JWST/NIRSpec Observations of the Planetary Mass Companion TWA 27B

We present 1-5um spectroscopy of the young planetary mass companion TWA 27B (2M1207B) performed with NIRSpec on board the James Webb Space Telescope. In these data, the fundamental band of CH_4 is absent and the fundamental band of CO is weak. The nondetection of CH_4 reinforces a previously observed trend of weaker CH_4 with younger ages among L dwarfs, which has been attributed to enhanced non-equilibrium chemistry among young objects. The weakness of CO may reflect an additional atmospheric property that varies with age, such as the temperature gradient or cloud thickness. We are able to reproduce the broad shape of the spectrum with an ATMO cloudless model that has T=1300 K, non-equilibrium chemistry, and a temperature gradient reduction caused by fingering convection. However, the fundamental bands of CH_4 and CO are somewhat stronger in the model. In addition, the model temperature of 1300 K is higher than expected from evolutionary models given the luminosity and age of TWA 27B (T=1200 K). Previous models of young L-type objects suggest that the inclusion of clouds could potentially resolve these issues; it remains to be seen whether cloudy models can provide a good fit to the 1-5um data from NIRSpec. TWA 27B exhibits emission in Paschen transitions and the He I triplet at 1.083um, which are signatures of accretion that provide the first evidence of a circumstellar disk. We have used the NIRSpec data to estimate the bolometric luminosity of TWA 27B (log L/L_sun=-4.466+/-0.014), which implies a mass of 5-6 MJup according to evolutionary models.Comment: Astrophysical Journal Letters, in pres

A Deep View into the Nucleus of the Sagittarius Dwarf Spheroidal Galaxy with MUSE. II. Kinematic Characterization of the Stellar Populations

The Sagittarius dwarf spheroidal galaxy is in an advanced stage of disruption but still hosts its nuclear star cluster (NSC), M54, at its center. In this paper, we present a detailed kinematic characterization of the three stellar populations present in M54: young metal-rich (YMR); intermediate-age metal-rich (IMR); and old metal-poor (OMP), based on the spectra of ~6500 individual M54 member stars extracted from a large Multi-Unit Spectroscopic Explorer (MUSE)/Very Large Telescope data set. We find that the OMP population is slightly flattened with a low amount of rotation (~0.8 km s−1) and with a velocity dispersion that follows a Plummer profile. The YMR population displays a high amount of rotation (~5 km s−1) and a high degree of flattening, with a lower and flat velocity dispersion profile. The IMR population shows a high but flat velocity dispersion profile, with some degree of rotation (~2 km s−1). We complement our MUSE data with information from Gaia DR2 and confirm that the stars from the OMP and YMR populations are comoving in 3D space, suggesting that they are dynamically bound. While dynamical evolutionary effects (e.g., energy equipartition) are able to explain the differences in velocity dispersion between the stellar populations, the strong differences in rotation indicate different formation paths for the populations, as supported by an N-body simulation tailored to emulate the YMR–OMP system. This study provides additional evidence for the M54 formation scenario proposed in our previous work, where this NSC formed via GC accretion (OMP) and in situ formation from gas accretion in a rotationally supported disk (YMR)

The Near-Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope: IV. Capabilities and predicted performance for exoplanet characterization

The Near-Inrared Spectrograph (NIRSpec) on the James Webb Space Telescope (JWST) is a very versatile instrument, offering multiobject and integral field spectroscopy with varying spectral resolution ($\sim$30 to $\sim$3000) over a wide wavelength range from 0.6 to 5.3 micron, enabling scientists to study many science themes ranging from the first galaxies to bodies in our own Solar System. In addition to its integral field unit and support for multiobject spectroscopy, NIRSpec features several fixed slits and a wide aperture specifically designed to enable high precision time-series and transit as well as eclipse observations of exoplanets. In this paper we present its capabilities regarding time-series observations, in general, and transit and eclipse spectroscopy of exoplanets in particular. Due to JWST's large collecting area and NIRSpec's excellent throughput, spectral coverage, and detector performance, this mode will allow scientists to characterize the atmosphere of exoplanets with unprecedented sensitivity

First results from the JWST Early Release Science Program Q3D: Ionization cone, clumpy star formation and shocks in a z=3z=3 extremely red quasar host

Massive galaxies formed most actively at redshifts $z=1-3$ during the period known as `cosmic noon.' Here we present an emission-line study of an extremely red quasar SDSSJ165202.64+172852.3 host galaxy at $z=2.94$, based on observations with the Near Infrared Spectrograph (NIRSpec) integral field unit (IFU) on board JWST. We use standard emission-line diagnostic ratios to map the sources of gas ionization across the host and a swarm of companion galaxies. The quasar dominates the photoionization, but we also discover shock-excited regions orthogonal to the ionization cone and the quasar-driven outflow. These shocks could be merger-induced or -- more likely, given the presence of a powerful galactic-scale quasar outflow -- these are signatures of wide-angle outflows that can reach parts of the galaxy that are not directly illuminated by the quasar. Finally, the kinematically narrow emission associated with the host galaxy presents as a collection of 1 kpc-scale clumps forming stars at a rate of at least 200 $M_{\odot}$ yr$^{-1}$. The ISM within these clumps shows high electron densities, reaching up to 3,000 cm$^{-3}$ with metallicities ranging from half to a third solar with a positive metallicity gradient and V band extinctions up to 3 magnitudes. The star formation conditions are far more extreme in these regions than in local star-forming galaxies but consistent with that of massive galaxies at cosmic noon. JWST observations reveal an archetypical rapidly forming massive galaxy undergoing a merger, a clumpy starburst, an episode of obscured near-Eddington quasar activity, and an extremely powerful quasar outflow simultaneously.Comment: 19 pages, 8 figures. Accepted for publication in Ap

First results from the JWST Early Release Science Program Q3D: The Warm Ionized Gas Outflow in z ~ 1.6 Quasar XID 2028 and its Impact on the Host Galaxy

Quasar feedback may regulate the growth of supermassive black holes, quench coeval star formation, and impact galaxy morphology and the circumgalactic medium. However, direct evidence for quasar feedback in action at the epoch of peak black hole accretion at z ~ 2 remains elusive. A good case in point is the z = 1.6 quasar WISEA J100211.29+013706.7 (XID 2028) where past analyses of the same ground-based data have come to different conclusions. Here we revisit this object with the integral field unit of the Near Infrared Spectrograph (NIRSpec) on board the James Webb Space Telescope (JWST) as part of Early Release Science program Q3D. The excellent angular resolution and sensitivity of the JWST data reveal new morphological and kinematic sub-structures in the outflowing gas plume. An analysis of the emission line ratios indicates that photoionization by the central quasar dominates the ionization state of the gas with no obvious sign for a major contribution from hot young stars anywhere in the host galaxy. Rest-frame near-ultraviolet emission aligned along the wide-angle cone of outflowing gas is interpreted as a scattering cone. The outflow has cleared a channel in the dusty host galaxy through which some of the quasar ionizing radiation is able to escape and heat the surrounding interstellar and circumgalactic media. The warm ionized outflow is not powerful enough to impact the host galaxy via mechanical feedback, but radiative feedback by the AGN, aided by the outflow, may help explain the unusually small molecular gas mass fraction in the galaxy host.Comment: 17 pages, 9 figures, accepted for publication in The Astrophysical Journa

Relativistic Binaries in Globular Clusters

Galactic globular clusters are old, dense star systems typically containing 10\super{4}--10\super{7} stars. As an old population of stars, globular clusters contain many collapsed and degenerate objects. As a dense population of stars, globular clusters are the scene of many interesting close dynamical interactions between stars. These dynamical interactions can alter the evolution of individual stars and can produce tight binary systems containing one or two compact objects. In this review, we discuss theoretical models of globular cluster evolution and binary evolution, techniques for simulating this evolution that leads to relativistic binaries, and current and possible future observational evidence for this population. Our discussion of globular cluster evolution will focus on the processes that boost the production of hard binary systems and the subsequent interaction of these binaries that can alter the properties of both bodies and can lead to exotic objects. Direct {\it N}-body integrations and Fokker--Planck simulations of the evolution of globular clusters that incorporate tidal interactions and lead to predictions of relativistic binary populations are also discussed. We discuss the current observational evidence for cataclysmic variables, millisecond pulsars, and low-mass X-ray binaries as well as possible future detection of relativistic binaries with gravitational radiation.Comment: 88 pages, 13 figures. Submitted update of Living Reviews articl

M• − σRelation For Intermediate-Mass Black Holes In Globular Clusters

Context. For galaxies hosting supermassive black holes (SMBHs), it has been observed that the mass of the central black hole (M center dot) tightly correlates with the effective or central velocity dispersion (s) of the host galaxy. The origin of this M center dot - sigma scaling relation is assumed to lie in the merging history of the galaxies, but many open questions about its origin and the behavior in different mass ranges still need to be addressed. Aims. The goal of this work is to study the black-hole scaling relations for low black-hole masses, where the regime of intermediatemass black holes (IMBHs) in globular clusters (GCs) is entered. Methods. We collected all existing reports of dynamical black-hole measurements in GCs, providing black-hole masses or upper limits for 14 candidates. We plotted the black-hole masses versus different cluster parameters including total mass, velocity dispersion, concentration, and half-mass radius. We searched for trends and tested the correlations to quantify their significance using a set of different statistical approaches. For correlations with a high significance we performed a linear fit, accounting for uncertainties and upper limits. Results. We find a clear correlation between the mass of the IMBH and the velocity dispersion of the GC. As expected, the total mass of the GC then also correlates with the mass of the IMBH. While the slope of the M center dot - sigma correlation differs strongly from the one observed for SMBHs, the other scaling relations M center dot - M-tot, and M center dot - L are similar to the correlations in galaxies. Significant correlations of black-hole mass with other cluster properties were not found in the present sample.DFG cluster of excellence OriginStructure of the UniverseAustralian Research Council through Future Fellowship grant FT0991052Astronom

First results from the JWST Early Release Science Program Q3D: The Warm Ionized Gas Outflow in z ~ 1.6 Quasar XID 2028 and its Impact on the Host Galaxy

International audienceQuasar feedback may regulate the growth of supermassive black holes, quench coeval star formation, and impact galaxy morphology and the circumgalactic medium. However, direct evidence for quasar feedback in action at the epoch of peak black hole accretion at z ~ 2 remains elusive. A good case in point is the z = 1.6 quasar WISEA J100211.29+013706.7 (XID 2028) where past analyses of the same ground-based data have come to different conclusions. Here we revisit this object with the integral field unit of the Near Infrared Spectrograph (NIRSpec) on board the James Webb Space Telescope (JWST) as part of Early Release Science program Q3D. The excellent angular resolution and sensitivity of the JWST data reveal new morphological and kinematic sub-structures in the outflowing gas plume. An analysis of the emission line ratios indicates that photoionization by the central quasar dominates the ionization state of the gas with no obvious sign for a major contribution from hot young stars anywhere in the host galaxy. Rest-frame near-ultraviolet emission aligned along the wide-angle cone of outflowing gas is interpreted as a scattering cone. The outflow has cleared a channel in the dusty host galaxy through which some of the quasar ionizing radiation is able to escape and heat the surrounding interstellar and circumgalactic media. The warm ionized outflow is not powerful enough to impact the host galaxy via mechanical feedback, but radiative feedback by the AGN, aided by the outflow, may help explain the unusually small molecular gas mass fraction in the galaxy host

Identification and properties of intense star-forming galaxies at redshifts z > 10

Surveys with the James Webb Space Telescope (JWST) have discovered candidate galaxies in the first 400 Myr of cosmic time. Preliminary indications have suggested these candidate galaxies may be more massive and abundant than previously thought. However, without confirmed distances, their inferred properties remain uncertain. Here we identify four galaxies located in the JWST Advanced Deep Extragalactic Survey Near-Infrared Camera imaging with photometric redshifts z of roughly 10–13. These galaxies include the first redshift z > 12 systems discovered with distances spectroscopically confirmed by JWST in a companion paper. Using stellar population modelling, we find the galaxies typically contain 100 million solar masses in stars, in stellar populations that are less than 100 million years old. The moderate star-formation rates and compact sizes suggest elevated star-formation rate surface densities, a key indicator of their formation pathways. Taken together, these measurements show that the first galaxies contributing to cosmic reionization formed rapidly and with intense internal radiation fields

Spectroscopic confirmation of four metal-poor galaxies at z = 10.3–13.2

Finding and characterizing the first galaxies that illuminated the early universe at cosmic dawn is pivotal to understand the physical conditions and the processes that led to the formation of the first stars. In the first few months of operations, imaging from the James Webb Space Telescope (JWST) has been used to identify tens of candidates of galaxies at redshift (z) greater than 10, less than 450 million years after the Big Bang. However, none of such candidates has yet been confirmed spectroscopically, leaving open the possibility that they are actually low-redshift interlopers. Here we present spectroscopic confirmation and analysis of four galaxies unambiguously detected at redshift 10.3 ≤ z ≤ 13.2, previously selected from JWST Near Infrared Camera imaging. The spectra reveal that these primeval galaxies are metal poor, have masses on the order of about 107–108 solar masses and young ages. The damping wings that shape the continuum close to the Lyman edge provide constraints on the neutral hydrogen fraction of the intergalactic medium from normal star-forming galaxies. These findings demonstrate the rapid emergence of the first generations of galaxies at cosmic dawn