| 1. |
- Luo, Yuanze, et al.
(författare)
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A Multiwavelength View of IC 860: What Is in Action inside Quenching Galaxies * * Herschel is an ESA space observatory with science instruments provided by European-led principal investigator consortia and with important participation from NASA.
- 2022
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 938:1
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Tidskriftsartikel (refereegranskat)abstract
- We present a multiwavelength study of IC 860, a nearby post-starburst galaxy at the early stage of transitioning from blue and star forming to red and quiescent. Optical images reveal a galaxy-wide, dusty outflow originating from a compact core. We find evidence for a multiphase outflow in the molecular and neutral gas phase from the CO position-velocity diagram and NaD absorption features. We constrain the neutral mass outflow rate to be ∼0.5 M ⊙ yr−1, and the total hydrogen mass outflow rate to be ∼12 M ⊙ yr−1. Neither outflow component seems able to escape the galaxy. We also find evidence for a recent merger in the optical images, CO spatial distribution, and kinematics, and evidence for a buried active galactic nucleus in the optical emission line ratios, mid-IR properties, and radio spectral shape. The depletion time of the molecular gas reservoir under the current star formation rate is ∼7 Gyr, indicating that the galaxy could stay at the intermediate stage between the blue and red sequence for a long time. Thus the timescales for a significant decline in star formation rate (quenching) and gas depletion are not necessarily the same. Our analysis supports the quenching picture where outflows help suppress star formation by disturbing rather than expelling the gas and shed light on possible ongoing activities in similar quenching galaxies.
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| 2. |
- Alatalo, K., et al.
(författare)
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After the interaction: An efficiently star-forming molecular disk in NGC 5195
- 2016
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Ingår i: Astrophysical Journal. - 1538-4357 .- 0004-637X. ; 830:2, s. 137-
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Tidskriftsartikel (refereegranskat)abstract
- We present new molecular gas maps of NGC 5195 (alternatively known as M51b) from the Combined Array for Research in Millimeter Astronomy, including 12CO(1-0), 13CO(1-0), CN(1-), CS(2-1), and 3 mm continuum. We also detected HCN(1-0) and HCO+(1-0) using the Onsala Space Observatory. NGC 5195 has a 12CO/13CO ratio (R12/13= 11.4 ± 0.5) consistent with normal star-forming galaxies. The CN(1-0) intensity is higher than is seen in an average star-forming galaxy, possibly enhanced in the diffuse gas in photo-dissociation regions. Stellar template fitting of the nuclear spectrum of NGC 5195 shows two stellar populations: an 80% mass fraction of old (10 Gyr) and a 20% mass fraction of intermediate-aged (?1 Gyr) stellar populations. This provides a constraint on the timescale over which NGC 5195 experienced enhanced star formation during its interaction with M51a. The average molecular gas depletion timescale in NGC 5195 is = 3.08 Gyr, a factor of larger than the depletion timescales in nearby star-forming galaxies, but consistent with the depletion seen in CO-detected early-type galaxies. While radio continuum emission at centimeter and millimeter wavelengths is present in the vicinity of the nucleus of NGC 5195, we find it is most likely associated with nuclear star formation rather than radio-loud AGN activity. Thus, despite having a substantial interaction with M51a ?1/2 Gyr ago, the molecular gas in NGC 5195 has resettled and is currently forming stars at an efficiency consistent with settled early-type galaxies.
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| 3. |
- Alatalo, K., et al.
(författare)
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Evidence of boosted 13CO/12CO ratio in early-type galaxies in dense environments
- 2015
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Ingår i: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 450:4, s. 3874-3885
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Tidskriftsartikel (refereegranskat)abstract
- We present observations of 13CO(1-0) in 17 Combined Array for Research in Millimeter Astronomy ATLAS3D early-type galaxies (ETGs), obtained simultaneously with 12CO(1-0) observations. The 13CO in six ETGs is sufficiently bright to create images. In these six sources, we do not detect any significant radial gradient in the 13CO/12CO ratio between the nucleus and the outlying molecular gas. Using the 12CO channel maps as 3D masks to stack the 13CO emission, we are able to detect 15/17 galaxies to >3σ (and 12/17 to at least 5σ) significance in a spatially integrated manner. Overall, ETGs show a wide distribution of 13CO/12CO ratios, but Virgo cluster and group galaxies preferentially show a 13CO/12CO ratio about two times larger than field galaxies, although this could also be due to a mass dependence, or the CO spatial extent (RCO/Re). ETGs whose gas has a morphologically settled appearance also show boosted 13CO/12CO ratios. We hypothesize that this variation could be caused by (i) the extra enrichment of gas from molecular reprocessing occurring in low-mass stars (boosting the abundance of 13C to 12C in the absence of external gas accretion), (ii) much higher pressure being exerted on the mid-plane gas (by the intracluster medium) in the cluster environment than in isolated galaxies, or (iii) all but the densest molecular gas clumps being stripped as the galaxies fall into the cluster. Further observations of 13CO in dense environments, particularly of spirals, as well as studies of other isotopologues, should be able to distinguish between these hypotheses.
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| 4. |
- Chen, C. T.J., et al.
(författare)
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The XMM-SERVS survey : New XMM-Newton point-source catalogue for the XMM-LSS field
- 2018
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Ingår i: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 478:2, s. 2132-2163
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Tidskriftsartikel (refereegranskat)abstract
- We present an X-ray point-source catalogue from the XMM-Large Scale Structure (XMMLSS) survey region, one of the XMM-Spitzer Extragalactic Representative Volume Survey (XMM-SERVS) fields. We target the XMM-LSS region with 1.3 Ms of new XMM-Newton AO-15 observations, transforming the archival X-ray coverage in this region into a 5.3 deg2 contiguous field with uniform X-ray coverage totaling 2.7 Ms of flare-filtered exposure, with a 46 ks median PN exposure time. We provide an X-ray catalogue of 5242 sources detected in the soft (0.5-2 keV), hard (2-10 keV), and/or full (0.5-10 keV) bands with a 1 per cent expected spurious fraction determined from simulations. A total of 2381 new X-ray sources are detected compared to previous source catalogues in the same area. Our survey has flux limits of 1.7 × 10-15, 1.3 × 10-14, and 6.5 × 10-15 erg cm-2 s-1 over 90 per cent of its area in the soft, hard, and full bands, respectively, which is comparable to those of the XMM-COSMOS survey. We identify multiwavelength counterpart candidates for 99.9 per cent of the X-ray sources, of which 93 per cent are considered as reliable based on their matching likelihood ratios. The reliabilities of these high-likelihood-ratio counterparts are further confirmed to be ≈97 per cent reliable based on deep Chandra coverage over ≈5 per cent of the XMM-LSS region. Results of multiwavelength identifications are also included in the source catalogue, along with basic optical-to-infrared photometry and spectroscopic redshifts from publicly available surveys. We compute photometric redshifts for X-ray sources in 4.5 deg2 of our field where forced-aperture multiband photometry is available; > 70 per cent of the X-ray sources in this subfield have either spectroscopic or high-quality photometric redshifts.
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| 7. |
- Nyland, K., et al.
(författare)
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The interplay of managerial and non-managerial controls, institutional work, and the coordination of laterally dependent hospital activities
- 2017
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Ingår i: Qualitative Research in Accounting & Management/Emerald. - : Emerald Group Publishing Ltd.. - 1176-6093 .- 1758-7654. ; 14:4, s. 467-495
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Tidskriftsartikel (refereegranskat)abstract
- Purpose - The purpose of this paper is to explore two hospital departments, one of which is laterally dependent on the other to function, but which are subject to distinct vertical managerial controls. This complexity in vertical-lateral relations generates tension amongst the hospital's senior managers and a perception of coordination difficulties. However, this paper shows how the interplay between managerial and non-managerial controls, plus important employee "work", moderates tension and facilitates day-to-day lateral coordination at the patient-facing level. Design/methodology/approach - This is a case-study, relying mostly on the findings of semistructured interviews. Theoretically, the paper draws from previous insights on inter-organisational relations (but informing the focus on intra-organisational coordination) and an "institutional work" perspective. Findings - Consistent with much extant literature, this paper reveals how non-managerial controls help to moderate tensions that could emerge from the coercive use of managerial controls. However, the authors also show a maintained influence and flexibility in the managerial controls at patient-facing levels, as new circumstances unfold. Research limitations/implications - The findings of this paper could generalise neither all laterally dependent spaces in hospitals nor patterns across different hospitals. The authors recommend future research into the dynamics and interaction of managerial and non-managerial controls in other complex settings, plus focus on the purposeful work of influential agents. Originality/value - The paper has two primary contributions: extending our knowledge of the interplay between managerial and non-managerial controls inside complex organisations, where non-managerial controls reinforce rather than displace managerial controls, and highlighting that it is seldom just controls per se which "matter", but also agents' purposeful actions that facilitate coordination in complex organisations.
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