Search Publications
Rejuvenated galaxies with very old bulges at the origin of the bending of the main sequence and of the `green valley'
Daddi, Emanuele; Juneau, Stéphanie; Liu, Daizhong +11 more
We investigate the nature of star-forming galaxies with reduced specific star formation rate (sSFR) and high stellar masses, those `green valley' objects that seemingly cause a reported bending, or flattening, of the star-forming main sequence. The fact that such objects host large bulges recently led some to suggest that the internal formation of…
Constraints on the chemical enrichment history of the Perseus Cluster of galaxies from high-resolution X-ray spectroscopy
Yamaguchi, H.; Simionescu, A.; Kaastra, J. S. +32 more
High-resolution spectroscopy of the core of the Perseus Cluster of galaxies, using the Hitomi satellite above 2 keV and the XMM-Newton Reflection Grating Spectrometer at lower energies, provides reliable constraints on the abundances of O, Ne, Mg, Si, S, Ar, Ca, Cr, Mn, Fe, and Ni. Accounting for all known systematic uncertainties, the Ar/Fe, Ca/F…
The outer halo globular cluster system of M31 - III. Relationship to the stellar halo
Côté, P.; Mackey, A. D.; Martin, N. F. +10 more
We utilize the final catalogue from the Pan-Andromeda Archaeological Survey to investigate the links between the globular cluster system and field halo in M31 at projected radii Rproj = 25-150 kpc. In this region the cluster radial density profile exhibits a power-law decline with index Γ = -2.37 ± 0.17, matching that for the stellar ha…
Butterfly in a Cocoon, Understanding the Origin and Morphology of Globular Cluster Streams: The Case of GD-1
Malhan, Khyati; Ibata, Rodrigo A.; Carlberg, Raymond G. +2 more
Tidally disrupted globular cluster (GC) streams are usually observed, and therefore perceived, as narrow, linear, and one-dimensional structures in the 6D phase space. Here, we show that the GD-1 stellar stream, which is the tidal debris of a disrupted GC, possesses a secondary diffuse and extended stellar component (∼100 pc wide) around it, detec…
Multiphase quasar-driven outflows in PG 1114+445. I. Entrained ultra-fast outflows
Piconcelli, Enrico; Tombesi, Francesco; Serafinelli, Roberto +3 more
Substantial evidence in the last few decades suggests that outflows from supermassive black holes (SMBH) may play a significant role in the evolution of galaxies. These outflows, powered by active galactic nuclei (AGN), are thought to be the fundamental mechanism by which the SMBH transfers a significant fraction of its accretion energy to the sur…
The most luminous blue quasars at 3.0 < z < 3.3. I. A tale of two X-ray populations
Marconi, A.; Vignali, C.; Gilli, R. +8 more
We present the X-ray analysis of 30 luminous quasars at z ≃ 3.0 - 3.3 with pointed XMM-Newton observations (28-48 ks) originally obtained by our group to test the suitability of active galactic nuclei as standard candles for cosmological studies. The sample was selected in the optical from the Sloan Digital Sky Survey Data Release 7 to be represen…
Massive galaxies on the road to quenching: ALMA observations of powerful high redshift radio galaxies
Lehnert, Matthew D.; De Breuck, Carlos; Wylezalek, Dominika +10 more
We present 0.″3 (band 6) and 1.″5 (band 3) ALMA observations of the (sub)millimeter dust continuum emission for 25 radio galaxies at 1 < z < 5.2. Our survey reaches a rms flux density of ∼50 µJy in band 6 (200-250 GHz) and ∼20 µJy in band 3 (100-130 GHz). This is an order of magnitude deeper than single-dish 850 µm observat…
Discriminating among theories of spiral structure using Gaia DR2
Rix, Hans-Walter; Carlberg, R. G.; Coronado, Johanna +2 more
We compare the distribution in position and velocity of nearby stars from the Gaia DR2 radial velocity sample with predictions of current theories for spirals in disc galaxies. Although the rich substructure in velocity space contains the same information, we find it more revealing to reproject the data into action-angle variables, and we describe…
ACR Proton Acceleration Associated with Reconnection Processes beyond the Heliospheric Termination Shock
Chen, Y.; Burlaga, L. F.; Zank, G. P. +6 more
One of the curious observations from the Voyagers is that the intensity of anomalous cosmic rays (ACRs) did not peak at the heliospheric termination shock (HTS) but instead a short distance (within ∼1 au) downstream of the HTS. One possible explanation is that the interaction of the wavy heliospheric current sheet with the HTS enhances magnetic re…
Gaia Data Release 2. All-sky classification of high-amplitude pulsating stars
Szabados, L.; Audard, M.; Plachy, E. +23 more
Context. More than half a million of the 1.69 billion sources in Gaia Data Release 2 (DR2) are published with photometric time series that exhibit light variations during the 22 months of observation.
Aims: An all-sky classification of common high-amplitude pulsators (Cepheids, long-period variables, δ Scuti/SX Phoenicis, and RR Lyrae stars) …