We find that the incidence of ionized gas outflows in AGN (U)LIRGs (∼72%) is much higher than that in weak/non-AGN ones (∼39%). The AGN ULIRGs have extreme outflow velocities (up to ∼2300 km s −1 ) and high mass-outflow rates (up to ∼60 M ⊙ yr −1 ). Our results suggest that starbursts are insufficient to produce such powerful outflows. We explore the correlations of SFR and specific SFR (sSFR) with ionized gas outflows. We find that AGN hosts with the highest SFRs exhibit a negative correlation between outflow velocity and sSFR. Therefore, in AGNs containing large amounts of gas, the negative feedback scenario might be suggested.
    Type of Medium: Online Resource
    ISSN: 0004-637X , 1538-4357
    URL: Article
    DOI: 10.3847/1538-4357/accf18
    RVK:
    UA 1000
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2023
    detail.hit.zdb_id: 2207648-7
    detail.hit.zdb_id: 1473835-1
    SSG: 16,12
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  • 5
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    Radio AGN selection and characterization in three Deep-Drilling Fields of the Vera C. Rubin Observatory Legacy Survey of Space and Time
    Oxford University Press (OUP) ; 2023
    In:  Monthly Notices of the Royal Astronomical Society Vol. 522, No. 3 ( 2023-05-02), p. 3506-3528
    Details
    In: Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP), Vol. 522, No. 3 ( 2023-05-02), p. 3506-3528
    Abstract: The Australia Telescope Large Area Survey (ATLAS) and the VLA survey in the XMM-LSS/VIDEO deep field provide deep (≈15 $\mu$ Jy beam−1) and high-resolution (≈4.5–8 arcsec) radio coverage of the three XMM-SERVS fields (W-CDF-S, ELAIS-S1, and XMM-LSS). These data cover a total sky area of 11.3 deg2 and contain ≈11 000 radio components. Furthermore, about 3 deg2 of the XMM-LSS field also has deeper MIGHTEE data that achieve a median RMS of 5.6 $\mu$ Jy beam−1 and detect more than 20 000 radio sources. We analyse all these radio data and find source counterparts at other wavebands utilizing deep optical and infrared (IR) surveys. The nature of these radio sources is studied using radio-band properties (spectral slope and morphology) and the IR–radio correlation. Radio AGNs are selected and compared with those selected using other methods (e.g. X-ray). We found 1656 new AGNs that were not selected using X-ray and/or MIR methods. We constrain the FIR-to-UV SEDs of radio AGNs using cigale and investigate the dependence of radio AGN fraction upon galaxy stellar mass and star formation rate.
    Type of Medium: Online Resource
    ISSN: 0035-8711 , 1365-2966
    URL: Article
    DOI: 10.1093/mnras/stad1178
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2023
    detail.hit.zdb_id: 2016084-7
    SSG: 16,12
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  • 6
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    Faint Active Galactic Nuclei Favor Unexpectedly Long Inter-band Time Lags
    American Astronomical Society ; 2021
    In:  The Astrophysical Journal Letters Vol. 912, No. 2 ( 2021-05-01), p. L29-
    Details
    In: The Astrophysical Journal Letters, American Astronomical Society, Vol. 912, No. 2 ( 2021-05-01), p. L29-
    Abstract: Inconsistent conclusions are obtained from recent active galactic nuclei (AGNs) accretion disk inter-band time-lag measurements. While some works show that the measured time lags are significantly larger (by a factor of ∼3) than the theoretical predictions of the Shakura & Sunyaev disk (SSD) model, others find that the time-lag measurements are consistent with (or only slightly larger than) that of the SSD model. These conflicting observational results might be symptoms of our poor understanding of AGN accretion physics. Here we show that sources with larger-than-expected time lags tend to be less luminous AGNs. Such a dependence is unexpected if the inter-band time lags are attributed to the light-travel-time delay of the illuminating variable X-ray photons to the static SSD. If, instead, the measured inter-band lags are related not only to the static SSD but also to the outer broad emission-line regions (BLRs; e.g., the blended broad emission lines and/or diffuse continua), our result indicates that the contribution of the non-disk BLR to the observed ultraviolet/optical continuum decreases with increasing luminosity ( L ), i.e., an anti-correlation resembling the well-known Baldwin effect. Alternatively, we argue that the observed dependence might be a result of coherent disk thermal fluctuations as the relevant thermal timescale, τ TH ∝ L 0.5 . With future accurate measurements of inter-band time lags, the above two scenarios can be distinguished by inspecting the dependence of inter-band time lags upon either the BLR components in the variable spectra or the timescales.
    Type of Medium: Online Resource
    ISSN: 2041-8205 , 2041-8213
    URL: Article
    DOI: 10.3847/2041-8213/abf9aa
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2021
    detail.hit.zdb_id: 2207648-7
    detail.hit.zdb_id: 2006858-X
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  • 7
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    The X-ray enhancements of radio-loud quasars at high redshift: New results at z = 4–7
    Oxford University Press (OUP) ; 2024
    In:  Monthly Notices of the Royal Astronomical Society
    Details
    In: Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP)
    Abstract: Highly radio-loud quasars (HRLQs; log R & gt; 2.5) at z ≳ 4 show apparent enhanced X-ray emission compared to matched HRLQs at lower redshifts, perhaps due to a redshift-dependent fractional contribution to the X-ray luminosity from inverse-Compton scattering of cosmic microwave background photons (IC/CMB). Using new Chandra observations and archival X-ray data, we investigate this phenomenon with an optically flux-limited sample of 41 HRLQs at z = 4–5.5 all with sensitive X-ray coverage, the largest sample utilized to date by a wide margin. X-ray enhancements are assessed using X-ray-to-optical flux ratios and spectral energy distributions. We confirm the presence of X-ray enhancements at a 4.9–5.3σ significance level, finding that the median factor of enhancement is ≈1.8 at our sample median redshift of z ≈ 4.4. Under a fractional IC/CMB model, the expected enhancement at lower redshifts is modest; e.g., ≈4% at z ≈ 1.5. We also investigate a sample of seven radio-loud quasars (RLQs; log R & gt; 1) at even higher redshifts of z = 5.6–6.8, using new and archival X-ray data. These RLQs also show evidence for X-ray enhancements by a median factor of ≈2.7 at a 3.7–4.9σ significance level. The X-ray spectral and other properties of these z = 5.6–6.8 RLQs, however, pose challenges for a straightforward fractional IC/CMB interpretation of their enhancements.
    Type of Medium: Online Resource
    ISSN: 0035-8711 , 1365-2966
    URL: Article
    DOI: 10.1093/mnras/stae656
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2024
    detail.hit.zdb_id: 2016084-7
    SSG: 16,12
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  • 8
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    Transient obscuration event captured in NGC 3227 : II. Warm absorbers and obscuration events in archival XMM-Newton and NuSTAR observations
    EDP Sciences ; 2022
    In:  Astronomy & Astrophysics Vol. 657 ( 2022-01), p. A77-
    Details
    In: Astronomy & Astrophysics, EDP Sciences, Vol. 657 ( 2022-01), p. A77-
    Abstract: The relationship between warm absorber (WA) outflows of active galactic nuclei and nuclear obscuration activities caused by optically thick clouds (obscurers) crossing the line of sight is still unclear. NGC 3227 is a suitable target for studying the properties of both WAs and obscurers because it matches the following selection criteria: WAs in both ultraviolet (UV) and X-rays, suitably variable, bright in UV and X-rays, and adequate archival spectra for making comparisons with the obscured spectra. In the aim of investigating WAs and obscurers of NGC 3227 in detail, we used a broadband spectral-energy-distribution model that is built in findings of the first paper in our series together with the photoionization code of SPEX software to fit the archival observational data taken by XMM-Newton and NuSTAR in 2006 and 2016. Using unobscured observations, we find four WA components with different ionization states (log  ξ [erg cm s −1 ] ∼ −1.0, 2.0, 2.5, 3.0). The highest-ionization WA component has a much higher hydrogen column density (∼10 22 cm −2 ) than the other three components (∼10 21 cm −2 ). The outflow velocities of these WAs range from 100 to 1300 km s −1 , and show a positive correlation with the ionization parameter. These WA components are estimated to be distributed from the outer region of the broad line region (BLR) to the narrow line region. It is worth noting that we find an X-ray obscuration event in the beginning of the 2006 observation, which was missed by previous studies. We find that it can be explained by a single obscurer component. We also study the previously published obscuration event captured in one observation in 2016, which needs two obscurer components to fit the spectrum. A high-ionization obscurer component (log  ξ  ∼ 2.80; covering factor C f  ∼ 30%) only appears in the 2016 observation, which has a high column density (∼10 23 cm −2 ). A low-ionization obscurer component (log  ξ  ∼ 1.0 − 1.9; C f  ∼ 20%−50%) exists in both 2006 and 2016 observations, which has a lower column density (∼10 22 cm −2 ). These obscurer components are estimated to reside within the BLR by their crossing time of transverse motions. The obscurers of NGC 3227 are closer to the center and have larger number densities than the WAs, which indicate that the WAs and obscurers might have different origins.
    Type of Medium: Online Resource
    ISSN: 0004-6361 , 1432-0746
    URL: Article
    DOI: 10.1051/0004-6361/202141599
    RVK:
    UA 1000
    RVK:
    US 1090
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2022
    detail.hit.zdb_id: 1458466-9
    SSG: 16,12
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  • 9
    Online Resource
    Online Resource
    VALES : VIII. Weak ionized gas outflows in star-forming galaxies at z ∼ 0.15 traced with VLT/MUSE
    EDP Sciences ; 2021
    In:  Astronomy & Astrophysics Vol. 654 ( 2021-10), p. A128-
    Details
    In: Astronomy & Astrophysics, EDP Sciences, Vol. 654 ( 2021-10), p. A128-
    Abstract: We characterize the ionized gas outflows in 15 low-redshift star-forming galaxies, a Valparaíso ALMA/APEX Line Emission Survey (VALES) subsample, using MUSE integral field spectroscopy and GAMA photometric broadband data. We measure the emission-line spectra by fitting a double-component profile, with the second and broader component related to the outflowing gas. This interpretation is in agreement with the correlation between the observed star-formation rate (SFR) surface density (Σ SFR ) and the second-component velocity dispersion ( σ 2nd ), expected when tracing the feedback component. By modeling the broadband spectra with spectral energy distribution fitting and obtaining the star-formation histories of the sample, we observe a small decrease in SFR between 100 and 10 Myr in galaxies when the outflow H α luminosity contribution is increased, indicating that the feedback somewhat inhibits the star formation within these timescales. The observed emission-line ratios are best reproduced by photoionization models when compared to shock ionization, indicating that radiation from the young stellar population is dominant and seems to be a consequence of a continuous star-formation activity instead of a “bursty” event. The outflow properties, such as the mass outflow rate (∼0.1  M ⊙ yr −1 ), the outflow kinetic power (∼5.2 × 10 −4 % L bol ), and the mass loading factor (∼0.12), point toward a scenario where the measured feedback is not strong and has a low impact on the evolution of galaxies in general.
    Type of Medium: Online Resource
    ISSN: 0004-6361 , 1432-0746
    URL: Article
    DOI: 10.1051/0004-6361/202141490
    RVK:
    UA 1000
    RVK:
    US 1090
    Language: English
    Publisher: EDP Sciences
    Publication Date: 2021
    detail.hit.zdb_id: 1458466-9
    SSG: 16,12
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  • 10
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    Online Resource
    [O iii] 5007 Å Emission Line Width as a Surrogate for σ ∗ in Type 1 AGNs?
    American Astronomical Society ; 2023
    In:  The Astrophysical Journal Vol. 945, No. 1 ( 2023-03-01), p. 59-
    Details
    In: The Astrophysical Journal, American Astronomical Society, Vol. 945, No. 1 ( 2023-03-01), p. 59-
    Abstract: We present a study of the relation between the [O iii ] 5007 Å emission line width ( σ [O III ] ) and stellar velocity dispersion ( σ * ), utilizing a sample of 740 type 1 active galactic nuclei (AGNs) with high-quality spectra at redshift z 〈 1.0. We find the broad correlation between the core component of the [O iii ] emission line width ( σ [ O III , core ] ) and σ * with a scatter of 0.11 dex for the low redshift ( z 〈 0.1) sample; for redshift (0.3 〈 z 〈 1.0) AGNs, the scatter is larger, being 0.16 dex. We also find that the Eddington ratio ( L bol / L Edd ) may play an important role in the discrepancies between σ [ O III , core ] and σ * . As the L bol / L Edd increases, σ [ O III , core ] tends to be larger than σ * . By classifying our local sample with different minor-to-major axis ratios, we find that σ * is larger than σ [ O III , core ] for those edge-on spiral galaxies. In addition, we also find that the effects of outflow strength properties such as maximum outflow velocity ( V max ) and the broader component of the [O iii ] emission line width and line shift ( σ [O III ,out] and V [O III ,out] ) may play a major role in the discrepancies between σ [ O III , core ] and σ * . The discrepancies between σ [ O III , core ] and σ * are larger when V max , V [O III ,out] , and σ [O III ,out] increase. Our results show that the outflow strengths may have significant effects on the differences between narrow-line region gas and stellar kinematics in AGNs. We suggest that caution should be taken when using σ [ O III , core ] as a surrogate for σ * . In addition, the substitute of σ [ O III , core ] for σ * could be used only for low luminosity AGNs.
    Type of Medium: Online Resource
    ISSN: 0004-637X , 1538-4357
    URL: Article
    DOI: 10.3847/1538-4357/acb770
    RVK:
    UA 1000
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2023
    detail.hit.zdb_id: 2207648-7
    detail.hit.zdb_id: 1473835-1
    SSG: 16,12
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