| 1. |
- Adamo, Angela, et al.
(författare)
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Super star clusters in Haro 11: properties of a very young starburst and evidence for a near-infrared flux excess
- 2010
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 407:2, s. 870-890
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Tidskriftsartikel (refereegranskat)abstract
- We have used multiband imaging to investigate the nature of an extreme starburst environment in the nearby Lyman break galaxy analogue Haro 11 (ESO350-IG038) by means of its stellar cluster population. The central starburst region has been observed in eight different high-resolution Hubble Space Telescope (HST) wavebands, sampling the stellar and gas components from UV to near-infrared. Photometric imaging of the galaxy was also carried out at 2.16μm by NaCo AO instrument at the ESO Very Large Telescope. We constructed integrated spectral energy distributions (SEDs) for about 200 star clusters located in the active star-forming regions and compared them with single stellar population models (suitable for physical properties of very young cluster population) in order to derive ages, masses and extinctions of the star clusters. The cluster age distribution we recover confirms that the present starburst has lasted for 40Myr, and shows a peak of cluster formation only 3.5 Myr old. With such an extremely young cluster population, Haro 11 represents a unique opportunity to investigate the youngest phase of the cluster formation process and evolution in starburst systems. We looked for possible relations between cluster ages, extinctions and masses. Extinction tends to diminish as a function of the cluster age, but the spread is large and reaches the highest dispersion for clusters in partial embedded phases (<5Myr). A fraction of low-mass (below 104 Msolar), very young (1-3Myr) clusters is missing, either because they are embedded in the parental molecular cloud and heavily extinguished, or because of blending with neighbouring clusters. The range of the cluster masses is wide; we observe that more than 30 per cent of the clusters have masses above 105 Msolar, qualifying them as super star clusters. Almost half of the cluster sample is affected by flux excesses at wavelengths >8000Å which cannot be explained by simple stellar evolutionary models. Fitting SED models over all wavebands leads to systematic overestimates of cluster ages and incorrect masses for the stellar population supplying the light in these clusters. We show that the red excess affects also the HST F814W filter, which is typically used to constrain cluster physical properties. The clusters which show the red excess are younger than 40Myr we discuss possible physical explanations for the phenomenon. Finally, we estimate that Haro 11 has produced bound clusters at a rate almost a factor of 10 higher than the massive and regular spirals, like the Milky Way. The present cluster formation efficiency is ~38 per cent of the galactic star formation rate.
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| 2. |
- Adrian-Martinez, S., et al.
(författare)
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A first search for coincident gravitational waves and high energy neutrinos using LIGO, Virgo and ANTARES data from 2007
- 2013
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Ingår i: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; :6
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Tidskriftsartikel (refereegranskat)abstract
- We present the results of the first search for gravitational wave bursts associated with high energy neutrinos. Together, these messengers could reveal new, hidden sources that are not observed by conventional photon astronomy, particularly at high energy. Our search uses neutrinos detected by the underwater neutrino telescope ANTARES in its 5 line configuration during the period January - September 2007, which coincided with the fifth and first science runs of LIGO and Virgo, respectively. The LIGO-Virgo data were analysed for candidate gravitational-wave signals coincident in time and direction with the neutrino events. No significant coincident events were observed. We place limits on the density of joint high energy neutrino - gravitational wave emission events in the local universe, and compare them with densities of merger and core-collapse events.
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| 3. |
- Cormier, D., et al.
(författare)
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The molecular gas reservoir of 6 low-metallicity galaxies from the Herschel Dwarf Galaxy Survey A ground-based follow-up survey of CO(1-0), CO(2-1), and CO(3-2)
- 2014
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 564
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Tidskriftsartikel (refereegranskat)abstract
- Context. Observations of nearby starburst and spiral galaxies have revealed that molecular gas is the driver of star formation. However, some nearby low-metallicity dwarf galaxies are actively forming stars, but CO, the most common tracer of this reservoir, is faint, leaving us with a puzzle about how star formation proceeds in these environments. Aims. We aim to quantify the molecular gas reservoir in a subset of 6 galaxies from the Herschel Dwarf Galaxy Survey with newly acquired CO data and to link this reservoir to the observed star formation activity. Methods. We present CO(1-0), CO(2-1), and CO(3-2) observations obtained at the ATNE Mopra 22-m, APEX, and IRAM 30-m telescopes, as well as [CII] 157 mu m and [OI] 63 mu m observations obtained with the Herschel/PACS spectrometer in the 6 low-metallicity dwarf galaxies: Haro 11, Mrk 1089, Mrk 930, NGC 4861, NGC 625, and UM 311. We derived their molecular gas masses from several methods, including using the CO-to-H-2 conversion factor X-CO (both Galactic and metallicity-scaled values) and dust measurements. The molecular and atomic gas reservoirs were compared to the star formation activity. We also constrained the physical conditions of the molecular clouds using the non-LTE code RADEX and the spectral synthesis code Cloudy. Results. We detect CO in 5 of the 6 galaxies, including first detections in Haro 11 (Z similar to 0.4 Z(circle dot)), Mrk 930 (0.2 Z(circle dot)), and UM 311 (0.5 Z(circle dot)), but CO remains undetected in NGC 4861 (0.2 Z(circle dot)). The CO luminosities are low, while [CII] is bright in these galaxies, resulting in [CII]/CO(1-0) >= 10 000. Our dwarf galaxies are in relatively good agreement with the Schmidt-Kennicutt relation for total gas. They show short molecular depletion timescales, even when considering metallicity-scaled X-CO factors. Those galaxies are dominated by their HI gas, except Haro 11, which has high star formation efficiency and is dominated by ionized and molecular gas. We determine the mass of each ISM phase in Haro 11 using Cloudy and estimate an equivalent X-CO factor that is 10 times higher than the Galactic value. Overall, our results confirm the emerging picture that CO suffers from significant selective photodissociation in low-metallicity dwarf galaxies.
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| 4. |
- Cumming, Robert, 1967
(författare)
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Astronom på hög höjd
- 2012
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Ingår i: Populär Astronomi. - 1650-7177. ; 13:3, s. 18-21
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- I norra Chile finns världens klaraste stjärnhimlar, ochvärldens torraste förhållanden. Där har Lars-Åke Nyman imer än 20 år arbetat med att driva banbrytande teleskop,nu med det största av alla, ALMA.
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| 5. |
- Cumming, Robert, 1967
(författare)
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Byggplats: Vintergatan
- 2011
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Ingår i: Populär Astronomi. - 1650-7177. ; 11:1, s. 34-37
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Byggplanerna för Vintergatan vet ingen hur de skulle hasett ut. Men före detta byggnadsingenjören, astronomenThomas Bensby, är sanningen på spåret.
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| 6. |
- Cumming, Robert, 1967
(författare)
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Eva har sikte på kometen
- 2014
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Ingår i: Populär Astronomi. - 1650-7177. ; 14:3, s. 22-24
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- I slutet av november riktas världens astronomiska blickarmot komet ISON. Vid Onsala rymdobservatorium är manredo, och projektledare är Eva Wirström.
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| 7. |
- Cumming, Robert, 1967
(författare)
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För rymden i riksdagen
- 2011
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Ingår i: Populär Astronomi. - 1650-7177. ; 12:3, s. 22-23
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Staffan Anger är riksdagsmannen som startade ett nätverk för rymdintresserade politiker. Han tycker att mer rymd ärprecis det som Sverige behöver. Men kan han övertyga sina egna partivänner i regeringen? [Intervju]
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| 8. |
- Cumming, Robert, 1967
(författare)
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Karin lotsar in i en ny tid för Rymdsverige
- 2013
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Ingår i: Populär Astronomi. - 1650-7177. ; 14:4, s. 22-24
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Turistflyg till rymden är bara en av många möjligheter som Karin Nilsdotter, vd för Spaceport Sweden, brinner för att göra möjligt.
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| 9. |
- Cumming, Robert, 1967
(författare)
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Kosmiskt strålande
- 2011
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Ingår i: Populär Astronomi. - 1650-7177. ; 12:2, s. 34-36
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- De kosmiska partiklarna regnar ner över oss hela tiden. Julia Becker vill veta var de kommer ifrån. [Intervju]
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| 10. |
- Cumming, Robert, 1967
(författare)
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LOFAR ser universum på ett helt nytt sätt
- 2012
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Ingår i: Fysikaktuellt. - 0283-9148. ; 2012:2, s. 12-13
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Radioteleskopet LOFAR är störst i världen och först i sittslag. Med mängder av enkla antenner och en oerhört kraftfulldator skapar det bilder av rymden på ett helt nytt sätt.
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