40 research outputs found
From Quasars to Extraordinary N-body Problems
We outline reasoning that led to the current theory of quasars and look at
George Contopoulos's place in the long history of the N-body problem. Following
Newton we find new exactly soluble N-body problems with multibody forces and
give a strange eternally pulsating system that in its other degrees of freedom
reaches statistical equilibrium.Comment: 13 pages, LaTeX with 1 postscript figure included. To appear in
Proceedings of New York Academy of Sciences, 13th Florida Workshop in
Nonlinear Astronomy and Physic
The path to a more accessible and inclusive future of meetings in astronomy
Science Communication and Societ
CO(1-0) detection of molecular gas in the massive Spiderweb Galaxy (z=2)
The high-redshift radio galaxy MRC 1138−262 (‘Spiderweb Galaxy’; z = 2.16) is one of the most massive systems in the early Universe and surrounded by a dense ‘web’ of proto-cluster galaxies. Using the Australia Telescope Compact Array, we detected CO(1–0) emission from cold molecular gas – the raw ingredient for star formation – across the Spiderweb Galaxy. We infer a molecular gas mass of MH2 = 6 × 1010 M⊙ (for MH2/L′CO = 0.8). While the bulk of the molecular gas coincides with the central radio galaxy, there are indications that a substantial fraction of this gas is associated with satellite galaxies or spread across the intergalactic medium on scales of tens of kpc. In addition, we tentatively detect CO(1–0) in the star-forming proto-cluster galaxy HAE 229, 250 kpc to the West. Our observations are consistent with the fact that the Spiderweb Galaxy is building up its stellar mass through a massive burst of widespread star formation. At maximum star formation efficiency, the molecular gas will be able to sustain the current star formation rate (SFR ≈ 1400 M⊙ yr−1, as traced by Seymour et al.) for about 40 Myr. This is similar to the estimated typical lifetime of a major starburst event in infrared luminous merger systems
Dark mammoth trunks in the merging galaxy NGC 1316 and a mechanism of cosmic double helices
NGC 1316 is a giant, elliptical galaxy containing a complex network of dark,
dust features. The morphology of these features has been examined in some
detail using a Hubble Space Telescope, Advanced Camera for Surveys image. It is
found that most of the features are constituted of long filaments. There also
exist a great number of dark structures protruding inwards from the filaments.
Many of these structures are strikingly similar to elephant trunks in H II
regions in the Milky Way Galaxy, although much larger. The structures, termed
mammoth trunks, generally are filamentary and often have shapes resembling the
letters V or Y. In some of the mammoth trunks the stem of the Y can be resolved
into two or more filaments, many of which showing signs of being intertwined. A
model of the mammoth trunks, related to a recent theory of elephant trunks, is
proposed. Based on magnetized filaments, the model is capable of giving an
account of the various shapes of the mammoth trunks observed, including the
twined structures.Comment: Accepted for publication in Astrophysics & Space Scienc
CO(1-0) survey of high-z radio galaxies: alignment of molecular halo gas with distant radio sources
We present a CO(1–0) survey for cold molecular gas in a representative sample of 13 highz
radio galaxies (HzRGs) at 1.4 <z< 2.8, using the Australia Telescope Compact Array.
We detect CO(1–0) emission associated with five sources: MRC 0114-211, MRC 0152-209,
MRC 0156-252, MRC 1138-262 and MRC 2048-272. The CO(1–0) luminosities are in the
range L
CO ∼ (5–9) × 1010 K km s−1 pc2. For MRC 0152-209 and MRC 1138-262, part of the
CO(1–0) emission coincides with the radio galaxy, while part is spread on scales of tens of
kpc and likely associated with galaxy mergers. The molecular gas mass derived for these two
systems is MH2 ∼ 6 × 1010 M� (MH2/L
CO = 0.8). For the remaining three CO-detected sources,
the CO(1–0) emission is located in the halo (∼50-kpc) environment. These three HzRGs are
among the fainter far-IR emitters in our sample, suggesting that similar reservoirs of cold
molecular halo gas may have been missed in earlier studies due to pre-selection of IR-bright
sources. In all three cases, the CO(1–0) is aligned along the radio axis and found beyond the
brightest radio hotspot, in a region devoid of 4.5 µm emission in Spitzerimaging. The CO(1–0)
profiles are broad, with velocity widths of ∼1000–3600 km s−1. We discuss several possible
scenarios to explain these halo reservoirs of CO(1–0). Following these results, we complement
our CO(1–0) study with detections of extended CO from the literature and find at marginal
statistical significance (95 per cent level) that CO in HzRGs is preferentially aligned towards
the radio jet axis. For the eight sources in which we do not detect CO(1–0), we set realistic
upper limits of L
CO ∼ 3–4 × 1010 K km s−1 pc2. Our survey reveals a CO(1–0) detection rate
of 38 per cent, allowing us to compare the CO(1–0) content of HzRGs with that of other types
of high-z galaxies