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Star formation

About: Star formation is a research topic. Over the lifetime, 37405 publications have been published within this topic receiving 1808161 citations. The topic is also known as: astrogenesis.


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Journal ArticleDOI
TL;DR: In this paper, the authors present a study on the evolution of the slope and scatter of the SFR-stellar mass relation for galaxies at 3.5? z? 6.5 using multi-wavelength photometry in GOODS-S from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) and Spitzer Extended Deep Survey.
Abstract: Distant star-forming galaxies show a correlation between their star formation rates (SFRs) and stellar masses, and this has deep implications for galaxy formation. Here, we present a study on the evolution of the slope and scatter of the SFR-stellar mass relation for galaxies at 3.5 ? z ? 6.5 using multi-wavelength photometry in GOODS-S from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) and Spitzer Extended Deep Survey. We describe an updated, Bayesian spectral-energy distribution fitting method that incorporates effects of nebular line emission, star formation histories that are constant or rising with time, and different dust-attenuation prescriptions (starburst and Small Magellanic Cloud). From z = 6.5 to z = 3.5 star-forming galaxies in CANDELS follow a nearly unevolving correlation between stellar mass and SFR that follows SFR?~? with a =0.54 ? 0.16 at z ~ 6 and 0.70 ? 0.21 at z ~ 4. This evolution requires a star formation history that increases with decreasing redshift (on average, the SFRs of individual galaxies rise with time). The observed scatter in the SFR-stellar mass relation is tight, ?(log SFR/M ? yr?1) 9?dex. Assuming that the SFR is tied to the net gas inflow rate (SFR?~ ), then the scatter in the gas inflow rate is also smaller than 0.3?0.4?dex for star-forming galaxies in these stellar mass and redshift ranges, at least when averaged over the timescale of star formation. We further show that the implied star formation history of objects selected on the basis of their co-moving number densities is consistent with the evolution in the SFR-stellar mass relation.

329 citations

Journal ArticleDOI
TL;DR: In this paper, high-sensitivity IRAS co-added survey data, coupled with new high sensitivity near-IR observations, are used to investigate the nature of embedded objects over an 4.3sq-pc area comprising the central star-forming cloud of the Ophiuchi molecular complex.
Abstract: High-sensitivity IRAS coadded survey data, coupled with new high-sensitivity near-IR observations, are used to investigate the nature of embedded objects over an 4.3-sq-pc area comprising the central star-forming cloud of the Ophiuchi molecular complex; the area encompasses the central cloud of the Rho Ophiuchi complex and includes the core region. Seventy-eight members of the embedded cluster were identified; spectral energy distributions were constructed for 53 objects and were compared with theoretical models to gain insight into their evolutionary status. Bolometric luminosities could be estimated for nearly all of the association members, leading to a revised luminosity function for this dust-embedded cluster.

329 citations

Journal ArticleDOI
TL;DR: In this article, the authors conduct kinematic analysis of the SDSS spectra of 568 obscured luminous quasars, with the emphasis on the Kinematic structure of the [OIII]5007 emission line.
Abstract: We conduct kinematic analysis of the SDSS spectra of 568 obscured luminous quasars, with the emphasis on the kinematic structure of the [OIII]5007 emission line. [OIII] emission tends to show blueshifts and blue excess, which indicates that at least part of the narrow-line gas is undergoing an organized outflow. The velocity width containing 90% of line power ranges from 370 to 4780 km/sec, suggesting outflow velocities up to 2000 km/sec. The velocity width of the [OIII] emission is positively correlated with the radio luminosity among the radio-quiet quasars. We propose that radio emission in radio-quiet quasars is due to relativistic particles accelerated in the shocks within the quasar-driven outflows; star formation in quasar hosts is insufficient to explain the observed radio emission. The median radio luminosity of the sample of nu L_nu[1.4GHz] = 10^40 erg/sec suggests a median kinetic luminosity of the quasar-driven wind of L_wind=3x10^44 erg/sec, or about 4% of the estimated median bolometric luminosity L_bol=8x10^45 erg/sec. Furthermore, the velocity width of [OIII] is positively correlated with mid-infrared luminosity, which suggests that outflows are ultimately driven by the radiative output of the quasar. As the outflow velocity increases, some emission lines characteristic of shocks in quasi-neutral medium increase as well, which we take as further evidence of quasar-driven winds propagating into the interstellar medium of the host galaxy. None of the kinematic components show correlations with the stellar velocity dispersions of the host galaxies, so there is no evidence that any of the gas in the narrow-line region of quasars is in dynamical equilibrium with the host galaxy. Quasar feedback appears to operate above the threshold luminosity of L_bol=3x10^45 erg/sec.

329 citations

Journal ArticleDOI
TL;DR: In this article, the authors describe narrowband and spectroscopic searches for emission-line star-forming galaxies in the redshift range 3-6 with the 10 m Keck II Telescope.
Abstract: We describe narrowband and spectroscopic searches for emission-line star-forming galaxies in the redshift range 3-6 with the 10 m Keck II Telescope. These searches yield a substantial population of objects with only a single strong (EW 100 A) emission line, lying in the 4000-8500 A range. Spectra of the objects found in narrowband-selected samples at λ~5390 and ~6741 A show that these very high equivalent width emission lines are generally redshifted Lyα 1216 A at z~3.4 and 4.5. The density of these emitters above the 5 σ detection limit of 1.5×10−17 ergs cm-2 s-1 is roughly 15,000 deg-2 per unit z at both z~3.4 and 4.5. A complementary deeper (1 σ~10−18 ergs cm-2 s-1) slit spectroscopic search covering a wide redshift range but a more limited spatial area (200 arcsec2) shows that such objects can be found over the redshift range z=3-6, with the currently highest redshift detected being at z=5.64. The Lyα flux distribution can be used to estimate a minimum star formation rate in the absence of reddening of roughly 0.01 M☉ Mpc-3 yr-1 (H0=65 km s-1 Mpc-1, q0=0.5). Corrections for reddening are likely to be no larger than a factor of 2, since observed equivalent widths are close to the maximum values obtainable from ionization by a massive star population. Within the still significant uncertainties, the star formation rate from the Lyα-selected sample is comparable to that of the color-break-selected samples at z~3 but may represent an increasing fraction of the total rates at higher redshifts. This higher z population can be readily studied with large ground-based telescopes.

328 citations

Journal ArticleDOI
TL;DR: In this article, images and long-slit echelle spectra of the H? emission from 14 dwarf galaxies and M82 have been used to identify expanding shells of ionized gas.
Abstract: Images and long-slit echelle spectra of the H? emission from 14 dwarf galaxies and M82 have been used to identify expanding shells of ionized gas. Supershells (radius >300 pc) are found in 12 of the dwarfs. The measured shell sizes and expansion speeds constrain the ages and power requirements of the bubbles. The dynamical age of the larger bubbles is typically about 10 Myr, and ionized shells older than 20 Myr are rare. An energy equivalent to 100-10,000 supernova explosions over this period is needed to drive the shock front that sweeps out the cavity. The current star formation rates are high enough to meet these power requirements. Many of the shells will break through the surrounding layer of H I supersonically, but the projected expansion speeds are typically less than the lower limits on the escape velocity. Some of the shell material may permanently escape from a few galaxies such as NGC 1569. Whether bound to the galaxy or not, these outflows probably play an important role in regulating the star formation rate and are expected to significantly influence the chemical evolution of the galaxies. The shells lift gas out of the disk at rates comparable to, or even greater than, the current galactic star formation rates. They will displace a substantial fraction of the interstellar gas only if their duty cycle is much longer than the rotational period of the disk.

328 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023742
20221,675
20211,238
20201,489
20191,497
20181,530