Extreme Star Formation in the Interacting Galaxy Arp 299 (IC 694 + NGC 3690) (original) (raw)
Related papers
Star clusters in the interacting galaxy system Arp 284
Monthly Notices of the Royal Astronomical Society, 2009
We present results from a study of proto-globular cluster candidates in the interacting galaxy system Arp 284 (NGC 7714/5) using data from the Hubble Space Telescope. Previous studies of the Antennae and M51 have suggested that the majority of young massive star clusters dissolve within 20 Myr due to mass loss. We use the evolutionary synthesis code starburst99 to estimate ages and extinctions for approximately 175 clusters visible with HST. We also use lower-resolution GALEX and ground-based Hα data to estimate the ages of the giant H ii regions in which these clusters are found, and compare the Spitzer colours of these H ii regions to those of star forming regions in other interacting systems. The ages are also used to aid in the interpretation of Chandra X-ray data.
The Astronomical Journal, 2007
As part of our Spitzer Spirals, Bridges, and Tails project to help understand the effects of galaxy interactions on star formation, we analyze GALEX ultraviolet, SARA optical, and Spitzer infrared images of the interacting galaxy pair Arp 82 (NGC 2535/6) and compare to a numerical simulation of the interaction. We investigate the multi-wavelength properties of several individual star forming complexes (clumps). Using optical and UV colors, EW(Hα), and population synthesis models we constrain the ages of the clumps and find that the median clump age is ∼9 Myr. The clumps have masses ranging from a few ×10 6 to 10 9 M ⊙ . In general, the clumps in the tidal features have similar ages to those in the spiral region, but are less massive. The clumps provide 33%, 36%, and 70% of the FUV, 8.0 µm, and 24 µm emission, respectively. The 8 µm and 24 µm luminosities are used to estimate the far-infrared luminosities and the star formation rates of the clumps. The total clump star formation rate is ∼2.0±0.8 M ⊙ yr −1 , while the entire Arp 82 system is forming stars at a rate of ∼4.9±2.0 M ⊙ yr −1 . We find, for the first time, stars in the H I arc to the southeast of the NGC 2535 disk. Population synthesis models indicate that all of the observed populations have young to intermediate ages. We conclude that although the gas disks and some old stars may have formed early-on, the progenitors may have been late-type or low surface brightness and the evolution of these galaxies seems to have halted until the recent encounter.
1999
We present adaptive optics observations of the Luminous Infrared Galaxy, Arp 299. This merging galaxy (NGC 3690) is the site of a very powerful starburst activity. Very high angular resolution observations at 2.2µm reveal many superclusters of newly formed stars. Those clusters feature intrinsic luminosities and surface densities well above the figures generally found in the Local Cluster, pointing to a highly efficient stellar formation with possibly very high mass stars. Comparison with hst images in V band allows us to extract a [V-K] map, and shows that the extinction varies largely within the area. Comparison of the very nucleus of Mkn 171A to a model point spread function shows that it is resolved in K band, with a FWHM of 0.4 leading to the conclusion that an AGN as the primary power source is very unlikely. The small size, high extinction and high intrinsic luminosity of this nucleus prompts us to suggest an ultra-compact starburst as primary source of luminosity.
The Astrophysical Journal, 2009
We present new mid-infrared (5 − 35µm) and ultraviolet (1539-2316Å) observations of the interacting galaxy system Arp 143 (NGC 2444/2445) from the Spitzer Space Telescope and GALEX. In this system, the central nucleus of NGC 2445 is surrounded by knots of massive star-formation in a ring-like structure. We find unusually strong emission from warm H 2 associated with an expanding shock wave between the nucleus and the western knots. At this ridge, the flux ratio between H 2 and PAH emission is nearly ten times higher than in the nucleus. Arp 143 is one of the most extreme cases known in that regard. From our multi-wavelength data we derive a narrow age range of the star-forming knots between 2 Myr and 7.5 Myr, suggesting that the ring of knots was formed almost simultaneously in response to the shock wave traced by the H 2 emission. However, the knots can be further subdivided in two age groups: those with an age of 2-4 Myr (knots A, C, E, and F), which are associated with 8µm emission from PAHs, and those with an age of 7-8 Myr (knots D and G), which show little or no 8µm emission shells surrounding them. We attribute this finding to an ageing effect of the massive clusters which, after about 6 Myr, no longer excite the PAHs surrounding the knots.
Star formation in the massive cluster merger Abell 2744
Monthly Notices of the Royal Astronomical Society, 2014
We present a comprehensive study of star-forming (SF) galaxies in the HST Frontier Field recent cluster merger A2744 (z = 0.308). Wide-field, ultraviolet-infrared (UV-IR) imaging enables a direct constraint of the total star formation rate (SFR) for 53 cluster galaxies, with SFR UV+IR = 343 ± 10 M ⊙ yr −1 . Within the central 4 arcmin (1.1 Mpc) radius, the integrated SFR is complete, yielding a total SFR UV+IR = 201±9 M ⊙ yr −1 . Focussing on obscured star formation, this core region exhibits a total SFR IR = 138 ± 8 M ⊙ yr −1 , a mass-normalised SFR IR of Σ SFR = 11.2 ± 0.7 M ⊙ yr −1 per 10 14 M ⊙ and a fraction of IR-detected SF galaxies f SF = 0.080 +0.010 −0.037 . Overall, the cluster population at z ∼ 0.3 exhibits significant intrinsic scatter in IR properties (total SFR IR , T dust distribution) apparently unrelated to the dynamical state: A2744 is noticeably different to the merging Bullet cluster, but similar to several relaxed clusters. However, in A2744 we identify a trail of SF sources including jellyfish galaxies with substantial unobscured SF due to extreme stripping (SFR UV /SFR IR up to 3.3). The orientation of the trail, and of material stripped from constituent galaxies, indicates that the passing shock front of the cluster merger was the trigger. Constraints on star formation from both IR and UV are crucial for understanding galaxy evolution within the densest environments.
Probing the Dust-enshrouded Regions of the Interacting Galaxy System ARP 299:A Near-Infrared Study
Astrophysical Journal, 1999
We present high spectral resolution (λ/δλ≅103) Paβ(1.28 μm) and Brγ(2.17 μm), 3.29 μm dust feature, and near-infrared broadband images of the Arp 299=NGC 3690/IC 694 galaxy system. The emission is found to be concentrated at the positions of three active regions, known as sources A, B, and C. From our Brγ/Paβ flux ratio we find the visual extinction toward the ionized gas in A, B, and C is ~6, 6, and 2 magnitudes, respectively, assuming case B recombination and a foreground screen geometry for the obscuring material. Our observations can be explained entirely by a starburst model for the Arp 299 system. The putative active galactic nucleus (AGN) in source A does not dominate the properties of this source. We see no evidence of broad recombination lines. In addition, the ratio of the 3.29 μm dust feature to total luminosity, a tracer of starburst activity, is consistent in each source with that seen in M82 and other starburst galaxies. Also, our imaging observations reveal that the dust feature emission is concentrated in the nucleus of source A, contrary to the extended annular distribution of the feature emission seen surrounding the nucleus of the more distant Seyfert galaxy NGC 7469. In this galaxy, the absence of the feature emission in the nucleus has been attributed to the destruction of the dust carriers in the hard radiation field surrounding the AGN. Our observations suggest that all of the active regions in Arp 299 are characterized by starburst episodes. The observed CO indices and Brγ equivalent widths imply that source B is older than source A and source C is the youngest star-forming region. Although these regions are probably complex physical systems not necessarily characterized by a single coeval population of stars, we have compared our observations with an instantaneous starburst model with a Salpeter initial mass function. Using this simple model, we find starburst ages of ~6×106, 8×106, and 4×106 for sources A, B, and C, respectively.
Formation of a Tidal Dwarf Galaxy in the Interacting System Arp 245 (NGC 2992/93)
The Astronomical Journal, 2000
Among the various phenomena observed in interacting galaxies is the ejection due to tidal forces of stellar and gaseous material into the intergalactic medium and its subsequent rearranging which can lead to the formation of self-gravitating tidal dwarf galaxies (TDGs). We investigate this process with a detailed multiwavelength study of the interacting system Arp 245 and a numerical model of the collision computed with a Tree-SPH code. Our observations consist of optical/near-infrared broad band imaging, Hα imaging, optical spectroscopy, H I VLA cartography and CO line mapping. The system, composed of the two spiral galaxies NGC 2992 and NGC 2993, is observed at an early stage of the interaction, about 100 Myr after perigalacticon, though at a time when tidal tails have already developed. The VLA observations disclose a third partner to the interaction: an edge-on, flat galaxy, FGC 0938, which looks strikingly undisturbed and might just be falling towards the NGC 2992/93 system. Our H I map shows prominent counterparts to the optical tails. Whereas the stellar and gaseous components of the plume that originates from NGC 2992 match, the stellar and H I tails emanating from NGC 2993 have a different morphology. In particular, the H I forms a ring, a feature that has been successfully reproduced by our numerical simulations. The H I emission in the system as a whole peaks at the tip of the NGC 2992 tail where a gas reservoir of about 10 9 M ⊙ , about 60% of the H I towards NGC 2992, coincides with a star-forming -2optical condensation, A245N. The latter tidal object exhibits properties ranging between those of dwarf irregular galaxies (structural parameters, gas content, star formation rate) and those of spiral disks (metallicity, star formation efficiency, stellar population). Although it is likely, based on our analysis of the HI and model datacube, that A245N might become an independent dwarf galaxy, the dynamical evidence is still open to debate. Prompted by the questions raised for this particular object, we discuss some issues related to the definition and identification of TDGs and highlight some specific conditions which seem required to form them. We finally outline what is needed in terms of future numerical simulations in order to further our understanding of these objects.
Progressive Starbursts and High Velocities in the Infrared-luminous, Colliding Galaxy Arp 118
The Astrophysical Journal, 1998
In this paper we demonstrate for the first time the connection between the spatial and temporal progression of star formation and the changing locations of the very dense regions in the gas of a massive disk galaxy (NGC 1144) in the aftermath of its collision with a massive elliptical (NGC 1143). These two galaxies form the combined object Arp 118, a collisional ring galaxy system. The results of 3D, time-dependent, numerical simulations of the behavior of the gas, stars, and dark matter of a disk galaxy and the stars and dark matter in an elliptical during a collision are compared with multiwavelength observations of Arp 118. The collision that took place approximately 22 Myr ago generated a strong, non-linear density wave in the stars and gas in the disk of NGC 1144, causing the gas to became clumped on a large scale. This wave produced a series of superstarclusters along arcs and rings that emanate from the central point of impact in the disk. The locations of these star forming regions match those of the regions of increased gas density predicted the time sequence of models.
Monthly Notices of …, 2011
Using 100 µm and 160 µm fluxes from GOODS-Herschel -the deepest survey yet undertaken by the Herschel telescope -we explore the infrared properties of X-ray selected active galactic nuclei (AGNs) up to z ≈ 3. We show that the observed 100 µm and 160 µm fluxes are dominated by emission from the host galaxy in the vast majority of cases (i.e., > 94 per cent), meaning that these far-infrared fluxes provide an uncontaminated view of the star formation in the host galaxies. There is no clear evidence of any correlation between the levels of nuclear and star formation activity at all surveyed redshifts. On the other hand, we confirm that the star formation rates of AGN hosts increase strongly with redshift; by a factor of 43 +27 −18 from z < 0.1 to z = 2 − 3 for AGNs with the same range of X-ray luminosities (L X = 10 42 -10 44 ergs s −1 ). This increase is entirely consistent with the factor of 25-50 increase in the specific star formation rates (SSFRs) of normal, star-forming (i.e., main-sequence) galaxies over the same redshift range. Indeed, the average SSFRs of AGN hosts are only marginally (i.e., ≈ 20 per cent) lower than those of main-sequence galaxies at all surveyed redshifts. We estimate that between 79 ± 10 per cent of moderate luminosity (L X = 10 42 -10 44 ergs s −1 ) AGNs are hosted in main-sequence galaxies, 15 ± 7 per cent in quiescent galaxies and < 10 per cent in strongly starbursting galaxies. We derive the fractions of all main sequence galaxies at z < 2 that are experiencing a period of moderate nuclear activity, noting that it is strongly dependent on galaxy stellar mass (M stars ); rising from just a few per cent at M stars ∼ 10 10 M ⊙ to 50 per cent at M stars 10 11 M ⊙ . We argue that our findings imply that the majority of moderate nuclear activity is fuelled by internal mechanisms rather than violent mergers, which suggests that high redshift disk instabilities could be an important AGN feeding mechanism.
THE BURIED STARBURST IN THE INTERACTING GALAXY II Zw 096 AS REVEALED BY THE SPITZER SPACE TELESCOPE
An analysis of data from the Spitzer Space Telescope, Hubble Space Telescope, Chandra X-ray Observatory, and AKARI Infrared Astronomy Satellite is presented for the z = 0.036 merging galaxy system II Zw 096 (CGCG 448-020). Because II Zw 096 has an infrared luminosity of log(L IR /L) = 11.94, it is classified as a Luminous Infrared Galaxy (LIRG), and was observed as part of the Great Observatories All-sky LIRG Survey (GOALS). The Spitzer data suggest that 80% of the total infrared luminosity comes from an extremely compact, red source not associated with the nuclei of the merging galaxies. The Spitzer mid-infrared spectra indicate no high-ionization lines from a buried active galactic nucleus in this source. The strong detection of the 3.3 μm and 6.2 μm polycyclic aromatic hydrocarbon emission features in the AKARI and Spitzer spectra also implies that the energy source of II Zw 096 is a starburst. Based on Spitzer infrared imaging and AKARI near-infrared spectroscopy, the star formation rate is estimated to be 120 M yr −1 and >45 M yr −1 , respectively. Finally, the high-resolution B-, I-, and H-band images show many star clusters in the interacting system. The colors of these clusters suggest at least two populations—one with an age of 1–5 Myr and one with an age of 20–500 Myr, reddened by 0–2 mag of visual extinction. The masses of these clusters span a range between 10 6 and 10 8 M. This starburst source is reminiscent of the extranuclear starburst seen in NGC 4038/9 (the Antennae Galaxies) and Arp 299 but approximately an order of magnitude more luminous than the Antennae. The source is remarkable in that the off-nuclear infrared luminosity dominates the entire system.