scholarly journals Investigating the Baryon Cycle in Interacting Dwarfs with the Very Large Array and Pan-STARRS

2022 ◽  
Vol 163 (2) ◽  
pp. 49
Author(s):  
N. Luber ◽  
Sarah Pearson ◽  
Mary E. Putman ◽  
Gurtina Besla ◽  
Sabrina Stierwalt ◽  
...  
Keyword(s):  
Dwarf Galaxies ◽  
Mass Scale ◽  
Large Array ◽  
Dynamical Modeling ◽  
Very Large Array ◽  
Tidal Interactions ◽  
Low Mass ◽  
Pass Through ◽  
Arm Pointing ◽  
Spiral Arm

Abstract We present resolved H i synthesis maps from the Very Large Array of three interacting dwarf systems: the NGC 3664 dwarf pair, the NGC 3264 dwarf pair, and the UGC 4638 dwarf triplet. All three dwarf systems are captured at various stages of interaction and span a range of environments. We detect clear hallmarks of tidal interactions through the presence of H i bridges and diffuse H i extensions that surround the dwarfs. We overlay the H i data on Pan-STARRS r-band images and find further evidence of tidal interactions through coincident distorted H i and tidal stellar features in NGC 3264 and UGC 4638, and an unwound spiral arm pointing toward its smaller companion in NGC 3264. In UGC 4638, both the gas and diffuse stars are extended to similar radii east of the primary, which could indicate that the smaller dwarf in the system has already completed one pass through the primary. We additionally find that our three systems, and those from the Local Volume TiNy Titans survey, are not H i deficient and thus the interaction has not resulted in a loss of gas from the systems. A comparison with noninteracting dwarf galaxies shows that the interactions have a significant impact on the kinematics of the systems. Our new resolved H i kinematics, combined with detailed stellar and H i morphologies, provide crucial constraints for future dynamical modeling of hierarchical mergers and the baryon cycle at the low-mass scale.

scholarly journals The formation of ultradiffuse galaxies in the RomulusC galaxy cluster simulation

2020 ◽  
Vol 497 (3) ◽  
pp. 2786-2810 ◽  
Author(s):  
M Tremmel ◽  
A C Wright ◽  
A M Brooks ◽  
F Munshi ◽  
D Nagai ◽  
...  
Keyword(s):  
Dark Matter ◽  
Stellar Evolution ◽  
Dwarf Galaxies ◽  
Galaxy Cluster ◽  
High Mass ◽  
Tidal Interactions ◽  
Low Surface Brightness ◽  
Low Mass ◽  
Tidal Heating ◽  
Low Surface Brightness Galaxies

ABSTRACT We study the origins of 122 ultradiffuse galaxies (UDGs) in the Romulus c zoom-in cosmological simulation of a galaxy cluster (M200 = 1.15 × 1014 M⊙), one of the only such simulations capable of resolving the evolution and structure of dwarf galaxies (M⋆ < 109 M⊙). We find broad agreement with observed cluster UDGs and predict that they are not separate from the overall cluster dwarf population. UDGs in cluster environments form primarily from dwarf galaxies that experienced early cluster in-fall and subsequent quenching due to ram pressure. The ensuing dimming of these dwarf galaxies due to passive stellar evolution results in a population of very low surface brightness galaxies that are otherwise typical dwarfs. UDGs and non-UDGs alike are affected by tidal interactions with the cluster potential. Tidal stripping of dark matter, as well as mass-loss from stellar evolution, results in the adiabatic expansion of stars, particularly in the lowest mass dwarfs. High-mass dwarf galaxies show signatures of tidal heating while low-mass dwarfs that survive until z = 0 typically have not experienced such impulsive interactions. There is little difference between UDGs and non-UDGs in terms of their dark matter haloes, stellar morphology, colours, and location within the cluster. In most respects cluster UDG and non-UDGs alike are similar to isolated dwarf galaxies, except for the fact that they are typically quenched.

scholarly journals Orbital Motions in Binary Protostellar Systems

2004 ◽  
Vol 191 ◽  
pp. 92-99
Author(s):  
L.F. Rodríguez
Keyword(s):  
Nuclear Reactions ◽  
Molecular Complexes ◽  
Close Approach ◽  
Young Star ◽  
Double Star ◽  
Large Array ◽  
Very Large Array ◽  
Low Mass ◽  
Third Law ◽  
The Masses

AbstractUsing high-resolution (~ 01), multi-epoch Very Large Array observations, we have detected orbital motions in several low-luminosity protobinary systems in the Taurus and ρ Ophiuchus molecular complexes. The masses obtained from Kepler’s third law are of the order of 0.5 to 2 M⊙, as expected for such low-mass protostars. The relatively large bolometric luminosities of these young systems corroborates the notion that protostars obtain most of their luminosity from accretion and not from nuclear reactions. In addition, in one of the sources studied (a multiple system in Taurus), a low-mass young star has shown a drastic change in its orbit after a close approach with another component of the system, presumed to be a double star. The large proper motion achieved by this low mass protostar (20 km s−1), suggests an ejection from the system.

scholarly journals A multifrequency study of the active star forming region NGC 6357

2006 ◽  
Vol 2 (S237) ◽  
pp. 400-400
Author(s):  
C. E. Cappa ◽  
R. H. Barbá ◽  
M. Arnal ◽  
N. Duronea ◽  
E. Fernández Lajús ◽  
...  
Keyword(s):  
Angular Resolution ◽  
Massive Stars ◽  
Radio Continuum ◽  
Large Array ◽  
Schmidt Telescope ◽  
Ionized Gas ◽  
Very Large Array ◽  
Active Star ◽  
Star Forming ◽  
Spiral Arm

To investigate the interaction of the massive stars with the gas and dust in the active star forming region NGC 6357, located in the Sagittarius spiral arm at a distance of 1.7-2.6 kpc (Massey et al. 2001), we analyzed the distribution of the neutral and ionized gas, and that of the dust, based on Hα, [OIII] and [SII] images obtained with the Curtis-Schmidt telescope at CTIO, radio continuum observations at 1.465 MHz obtained with the Very Large Array (NRAO) in the DnC configuration (synthesized beam = 38″), Hi data from the Parkes survey (angular resolution = 15′), CO(1-0) observations obtained with the Nanten radiotelescope at Las Campanas Observatory (angular resolution = 2.7′), and IR images in the four MSX bands (angular resolution = 18.3″).

Water Maser Survey toward Low‐Mass Young Stellar Objects in the Northern Sky with the Nobeyama 45 Meter Telescope and the Very Large Array

2003 ◽  
Vol 144 (1) ◽  
pp. 71-134 ◽  
Author(s):  
Ray S. Furuya ◽  
Yoshimi Kitamura ◽  
Alwyn Wootten ◽  
Mark J. Claussen ◽  
Ryohei Kawabe
Keyword(s):  
Young Stellar Objects ◽  
Large Array ◽  
Stellar Objects ◽  
Very Large Array ◽  
Low Mass ◽  
Water Maser

scholarly journals Quasi-simultaneous radio and X-ray observations of Aql X-1 : probing low luminosities

2019 ◽  
Vol 492 (2) ◽  
pp. 2858-2871 ◽  
Author(s):  
N V Gusinskaia ◽  
J W T Hessels ◽  
N Degenaar ◽  
A T Deller ◽  
J C A Miller-Jones ◽  
...  
Keyword(s):  
Neutron Star ◽  
Large Array ◽  
Very Large Array ◽  
X Ray ◽  
Upper Limits ◽  
Order Of Magnitude ◽  
Low Mass ◽  
Low X ◽  
Power Law Index ◽  
X Ray Binaries

ABSTRACT Aql X-1 is one of the best-studied neutron star low-mass X-ray binaries. It was previously targeted using quasi-simultaneous radio and X-ray observations during at least seven different accretion outbursts. Such observations allow us to probe the interplay between accretion inflow (X-ray) and jet outflow (radio). Thus far, these combined observations have only covered one order of magnitude in radio and X-ray luminosity range; this means that any potential radio–X-ray luminosity correlation, LR ∝ LXβ, is not well constrained (β ≈ 0.4–0.9, based on various studies) or understood. Here we present quasi-simultaneous Very Large Array and Swift-XRT observations of Aql X-1’s 2016 outburst, with which we probe one order of magnitude fainter in radio and X-ray luminosity compared to previous studies (6 × 1034 erg s−1 < LX <3 × 1035 erg s−1, i.e. the intermediate to low-luminosity regime between outburst peak and quiescence). The resulting radio non-detections indicate that Aql X-1’s radio emission decays more rapidly at low X-ray luminosities than previously assumed – at least during the 2016 outburst. Assuming similar behaviour between outbursts, and combining all available data in the hard X-ray state, this can be modelled as a steep β =$1.17^{+0.30}_{-0.21}$ power-law index or as a sharp radio cut-off at LX ≲ 5 × 1035 erg s−1 (given our deep radio upper limits at X-ray luminosities below this value). We discuss these results in the context of other similar studies.

A Very Large Array Search for Water Masers in Six HiiRegions: Tracers of Triggered Low‐Mass Star Formation

2004 ◽  
Vol 610 (2) ◽  
pp. 835-850 ◽  
Author(s):  
Kevin R. Healy ◽  
J. Jeff Hester ◽  
Mark J. Claussen
Keyword(s):  
Star Formation ◽  
Mass Star ◽  
Large Array ◽  
Very Large Array ◽  
Low Mass ◽  
Water Masers

scholarly journals Neutral Hydrogen in HCG 95

2000 ◽  
Vol 174 ◽  
pp. 154-157 ◽  
Author(s):  
W. K. Huchtmeier ◽  
Lourdes Verdes-Montenegro ◽  
Min Yun ◽  
A. del Olmo ◽  
J. Perea
Keyword(s):  
Spiral Galaxies ◽  
Dwarf Galaxies ◽  
Elliptical Galaxy ◽  
Neutral Hydrogen ◽  
Radio Continuum ◽  
Continuum Emission ◽  
Large Array ◽  
Foreground Object ◽  
Very Large Array ◽  
Group Center

AbstractWe have observed Hɪ emission and radio continuum emission from the compact group of galaxies HCG 95 with the Very Large Array (VLA)1. Two continuum sources coincide in with galaxies in this group: HCG 95 B (3.9 mJy) and HCG95C (6 mJy). Hɪ emission and absorption was detected in galaxy HCG 95 C. In addition we detected two so far unknown dwarf galaxies by their Hɪ emission within 3.5 arcmin of the group center. We did not detect galaxy b (with ç = 8000 kms−1 it is obviously a foreground object) and galaxy d — an edge-on Sc galaxy. This group definitely is Hɪ deficient compared with the average Hɪ content expected for spiral galaxies of the same luminosity and type. The first-ranked elliptical galaxy HCG 95 A might be responsible for the observed Hɪ deficiency in this group.

scholarly journals Dark-matter-deficient galaxies in hydrodynamical simulations

2019 ◽  
Vol 488 (3) ◽  
pp. 3298-3307 ◽  
Author(s):  
Yingjie Jing ◽  
Chunxiang Wang ◽  
Ran Li ◽  
Shihong Liao ◽  
Jie Wang ◽  
...  
Keyword(s):  
Dark Matter ◽  
Binding Energy ◽  
Galaxy Formation ◽  
Dwarf Galaxies ◽  
State Of The Art ◽  
Tidal Interactions ◽  
Group Environment ◽  
Central Regions ◽  
Low Mass ◽  
Hydrodynamical Simulations

Abstract Low-mass galaxies are expected to be dark-matter-dominated even within their central regions. Recently, two observations reported two dwarf galaxies in a group environment with very little dark matter in their central regions. We explore the population and origins of dark-matter-deficient galaxies (DMDGs) using two state-of-the-art hydrodynamical simulations, the EAGLE and Illustris projects. For all satellite galaxies with 109 < M* < 1010 M$\odot$ in groups with M200 > 1013 M$\odot$, we find that about $2.6\, {\rm per\, cent}$ of them in EAGLE, and $1.5\, {\rm per\, cent}$ in Illustris are DMDGs with dark matter fractions below $50\, {\rm per\, cent}$ inside two times the half-stellar-mass radius. We demonstrate that DMDGs are highly tidally disrupted galaxies, and that because dark matter has a higher binding energy than stars, mass loss of the dark matter is much more rapid than that of stars in DMDGs during tidal interactions. If DMDGs were confirmed in observations, they are expected in current galaxy formation models.

scholarly journals Radio emission in ultracool dwarfs: The nearby substellar triple system VHS 1256–1257

2018 ◽  
Vol 610 ◽  
pp. A23 ◽  
Author(s):  
J. C. Guirado ◽  
R. Azulay ◽  
B. Gauza ◽  
M. A. Pérez-Torres ◽  
R. Rebolo ◽  
...  
Keyword(s):  
Radio Emission ◽  
Flux Density ◽  
Upper Bound ◽  
Equal Mass ◽  
Large Array ◽  
Turnover Frequency ◽  
Radio Flux ◽  
Very Large Array ◽  
Upper Limit ◽  
Low Mass

Aim. With the purpose of investigating the radio emission of new ultracool objects, we carried out a targeted search in the recently discovered system VHS J125601.92–125723.9 (hereafter VHS 1256–1257); this system is composed by an equal-mass M7.5 binary and a L7 low-mass substellar object located at only 15.8 pc. Methods. We observed in phase-reference mode the system VHS 1256–1257 with the Karl G. Jansky Very Large Array at X band and L band and with the European VLBI Network at L band in several epochs during 2015 and 2016. Results. We discovered radio emission at X band spatially coincident with the equal-mass M7.5 binary with a flux density of 60 μJy. We determined a spectral index α = −1.1 ± 0.3 between 8 and 12 GHz, suggesting that non-thermal, optically thin, synchrotron, or gyrosynchrotron radiation is responsible for the observed radio emission. Interestingly, no signal is seen at L band where we set a 3σ upper limit of 20 μJy. This might be explained by strong variability of the binary or self-absorption at this frequency. By adopting the latter scenario and gyrosynchrotron radiation, we constrain the turnover frequency to be in the interval 5–8.5 GHz, from which we infer the presence of kG-intense magnetic fields in the M7.5 binary. Our data impose a 3σ upper bound to the radio flux density of the L7 object of 9 μJy at 10 GHz.

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