Search for: All records

We present a study of new 7.7–11.3 μm data obtained with theJames WebbSpace Telescope Mid-InfraRed Instrument in the starburst galaxy M 82. In particular, we focus on the dependency of the integrated CO(1–0) line intensity on the MIRI-F770W and MIRI-F1130W filter intensities to investigate the correlation between H₂content and the 7.7 and 11.3 μm features from polycyclic aromatic hydrocarbons (PAH) in M 82’s outflows. To perform our analysis, we identify CO clouds using the archival¹²CO(J = 1 − 0) NOEMA moment 0 map within 2 kpc from the center of M 82, with sizes ranging between ∼21 and 270 pc; then, we compute the CO-to-PAH relations for the 306 validated CO clouds. On average, the power-law slopes for the two relations in M 82 are lower than what is seen in local main-sequence spirals. In addition, there is a moderate correlation betweenI_{CO(1 − 0)} − I_7.7 μm/I_11.3 μmfor some of the CO cloud groups analyzed in this work. Our results suggest that the extreme conditions in M 82 translate into CO not tracing the full budget of molecular gas in smaller clouds, perhaps as a consequence of photoionization and/or emission suppression of CO molecules due to hard radiation fields from the central starburst. 

Synopsis The gastropod shell is a composite composed of minerals and shell matrix proteins (SMPs). SMPs have been identified by proteomics in many molluscs, but few have been studied in detail. Open questions include (1) what gene regulatory networks regulate SMP expression, (2) what roles individual SMPs play in biomineralization, and (3) how the complement of SMPs changes over development. These questions are best addressed in a species in which gene perturbation studies are available; one such species is the slipper snail, Crepidula fornicata. Here, SEM and pXRD analysis demonstrated that the adult shell of C. fornicata exhibits crossed lamellar microstructure and is composed of aragonite. Using high-throughput proteomics we identified 185 SMPs occluded within the adult shell. Over half of the proteins in the shell proteome have known biomineralization domains, while at least 10% have no homologs in public databases. Differential gene expression analysis identified 20 SMP genes that are up-regulated in the shell-producing mantle tissue. Over half of these 20 SMPs are expressed during development with two, CfSMP1 and CfSMP2, expressed exclusively in the shell gland. Together, the description of the shell microstructure and a list of SMPs now sets the stage for studying the consequences of SMP gene knockdowns in molluscs. 

Linking South and North America via a South Atlantic high-performance Research & Education Network (REN) with the nations of Africa’s researchers, students, and knowledge sharing communities has become an increasingly strategic priority. Africa offers research and education communities with unique biological, environmental, geological, anthropological, and cultural resources. Research challenges in atmospheric and geosciences, materials sciences, tropical diseases, biology, astronomy, and other disciplines will benefit by enhancing the technological and social connections between the research and education communities of the U.S., Brazil / Latin America, and Africa. For many years, we have seen the dramatic benefits of high-performance networking in all areas of science and engineering. The Americas Africa Research and eduCation Lightpaths (AARCLight) project (NSF OAC-1638990) provided support for a grant to plan, design, and define a strategy for high capacity research and education network connectivity between the U.S. and West Africa. The study indicated a high level of enthusiasm to engage in collaborative research between the U.S., Brazil, and the African communities. There is collaborative interest in sharing network infrastructure resources in the US at AMPATH in Miami, in Fortaleza and Sao Paulo, Brazil where RedClara and ANSP connect at SouthernLight, and in Cape Town, South Africa. There is strong evidence of multiple ongoing domain science projects between the U.S., Brazil, and Africa that would benefit from a new South Atlantic link. The results of this planning grant successfully supported the need to light a 100G pathway using the South Atlantic Cable System (SACS) connecting to AmLight-ExP in Fortaleza, Brazil, and via the West African Cable System (WACS) cable to the Cape Town, South Africa open exchange point. Based on these findings, AmLight-ExP , a high-performance R&E network supported by a consortium of participants and funding from the NSF is the steward of the SACS 100G link. With collaborative support from UbuntuNet Alliance, RNP, SANReN, and others, AmLight is taking steps to make this first South Atlantic R&E network path available to connect all three continents. This critical infrastructure establishes a new South Atlantic route to integrate with AmLight-ExP, adding resiliency to the global R&E network fabric by adding a new path to Africa and Europe from the southern hemisphere. The SACS cable, shown on Figure 1 as a purple dashed line between Fortaleza, Brazil, and Luanda, Angola, is the first east - west subsea cable in the South Atlantic. We will leverage network infrastructure in the southern hemisphere that is available to the R&E community including spectrum on Monet committed to the AmLight-ExP linking Miami, Fortaleza and São Paulo; a 100G Ethernet link on SACS; TENET’s capacity on WACS; the R&E exchange point in Cape Town-ZAOXI operated by SANReN (South African National Research Network) and TENET connected to WACS and the Ubuntunet Alliance Network connecting East Africa; and the South America eXchange R&E exchange point (SAX) in Fortaleza, operated by RNP and connected via AmLight-ExP via Monet to São Paulo and Miami. The paper will present 1) the key partners in the AmLight-SACS collaboration, 2) the activation plan, 3) how the network will be instrumented for performance measurements, and to capture data for network analytics, and 4) science drivers that will benefit from the use of a South Atlantic network route between the U.S., South America and West Africa. 

Linking South and North America via a South Atlantic high-performance Research & Education Network (REN) with the nations of Africa’s researchers, students, and knowledge sharing communities has become an increasingly strategic priority. Africa offers research and education communities with unique biological, environmental, geological, anthropological, and cultural resources. Research challenges in atmospheric and geosciences, materials sciences, tropical diseases, biology, astronomy, and other disciplines will benefit by enhancing the technological and social connections between the research and education communities of the U.S., Brazil / Latin America, and Africa. For many years, we have seen the dramatic benefits of high-performance networking in all areas of science and engineering. The Americas Africa Research and eduCation Lightpaths (AARCLight) project (NSF OAC-1638990) provided support for a grant to plan, design, and define a strategy for high capacity research and education network connectivity between the U.S. and West Africa. The study indicated a high level of enthusiasm to engage in collaborative research between the U.S., Brazil, and the African communities. There is collaborative interest in sharing network infrastructure resources in the US at AMPATH in Miami, in Fortaleza and Sao Paulo, Brazil where RedClara and ANSP connect at SouthernLight, and in Cape Town, South Africa. There is strong evidence of multiple ongoing domain science projects between the U.S., Brazil, and Africa that would benefit from a new South Atlantic link. The results of this planning grant successfully supported the need to light a 100G pathway using the South Atlantic Cable System (SACS) connecting to AmLight-ExP in Fortaleza, Brazil, and via the West African Cable System (WACS) cable to the Cape Town, South Africa open exchange point. Based on these findings, AmLight-ExP , a high-performance R&E network supported by a consortium of participants and funding from the NSF is the steward of the SACS 100G link. With collaborative support from UbuntuNet Alliance, RNP, SANReN, and others, AmLight is taking steps to make this first South Atlantic R&E network path available to connect all three continents. This critical infrastructure establishes a new South Atlantic route to integrate with AmLight-ExP, adding resiliency to the global R&E network fabric by adding a new path to Africa and Europe from the southern hemisphere. The SACS cable, shown on Figure 1 as a purple dashed line between Fortaleza, Brazil, and Luanda, Angola, is the first east - west subsea cable in the South Atlantic. We will leverage network infrastructure in the southern hemisphere that is available to the R&E community including spectrum on Monet committed to the AmLight-ExP linking Miami, Fortaleza, and São Paulo; a 100G Ethernet link on SACS; TENET’s capacity on WACS; the R&E exchange point in Cape Town-ZAOXI operated by SANReN (South African National Research Network) and TENET connected to WACS and the Ubuntunet Alliance Network connecting East Africa; and the South America eXchange R&E exchange point (SAX) in Fortaleza, operated by RNP and connected via AmLight-ExP via Monet to São Paulo and Miami. The paper will present 1) the key partners in the AmLight-SACS collaboration, 2) the activation plan, 3) how the network will be instrumented for performance measurements, and to capture data for network analytics, and 4) science drivers that will benefit from the use of a South Atlantic network route between the U.S., South America, and West Africa. 

ABSTRACT We report the discovery of the closest known black hole candidate as a binary companion to V723 Mon. V723 Mon is a nearby ($$d\sim 460\, \rm pc$$), bright (V ≃ 8.3 mag), evolved (Teff, giant ≃ 4440 K, and Lgiant ≃ 173 L⊙) red giant in a high mass function, f(M) = 1.72 ± 0.01 M⊙, nearly circular binary (P = 59.9 d, e ≃ 0). V723 Mon is a known variable star, previously classified as an eclipsing binary, but its All-Sky Automated Survey, Kilodegree Extremely Little Telescope, and Transiting Exoplanet Survey Satellite light curves are those of a nearly edge-on ellipsoidal variable. Detailed models of the light curves constrained by the period, radial velocities, and stellar temperature give an inclination of $$87.0^{\circ ^{+1.7^\circ }}_{-1.4^\circ }$$, a mass ratio of q ≃ 0.33 ± 0.02, a companion mass of Mcomp = 3.04 ± 0.06 M⊙, a stellar radius of Rgiant = 24.9 ± 0.7 R⊙, and a giant mass of Mgiant = 1.00 ± 0.07 M⊙. We identify a likely non-stellar, diffuse veiling component with contributions in the B and V band of $${\sim }63{{\ \rm per\ cent}}$$ and $${\sim }24{{\ \rm per\ cent}}$$, respectively. The SED and the absence of continuum eclipses imply that the companion mass must be dominated by a compact object. We do observe eclipses of the Balmer lines when the dark companion passes behind the giant, but their velocity spreads are low compared to observed accretion discs. The X-ray luminosity of the system is $$L_{\rm X}\simeq 7.6\times 10^{29}~\rm ergs~s^{-1}$$, corresponding to L/Ledd ∼ 10−9. The simplest explanation for the massive companion is a single compact object, most likely a black hole in the ‘mass gap’. 

The complex physical, kinematic, and chemical properties of galaxy centres make them interesting environments to examine with molecular line emission. We present new 2 − 4″ (∼75 − 150 pc at 7.7 Mpc) observations at 2 and 3 mm covering the central 50″ (∼1.9 kpc) of the nearby double-barred spiral galaxy NGC 6946 obtained with the IRAM Plateau de Bure Interferometer. We detect spectral lines from ten molecules: CO, HCN, HCO + , HNC, CS, HC 3 N, N 2 H + , C 2 H, CH 3 OH, and H 2 CO. We complemented these with published 1 mm CO observations and 33 GHz continuum observations to explore the star formation rate surface density Σ SFR on 150 pc scales. In this paper, we analyse regions associated with the inner bar of NGC 6946 – the nuclear region (NUC), the northern (NBE), and southern inner bar end (SBE) and we focus on short-spacing corrected bulk (CO) and dense gas tracers (HCN, HCO + , and HNC). We find that HCO + correlates best with Σ SFR , but the dense gas fraction ( f dense ) and star formation efficiency of the dense gas (SFE dense ) fits show different behaviours than expected from large-scale disc observations. The SBE has a higher Σ SFR , f dense , and shocked gas fraction than the NBE. We examine line ratio diagnostics and find a higher CO(2−1)/CO(1−0) ratio towards NBE than for the NUC. Moreover, comparison with existing extragalactic datasets suggests that using the HCN/HNC ratio to probe kinetic temperatures is not suitable on kiloparsec and sub-kiloparsec scales in extragalactic regions. Lastly, our study shows that the HCO + /HCN ratio might not be a unique indicator to diagnose AGN activity in galaxies. 

ABSTRACT The feedback from young stars (i.e. pre-supernova) is thought to play a crucial role in molecular cloud destruction. In this paper, we assess the feedback mechanisms acting within a sample of 5810 H ii regions identified from the PHANGS-MUSE survey of 19 nearby (<20 Mpc) star-forming, main-sequence spiral galaxies [log(M⋆/M⊙) = 9.4–11]. These optical spectroscopic maps are essential to constrain the physical properties of the H ii regions, which we use to investigate their internal pressure terms. We estimate the photoionized gas (Ptherm), direct radiation (Prad), and mechanical wind pressure (Pwind), which we compare to the confining pressure of their host environment (Pde). The H ii regions remain unresolved within our ∼50–100 pc resolution observations, so we place upper (Pmax) and lower (Pmin) limits on each of the pressures by using a minimum (i.e. clumpy structure) and maximum (i.e. smooth structure) size, respectively. We find that the Pmax measurements are broadly similar, and for Pmin the Ptherm is mildly dominant. We find that the majority of H ii regions are overpressured, Ptot/Pde = (Ptherm + Pwind + Prad)/Pde > 1, and expanding, yet there is a small sample of compact H ii regions with Ptot,max/Pde < 1 (∼1 per cent of the sample). These mostly reside in galaxy centres (Rgal < 1 kpc), or, specifically, environments of high gas surface density; log(Σgas/M⊙ pc−2) ∼ 2.5 (measured on kpc-scales). Lastly, we compare to a sample of literature measurements for Ptherm and Prad to investigate how dominant pressure term transitions over around 5 dex in spatial dynamic range and 10 dex in pressure. 

New international academic collaborations are being created at a fast pace, generating data sets each day, in the order of terabytes in size. Often these data sets need to be moved in real-time to a central location to be processed and then shared. In the field of astronomy, building data processing facilities in remote locations is not always feasible, creating the need for a high bandwidth network infrastructure to transport these data sets very long distances. This network infrastructure normally relies on multiple networks operated by multiple organizations or projects. Creating an end-to-end path involving multiple network operators, technologies and interconnections often adds conditions that make the real-time movement of big data sets challenging. The Large Synoptic Survey Telescope (LSST) is an example of astronomical applications imposing new challenges on multi-domain network provisioning activities. The network for LSST is challenging for a number of reasons: (1) with the telescope in Chile and the archiving facility in the USA, the network has a high propagation delay, which affects traditional transport protocols performance; (2) the path is composed of multiple network operators, which means that the different network operating teams involved must coordinate technologies and protocols to support all parallel data transfers in an efficient way; (3) the large amount of data produced (12.7GB/image) and the small interval available to transfer this data (5 seconds) to the archiving facility requires special Quality of Service (QoS) policies; (4) because network events happen, the network needs to be prepared to be adjusted for rainy days, where some data types will be prioritized over others. To guarantee data transfers will happen within the required interval, each network operator in the path needs to apply QoS policies to each of its network links. These policies need to be coordinated end-to-end and, in the case where the network is affected by parallel events, all policies might need to be dynamically reconfigured in real-time to accommodate specific QoS policies for rainy days. Reconfiguring QoS policies is a very complex activity to current network protocols and technologies, sometimes requiring human intervention. This presentation aims to share the efforts to guarantee an efficient network configuration capable of handling LSST data transfers in sunny and rainy days across multiple network operators from South to North America.