262 research outputs found
The cumulative star formation histories of dwarf galaxies with TNG50. I: Environment-driven diversity and connection to quenching
Get PDFWe present the cumulative star formation histories (SFHs) of >15 000 dwarf galaxies (M. = 107-10M⊙) simulated with the TNG50 run of the IllustrisTNG suite across a vast range of environments. The key factors that determine the dwarfs' SFHs are their central/satellite status and stellar mass, with centrals and more massive dwarfs assembling their stellar mass at later times, on average, compared to satellites and lower mass dwarfs. Satellites (in hosts of mass M200c,host = 1012-14.3M⊙) assembled 90 per cent of their stellar mass ∼7.0+3.3-5.5 Gyr ago, on average and within the 10th to 90th percentiles, while the centrals did so only ∼1.0+4.0-0.5 Gyr ago. TNG50 predicts a large diversity in SFHs, so that individual dwarfs can have significantly different cumulative SFHs compared to the stacked median SFHs. Satellite dwarfs with the highest stellar mass to host cluster mass ratios have the latest stellar mass assembly. Conversely, satellites at fixed stellar and host halo mass found closer to the cluster centre or accreted at earlier times show significantly earlier stellar mass assembly. These trends and the shapes of the SFHs themselves are a manifestation of the varying proportions within a given subsample of quenched versus star-forming galaxies, which exhibit markedly distinct SFH shapes. Finally, satellite dwarfs in the most massive hosts have higher SFRs at early times, well before accretion into their z = 0 host, compared to a control sample of centrals mass-matched at the time of accretion. This is the result of the satellites being preprocessed in smaller hosts prior to accretion. Our findings are useful theoretical predictions for comparison to future resolved stellar population observations
The distinct stellar-to-halo mass relations of satellite and central galaxies: Insights from the IllustrisTNG simulations
Get PDFWe study the stellar-to-halo mass relation (SHMR) for central and satellite galaxies with total dynamical masses above 1010.5 M⊙ using the suite of cosmological magnetohydrodynamical simulations IllustrisTNG. In particular, we quantify environmental effects on satellite populations from TNG50, TNG100, and TNG300 located within the virial radius of group- and clusterlike hosts with total masses of 1012-15.2 M⊙. At fixed stellar mass, the satellite SHMR exhibits a distinct shift towards lower dynamical mass compared to the SHMR of centrals. Conversely, at fixed dynamical mass, satellite galaxies appear to have larger stellar-to-total mass fractions than centrals by up to a factor of a few. The systematic deviation from the central SHMR is larger for satellites in more massive hosts, at smaller cluster-centric distances, with earlier infall times, and that inhabits higher local density environments; moreover, it is in place already at early times (z 2). Systematic environmental effects might contribute to the perceived galaxy-to-galaxy variation in the measured SHMR when galaxies cannot be separated into satellites and centrals. The SHMR of satellites exhibits a larger scatter than centrals (by up to ∼0.8 dex), over the whole range of dynamical mass. The shift of the satellite SHMR results mostly from tidal stripping of their dark matter, which affects satellites in an outside-in fashion: The departure of the satellite SHMR from the centrals' relation diminishes for measurements of dynamical mass in progressively smaller apertures. Finally, we provide a family of fitting functions for the SHMR predicted by IllustrisTNG
Some properties of hypergeometric series associated with mirror symmetry.
No full textThe paper is devoted to the investigation of properties of certain hypergeometric series used in string theory and algebraic geometry, particularly in the theory of the mirror symmetry for Calabi-Yau hypersurfaces in connection with the calculation of Gromov-Witten (GW) invariants of a quintic threefold and a Calabi-Yau projective hypersurface.\par The first prediction (1991) of the genus zero GW invariants of a quintic threefold was formulated in terms of the function of hypergeometric type \cal F (see below). It was mathematically verified five years later. The mirror-theoretical prediction (1993) of genus one GW invariants for the same quintic was verified in [\it A. Zinger, ``The reduced genus-one Gromov-Witten invariants of Calabi-Yau hypersurfaces", \urlarXiv:0705.2397v3], and a generalization to degree n hypersurfaces in \Bbb CP^n-1 for an arbitrary n proved in [\it A. Zinger, ``Standard vs. reduced genus-one Gromov-Witten invariants", \urlarXiv:0706.0715v3]. The proofs of these results use the properties of \cal F described in the paper under review. These properties may also be used for the computation of the higher genus GW invariants.\par Let \cal P\subset 1+x\Bbb Q(w)[[x]] be the subgroup of power series in x with constant term 1 whose coefficients are rational functions in w which are holomorphic at w=0.The following maps are defined: \cal P→ 1+x\Bbb Q[[x]],\quad F(w,x)\mapsto F(0,x), \bold M:\cal P→ \cal P,\quad\bold MF(w,x)=\bigg [1+\fracxw \frac\partial\partial x \bigg]\fracF(w,x)F(0,x). The function \cal F\in\cal P mentioned above has the form \cal F(w,x)= \sumd=0 ^ ∞ x^d \frac\prodr=1^r=nd(nw+r)\prodr=1 ^r=nd((w+r)^n-w^n), and it satisfies the relation \bold M^n\cal F=\cal F.\par The authors obtain a series of relations for \bold M^p\cal F(w,x) and Ip(x)=\cal Fp(0,x). Besides the asymptotic expansion for \cal F(w,x) is given: \cal F(w,x)∼ e^μ(x)w\sums=0^∞ \Phis(x) w^-s for w→∞ where μ=μ-1, \Phi0=e^μ0, \Phi1=\Phi0 μ1,\dots in \Bbb Q[[x]].\par For the coefficients μ(x), \Phi0(x) and \Phi1(x) the explicit formulas are given. For computing \Phis an algorithm of differential recursion is given. Some conjectural properties concerning higher genus GW invariants are stated
Ejective and preventative: The IllustrisTNG black hole feedback and its effects on the thermodynamics of the gas within and around galaxies
Get PDFSupermassive black holes (SMBHs) that reside at the centres of galaxies can inject vast amounts of energy into the surrounding gas and are thought to be a viablemechanism to quench star formation inmassive galaxies. Here, we study the 109-12.5M⊙stellar mass central galaxy population of the IllustrisTNG simulation, specifically the TNG100 and TNG300 volumes at z =0, and show how the three components - SMBH, galaxy, and circumgalactic medium (CGM) - are interconnected in their evolution.We find that gas entropy is a sensitive diagnostic of feedback injection. In particular, we demonstrate how the onset of the low-accretion black hole (BH) feedback mode, realized in the IllustrisTNG model as a kinetic, BH-driven wind, leads not only to star formation quenching at stellar masses ≥ 1010.5M⊙but also to a change in thermodynamic properties of the (non-star-forming) gas, both within the galaxy and beyond. The IllustrisTNG kinetic feedback from SMBHs increases the average gas entropy, within the galaxy and in the CGM, lengthening typical gas cooling times from 10-100 Myr to 1-10Gyr, effectively ceasing ongoing star formation and inhibiting radiative cooling and future gas accretion. In practice, the same active galactic nucleus (AGN) feedback channel is simultaneously 'ejective' and 'preventative' and leaves an imprint on the temperature, density, entropy, and cooling times also in the outer reaches of the gas halo, up to distances of several hundred kiloparsecs. In the IllustrisTNG model, a long-lasting quenching state can occur for a heterogeneous CGM, whereby the hot and dilute CGM gas of quiescent galaxies contains regions of low-entropy gas with short cooling times
Jellyfish galaxies with the IllustrisTNG simulations -- No enhanced population-wide star formation according to TNG50
Get PDFDue to ram-pressure stripping, jellyfish galaxies are thought to lose large
amounts, if not all, of their interstellar medium. Nevertheless, some, but not
all, observations suggest that jellyfish galaxies exhibit enhanced star
formation compared to control samples, even in their ram pressure-stripped
tails. We use the TNG50 cosmological gravity+magnetohydrodynamical simulation,
with an average spatial resolution of 50-200 pc in the star-forming regions of
galaxies, to quantify the star formation activity and rates (SFRs) of more than
700 jellyfish galaxies at with stellar masses
in hosts with mass
. We extract their global SFRs, the SFRs
within their main stellar body vs. within the tails, and we follow the
evolution of the star formation along their individual evolutionary tracks. We
compare the findings for jellyfish galaxies to those of diversely-constructed
control samples, including against satellite and field galaxies with matched
redshift, stellar mass, gas fraction and host halo mass. According to TNG50,
star formation and ram-pressure stripping can indeed occur simultaneously
within any given galaxy, and frequently do so. Moreover, star formation can
also take place within the ram pressure-stripped tails, even though the latter
is typically subdominant. However, TNG50 does not predict elevated
population-wide SFRs in jellyfish compared to analog satellite galaxies with
the same stellar mass or gas fraction. Simulated jellyfish galaxies do undergo
bursts of elevated star formation along their history but, at least according
to TNG50, these do not translate into a population-wide enhancement at any
given epoch.Comment: 20 pages, 10 figures, 1 table, accepted to MNRAS. See additional
jellyfish companion papers today on astro-ph: Zinger et al. and Rohr et a
Summary statistics (mean, SE, minimum, and maximum) of behavioural/reflex durations post killing treatment application, as well as statistical differences (<i>F</i> statistic and <i>p</i> value) dependent on killing treatment (Modified Armadillo (MARM); novel mechanical cervical dislocation (NMCD); Modified Zinger (MZIN) and manual cervical dislocation (MCD)).
No full textSummary statistics (mean, SE, minimum, and maximum) of behavioural/reflex durations post killing treatment application, as well as statistical differences (F statistic and p value) dependent on killing treatment (Modified Armadillo (MARM); novel mechanical cervical dislocation (NMCD); Modified Zinger (MZIN) and manual cervical dislocation (MCD)).</p
Percentage of birds for which the post-mortem measure was present, according to killing treatment (Modified Zinger (MZIN) and Modified Armadillo (MARM)) and whether the kill was successful or not, as well as statistical differences (<i>F</i> statistic and <i>p</i> value) dependent on killing treatment.
No full textPercentage of birds for which the post-mortem measure was present, according to killing treatment (Modified Zinger (MZIN) and Modified Armadillo (MARM)) and whether the kill was successful or not, as well as statistical differences (F statistic and p value) dependent on killing treatment.</p
Mean (±SE) age and weight at time of killing for each bird type and age group, as well as numbers of birds allocated to each killing treatment (Modified Armadillo (MARM); Modified Zinger (MZIN); novel mechanical cervical dislocation (NMCD) and manual cervical dislocation (MCD).
No full textMean (±SE) age and weight at time of killing for each bird type and age group, as well as numbers of birds allocated to each killing treatment (Modified Armadillo (MARM); Modified Zinger (MZIN); novel mechanical cervical dislocation (NMCD) and manual cervical dislocation (MCD).</p
QUANTIFICAÇÃOD E DANOS E PERDAS E MANEJO DOS NEMATOIDES DAS GALHAS EM CAFEEIRO CONILON
Get PDFCommercial exploitation of the coffee crop is one of the most important activities in the world’s agricultural sector. One of the main phytosanitary problems affecting the crop is the presence of Meloidogyne incognita. Several measures have been tested for the management of this pathogen, albeit with low efficiency. The objective of this work was to quantify the damage and losses and to manage M. incognita race 1 with Pochonia chlamydosporia and Trichoderma harzianum biological nematicides, comparing them to a chemical nematicide. The experiment was carried out in a commercial area naturally infested by the nematode and cultivated with the conilon coffee variety ‘Vitória INCAPER 8142’, clone V02. The treatments were tested with Carbofuran nematicide and with biological nematicides composed of P. chlamydosporia Pc-10 and T. harzianum ESALQ 1306. The biological products were applied alone or in combination. The lowest NPF (final nematode population) occurred in plants treated with P. chlamydosporia and Carbofuran. P. chlamydosporia was the most effective biological agent in the management of M. incognita. There was a reduction in production with an increase in the nematode population. The highest application costs of management methods for M. incognita race 1 per hectare were for three and two applications of Carbofuran and three applications of P. chlamydosporia + T. harzianum. The treatments with lowest application costs were one application of T. harzianum and one application of P. chlamydosporia. It was concluded that all treatments were efficient for the management of M. incognita race 1, causing a decrease in the roots and soil population.
A exploração comercial da cultura do café é uma das atividades mais importantes do setor agropecuário mundial. Um dos principais problemas fitossanitários da cultura é a presença de Meloidogyne incognita. Várias medidas têm sido testadas para o manejo desse patógeno, porém, com baixa eficiência. O objetivo deste trabalho foi quantificar os danos e as perdas e manejar M. incognita raça 1 com nematicidas biológicos à base de Pochonia chlamydosporia e Trichoderma harzianum. O experimento foi conduzido em uma área comercial naturalmente infestada pelo nematoide e cultivada com a variedade de café conilon ‘Vitória INCAPER 81421’, clone V02. Foram testados os tratamentos: nematicida Carbofurano; nematicidas biológicos à base de P. chlamydosporia Pc-10 e T. harzianum ESALQ 1306. Os produtos biológicos foram aplicados isoladamente ou associados. As menores populações finais de nematoides ocorreram em plantas tratadas com P. chlamydosporia e Carbofurano. P. chlamydosporia foi o agente biológico mais eficaz no manejo de M. incognita. Houve redução de produção com o aumento da população do nematoide. Os maiores custos de aplicação dos métodos de manejo para M. incognita raça 1 por hectare foram para três e duas aplicações de Carbofuran e três aplicações de P. chlamydosporia + T. harzianum. Os tratamentos com menores custos de aplicação foram uma aplicação de T. harzianum e uma aplicação de P. chlamydosporia. Conclui-se que todos os tratamentos foram eficientes para o manejo de M. incognita raça 1, acarretando diminuição da população do nematoide nas raízes e no solo.
 
Pathfinder of the middle of XX century
Get PDFStory of the course of life and scientific achievements of well-known Russian glaciologist and specialist in permafrost studies Boris Vtyurin
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